Prevalence and Antimicrobial Susceptibility of Listeria spp. in Dairy Food Products and Water Samples in Dhaka, Bangladesh

Abstract

A total of 57 samples, of which 17 were surface water samples and 40 were dairy food samples (raw milk, pasteurized milk, icecream, sweet, milk based drink like matha and borhani) were tested for the isolation of Listeria spp. Putative Listeria isolates were identified by conventional microbiological tests and Analytical Profile Index. Overall prevalence of Listeria spp. in both food and water samples were 8.77%, of which one was (1.75%) Listeria monocytogenes, 2 (3.5%) were Listeria innocua and 2 were (3.5%) Listeria welshimeri. When compared between two types of samples, water samples contained two Listeria spp. (11.76%) of which one was pathogenic Listeria monocytogenes and the other was Listeria innocua. In case of food samples, three Listeria spp. (7.5%) were isolated of which one was Listeria innocua (icecream sample) and two were Listeria welshimeri (icecream sample and raw milk). No Listeria was found in pasteurized milk, sweet, matha and borhani. Antibiotic resistance profile of the Listeria isolates showed that 60% isolates were resistant to Ampicillin and Erythromycin, 20% isolates were Sulphamethoxazole and Ciprofloxacin resistant. No resistance was observed to Chloramphenicol for any Listeria isolates.