Tracking Antimicrobial Resistance Determinants in Diarrheal Pathogens: A Cross-Institutional Pilot Study

Area of Science:

• Microbiology
• Genetics
• Public Health

Background:

• Infectious diarrhea causes millions of deaths annually, necessitating effective antimicrobial treatments.
• Overuse and misuse of antimicrobials have led to alarming increases in antimicrobial resistance (AMR).
• Standardized geographic surveillance is essential for monitoring and combating the global spread of AMR.

Purpose of the Study:

• To demonstrate the feasibility of a standardized methodology for molecular surveillance of AMR genes in diarrheal pathogens.
• To assess the prevalence and diversity of AMR determinants in pathogens from diverse geographic locations.

Main Methods:

• A pilot study analyzed 130 diarrheal pathogens (*Campylobacter* spp., *Escherichia coli*, *Salmonella*, and *Shigella* spp.) from the USA, Peru, Egypt, Cambodia, and Kenya.
• Over 200 antimicrobial resistance (AMR) determinants were screened for presence/absence in the selected pathogens.
• Molecular methods were employed for the detection of specific AMR genes.

Main Results:

• Fifty-five different AMR determinants were detected, conferring resistance to ten antimicrobial categories.
• Commonly detected genes included *bla*_TEM, *tet*(A), *tet*(B), *mac*(A), *mac*(B), *aadA1/A2*, *strA*, *strB*, *sul1*, *sul2*, *qacE*Δ1, *cmr*, and *dfrA1*.
• Isolates from Egypt showed a higher number and diversity of AMR genes per isolate, including carbapenemase genes (*bla*_OXA-48, *bla*_NDM) and genes for azithromycin resistance and extended-spectrum β-lactamases (CTX-M-1, CTX-M-9).

Conclusions:

• The study successfully demonstrated a standardized methodology for molecular surveillance of AMR genes in diarrheal pathogens.
• Geographic variations in AMR gene prevalence were observed, with Egypt exhibiting particularly high levels of resistance.
• The findings support international surveillance efforts and can inform geospatially targeted medical interventions for infectious diarrhea.