91丝瓜视频

2026 Annual AMR Symposium Poster presentations听(alphabetical by author)

1. Amer Abdelgany, Biology/Animal Health, Carleton University/CFIA, Supervisors: Alex Wong/Jiewen Guan
鈥淟ow-Level Tetracycline Exposure Promotes Long-Term Salmonella Persistence and Plasmid-Mediated Gene Transfer in a Dysbiotic Murine Gut Model"

2. Nancy Allard, Microbiologie et infectiologie, Universit茅 de Sherbrooke, Supervisor: Louis-Patrick Haraoui
鈥淭racking Antimicrobial Resistance in Migratory Birds: A One Health Surveillance Approach Across Canadian Ecosystems"

3. Khlood Alsulami, Experimental Medicine, 91丝瓜视频, Supervisor: Alexander Lawandi
"Dabigatran Does Not Enhance Cefazolin Activity or Alter the Staphylococcus aureus Proteome In Vitro"

4. Adriana Alvarez De La Hoz, Civil, Geological and Mining Engineering, Polytechnique Montr茅al, Supervisor: 脡milie B茅dard (flash talk #1)
"Insights Into the Distribution of Antimicrobial Resistance Genes in Sink Drains of Neonatal Care Units"

5. Hafiz Muhammad Arfan, Animal Sciences ,91丝瓜视频, Supervisor: Xin Zhao
鈥淩eal-time LAMP Assay for Direct Detection Of Staphylococcus Aureus In Milk Samples of a Drug-Discovery Pipeline to Identify Polysaccharide Secretion-Blocking Compound"

6.听Erick Arroyo Perez, Microbiology and Immunology, Universit茅 de Montr茅al, Supervisor: Yves Brun
鈥淎I-Guided Discovery of Novel Antibiotics鈥�

7. Safae Benali Lietefti, Dental Medicine and Oral Health Sciences, 91丝瓜视频, Supervisor: Belinda Nicolau
鈥淎ntimicrobial Stewardship in Dental Education: Perspectives of DMD Students Across Quebec鈥�

8. Rewant Chauhan,听Dental Medicine and Oral health sciences,听91丝瓜视频, Supervisor: Belinda Nicolau
"Recent Antibiotic Use and Oral Microbial Community Type Membership: Evidence from Nationally Representative Cross-Sectional Study of US Adults"

9. Natalia F Frota, Biochemistry, 91丝瓜视频, Supervisor: Martin Schmeing
鈥淐an we make new therapeutics by bioengineering NRPSs?鈥�

10. Toluwase Fatoki, Chemistry and Biochemistry, Concordia University, Supervisor: Christine DeWolf (Flash talk #2)
"pH- and Ion-Regulated Interfacial Behavior of the Antimicrobial Peptide GL13K"

11. Zhixuan (Tiffany) Feng, Natural Resource Science, 91丝瓜视频, Supervisor: Lyle Whyte (Flash talk #3)
鈥淐haracterizing Potential Antibiotic Resistance Genes (ARGs) in Polar Environments鈥�

12. Brenna Fox, Microbiology & Immunology, 91丝瓜视频, Supervisors: Dao Nguyen, Jesse Shapiro
鈥淪ame-Day Tagmentation PCR-Based Whole Genome Sequencing of Bacteriophage Genomes from Single Plaques Without DNA Extraction鈥�

13. Sophia Goldman, Microbiology & Immunology, 91丝瓜视频, Supervisor: Dao Nguyen
"Gremubamab improves bacterial clearance and reduces lung pathology caused by Pseudomonas aeruginosa isolates from new onset CF infections that failed eradication therapy"

14. Isabelle Gurney, Biology, 91丝瓜视频, Supervisor: Rees Kassen (Flash talk #4)
鈥淎MR in a Haystack: Environmental Metagenomics for Surveillance of Antimicrobial Resistance in Hospitals鈥�

15. Poppy Honeybone, Biochemistry, 91丝瓜视频, Supervisor: Albert Berghuis
鈥淭he search for antifungal drug targets: Structural studies of fungal cell wall synthesis enzymes鈥�

16. James Iarocci, Anatomy and Cell Biology, 91丝瓜视频, Supervisor: Shuaiqi Guo
"In Situ architecture of the Tad Pilus Machine in Caulobacter crescentus"

17. Ziad Jabbour, Microbiology and Infectious Diseases/Biology, Universit茅 de Sherbrooke, Supervisors: Louis-Patrick Harraoui/S茅bastian Rodrigue.
鈥淚n-silico Inverse Folding and In-vivo Accelerated Evolution for the Identification of Novel Antimicrobial Resistance Genes.鈥�

18. Afia Jahin, Civil Engineering, 91丝瓜视频, Supervisor: Dominic Frigon
鈥淚ntegrating Metagenomic Surveillance Data of Antimicrobial Resistance (AMR) in Modeling to Assess Dissemination in a One Health System鈥�

19. Emma Kelly, Biochemistry, 91丝瓜视频, Supervisor: Albert M. Berghuis (Flash talk #5)
鈥淗ydration and hydrolysis define antibiotic resistance conferred by macrolide esterases鈥�

20. Liam Keogh, Pharmacology & Therapeutics, 91丝瓜视频, Supervisor: Bastien Castagner
鈥淕lycan-based prebiotic against C. difficile infection鈥�

21. Rim Khanfour, Civil Engineering, University of Toulouse, Supervisor: Dominic Frigon
鈥�Segment-Specific Activity on the Gut Microbiota of Oral Oxytetracycline in a Pig Model鈥�

22. Nahla Koukene, Civil, Geological and Mining Engineering, Polytechnique Montreal, Supervisor: 脡milie B茅dard鈥�
鈥淪urveillance of Antimicrobial Resistance Genes in Hospital Sink Drains: Toward Better Prevention of Nosocomial Infection鈥�

23. Shenmiao (Ivy) Li, Food Science and Agricultural Chemistry, 91丝瓜视频, Supervisor: Xiaonan Lu (Flash talk #6)
鈥淐lpP-dependent proteostasis supports antibiotic persistence in Campylobacter jejuni by maintaining bioenergetics homeostasis鈥�

24. Chenxiao Liu, Civil Engineering, 91丝瓜视频, Supervisors: Dominic Frigon/Jesse Shapiro
鈥淎RG Abundance Reduction Masks Qualitative Resistome Restructuring During Anaerobic Digestion鈥�

25. Siyao Ma, Dental Medicine and Oral Health Sciences, 91丝瓜视频, Supervisor: Belinda Nicolau听(Flash talk #7)
鈥淎ntimicrobial Resistance Awareness among Doctor of Dental Medicine (DMD) Students in Quebec鈥�

26. Anirudh Mantri, Biochemistry, 91丝瓜视频, Supervisor: Martin Schmeing
鈥淪tructural mapping of antibiotic synthesis by a hybrid megaenzyme鈥�

27. Alec McAlpine, Chemistry, 91丝瓜视频, Supervisor: Karine Auclair
鈥淧antothenamide-mimicking compounds as novel antiplasmodial agents鈥�

28. Louise McDonald, Institute of Parasitology, 91丝瓜视频, Supervisor: Thavy Long
鈥淚nvestigating the intergenic region between two single nucleotide polymorphisms associated with macrocyclic lactone resistance in Dirofilaria immitis鈥�

29. Ashley McGibbon, Microbiology and Immunology, 91丝瓜视频, Supervisor: Dao Nguyen
鈥淓xploring the Antibacterial Activity and Bacterial Stress Responses to Copper-based Coatings鈥�

30. Geoffrey McKay, Meakins-Christie Laboratories, RIMUHC, Supervisor: Dao Nguyen
鈥淎 Semi-Automated Computational Pipeline for High-Throughput IC50 and MIC Analysis Against Clinically Relevant ESKAPEE Pathogens鈥�

