Microbiological Quality of Pasteurized Milk Available in the Dar es Salaam Market, Tanzania

Abstract

Twenty packs of pasteurized milk were randomly purchased from various sources in three municipalities of Dar es Salaam City, Tanzania, with the aim of quantifying and identifying contaminant bacteria. A total of 24 bacterial strains were isolated following aerobic incubation at 37 ºC for 48 hours. The average aerobic count was 4.3 × 105 cfu/ml with 75 % of the milk samples found to be heavily contaminated. More than half (54 %) of the samples were contaminated with Staphylococcus aureus. The isolated bacteria were subjected to antibiotic susceptibility tests against 20 commonly used antibiotics using the Kirby-Bauer disk diffusion method. The inhibition zones obtained with the isolates were compared to those obtained when reference strains of microorganisms were similarly treated. Results were analyzed by SPSS software. About 29.2 % of the isolated bacteria were totally resistant to tested antibiotics. These findings advocate for more rigid sanitary measures during production and storage of pasteurized milk and other dairy products that are available in the market.