Total Bacterial Count and Identification of Staphylococcus species from Critical Control Points of Raw and Processed Milk in Selected Dairy Farm in Bishoftu Town, Ethiopia

Abstract

A cross-sectional study was carried out from November 2016 to May 2017 in Bishoftu town, Ethiopia to study total bacterial count (TBC) and detection of Staphylococcus aureus from critical control points (CCPs) at dairy farm (water, milker’s hands, milking bucket, udder milk, milk storage, pooled milk, pasteurized milk and yoghurt). A total of 60 samples were subjected for plate count agar (to estimate the colony forming units (cfu) per ml), and bacteriological culture and biochemical tests for the detection of S. aureus and other gram-positive cocci. Descriptive statistics and analytic statistics such as one way ANOVA test was used to calculate the mean difference in cfu/ml among sample sources. The log10 cfu/ml of mean value of bacterial load were 6.10, 5.78, 5.35, 5.15, 4.75, 4.52, 4.42, and 4.32 for pooled milk, water, milker’s hands, udder milk, milk storage, yoghurt, milking bucket, and pasteurized milk, respectively. Comparison of TBC from different sampling points indicated that pooled milk samples had significantly higher (p<0.05) bacterial load than other sampling points. Generally, raw milk had significantly higher (p<0.05) bacterial load (5.63x10⁵ cfu/ml) as compared to the processed milk and contact materials. Out of the total 60 bacterial growth, Staphylococcus species accounts 73.3% (44/60) of the total growth, with coagulase negative staphylococci (CNS) and Staphylococcus aureus accounting for 36 (60.0%), and 8 (13.33%) of the isolates, respectively. S. aureus was isolated mainly from milker’s hand, udder milk, and pooled milk samples. We found that the total bacterial count from contact surfaces, raw milk and dairy products was below the recommended standard and the presence of Staphylococcus isolates at different CCPs indicates poor milk production practices. The high level of contamination and presence of potentially pathogenic bacteria could pose public health risk due to infection and intoxications. Hence, the dairy farm should design a strategy to improve the hygienic practice on milk production, handling, and processing.