31. Xin Yuan Mei, Microbiologie, Infectiologie & Immunologie, Universit茅 de Montr茅al, Supervisor: Marylise Duperthuy
鈥淚dentifying the Genetic Determinants of Membrane Vesicle Biogenesis and Their Role in Antimicrobial Peptide Resistance in Vibrio cholerae鈥�

32.听Julie Nadeau, Anatomy and cell biology, 91丝瓜视频, Supervisor: Shuaiqi Guo
鈥淏uild to stick: a large adhesin produced by the human pathogen Vibrio Vulnificus鈥�

33.听Rose Okonkwo, Pharmacy and Medical Sciences, Griffith University, Supervisors: Sohil Khan, Gary Grant, Henry Ndukwe
鈥淎 Health System Approach to Community Antimicrobial Stewardship鈥�

34. Jacob Pierscianowski, Chemistry, 91丝瓜视频 University, Supervisor: Karine Auclair听(Flash talk #8)
"Targeting intramacrophage bacteria for the development of selective antimicrobials"

35. Emma Maria Proven莽al, Institute of Parasitology, 91丝瓜视频, Supervisor: Thavy Long
鈥淭he role of the kynurenine pathway in macrocyclic lactone resistance in Dirofilaria immitis鈥�

36. Tarasha Sharma, Chemistry, 91丝瓜视频, Supervisors: Karine Auclair, Nicolas Moitessier
鈥淚taconate resensitizers: A new approach to treat intracellular bacterial infections鈥�

37. Anna Shen, Biochemistry, 91丝瓜视频, Supervisor: Peter Siegel
鈥淣eutrophil-mediated NK cell dysfunction and promotes breast cancer liver metastasis鈥�

38. Dayana Shoukair, Biology, Universit茅 de Sherbrooke, Supervisor: Louis-Patrick Harraoui
鈥淎 Fitness Burden Drives the Reversion of in vitro-Acquired Doxycycline Resistance in V. cholerae O1"

39. Clara Thomas, Microbiology and Immunology, 91丝瓜视频, Supervisor: Jasmin Chahal
鈥淚dentifying Antimicrobial-Producing Bacteria from Soil鈥�

40. Mingyu Wang, Anatomy and Cell Biology, 91丝瓜视频, Supervisor: Shuaiqi Guo
"Ligand antagonists block the Vibriocholerae adhesion to human cells"

41. Thisuri Wanniarachchi, Biochemistry, 91丝瓜视频, Supervisor: Martin Schmeing
鈥淪tructural insights into hybrid NRPS-PKS megaenzymes for future antibiotic development鈥�

42. Ryu Williston, Anatomy and Cell Biology, 91丝瓜视频, Supervisor: Shuaiqi Guo
鈥淩ethinking PilY1's role in regulating the Type IV pilus in Pseudomonas aeruginosa"

43. Kaitlin Wong, Microbiology and Immunology, 91丝瓜视频, Supervisor: Andr茅anne Lupien
鈥淥ptimizing the identification of novel mutations causing antibiotic resistance in Mycobacterium abscessus complex鈥�

44. Asher Woodhead, Chemistry & Biochemistry, Concordia University, Supervisor: Brandon Findlay
鈥淣ovel antimicrobials from the outer membrane vesicles of Arctic marine bacteria鈥�

45. Alla Yushchenko, Animal Science, 91丝瓜视频, Supervisor: Jennifer Ronholm
"Prevalence of Antimicrobial Resistance in Canadian Wild Carnivores"

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Abstracts by title:

A Fitness Burden Drives the Reversion of in vitro-Acquired Doxycycline Resistance in V. cholerae O1
Introduction: Antibiotic exposure in both clinical and environmental settings can select for resistant isolates with expanded cross-resistance including last-resort drugs. In Vibrio cholerae, such patterns emerge under sustained doxycycline exposure; however, the Evolutionary dynamics and long-term stability of this adaptation remain unresolved. Methods: Here, we applied long-term experimental evolution to investigate the induction, fitness-costs, and reversion of doxycycline resistance in V. cholerae O1. Isolates were exposed to sub-inhibitory doxycycline concentrations over 13 weeks, followed by phenotypic, genomic, and phylogenetic analyses. Resistance stability was assessed after a 2-week subculture period in the absence of doxycycline. Results: Doxycycline-susceptible V. cholerae O1 isolates from the 2022 Lebanon outbreak evolved high-level resistance within 13 weeks of sustained exposure. The evolved resistance extended to colistin, while showing collateral sensitivity to azithromycin. Resistance imposed a marked fitness burden characterized by impaired growth and reduced yield. Notably, drug withdrawal restored both doxycycline susceptibility and fitness. Whole-genome sequencing revealed recurrent high-impact mutations in tetR and LysR family regulators and efflux-associated pathways. Revertants were characterized by the loss of these variants and the accumulation of compensatory mutations in metabolism and membrane structure. Phylogenetic analysis showed that resistance evolved within the original lineages, with evolved isolates clustering closely with globally distributed resistant clinical strains. Conclusion: Doxycycline resistance in V. cholerae O1 emerges rapidly under antibiotic pressure but represents a transient, high-cost adaptation that is reversible upon drug withdrawal. These findings highlight the fitness burden associated with resistance and demonstrate reproducible evolutionary trajectories, with important implications for antimicrobial stewardship strategies. Back to Dayana

A Health System Approach to Community Antimicrobial Stewardship
Background: Antimicrobial resistance (AMR) is a global health threat, yet antimicrobial stewardship (AMS) in community settings鈥攚here most antimicrobial use occurs鈥攔emains fragmented and underdeveloped. This study aimed to develop a system-level quality improvement (QI) strategy for community AMS. Methods: This study used a sequential multi-method qualitative design in Queensland, Australia, including literature synthesis and interviews with health professionals, consumers, and health-system managers. Reflexive thematic and deductive analyses informed strategy development. Results: Findings revealed fragmented governance, unclear stakeholder roles, limited monitoring systems, and minimal consumer engagement. Synthesised evidence informed a system-level QI strategy centred on stakeholder governance and communication systems, using a nationally directed, regionally coordinated model with multidisciplinary leadership and structured audit-and-feedback mechanisms. Conclusions: Reframing community AMS as a system-level health function supports more coordinated stewardship interventions. By addressing key system-level gaps in community AMS, this model provides a practical framework for strengthening AMS across community settings in Australia, with potential relevance to other high-income health systems. Back to Rose

A Semi-Automated Computational Pipeline for High-Throughput IC50 and MIC Analysis Against Clinically Relevant ESKAPEE Pathogens
"Screening novel compounds for activity against clinically relevant pathogens generates vast susceptibility datasets. Our workflow with an 18-strain ESKAPEE panel, including multidrug-resistant isolates, produces over 400 MIC and IC50 determinations daily. Manual processing of this throughput is technician-dependent, time-consuming, and subject to inter-observer subjectivity, and prone to technical variability. To improve data reliability, we developed a semi-automated workflow using a Python-based four-parameter variable slope model. This tool simultaneously calculates IC鈧呪個 values, MICs, and dose鈥搑esponse curves while incorporating automated quality-control (QC) checks to flag atypical growth patterns and low R虏 values. Visual curve fits allow for rapid expert validation. This approach enhances consistency across diverse pathogens, reduces analytical errors, and accelerates data turnaround. By improving the robustness and reproducibility of susceptibility testing, this workflow supports more efficient prioritization of candidate compounds targeting high-priority antimicrobial resistance (AMR) pathogens. Back to Geoffrey

