Prevalence, Molecular Characterization and Antibiotic Resistance of Listeria monocytogenes in Raw and Processed Milk from Sarawak

Mildred Pemela, Jalin (2017) Prevalence, Molecular Characterization and Antibiotic Resistance of Listeria monocytogenes in Raw and Processed Milk from Sarawak. Masters thesis, Universiti Malaysia Sarawak.

PDF (Please get the password by email to repository@unimas.my , or call ext: 3914 / 3942 / 3933) Mildred Pemela.pdf Restricted to Registered users only Download (7MB)

Abstract

Listeria monocytogenes has been reported as causative agent of listeriosis, a foodborne disease in susceptible human groups. Various studies on L. monocytogenes in foods have been done in Malaysia including chicken, beef and ready-to-eat foods. However, the study of L. monocytogenes in raw milk and processed milk are still not well established especially in the aspect of prevalence and characterization of the bacteria in food samples from Sarawak. The main objectives of this study were to investigate the prevalence of L. monocytogenes in raw and processed milk; and to characterize the L. monocytogenes isolated from the sources. A total of forty-nine raw milk and fifty-seven processed milk samples collected from Kota Samarahan and Kuching, Sarawak were analyzed for the presence of L. monocytogenes. Samples were enriched using Tryptone Soy Broth, and then inoculated on PALCAM agar for isolation purposes. The colonies formed on PALCAM agar were further confirmed by species-specific PCR using LM1 and LM2 specific primer for detection of hlyA genes of L. monocytogenes. A total of eighty-four confirmed isolates were then characterized molecularly using RAPD-PCR method with two sets of 10-mer primers, OPA14 and GEN15009 to determine their genetic diversity. All the 84 isolates were analyzed for their antibiotic profiles using penicillin (1u), ampicillin (2 µg), meropenem (10 µg), erythromycin (15 µg) and trimetophrim- sulfamethoxazole (1.25- 23.75 µg). The prevalence value for both raw milk and processed milk samples are 28.57% and 1.75% respectively with the highest prevalence value was contributed by samples from Petrajaya. Meanwhile, the generated dendograms show four major clusters for OPA14 and five major clusters for GEN15009 indicating the genetic diversity among isolates. Antibiotic susceptibility profiles was then performed and multiple antibiotic resistance index (MAR) was determined. In this research, the MAR of each sample is not exceeding iv 0.200 thus it is still not hazardous towards the environment and still under control. Antibiotic resistance profile shows that L. monocytogenes isolates are 100% resistant towards three types of antibiotics which are ampicillin, erythromycin and trimetophrimsulfamethoxazole.

Actions (For repository members only: login required)

View Item