Molecular characterization and antibiotic resistance profile of listeria monocytogenes isolated from fish and broiler meat

Listeriosis is a foodborne disease with low incidence and high fatality rate. It occurs by the intake of food-soiled with Listeria monocytogenes. A study was conducted to discern the presence of L. monocytogenes from fish and broiler meat. A total of 160 samples, fish (n=80) and broiler (n=80) were collected from the markets of Lahore and Rawalpindi. These samples were enriched in Listeria enrichment broth (LEB) at 37 degrees C for 48hours. A loop ful of the LEB was streaked on PALCAM agar plates and these plates were incubated at 37 degrees C for 48hours. Isolated gray-green colonies on the agar were identified by grams staining, catalase and oxidase tests. The results indicated that 21% (34) of total samples were positive for Listeria monocytogenes. These isolates were further subjected to PCR targeting its prfA gene of 479bp, and this molecular technique confirmed only 15% (24 of 34) isolates as Listeria monocytogenes. The prevalence of the bacterium was 17.50% more in fish (23.75%) than in broiler (6.25%). Ampicillin showed highest sensitivity 91.6% followed by trimethoprim 83.3% and tetracycline 75% to the isolates. Our study conclude that Listeria monocytogenes is prevalent in both fish meat and broiler meat however it is present more in fish meat than in broiler meat. The polymerase chain reaction is a specific tool for its detection. Our study demonstrate that this problem can easily be treated as most of the isolates were sensitive to the commonly used antibiotic.