Prevalence, genetic diversity and antimicrobial susceptibility of Campylobacter jejuni isolated from retail food in China

Abstract

The aim of this study was to determine the prevalence, antimicrobial resistance and molecular epidemiology of Campylobacter jejuni isolated from retail food samples in China and assess the potential risk to consumer' health. A total of 34 strains of C. jejuni isolated from 1798 retail food samples in China were identified using conventional methods and duplex PCR aimed 16S and hipo genes. There are 59 positive samples by conventional method, and the prevalence of C. jejuni was 3.30% (59/1798). Using flaA RFLP-PCR (flaA Restriction Fragment Length Polymorphism) typing with a relative similarity coefficient of 0.81, the 34 isolates and 1 reference strains were grouped into 4 clusters and 2 singletons. Antibiotic resistance profiles determined using the disk diffusion method showed that a high proportion of C. jejuni isolates were resistant to the tested antibiotics, particularly for ciprofloxacin (88.5%) and nalidixic acid (88.5%). Most isolates were multidrug resistant, with 20 strains showing resistance to 5–8 antibiotics and 2 strains showing resistance to 9 antibiotics. Moreover, analysis using MAMA-PCR to determine the gyrA mutation status (C257T) indicated that approximately 30 strains had mutations, and these findings were consistent with disk diffusion assay results. Examination for the presence of 11putative virulence genes showed that the majority of these genes were detected in all C. jejuni strains. There was no direct evidence to suggest a connection between antibiotic resistance and virulence genes. This study is the first to explore the potential sources of C. jejuni contamination in retail foods in China and provide comprehensive surveillance on its incidence in retail foods. These data will ensure more accurate treatment of human campylobacteriosis using effective antibiotics.