Characterization of L. Monocytogenes in raw milk in Kuching, Sarawak

Woo, Kar Mun (2014) Characterization of L. Monocytogenes in raw milk in Kuching, Sarawak. [Final Year Project Report] (Unpublished)

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Abstract

Listeriosis is known as a pathogenic foodborne illness which due to the pathogenic Listeria monocytogenes strain 4b, 1/2a and 1/2b. Widespread of L. monocytogenes in food sources such as raw meat, vegetables, seafood and especially in raw milk, leaves significant impacts for humankind. Consequences for mild symptoms are fever or diarrhea while severe impact includes some clinical manifestation such as meningoencephalitis, gastroenteritis, septicaemia or even death. Thus, the aim of this study is to isolate and characterise L. monocytogenes from raw milk samples collected from dairy farm around Kuching area in Sarawak. Isolation was conducted using selective broth Trypticase Soy Broth (TSB) for enrichment purpose and PALCAM selective agar for differentiating Listeria spp. from other microflora. The L. monocytogenes ATCC 19155 strain or also known as L. monocytogenes serotype 4b was used as positive reference strain for polymerase chain reaction (PCR) using two specific primers in targeting listeriolysin O (LLO) gene at size 234 bp; LM1 (f) 5’-CAT TAG TGG AAA GAT GGA ATG-3’and LM2 (r) 5’-GTA TCC TCC AGA GTG ATC GA-3’. The identified positive isolates of L. monocytogenes were then grown on the non-selective agar, Trypticase Soy Agar (TSA) as transferred from PALCAM agar by using aseptic technique and streaking method. The L. monocytogenes are then characterized through several biochemical tests and gram staining. Biochemical tests used were methyl red test, Voges Proskauer test, catalase production, indole production, motility test, acid production and citrate utilisation. Based on this study, a total of 2 samples (4 isolates) have been identified as positive for L. monocytogenes from 12 samples (81 isolates). The presence of L. monocytogenes poses health hazard to the people around the study area. Raw milk should be handled more cautiously as to avoid L. monocytogenes contamination in dairy farm and directly affect the consumer

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