Prevalence of Common Microbiological Pathogen Contamination in Processed Milk and Milk Products in Nairobi County, Kenya

Abstract

Milk has an outstanding nutritional quality but it is also an excellent medium for bacterial growth and an important source of bacterial infection when consumed without pasteurization. This study aimed at establishing the prevalence of Total Viable Count (TVC), Escherichia coli, Staphylococcus aureus and Listeria monocytogenes contamination on processed milk and milk products. The study was carried out in Karen, Kibera and Langata Sub- Counties of Nairobi County which were purposively chosen because they have glaring contrasts in living standards. Samples of fresh milk, yoghurt cheese and ice creams were collected from supermarkets and prepared for analysis of microorganisms. All isolates were characterized and identified based on their morphological and cultural characteristics. TVC were detected in 100% of the samples collected and there was significant statistical variation (P ≤ 0.05) in the contamination level among the products. Of the samples collected in Karen, ice cream had the highest contamination level (3.26 log10 CFU ml-1). Ice cream samples from Langata had the highest TVC contamination levels at 4.35 log10 CFU ml-1. The overall prevalence of E. coli in milk and milk products was 41.6% with a mean count of 0.34 log10 CFU ml-1 in Karen, 0.07 log 10 CFU ml -1 in Kibera and 0.11 log 10 CFU ml -1 in Langata while Staphylococcus aureus was detected in 33.3% of the milk and milk products. The occurrence and detection of E. coli and S. aureus foodborne pathogens in milk and milk products represent a health risk to consumers. Therefore, there is need to improve the microbial quality of milk and milk products by employing measures that will establish proper management practices to ensure improved hygiene, good manufacturing practices and food systems that will help to minimize microbial contamination.