AI-guided discovery of novel antibiotics
The discovery of new therapeutic antimicrobials has slumped in the past decades, while the prevalence of antibiotic resistance is on the rise. In fact, no new treatments have been approved for the World Health Organization鈥檚 Priority Bacterial Pathogens since their categorization as such (WHO 2024). New algorithms using artificial intelligence can predict antimicrobial activity in new molecules, increasing the hit-rate at early stages of high-throughput screening. In our lab, we have built a high-throughput screening platform focused on phenotypic screens of microorganisms. In collaboration with the Machine Learning Institute of Quebec (Mila), we have developed a pipeline to screen large chemical libraries for antibacterial activity, and to use the data to improve the machine learning models in an iterative campaign of active learning. We screened the Enamine Antibacterial collection of 32k molecules (ABAC-32) aganist the model bacterium Escherichia coli. We also did a virtual screen of the 2 M molecules comprising the Enamine Liquid Stock. We experimentally tested the almost 4000 virtual hits, and observed a 10-old increased hit rate compared to the ABAC-32 collection.听Back to Erick

AMR in a Haystack: Environmental Metagenomics for Surveillance of Antimicrobial Resistance in Hospitals
The prevalence of antimicrobial resistance (AMR) in hospitals informs antimicrobial prescribing but lacks ward-level spatial resolution and lags by 1-2 years. Ward-level resolution for AMR surveillance is important because antimicrobial prescribing varies between hospital wards, presumably generating differing selection pressures for resistance within a single hospital. Current AMR resources, such as antibiograms, are based on patient infection data and so rely on positive culture tests. This project seeks to establish environmental (floor) sampling and targeted metagenomic sequencing methods to generate complementary resources to aid physicians in antimicrobial prescribing. Environmental sampling could detect resistance genes that are not captured in patient surveillance. Samples will be collected across 17 low- to high-antimicrobial use wards at six hospitals for 15 months to both capture monthly snapshots of AMR in environmental antibiograms and track its spatiotemporal dynamics driven by the varied selection environment.听Back to Isabelle

Antimicrobial Resistance Awareness among Doctor of Dental Medicine (DMD) Students in Quebec
Background: Antimicrobial resistance (AMR) is a major global health threat, yet little was known about AMR awareness among Doctor of Dental Medicine (DMD) students. Objective: To assess AMR awareness and identify latent profiles of awareness and educational demand among dental students. Methods: A cross-sectional online survey was completed by 530 DMD students from three Quebec dental schools. The questionnaire assessed AMR awareness, confidence, and educational needs. Latent class analysis identified awareness profiles. Results: A total of 530 students from three universities completed the survey. Most students recognized AMR as important for dentists (96.8%) but ranked it relatively low among global health priorities. Two profiles emerged: a majority 鈥渕ixed awareness but unengaged鈥� group (72.5%) and a minority 鈥渉igh awareness and proactive鈥� group (27.5%). Research-engaged students assigned higher priority to AMR (p<0.01). Conclusions: DMD students recognize AMR relevance but underprioritize its broader public health importance, highlighting the need for strengthened AMR education.听Back to Siyao

Antimicrobial Stewardship in Dental Education: Perspectives of DMD Students Across Quebec
Background: Antimicrobial stewardship (AMS) represents an important potential role for dentists in the growing global health crisis related to antimicrobial resistance (AMR). Understanding dental students鈥� knowledge and approach to antibiotic prescription is essential for optimal clinical practice. Aim: To explore DMD students鈥� perceptions, attitudes, beliefs, and recommendations regarding antibiotic prescribing practices. Methods: Our team engaged in a qualitative descriptive study across the three Quebec dental schools, conducting 13 focus groups with an average of 10 DMD students each. Guided by the Health Belief Model, we thematically analyzed the focus groups deductively and inductively. Results: Students identified major barriers to optimal prescribing, including inconsistent clinical supervision, unclear guidelines, patient pressure, transitioning from classroom to clinic, overprescription, professional responsibility, interdisciplinary isolation and lack of formal stewardship. Conclusion: Educational and systemic challenges continue to limit AMS and AMR. Strengthening clinical integration and stewardship-focused education would better prepare future dentists for evidence-based antibiotic prescribing.听Back to Safae

ARG Abundance Reduction Masks Qualitative Resistome Restructuring During Anaerobic Digestion
Anaerobic digestion (AD) is widely used to reduce antibiotic resistance genes (ARGs) in organic waste, and read-level metagenomic studies consistently report significant ARG abundance declines. However, whether persisting ARG sequences originate from the feedstock or represent a distinct digester-adapted resistome remains unexplored. We applied a metagenomic pipeline across varying feedstocks and pre-treatments 鈥� including thermo-alkaline lysis, ozonation, and baro-thermal lysis 鈥� quantifying ARG abundance and community composition, performing assembly, ARG annotation, and pairwise ANI comparisons between feed and digester ARG-carrying contigs linked to metagenome-assembled genomes (MAGs). Read-level analysis confirmed ARG reduction; yet most digester ARG contigs shared <95% ANI with feed sequences, originating instead from anaerobic-specialist taxa and co-localizing with mobile genetic elements. Pre-treatment type further shaped resistome composition. These results reveal that ARG reduction is not a simple removal process, but involves ecological succession and horizontal gene transfer-driven resistome restructuring, underscoring the need for ARG allele-level tracking in risk assessment frameworks.听Back to Chenxiao

Build to stick: a large adhesin produced by the human pathogen Vibrio Vulnificus
Vibrio vulnificus is a marine Gram-negative pathogen capable of causing rapidly progressing septicemia and life-threatening wound infections, with mortality rates reaching 30鈥�50%. As antimicrobial resistance limits treatment options, there is growing interest in targeting early stages of infection, such as host adhesion. We investigated Vv1, a ~305 kDa RTX adhesin predicted to mediate host attachment, by characterizing its ligand-binding region (Vv1-LBR). Circular dichroism revealed that Vv1-LBR adopts a folded structure only in the presence of calcium, highlighting the importance of divalent cations in its stability. Consistent with a role in colonization, Vv1-LBR bound multiple epithelial cell lines. Cryo-EM (~8 脜) showed an elongated architecture with co-oriented CBM and vWFa domains, suggesting coordinated, multivalent interactions. Supporting this, the vWFa domain binds fibronectin in a metal-dependent manner, while the CBM recognizes carbohydrates like galactose. Together, these findings position Vv1 as a high-value anti-virulence target, opening new avenues for therapeutics that bypass traditional antibiotic resistance.听Back to Julie

Can we make new therapeutics by bioengineering NRPSs?
Nonribosomal peptide synthetases (NRPSs) are biosynthetic enzymes that produce many important natural product medicines. Their modular assembly-line organization makes them attractive targets for bioengineering, as rearranging modules or domains could enable the rational design of novel compounds. However, module-swapping approaches often fail to generate high peptide yields because of incompatibilities between interacting domains. To resolve this, we are applying yeast display, a high-throughput protein engineering technique that enables selection and quantitative screening of variant libraries through fluorescence-activated cell sorting. We generated a library of variants in the condensation domain of an NRPS module displayed on the yeast surface and selected variants capable of peptide bond formation with a mismatched donor module supplied in trans. Across five increasingly stringent selection rounds, variants with enhanced domain:domain compatibility and condensation activity were enriched and subsequently expressed and characterized in vitro. Several variants showed substantially enhanced peptide synthesis rates. Our results demonstrate that yeast display 鈥減olishing鈥� of module swapped NRPSs hold promise for generating active bioengineered NRPSs.听Back to Natalia

Characterizing Potential Antibiotic Resistance Genes (ARGs) in Polar Environments
ARGs naturally exist in bacteria living in harsh environments with limited nutrients, thereby increasing competitiveness. Although they are unlikely to pose an immediate threat, the possibility of horizontal gene transfer of ARGs into clinically relevant pathogens remains a public health concern. In this study, we aim to identify potential ARGs in the polar region, characterize their distribution, and collect these gene datasets for further tracing.Metagenomic datasets from previous studies in the Whyte Lab from 4 polar regions were analyzed using multiple ARG prediction methods. In addition, samples from White Glacier were compared across different environmental contexts (glacial ice vs. forefield soil). As a result, ARGs associated with resistance were detected across all samples. Also, in White Glacier, ARG composition and diversity differed between glacial ice and forefield soil. Overall, multidrug resistance genes are present in both environments, while some ARGs were more diverse in soil than in ice. Back to Zhixuan听

