Occurrence and spread of antibiotic‑resistant enterococci in pork processing plants

Abstract

BACKGROUND AND AIM Enterococci can form biofilms resistant to disinfectants. Moreover, due to their resistance to antibiotics, Enterococcus faecium and E. faecalis species are recognized as leading causes of infections worldwide. Detection of their reservoirs requires special attention not only in the context of food safety but also regarding the health of workers in meat processing plants. The aim of this study was to assess the prevalence of antibiotic‑resistant enterococci in pork processing plants and to evaluate their biofilm-forming potential. METHODS In three pork processing plants, the samples of raw meat, swabs from work surfaces (tabletops, floors, machine parts, tools) and from employees' hands were collected. Bacteria were identified to species level using both the culture method and MALDI-TOF MS. The predominant enterococci were tested for susceptibility to 15 antibiotics by disc diffusion method. The assessment of biofilm-forming potential was studied by the microplate method. RESULTS The performed analyses indicate that all raw meat samples, plant surfaces and equipment were contaminated with enterococci. The highest level of enterococci was observed for floors, stainless tables and containers (5.7*10³, 8.5*10¹ and 13.5*10¹ cfu/cm², respectively). Enterococcus faecium was the most frequently isolated species followed by E. faecalis. More than 63% of enterococci isolates had the ability to form a biofilm. E. faecium and E. faecalis isolates showed high resistance to penicillin (89%), vancomycin (71%), cefotaxime (68%), erythromycin (57%), rifampicin (56%) and imipenem (21%). CONCLUSIONS Resistance to several antibiotics and high adherence ability of enterococci isolates suggest that these agents may play an important role in the spread of drug resistance in the meat production chain through contaminated surfaces, raw meat and workers' hands. Controlling the contamination and antimicrobial resistance patterns of enterococci in meat processing plants is essential to public health and food safety. KEYWORDS Enterococcus; pork processing plants; antimicrobial resistance; VRE