Antimicrobial resistance profiles and molecular characterization of Escherichia coli strains isolated from healthy adults in Ho Chi Minh City, Vietnam

J Vet Med Sci. 2017 Mar 18;79(3):479-485. doi: 10.1292/jvms.16-0639. Epub 2017 Jan 26.

Abstract

In this study, we attempted to isolate Escherichia coli from healthy adults in Ho Chi Minh City, Vietnam, and characterized its antimicrobial resistance profile, extended-spectrum β-lactamase (ESBL) genotype, phylogenetic grouping and virulence gene profile. A total of 103 E. coli isolates were obtained, and most of them were antimicrobial resistant such to streptomycin (80.6%), tetracycline (67.0%), ampicillin (65.0%), sulfamethoxsazole/trimethoprim (48.5%), nalidixic acid (43.7%), chloramphenicol (34.0%), cefotaxime (15.5%), ciprofloxacin (15.5%), kanamycin (12.6%), ceftazidime (10.7%), fosfomycin (4.9%) and gentamicin (2.9%). However, all these E. coli strains were susceptible to imipenem. Surprisingly, of 103 strains, 74 (71.8%) and 43 (41.7%) strains showed resistance to more than 3 and 5 classes of antimicrobials, respectively. Furthermore, 10 E. coli strains were ESBL-producers and positive for blaCTX-M genes (7 for blaCTX-M-9 and 3 for blaCTX-M-1), while five were additionally positive for blaTEM genes. S1-nuclease pulsed-field gel electrophoresis analysis revealed that 7 and 3 strains of E. coli carry blaCTX-M genes on their large plasmid and chromosome, respectively. Phylogenetic analysis exhibited that majority of the E. coli strains was grouped into A (44.7%), followed by B1 (23.3%), B2 (18.4%) and D (13.6%). Virulence genes associated with diarrheagenic E. coli, such as astA, EAF, eaeA, elt and eagg were also detected in ESBL-producing E. coli as well as antimicrobial resistant strains. These data suggest that commensal E. coli of healthy human could be a reservoir for antimicrobial resistance determinants and some of them might be harmful to human.

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Bacterial*
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli / pathogenicity
  • Feces / microbiology
  • Gastrointestinal Microbiome / drug effects
  • Humans
  • Microbial Sensitivity Tests
  • Middle Aged
  • Vietnam
  • Virulence / genetics
  • Young Adult
  • beta-Lactamases / metabolism

Substances

  • Anti-Bacterial Agents
  • beta-Lactamases