ClpP-dependent proteostasis supports antibiotic persistence in Campylobacter jejuni by maintaining bioenergetics homeostasis
Antibiotic persistence allows a small bacterial subpopulation to survive otherwise lethal drug exposure without acquiring heritable resistance, but the underlying physiology remains poorly defined in Campylobacter jejuni. We investigated how C. jejuni adapts to ampicillin and ciprofloxacin, two bactericidal antibiotics with distinct targets. Across multiple strains, treatment generated biphasic killing dynamics without increased MIC after repeated challenge. Multi-omics, respiratory and infection assays showed that tolerant cells did not undergo global metabolic shutdown, but entered a metabolically constrained and selectively active state marked by protein quality control, respiratory remodeling, redox-oriented metabolism and membrane lipid turnover. Genetic analysis identified the ATP-dependent protease ClpP as a key tolerance determinant. Loss of ClpP impaired antibiotic-induced respiration, altered bd-like terminal oxidase CydA integrity, increased redox/membrane stress and reduced survival in macrophages and mice. These findings identify ClpP-dependent proteostasis as a survival hub linking antibiotic tolerance, bioenergetic homeostasis and host-associated fitness in C. jejuni.听Back to Shenmiao

Dabigatran Does Not Enhance Cefazolin Activity or Alter the Staphylococcus aureus Proteome In Vitro
Background: Infective endocarditis caused by Staphylococcus aureus may involve staphylothrombin-mediated fibrin formation that promotes immune evasion. Dabigatran (DAB) has been proposed to reduce virulence by inhibiting fibrin clot formation. Objective: To determine whether DAB exhibits antistaphylococcal activity, enhances cefazolin killing, or induces proteomic remodeling in methicillin-susceptible S. aureus (MSSA). Methods: 12 MSSA isolates underwent checkerboard, time-kill and LC-MS/MS proteomic analyses with cefazolin and DAB (120 ng/mL) exposure. Biofilm formation was assessed in 10 isolates across DAB concentrations of 120鈥�480 ng/mL. Results: DAB alone neither affected viability nor enhanced cefazolin-mediated killing. Proteomic analysis identified no differentially expressed proteins following DAB exposure. Biofilm responses were heterogeneous, with some isolates demonstrating dose-dependent reductions while others showed minimal or variable effects. Conclusions: DAB did not demonstrate direct antistaphylococcal activity, synergy with cefazolin, or measurable proteomic remodeling in MSSA under the conditions tested, although isolate-specific effects on biofilm formation warrant further investigation.听Back to Khlood

Exploring the Antibacterial Activity and Bacterial Stress Responses to Copper-based Coatings
High-touch surfaces represent key reservoirs for nosocomial pathogen transmission. Replacing conventional materials with antimicrobial copper (Cu) may reduce surface-mediated transmission. Deposition of Cu powders onto existing infrastructure via cold-spray technology offers a durable, scalable, low-cost alternative to bulk Cu. Here, we evaluate cold-spray copper coatings (CuCS) antibacterial activity and investigate mechanisms of Cu surface-mediated toxicity using Pseudomonas aeruginosa. We optimized a reproducible time-kill assay and identified bacterial contact area as a critical determinant of killing kinetics. Key nosocomial pathogens, the ESKAPEE pathogens, were evaluated on bulk Cu and CuCS surfaces and showed consistent antibacterial performance, with species-specific differences in killing. Mechanistic studies using Cu homeostasis transposon mutants suggest Cu surface-mediated toxicity involves intracellular targets beyond canonical contact killing, with periplasmic Cu homeostasis regulation systems playing a greater role. Specifically, copS disruption within the periplasmic CopRS-system had increased survival on Cu surfaces, while cytoplasmic copA1 and cueR mutants resembled wildtype killing.听Back to Ashley

Glycan-based prebiotic against C. difficile infection
Clostridioides difficile infection (CDI) is the leading cause of healthcare-associated infectious diarrhea in Canada, typically arising after antibiotic-induced dysbiosis that disrupts colonization resistance. Standard treatments (vancomycin, fidaxomicin) prolong dysbiosis and yield 15-25% recurrence. While microbiome-based therapies reduce recurrence, they face safety and scalability constraints. Glycan-based prebiotics offer a complementary approach. Inulin, a fermentable fructan, reaches the colon intact and promotes short-chain fatty acid (SCFA) production and secondary bile acid metabolism. However, clinical efficacy is inconsistent, likely due to interindividual microbiota variability and depletion of glycan-utilizing taxa post-antibiotics. Using ex vivo fermentation of 36 donor microbiotas, we identified four SCFA metabotypes with distinct inulin consumers. Germ-free mice colonized with representative microbiotas showed that inulin conferred complete or partial protection from CDI in specific contexts, associated with expansion of Lachnospiraceae and Bacteroidaceae spp. These findings demonstrate microbiota-dependent efficacy of inulin and support the development of precision prebiotic or synbiotic strategies for CDI.听Back to Liam

Gremubamab improves bacterial clearance and reduces lung pathology caused by Pseudomonas aeruginosa isolates from new onset CF infections that failed eradication therapy
New-onset Pseudomonas aeruginosa (P.a) infections in cystic fibrosis patients are often treated with inhaled tobramycin (Tob), but eradication therapy fails in up to 40% of cases. Novel therapeutic strategies are thus needed. This study examined a bispecific monoclonal antibody (mAb) targeting Psl and the type III secretion system protein PcrV to enhance neutrophil (N蠁) mediated opsonophagocytic killing (OPK) in vitro and improve P.a clearance in vivo. The mAb enhanced N蠁 OPK of persistent P.a isolates in vitro. An in vivo P.a pulmonary infection model assessed the mAb's effect alone or with Tob on bacterial clearance. Results showed the mAb enhanced in vitro N蠁 OPK of persistent isolates and that a prophylactic dose significantly improved in vivo bacterial clearance. Combining the mAb with Tob may further enhanced bacterial clearance compared to single modality therapy and protected against pulmonary injury.听Back to Sophia

Hydration and hydrolysis define antibiotic resistance conferred by macrolide esterases
Macrolides are an antibiotic class widely used in both human and veterinary medicine, and function by interfering with protein synthesis. Regrettably, numerous strategies for evading the antibiotic properties of macrolides have been found in bacteria, including enzyme-mediated inactivation. These mechanisms are now widely disseminated among pathogenic, animal-associated and environmental bacteria making them a One Health issue. Macrolide esterases, which hydrolyze the macrolactone鈥檚 ester bond, confer one such resistance mechanism. Two types of macrolide esterases have thus far been identified, the well-studied erythromycin esterases and the recently discovered Est-type enzymes that belong to the 伪/尾-hydrolase superfamily. We present detailed structure-function studies for four diverse Est type esterases: which only share 44-66% sequence identity (EstTSf, EstTSt, EstTBc, and EstXEc). In addition to resistance profiling and substrate specificity studies, we present structures for all four enzymes, including structures for EstTBc and EstXEc in complex with tylosin and tylvalosin macrolides, post hydrolysis. Complementing the data with mutational and kinetic studies allowed for a detailed analysis of the structural basis for macrolide-enzyme interactions. Combined the data suggest that promiscuous binding and imprecise positioning, mediated by a water-cage, dictate substrate specificity for Est-type macrolide resistance enzymes. These insights may prove beneficial for next-generation antibiotic development.听Back to Emma

