Contamination of informally marketed bovine milk with Staphylococcus aureus in urban and peri urban areas of Debre-Zeit, Ethiopia

Abstract

A cross-sectional study was conducted from October, 2009 to March, 2010 to assess the level of contamination of informally marketed milk with Staphylococcus aureus at farms and milk collection centers in Debre-Zeit, Ethiopia. One hundred and seventy raw farm bulk milk samples, 25 mixed bulk milk samples and 20 pasteurized and packaged milk samples were collected from 14 milk collection centers and isolation and identification of S. aureus were carried out following standard method. S. aureus was isolated from 44% of farm bulk milk and 72% of milk collection centers' bulk milk and it was not detected from pasteurized milk samples. Contamination rates of farm bulk milk with S. aureus were significantly different among the collection centers (χ 2 = 31.8, df = 13, p = 0.003). The milk produced and collected in peri-urban areas was significantly more contaminated with S. aureus (64%) than milk produced and collected in urban areas (38%) (χ 2 = 7.18, df = 1, p = 0.007). The frequency of isolation of S. aureus in milk collection centers bulk milk varied between 67 and 100% among collection centers. However, the contamination rates were not significantly different among these collection centers (χ 2 = 1.5, df = 4, p = 0.83). The overall contamination rate at collection centers (72%) was significantly higher than that at the farm level (33%, χ 2 = 10.6, df = 1, p = 0.001). Overall, the study revealed that milk produced and collected in and around Debre-Zeit was found to be contaminated with S. aureus, raising the issue of quality control and improving the safety of milk to safeguard the consumer from associated health problems and enabling the producers to earn much more from milk sale.

Occurrence, antimicrobial susceptibility, and resistance genes of Staphylococcus aureus in milk and milk products in the Arsi highlands of Ethiopia

“…This pattern is likely influenced by the extensive use of oxytetracycline, the predominant antibiotic for treating animal bacterial infections in Ethiopia [ 73 ]. Our findings are consistent with previous studies documenting tetracycline resistance rates ranging from 32.4 to 47.8% in milk and milk products in Ethiopia [ 11 , 53 , 70 ], Algeria [ 2 ], Egypt [ 46 ], and China [ 5 ]. Contrary to our results, earlier studies in Ethiopia [ 22 , 48 ], Iran [ 9 ], and Uganda [ 54 ] reported a high proportion of tetracycline-resistant S. aureus strains, ranging from 56.1 to 83.33%.…”

“…Similarly, in agreement with the present study, prevalence of 41.1% and 53% were reported in retail markets in Egypt [ 44 ] and bulk cooling tanks in Portugal, respectively. On the other hand, higher contamination rates of 80% and 72% were observed in MCCs in Sebeta [ 22 ] and Debre-Zeit [ 46 ] in Ethiopia, respectively, and 61.7% in retail raw milk samples in China [ 47 ]. In contrast, earlier investigations reported lower contamination rates, including 23.08% in Holeta at collection centers [ 11 ], 17.5% in Ambo and Bako towns in bulk tank milk at farm level [ 48 ] in Ethiopia, and 15.7% in raw cow milk in Iran [ 9 ].…”

Factors affecting the microbiological quality and contamination of farm bulk milk by Staphylococcus aureus in dairy farms in Asella, Ethiopia

“…The result of this study showed that the occurrence of S. aureus in bulk milk (42%) was high compared to previous reports from other parts of Ethiopia [26,28,54,74], Uganda [75], Brazil [76], the USA [17] and China [77]. Our finding complies with previous reports from Ethiopia [27], Greece [70] and Italy [78]. In contrast, slightly higher S. aureus-occurrences of 66, 61, 54, 51, 48% were reported in Brazil [15], India [58], Portugal [73], Ireland [49] and the USA [79], respectively.…”

“…Staphylococcus aureus is a major cause of bovine mastitis [20], resulting in large economic losses due to reduced milk production and quality [21]. S. aureus is frequently isolated from cows with mastitis [22][23][24][25] and bulk milk [26][27][28] in Ethiopia. The presence of S. aureus in bulk milk samples indicates that infected cows are present in a herd [9].…”

Detection and Determination of Staphylococcus aureus in Camel Milk and Associated Factors in Fedis, Eastern Hararghe, Ethiopia

“…15,16 Consumption of raw milk and its products such as cheese, cream, and yogurt is common in sub-Saharan Africa, including Ethiopia. 16,17 However, the production and consumption of raw milk and various dairy products often takes place under poor hygiene conditions. 16,18 However, still there is a limited evidence on the prevalence of S. aureus in camel milk and determinant factors in Ethiopia, which cover both production and market areas.…”