Occurrence of Listeria monocytogenes in Camel Milk Cheese from two township markets of Borno and Kano States, Nigeria

Abstract

Introduction: Camel milk cheese is one of the major camel milk products consumed in Northern Nige-ria. The conditions in which the cheese is sold in markets pose a risk of cross-contamination with foodborne pathogens such as Listeria monocytogenes. The study was carried out to evaluate the microbial quality of raw camel milk cheese sold in two different markets. Methods: A total of 200 cheese samples, (100 samples from each market) of Kano and Borno States, of Northern Nigeria were analysed for total aerobic plate count (TAPC) and total coliform count (TCC). Listeria species were isolated from the samples and the isolates were subjected for antimicrobial susceptibility test with commonly used antibiotics. Results: The results of the study show that mean TAPC of the sampled cheese was 5.90 log10 cfu/g and 5.70 log10 cfu/g for the Kano and Borno markets, respectively. While the mean for TCC per gram sampled was 3.75 log10 cfu/g and 3.81 log10 cfu/g for Kano and Borno, respectively. The occurrence rate of Listeria monocytogenes was 1(0.5%) in Kano and none in Borno market. However other Listeria species were isolated in both markets with overall occurrence rate of L. ivanovii 6(3%), L. welshimeri 1(0.5%) and L. grayi 2 (1%). The results of antimicrobial susceptibility test of the isolates show resistance of 77.7%, 66.7% and 55.6% to penicillin, gentamicin and tetracycline, respectively while 66.7% of the isolates were susceptible to erythromycin. Significance: This study has demonstrated the need for food regulatory agency to carry out routine investigation of ready to eat foods sold in the market to ascertain safety of such food for human consumption.