Identifying Antimicrobial-Producing Bacteria from Soil
The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) exhibit widespread multidrug resistance. The Tiny Earth initiative aims to address this crisis by discovering novel antibiotics from soil microorganisms. 91丝瓜视频鈥檚 MIMM212 students isolated soil bacteria, screened for antimicrobial activity, and performed characterization tests. From the 2024 cohort, 110 isolates showed activity against safe ESKAPE relatives.鈥� Here, we further characterized these isolates by testing them against 16 Escherichia coli strains carrying resistance genes representing major antibiotic classes. We hypothesized that isolates inhibiting the growth of all 16 E. coli strains may produce a novel antibiotics.鈥� Our dereplication assay identified 20 promising isolates with potential novel activity, 12 of which were non-toxic to eukaryotic cells. Most (70%) belong to the Pseudomonas genus. These candidates require further testing against ESKAPE pathogens and characterization of their active metabolites to support efforts against antimicrobial resistance.听Back to Clara

Identifying the Genetic Determinants of Membrane Vesicle Biogenesis and Their Role in Antimicrobial Peptide Resistance in Vibrio cholerae
Antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics, but bacteria like Vibrio cholerae resist them in part by producing membrane vesicles (MVs) that can trap and neutralize AMPs. Despite its importance, the genetic control of MV biogenesis remains poorly understood. We hypothesize that vesiculation is a genetically regulated process and that distinct MV types (outer membrane vesicles vs. explosive lysis-derived vesicles) play different roles in AMP resistance. Using a Tn10 transposon library of ~1,860 mutants, we screened for altered MV production. We identified four hypo鈥憊esiculating mutants and four hyper鈥憊esiculating mutants. These hits link MV production to membrane integrity, LPS structure, and virulence regulation. Ongoing work includes clean deletion and complementation of candidate genes, followed by AMP trapping assays. This project aims to establish the first genetic map of MV biogenesis in V. cholerae and open avenues for anti-virulence therapies.听Back to Xin Yuan

In Situ architecture of the Tad Pilus Machine in Caulobacter crescentus
Bacteria rely on specialized surface structures to interact with their environment, enabling processes such as adhesion, motility, biofilm formation, and host interactions. Type IV pili (T4P) are dynamic filamentous appendages assembled by membrane-embedded nanomachines. Among these, the tight adherence (Tad) pilus is an evolutionarily distinct and widely distributed subclass involved in adhesion, surface sensing, and bacterial predation. Despite their importance, the architecture and assembly of Tad pili remain poorly understood, and no intact Tad machine structure has previously been reported. Here, we use cryo-electron tomography and subtomogram averaging to resolve the in situ architecture of the Tad pilus machine in Caulobacter crescentus. Three-dimensional classification reveals multiple assembly intermediates, while integrative modeling incorporating AlphaFold3 predictions defines the spatial organization of core components. Together, these results establish the first structural framework for Tad pilus assembly and provide insight into the architecture of related systems.听Back to James

Insights into the distribution of antimicrobial resistance genes in sink drains of neonatal care units
Hospital sink drains are critical for antimicrobial resistance genes (ARGs) transmission to nosocomial pathogens. This study aimed to explore the prevalence of 9 尾-lactamase-encoding genes and sul1 and intI1 genes in sink drains of neonatal care units and evaluate the water vapor disinfection effect on targeted genes or the sink drain microbiota. DNA was extracted from drain water and biofilm samples from 32 sinks of an intermediate care unit and 4 sinks of an intensive care unit before and after disinfection (72 samples). High-throughput qPCR and 16S rRNA sequencing were used for targeted genes and microbiota analyses. The sul1 gene showed the highest prevalence (56%), followed by intI1 (46%), and blaTEM (43%). Water vapor disinfection had no significant effect on ARG distribution or composition of microbial communities, and both variables were uncoupled. These findings advance our understanding of ARG distribution in sink drains and suggest drain-resident microbiota recolonization after disinfection.听Back to Adriana

In-silico Inverse Folding and In-vivo Accelerated Evolution for the Identification of Novel Antimicrobial Resistance Genes
Antimicrobial resistance is a major global health concern driven by the spread of antimicrobial resistance genes (ARGs) across clinical, agricultural, veterinary and environmental settings. Although sequence-based tools such as BLAST, DIAMOND, Hidden Markov Models and deep-learning approaches have improved ARG detection, they remain limited in identifying distant homologs and experimentally validating novel resistance determinants. This project combines in-silico inverse folding and in-vivo accelerated evolution to identify potentially novel antimicrobial resistance determinants. Using the high-resolution crystal structure of NDM-1 as a template, an inverse folding approach using proteinMPNN was used to generate 27430 candidate sequences that vary between 20 to 70% sequence identity to NDM-1 while preserving zinc-binding residues. Preliminary analyses showed that modifying the sampling temperature of the tool strongly influenced the sequence diversity while the fold was mostly conserved (ptm >0.8). Candidate proteins were further evaluated using AlphaFold, Foldseek, database screening and ligand-interaction predictions. This workflow establishes a structure-guided strategy to explore novel ARG space, followed by gene synthesis, cloning, susceptibility testing and accelerated evolution.听Back to Ziad

Integrating Metagenomic Surveillance Data of Antimicrobial Resistance (AMR) in Modeling to Assess Dissemination in a One Health System
Antimicrobial resistance (AMR) spreads across humans, animals, and the environment, yet current surveillance often misses resistance genes carried by mixed microbial communities. This project integrates metagenomic surveillance data with the Canadian integrated assessment model for AMR (iAM.AMR) to improve One Health risk assessment. Using two years of samples from municipal wastewater, hospital effluent, surface water, and animal manure in Mont茅r茅gie, Qu茅bec, the study will focus on clinically important ESBL and carbapenemase-associated antimicrobial resistance genes (ARGs). Preliminary Resistomap analyses identified both shared and reservoir-specific ARGs, suggesting potential transmission pathways among environmental, animal, and human reservoirs. Amplicon sequencing and metagenomic analyses will be used to characterize resistome connectivity and refine transmission pathways in iAM.AMR. The extended model will compare baseline and intervention scenarios and link resistant exposure to health and economic outcomes, which will support more complete One Health AMR risk assessment for surveillance and policy planning.听Back to Afia

Investigating the intergenic region between two single nucleotide polymorphisms associated with macrocyclic lactone resistance in Dirofilaria immitis
Dirofilaria immitis is a mosquito-transmitted parasite causing heartworm disease in dogs and can occasionally be zoonotic. Prevention relies almost exclusively on macrocyclic lactones (MLs) but increasing reports of ML resistance in the southern United States threaten their efficacy. Previous studies identified multiple single nucleotide polymorphisms (SNPs) associated with resistance. Our lab has developed a digital droplet PCR (ddPCR) assay that distinguishes susceptible and resistant isolates. SNP1 and SNP2 correlate strongly with the resistance phenotype, although inconsistent genotypes among isolates suggest a more complex genetic basis. This project investigates the ~50 kb genomic region between these two SNPs to identify genetic features potentially contributing to resistance. Genomic DNA from resistant and susceptible adult male worms was extracted and genotyped using ddPCR. Their genomes were sequenced, and comparative analyses and annotation are currently ongoing. This study aims to characterize the intergenic region and identify variants associated with ML resistance in D. immitis.听Back to Louise

Itaconate resensitizers: A new approach to treat intracellular bacterial infections
New antibiotics inevitably become obsolete as they merely delay the emergence of resistant bacteria, contributing to the antimicrobial resistance crisis. We present a new approach to treating infections by resensitizing bacteria to human immune defences. Itaconate, produced by activated myeloid immune cells, is an antimicrobial that kills intracellular pathogens. However, certain pathogens such as Mycobacterium tuberculosis can evade itaconate by expressing itaconate-degrading enzymes: itaconate CoA transferase (Ict), itaconyl-CoA hydratase (Ich), and (S)-citramalyl-CoA lyase (Ccl), enabling long-term intracellular survival. Genetic studies show that inhibiting Ich can restore immune cell potency. Our group previously developed prodrug CoA substrate mimics of Ich, two of which reduced bacterial burden in a mouse salmonellosis model. Given prodrug limitations, we used the recently published Ich crystal structure to conduct in-silico screening for new inhibitor classes. Top hits from virtual screening were tested for activity, revealing important structure-activity relationships to guide next-generation inhibitor design, paving the way for a novel strategy to treat intracellular bacterial infections.听Back to Tarasha

