Prevalence and Antimicrobial Susceptibility of Listeria monocytogenes Isolated from Beef, Pork and Chicken Sold in Makurdi Metropolis

Background: The demand for meat and meat products has been on the increase because of its nutritive value. Meat and meat products have been implicated in cases of foodborne diseases in both developed and developing countries. In Nigeria, there exist a dearth of information on the prevalence of Listeria monocytogenes which is a known pathogen of man and a major contaminant of meat.

Aim: To investigate the presence of Listeria monocytogenes in beef, pork and chicken, determine its distribution in markets within Makurdi, Benue State as well as its antimicrobial susceptibility to antibiotics.

Place and Duration of Study: The study was conducted between June and November 2013, at the Veterinary Pathology and Microbiology Laboratory of Federal University of Agriculture in Makurdi, Benue State, Nigeria.

Methodology: Two hundred and five samples of raw beef, pork and chicken were sourced from open markets in Makurdi and analyzed for the presence of Listeria monocytogenes following standard microbiological procedures. L. monocytogenes isolation and identification involved the use of Listeria Enrichment Broth (LEB), Listeria Selective Agar (LSA), haemolysis, sugar fermentation and Christie Atkins Munch Peterson (CAMP) tests. Antimicrobial susceptibility of L. monocytogenes isolates was tested against eight (8) different antibiotics, using the Kirby Bauer disc diffusion method. One Way Analysis of Variance (ANOVA) and Chi-squared test were used to analyze collected data.

Results: Contamination rate of L. monocytogenes was found to be 16 (7.8%) indicating that the organism is prevalent in Makurdi markets. L. monocytogenes contamination rate in pork, beef and chicken were 8 (11.1%), 6 (6.5%) and 2 (5.0%) respectively. There was however no statistically significant difference between the levels of contamination in the meat samples as well as the markets (p>0.05). All the isolates were found to be susceptible to erythromycin, gentamycin, cotrimoxazole and chloramphenicol but resistant to augmentin, amoxicillin, tetracycline and cloxacillin. L. monocytogenes contamination in the markets were 6 (37.5%), 5 (31.3%), 2 (12.5%), 2 (12.5%) and 1 (6.3%) for Wurukum, Wadata, North Bank, Modern and High level markets respectively.

Conclusion: There is a high incidence of L. monocytogenes contamination in raw beef, pork and chicken sold in Makurdi and hence, an urgent need to curb contamination of raw meat by this pathogen so as to safeguard the health of consumers.