Travelers Can Import Colistin-Resistant Enterobacteriaceae, Including Those Possessing the Plasmid-Mediated mcr-1...

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• Antimicrobial resistance (AMR) is a growing global health threat.
• Enterobacteriaceae producing extended-spectrum cephalosporins (ESCs) and carbapenems are significant pathogens.
• Colistin is a last-resort antibiotic, and resistance, particularly mediated by mcr genes, is a major concern.

Purpose of the Study:

• To screen travelers returning from India for colonization with resistant Enterobacteriaceae.
• To investigate the prevalence of colistin resistance and the mcr-1 gene in this population.

Main Methods:

• Stool samples from 38 travelers were analyzed using standard selective plates.
• Overnight enrichment and CHROMagar Orientation plates supplemented with colistin were employed.
• Resistant isolates were characterized for specific resistance genes and plasmid types.

Main Results:

• Seventy-six percent of travelers were colonized with ESC- or carbapenem-resistant Enterobacteriaceae (CTX-M or DHA producers).
• No colistin-resistant or mcr-1 positive strains were detected using initial screening.
• However, enhanced methods identified 10.5% of travelers colonized with colistin-resistant Escherichia coli.
• One cephalosporin-susceptible E. coli strain (ST10) harbored an ISApl1-mcr-1-ISApl1 element on an IncHI2 plasmid.

Conclusions:

• Travelers returning from India can carry diverse resistant Enterobacteriaceae.
• Standard screening methods may underestimate the prevalence of colistin resistance.
• The detection of mcr-1 in a cephalosporin-susceptible E. coli highlights the potential for resistance gene dissemination.