Ligand antagonists block the Vibrio cholerae adhesion to human cells
Vibrio cholerae is a marine Gram-negative bacterium responsible for the severe diarrheal disease cholera. The large surface adhesin flagellar-regulated hemagglutinin (FrhA) contributes to host-cell adhesion and pathogenesis in cholera. Using cryo-electron tomography combined with immunogold labeling, we show that FrhA assembles into clusters of thin filaments that anchor bacteria to human red blood cells. Single-particle cryo-electron microscopy reveals the ligand-binding domain of FrhA as a bidentate architecture suggesting multivalency. The ligand-binding region contains a peptide-binding domain (FrhA-PBD) that contributes to hemagglutination and a carbohydrate-binding module (FrhA-CBM) that binds human cells through fucosylated glycans. The X-ray crystal structure of FrhA-PBD in complex with the peptide inhibitor AGYTD allows structure-guided design of more potent inhibitors. Isothermal titration calorimetry and cell-binding assays show that the sugar L-fucose can bind to and inhibit FrhA-CBM. Together, these findings establish a multivalent adhesion mechanism and highlight anti-adhesion strategies targeting FrhA as a potential therapeutic approach.听Back to Mingyu

Low-Level Tetracycline Exposure Promotes Long-Term Salmonella Persistence and Plasmid-Mediated Gene Transfer in a Dysbiotic Murine Gut Model
Antimicrobial resistance (AMR) is a major One Health challenge driven by the persistence of resistant pathogens and dissemination of plasmid-borne resistance genes within complex microbial ecosystems. The gastrointestinal tract is a key site of horizontal gene transfer (HGT), particularly under antibiotic-induced dysbiosis. However, the impacts of low-level tetracycline exposure on Salmonella persistence and plasmid transfer remain poorly understood. Using a murine model, mice were colonized with multidrug-resistant Salmonella carrying a conjugative AMR plasmid and exposed to different concentrations of tetracycline. Longitudinal fecal samples were analyzed using culture-based methods, qPCR, whole-genome sequencing (WGS), and 16S rRNA gene sequencing. Salmonella persisted across all exposure groups, with the highest persistence observed under the highest tetracycline concentration. Plasmid transfer to commensal Enterobacteriaceae was detected across tetracycline exposures, accompanied by microbiome disruption characterized by reduced diversity and increased Proteobacteria abundance.听Back to Amer

Neutrophil-mediated NK cell dysfunction and promotes breast cancer liver metastasis
BACKGROUND: Breast cancer is the most common cancer diagnosed among women. Four out of five women diagnosed with metastatic breast cancer, where the primary cancer has spread to different organs, die within five years of diagnosis. To metastasize, cancer cells need to escape the immune system. Neutrophils, the most abundant white blood cells, have been implicated in promoting the metastasis of breast cancer cells in cancer patients. We hypothesize that neutrophils promote liver metastases by suppressing natural killer (NK) cells, which are cytolytic lymphocytes that eliminate cancer cells without prior sensitization. RESULTS: Using a syngeneic mouse model of triple-negative breast cancer, we show that neutrophils accumulate in the metastatic liver and progressively outnumber NK cells during growth of breast cancer liver metastases. Neutrophils isolated from metastasis-bearing mice suppressed NK cell cytotoxicity and induced downregulation of key regulators of NK cell effector function through a contact-dependent mechanism. NK cells from metastasis-bearing mice exhibited hallmarks of functional exhaustion, including reduced activating receptor expression and elevated inhibitory receptor expression. CONCLUSION: These findings identify a novel immunosuppressive axis in the metastatic liver microenvironment whereby neutrophils directly interact with NK cells, leading to the downregulation of NK transcription factors, which impairs NK-mediated tumor killing. This work advances our understanding of neutrophil-driven immune regulation in metastasis and provides mechanistic insight into the limited efficacy of NK cell鈥揵ased immunotherapies in solid tumors. Targeting neutrophil鈥揘K cell interactions may represent a promising therapeutic strategy to restore innate immune function and limit metastatic outgrowth.听Back to Anna

Novel antimicrobials from the outer membrane vesicles of Arctic marine bacteria
Many hydrophobic bioactive compounds show strong therapeutic potential but are limited by poor bioavailability. Can we learn a trick from Arctic marine bacteria which deliver hydrophobic compounds to targets in membrane-bound packages? This project investigates antimicrobial and cytotoxic compounds produced by Pseudoalteromonas arctica, isolated from the Beaufort Sea (Ualiniup Tariunga). Preliminary results suggest this strain produces novel lipophilic metabolites capable of selectively killing Gram-positive bacteria and HeLa cells. We will explore whether outer membrane vesicles act as a natural delivery system for these compounds using metabolomic and genomic approaches. This work demonstrates that the Arctic is a chemically rich environment, and that through studying it鈥檚 microbial interactions we can discover new resources to combat the global threat of antimicrobial resistance.听Back to Asher

Optimizing the identification of novel mutations causing antibiotic resistance in Mycobacterium abscessus complex
Mycobacterium abscessus complex (MABSC) is a group of emerging pathogens that can cause severe pulmonary disease in people with cystic fibrosis. MABSC infections are notoriously difficult to treat due to the bacteria's intrinsic and acquired resistance to many antibiotics. Heterogeneity in genotype and antibiotic susceptibility among MABSC clinical isolates, along with limited knowledge of antibiotic resistance mechanisms, highlight the need to develop molecular tools that can allow for high-throughput analysis of MABSC antibiotic susceptibility profiles. The objective of this project is to develop a fragment-based whole-genome transformation technique optimized for MABSC. We hypothesize that this technique will allow for the rapid discovery of novel single-nucleotide polymorphisms (SNPs) involved in antimicrobial resistance (AMR), leading to more effective clinical treatments. Genomic DNA (gDNA) extracted from a clinical isolate (L00007906) will be cut into ~150bp fragments and denatured into single-stranded DNA (ssDNA). This library of ssDNA fragments will be electroporated into a drug-susceptible Mycobacterium abscessus subspecies abscessus (MAB) ATCC19977 smooth strain containing RecET-like recombinases from the pJV53-KanamycinR plasmid. Following its selection on 7H10 agar plates containing an antibiotic, the clones acquiring antibiotic resistance will be sequenced. The drug susceptibility profiles were established in 25 MABSC clinical isolates. A phylogeny tree will be constructed to assess the SNP distance between these isolates. The recipient strain has been engineered to have an erm(41) knock out to allow for macrolide susceptibility. The fragment-based whole-genome transformation technique will be optimized to increase recombination and transformation efficiency in MABSC.听Back to Kaitlin

