Prevalence and antibiotic resistance of Listeria species in food products in Taipei, Taiwan

Abstract

A total of 400 samples including meat products, dairy and dairy products, fresh vegetables, fresh seafood, and ready-to-eat food products from supermarkets in Taipei area were collected and analyzed for the prevalence of Listeria species. The overall occurrence ofListeria spp. was 16.5%, and most of them were isolated from meat products and vegetables. Listeria monocytogenes was isolated from 22 out of the 400 (5.5%) samples studied. Other species found were Listeria innocua (7.5%), Listeria ivanovii (1%), Listeriaseeligeri (0.5%), Listeria grayi (0.5%) and Listeria welshimeri (1.5%). The possibility of antibiotic resistance of the 66 isolated Listeria spp. was also examined by the standard disk diffusion method. L. monocytogenes strains isolated from food sample were treated with 8 antibiotics currently used in human or domestic animal therapy. Considering the fact that L. monocytogenes is slowly becoming antibiotic resistant, a continuous examination of emerging antimicrobial resistance of this pathogen is important to ensure effective treatment of human listeriosis. Overall, Listeria spp. was resistant to penicillin (7.58%), chloramphenicol (3.7%) and tetracycline (1.96%), but sensitive to amoxicillin, vancomycin, ampicillin, rifampicin and sulfamethoxazole. The results in this study are helpful in enriching the data on antibiotic resistance of strains isolated from food and in developing effective risk management strategies. Key words: Listeria spp., Listeria monocytogenes, moxicillin, vancomycin, ampicillin, rifampicin.