Co-occurrence of antimicrobial resistance and virulence determinants in enterococci isolated from traditionally fermented fish products.

Abstract

Fermented foods frequently consumed in Northeast India can act as a reservoir for disseminating pathogenic organisms. Enterococci are often responsible for contamination of food products. This study investigated the antimicrobial resistance and co-existing virulence determinants of enterococci found in traditionally processed foods in India. A total of 38 enterococci isolates identified as Enterococcus faecalis isolated from fermented fish samples from retail markets of Northeast India were selected for screening of pathogenic traits. Of the 38 isolates, 8 (21%) were able to hydrolyse gelatin and 13 (34%) showed protease activity. Screening for haemolytic activity of the isolates showed no positive test on sheep blood. The presence of virulence genes (gelE, agg, esp, cpd, efaAfs and cylA) was investigated by PCR. gelE, agg and esp were present in 17, 13 and 4 isolates, respectively. cpd and efaAfs were found in all isolates, whereas cylA was not detected. High resistance percentages to various antibiotics included kanamycin (63%), vancomycin and gentamicin (58%), tetracycline (53%) and rifampicin (50%). The vanA genotype was confirmed in 15 multidrug- and vancomycin-resistant strains. The simultaneous occurrence of virulence determinants and antimicrobial resistance in enterococci prevalent in the fermented fish products studied poses a potential threat of transmission to humans through the food chain. This study highlights the importance of E. faecalis as a reservoir of antimicrobial resistance and virulence factors and their potential transfer to humans. The findings reopen the issue of food safety regarding enterococci prevalent in traditionally processed fish products in the region.