Pantothenamide-mimicking compounds as novel antiplasmodial agents
Antimicrobial resistance is an ever-growing global health crisis in which we urgently require new drugs with novel modes of action. Pantothenamides, amides of pantothenate (vitamin B5), are a promising class of compounds that display a novel mechanism of antiplasmodial activity. In microbes, these molecules are selectively transformed into CoA derivatives, before inhibiting CoA utilization. These antimetabolites display a multi-target mechanism of action that is highly desired due to an expected slower onset of resistance. Yet, pantothenamides are hydrolyzed by pantetheinases in the blood, rendering them inadequate as clinical candidates. To prevent this hydrolysis, we have either replaced the labile amide bond or increased the steric bulk of the 尾-alanine linker. This has led us to several potent classes of pantothenamide mimics that are stable against pantetheinases and are non-toxic to human cells while displaying activity at micromolar-to-nanomolar concentrations, making them promising lead compounds for the discovery of new antiplasmodial.听Back to Alec

pH- and Ion-Regulated Interfacial Behavior of the Antimicrobial Peptide GL13K
Antimicrobial resistance is at an alarmingly rate, and about 28 million deaths have been forecasted to occur between 2025-2050. GL13K is an emerging antimicrobial peptide currently being explore and develop for topical/local application. GL13K peptide has strong anti-inflammatory and antibacterial activities against both Gram-positive and Gram-negative bacteria, as well as low hemolytic and cytotoxic activities. In this study, we computationally and biophysically investigate how pH and Ca2+/Mg2+ modulate the interfacial behavior, secondary structure, and membrane interactions of the GL13K and its enantiomer (D-GL13K) at model outer membrane of Gram positive bacteria. The molecular dynamics (MD) simulations and circular dichroism (CD) spectroscopy were used to investigate D/L-GL13K in the absence/presence of outer membrane components at varying pH and Ca2+/Mg2+ conditions respectively. This study correlate results from MD simulations and CD spectroscopy, to establish the salient differences in behavior of D-GL13K and L-GL13K, linked to the membrane disruption antimicrobial activity.听Back to Toluwase

Prevalence of Antimicrobial Resistance in Canadian Wild Carnivores
Antimicrobial resistance (AMR) is a rising One Health challenge and one of the leading public health threats of the 21st century. In Canada, , the persistence of AMR in natural environments, particularly at the wildlife鈥搇ivestock interface, remains poorly understood. This study aims to characterize AMR profiles of bacteria isolated from wild carnivores against antimicrobials commonly used in human and veterinary medicine. Gram-negative isolates (n=53) recovered from intestinal samples of 44 wild carnivores across Saskatchewan were identified using MALDI-TOF MS and tested against 16 antimicrobials using disk-diffusion. Most isolates demonstrated broad susceptibility, with sporadic resistance primarily observed to ampicillin (6%). Among Escherichia coli isolates, intermediate resistance was most frequently detected for oxytetracycline (34%), followed by colistin (19%), streptomycin (9%), and ampicillin (4%). One E.coli and one Serratia liquefaciens isolate exhibited multidrug resistance. Ongoing genomic analyses will further characterize resistome composition to support AMR surveillance effort and inform antimicrobial stewardship policies.听Back to Alla

Real-time LAMP assay for direct detection of Staphylococcus aureus in milk samples
Rapid and reliable detection of Staphylococcus aureus is essential for evidence-based treatment of bovine mastitis. However, culture-based methods are time-consuming and may exhibit reduced sensitivity at low bacterial loads, following prior antimicrobial exposure, or in physiologically adapted bacterial states. In contrast, PCR requires specialized instrumentation and multistep workflows. Loop-mediated isothermal amplification (LAMP) offers a rapid alternative; however, endpoint-based interpretation remains vulnerable to false-positive results caused by delayed non-specific amplification. In this study, a real-time LAMP assay targeting the nuc gene of S. aureus was optimized using a simplified heat-lysis DNA extraction workflow without commercial DNA extraction or enrichment. Under optimized conditions, S. aureus amplified earlier than non-target and non-template controls, with mean TTP values of 18.95 卤 4.46 min, 42.81 卤 5.96 min, and 42.68 卤 4.81 min, respectively. Direct detection in milk was achieved following simplified heat lysis, with S. aureus amplifying earlier than negative controls. Serially diluted milk-spiked samples (10鈦糕��10鈦� CFU/mL) showed concentration-dependent amplification kinetics. These findings support the potential utility of real-time LAMP for rapid field-level mastitis screening under resource-limited conditions.听Back to听Hafiz听

Recent Antibiotic Use and Oral Microbial Community Type Membership: Evidence from Nationally Representative Cross-Sectional Study of US Adults
Background: The human oral cavity harbors over 700 microbial species. Antibiotic exposure disrupts oral ecosystems and may promote antimicrobial resistance. We characterized oral microbiome composition among US adults and estimated associations of antibiotic use with community types and diversity.听Methods: Using NHANES 2009鈥�2012 data (n=8,237), oral microbiome profiles were derived from oral rinse 16S rRNA gene sequencing. Recent antibiotic use was self-reported within 30 days. Dirichlet multinomial mixture modelling identified community types; 伪-diversity (Shannon, Chao1) and 尾-diversity (Bray鈥揅urtis) were calculated. Survey-weighted regression estimated associations, adjusted for sociodemographic, lifestyle, and oral health covariates.听Results: Of 8,237 adults, 274 (3.3%) reported recent antibiotic use. Six community types were identified. Antibiotic users showed lower 伪-diversity and higher odds of Prevotella_7-associated (CT2; aOR=3.87) and Lactobacillus-associated low-diversity communities (CT6; aOR=5.19). Community type explained the largest 尾-diversity variation (R虏=20.71%).听Conclusion: Recent antibiotic use was associated with lower oral microbial richness and two specific community types. Longitudinal studies with resistome profiling are needed to clarify temporality and functional relevance. Back to Rewant

Rethinking PilY1's role in regulating the Type IV pilus in Pseudomonas aeruginosa
Type IV pili are dynamic filaments used by many bacteria for surface sensing, motility, DNA uptake, and biofilm formation. In Pseudomonas aeruginosa, pilus assembly is initiated by a priming complex composed of five minor pilins and the non-pilin protein PilY1, which also contributes to mechanosensing. PilY1 contains an N-terminal vWA-like domain and a C-terminal 尾-propeller domain with a Ca虏鈦�-binding loop previously implicated in preventing pilus retraction. Here, we reassess this model by introducing point mutations in the Ca虏鈦�-binding loop directly into the chromosome. Contrary to prior plasmid-based studies, these mutations primarily impair pilus initiation and assembly rather than retraction. Cryo-electron tomography of mutant pili in situ reveals structural defects consistent with disrupted biogenesis. Altogether, these findings redefine the role of PilY1鈥檚 C-terminus and highlight its importance in early stages of type IV pilus assembly. Back to Ryu

Same-Day Tagmentation PCR-Based Whole Genome Sequencing of Bacteriophage Genomes from Single Plaques Without DNA Extraction
DNA sequencing is at the core of identifying and characterizing novel microorganisms including bacteriophages. Bacteriophages, due to their inherent ability to target and infect bacteria, serve as a powerful tool for medicinal and agricultural applications. Current approaches to isolating and sequencing bacteriophages rely on cycles of purification and amplification for each plaque of interest. This time-consuming approach hinders the speed of phage identification and therefore significantly affects their downstream applications. To improve the efficiency of phage identification, an adapted Nanopore Rapid PCR Barcoding protocol was developed to be applied directly on individual plaques. This was demonstrated to produce highly accurate genome assemblies in under 4 hours. Due to the design of this protocol, intermediate steps such as producing concentrated phage lysates or extracting DNA can be skipped entirely. This streamlined technique provides DNA sequences that are comparable to traditional Whole Genome Sequencing using Illumina, producing a mean average nucleotide identity (ANI) of 99.97%. We present this method of isolating and sequencing phage DNA directly from plaques as an accurate and rapid approach to identifying novel phages, with applications expanding to identification of contaminants or assessing phage diversity in a sample.听Back to Brenna

