High prevalence of atypical enteropathogenic Escherichia coli contaminating retail chicken meat in Vietnam: virulence gene profiles, sequence types, and antimicrobial resistance.

OBJECTIVES Foodborne contamination with pathogenic Escherichia coli poses a significant public health concern, particularly in low- and middle-income countries. This study investigated the prevalence, virulence gene profiles, and antimicrobial resistance (AMR) characteristics of eae-positive E. coli in retail chicken meat from Vietnam, with samples from Japan included for comparative analysis.

METHODS A total of 123 retail chicken meat samples (108 from Vietnam and 15 from Japan) were collected. The presence of pathogenic E. coli was evaluated by quantitative detection of virulence genes using real-time PCR targeting DNA extracted from the samples. Antimicrobial susceptibility of E. coli strains was determined by the broth microdilution method. Virulence and AMR genes were characterized by whole-genome sequencing (WGS) of the strains.

RESULTS The eae gene-a key virulence determinant of enteropathogenic E. coli (EPEC)-was detected in 73.1% (79/108) of Vietnamese samples and 46.7% (7/15) of Japanese samples. Six eae-positive strains were successfully isolated (five from Vietnam and one from Japan). WGS analysis revealed that all strains possessed genes encoding the locus of enterocyte effacement (LEE) pathogenicity island (LEE1-LEE5) but lacked bfpA, and were therefore classified as atypical EPEC (aEPEC). Antimicrobial susceptibility testing showed that three Vietnamese strains exhibited multidrug resistance, including extended-spectrum β-lactamase production, and three strains harbored quinolone resistance-associated gyrA mutations.

CONCLUSIONS These findings indicate substantial contamination of retail chicken meat in Vietnam with aEPEC strains carrying clinically relevant AMR determinants. Strengthened surveillance and targeted control measures are warranted to reduce the risk of foodborne transmission.