Detection of tetracycline-resistance Enterococcus spp. in ready-to-eat Thai traditional fermented products

Abstract

This study detected tetracycline-resistance (Tcʳ) Enterococcus spp. in 70 samples of 5 different kinds of ready-to-eat Thai traditional fermented foods (fish, pork, crab, shrimp, and shell). It was found that 28 samples (40%) were contaminated with Tcʳ Enterococcus spp. All five different kinds of food samples were contaminated with Enterococcus spp. except for fermented shell. High percentage of Tcʳ Enterococcus spp. was found in isolates from fish and shrimp (77.46% and 57.89% respectively). The tetracycline minimum inhibitory concentration (TC MIC) of Enterococcus spp. was found between 16 and 512 µg/ml. Most of the enterococcal isolates had TC MIC in the range from >64 to 128 µg/ml, except for isolated from crab that had MIC in the range from >128 to 256 µg/ml. The high level of TC MIC (>256-512 µg/ml) was only found in isolated from fish and crab. The clinically relevant Enterococcus spp. were also found including 46.15% E. faecalis and 35.58% E. faecium. E. faecalis was found only in fermented fish and pork but E. faecium was found in all 4 different kinds of fermented food. The results from this study indicated that some ready-to-eat Thai traditional fermented foods can be reservoir for transmission of antibiotic resistant enterococci or antimicrobial determinant which may cause serious health problem. In order to prevent this problem, the reduction of enterococcal contamination in food should be implemented including heat inactivation, properly cooked before consumption as well as good sanitation and hygiene practice in preparation of foods. Moreover, restriction of using antibiotic in animal feed and aquaculture should be in consideration.