Segment-Specific Activity on the Gut Microbiota of Oral Oxytetracycline in a Pig Mode
Antimicrobial resistance (AMR) is a One Health crisis partly driven by antibiotic exposure across human, animal, and environmental compartments. After oral administration, antibiotics form concentration gradients along the gastrointestinal tract, and binding within intestinal contents can markedly reduce pharmacologically active fractions - yet most studies rely on fecal samples and lack segment-resolved measurements. Using pigs as a translational model, we administered a single oral dose of oxytetracycline (20 mg/kg) and sampled jejunal, cecal, and rectal contents at 6 and 24 h. Total concentrations were quantified by UHPLC鈥揢V, antibiotic activity assessed by time-kill assays in broth and segment-matched intestinal matrices, microbiota characterized by 16S rRNA amplicon sequencing, and seven tetracycline resistance genes quantified by qPCR. Intestinal matrices strongly attenuated activity, yet no consistent microbiota or resistance gene shifts were detected within 24 h. These findings highlight the need to integrate segment-resolved pharmacokinetics, matrix-aware pharmacodynamics, and microbiome measurements for AMR risk assessment.听Back to Rim

Structural insights into hybrid NRPS-PKS megaenzymes for future antibiotic development
Microbial natural products produced by hybrid nonribosomal peptide synthetase-polyketide synthase (NRPS-PKS) megaenzymes represent a rich source of clinically important bioactive molecules, including antibiotics and anti-fungal compounds. These hybrid megaenzymes combine the C-C bond formation capability of PKS with the C-N bond formation in NRPS, making them versatile in synthesizing structurally complex molecules, yet the structural and mechanistic features of these enzymes remain poorly understood. To gain insights, we focus on ClbB, a modular NRPS-PKS megaenzyme involved in the colibactin biosynthetic pathway. Colibactin is a genotoxic secondary metabolite known to induce DNA interstrand crosslinks leading to colorectal cancer progression. This project aims to solve the structure of ClbB at various stages of its catalytic cycle using cryo-electron microscopy (cryo-EM) to reveal critical aspects of its domain organization and the molecular basis for NRPS-PKS crosstalk. Our findings will provide the foundation for future efforts to engineer hybrid systems for the production of novel therapeutic compounds.听Back to Thisuri

Structural mapping of antibiotic synthesis by a hybrid megaenzyme
Natural products are a class of molecules made by microbes that increase their evolutionary fitness. Among the many enzymes making natural products are two systems that both work in an assembly line fashion: PKSs and NRPSs. Interestingly, they are often found in hybrid assembly lines such as in the biosynthesis of the blockbuster drug rapamycin. To date, such hybrids have not been thoroughly characterized structurally and functionally. Here, we solved the first bimodular PKS-NRPS hybrid structure, targeting the most common hybrid system ikarugamycin synthetase (IkaA), which makes the backbone of ikarugamycin. Ikarugamycin has anti-tumour effects and is used in cell biology experiments as an inhibitor of clathrin mediated endocytosis. Using mechanism-based crosslinking and biochemical assays, we mapped the complete biosynthetic trajectory of carrier protein in ikarugamycin biosynthesis. We then observed each of these states using single-particle cryo-EM. Overall, this work represents a compelling example of the structural and biochemical basis of how PKS- NRPS hybrids generate complex natural products.听Back to听Anirudh

Surveillance of Antimicrobial Resistance Genes in Hospital Sink Drains: Toward Better Prevention of Nosocomial Infections
Nosocomial infections pose a major threat to public health and are becoming difficult to manage with the emergence of antibiotic-resistant bacteria. Hospital sink drains are considered as a reservoir for the transmission of antimicrobial resistance genes (ARGs) due to the presence of biofilms. This study aimed to survey sink drains in four hospitals to determine the prevalence of 11 targeted ARGs and identify key variables that may influence outbreaks. Drain water and biofilm samples were collected and extracted DNA was used to quantify ARGs including blaKPC using high-throughput q-PCR and to analyse microbial diversity through 16S rRNA sequencing. Preliminary results suggest that sul1 gene was strongly associated with class-1 integrons, but the hospital was not a significant variable. Factors such as sink usage frequency helped explain the observed differences. Overall, this study contributes to a better understanding of ARG distribution in hospital drains, laying the groundwork for effective disinfection procedures.听Back to Nahla

Targeting intramacrophage bacteria for the development of selective antimicrobials
The Auclair Lab is developing antimicrobials with two key goals: pathogen specificity and reduced selection for resistance. By targeting bacterial metabolic pathways that are essential only under infection-relevant conditions, this strategy minimizes disruption of the protective, natural microbiota while limiting where selective pressure for resistance can occur. Intracellular bacteria such as Salmonella Typhimurium (STm) survive within macrophages by adapting to the nutrient-limited, hostile conditions imposed by the immune system, making these pathways attractive therapeutic targets. This work describes the discovery of pantothenate-mimicking prodrugs selectively active against intramacrophage STm. A multi-tiered screening pipeline identified compounds with potent intracellular activity and low host-cell toxicity. Mechanistic studies identified that their activity is linked to the disruption of coenzyme A biosynthesis through inhibition of pantothenate production. Resistance emerged only under nutrient-limited conditions, while in-vivo studies demonstrated reduced bacterial burden in a murine STm infection model, therefore supporting this targeted antimicrobial strategy.听Back to Jacob

The role of the kynurenine pathway in macrocyclic lactone resistance in Dirofilaria immitis
Macrocyclic lactones (MLs) are the only approved preventatives against Dirofilaria immitis, a parasite that causes canine heartworm disease. ML resistance has been reported in North America, and the underlying mechanisms remain unclear. Unlike other nematodes, MLs in filarial species seem to disrupt the secretion of immunomodulatory products involved in immune evasion. Our lab identified the kynurenine pathway (KP), important in tryptophan metabolism and immunoregulation, as a potential contributor to ML resistance. Transcriptomic analyses of susceptible and resistant isolates revealed altered expression of KP-associated genes, including kynureninase (kynu). Our work in Caenorhabditis elegans links the KP to ML sensitivity, as KP mutants showed altered drug responses. To investigate KP gene function in ML sensitivity in D. immitis, we are creating transgenic C. elegans expressing D. immitis kynu. These will be used to assess ivermectin sensitivity using larval development assays. This work will clarify the contribution of kynu to ML resistance.听Back to Emma Maria

The search for antifungal drug targets: Structural studies of fungal cell wall synthesis enzymes
Amid rising antimicrobial resistance, the development of new antifungal therapies remains restricted by limited structural information available for key cell-wall biosynthetic enzymes. The pathway for cell wall synthesis is an attractive antifungal drug target, essential to fungal cell survival and composed of enzymes Och1, M-Pol I, and M-Pol II. We focus on the glycosyltransferase M-Pol I, a Golgi-localized heterodimer responsible for initiation and extension of the 伪-1,6-mannan backbone of N-linked glycans which eventually make up the thick outer fungal cell wall. Our work establishes a reproducible workflow for purification and crystallization of caM-Pol I and its individual subunits caMnn9 and caVan1. Here, we present a novel structure of caMnn9, solved to 2.45 脜. Ongoing work involves optimization of workflows for caM-Pol I and caVan1. Our results support future crystallographic studies that can ultimately provide the structural framework required to target cell wall synthesis in antifungal drug design.听Back to Poppy

Tracking Antimicrobial Resistance in Migratory Birds: A One Health Surveillance Approach Across Canadian Ecosystems
This study explores the role of migratory birds in the dissemination of antimicrobial resistance genes (ARGs) across Canadian oceanic and Arctic ecosystems. Antimicrobial resistance is a growing global health threat shaped by interactions between humans, animals, and the environment. Using a One Health framework, fecal and environmental samples were collected along migratory routes and analyzed through metagenomic sequencing to characterize ARG diversity and abundance. Methodological optimization improved microbial DNA recovery from challenging samples. Preliminary results show diverse ARG profiles within bird microbiomes, varying by species and habitat. The most common ARGs confer resistance to 尾-lactams, aminoglycosides, and tetracyclines. These findings highlight the ecological role of migratory birds as potential reservoirs and vectors of resistance. Incorporating wildlife into AMR surveillance systems could strengthen our understanding of ARG spread and support the development of more effective, cross-sectoral mitigation strategies to protect global public health.听Back to Nancy

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