Isolation and Identification of Staphylococcus aureus from Milk and Milk Products, Associated Factors for Contamination, and Their Antibiogram in Holeta, Central Ethiopia

Abstract

Staphylococcus aureus is a pathogenic bacterium-contaminating milk and milk products causing food poisoning primarily due to its enterotoxins. The study aimed at estimating the prevalence of S. aureus in milk and milk products, assessing potential risk factors for contamination, and determining the load and the antimicrobial susceptibility profile of the isolates. A cross-sectional study design was employed to collect a total of 486 samples, comprising 383 raw milk, 47 bulk tank milk, 29 curd milk (Ergo), and 28 Ethiopian cottage cheese (Ayib) samples. Enumeration, isolation, and identification of S. aureus were carried out following standard microbiological techniques. Antibiogram was performed using 12 antimicrobials following the Kirby–Bauer disc diffusion method. Logistic regression analyses were used to assess the association between the occurrence of S. aureus in milk and milk products and potential risk factors. The overall prevalence of S. aureus was 10.69% (52/486) [95% confidence interval (CI):8.09–13.79%]. The prevalence of S. aureus in raw milk, curd milk, bulk tanks at the farm, bulk tanks at milk collection facilities, and cottage cheese was 8.64%, 24.14%, 14.73%, 23.08%, and 14.29%, respectively. The rate of isolation of S. aureus was significantly high in curd milk than in other types of samples (P = 0.010). The study revealed that teat washing (OR: 4.93, 95% CI: 2.06–11.81), use of towel (OR: 12.13, 95% CI: 3.74–39.29), and tick infestations (OR: 4.31, 95% CI: 1.28–14.44) were risk factors associated with the occurrence of S. aureus in milk. About 48.39% of the milk samples assessed had the S. aureus count higher than 105 CFU/ml. The highest rate of resistance was observed to ampicillin (95%), amoxicillin (95%), oxacillin (87.5%), and cefotaxime (80%). All isolates are resistant to at least two classes of antimicrobial drugs, while 65.0% of the isolates were found to be multidrug-resistant. The moderate prevalence, high load, and antimicrobial resistance of S. aureus indicate the higher public health risk due to the widespread consumption of raw milk in the area. Good hygienic practices, regular surveillance of antimicrobial resistance, and prudent use of drugs are suggested.

Staphylococcus aureus in cow milk and milk products in Ambo and Bako towns, Oromia, Ethiopia: Prevalence, associated risk factors, hygienic quality, and antibiogram

“…Analysis of multidrug resistance patterns in the current study indicated that 43.94% (29/66) of S. aureus isolates from milk and milk products showed multiple drug resistance. In contrast to this nding, a higher (62.5%) and lower percent (2.4%) of multidrug-resistant S. aureus isolated from milk and milk products were reported by Gebremedhin et al [21] and Regasa et al [63], respectively. The emergence of resistance to numerous drugs represents public health hazard because foodborne outbreaks might be di cult to treat and the group of multidrug resistance S. aureus in the food supply represents a reservoir for communicable resistant genes [62].…”

“…previously reported resistances from various sources [21,24,31,45]. The existence of an alarming level S.…”

“…However, the high incidence of SFP is likely to occur due to poor hygiene during food production and preparation, scarcity of cooling facilities [18,19], and raw milk consumption practices in the country [20]. Previous studies conducted in the Toke Kutaye, Dendi, and Cheliya districts of the West Shoa Zone, Oromia region, Ethiopia showed high isolation rate of Staphylococcus species from raw milk [22] and high prevalence of multidrug-resistant S. aureus in raw milk and milk products from a study conducted in Holeta, central Ethiopia [21]. However, there is a scarcity of data on the prevalence and antimicrobial susceptibility pro le of S. aureus in raw cow milk and milk products, and risk factors contributing to contamination in Ambo and Bako towns, West Shoa Zone of Oromia region, Ethiopia.…”

Molecular characterization of multi-drug-resistant Staphylococcus aureus in mastitis bovine milk from a dairy farm in Anhui, China

“…Mastitis is the inflammation of the udder due to the infection of a variety of bacteria that enter the mammary glands and damage them ( 1 ). Mastitis is a serious livestock disease, which usually causes significant economic losses along with clinical and sub-clinical symptoms in highly productive dairy animals ( 2 ). The opportunistic pathogen Staphylococcus aureus ( S. aureus ) is a representative microflora species, which is commonly disseminated on healthy skin and mucous membranes of people and animals ( 3 – 7 ).…”

“…In Asia, S. aureus is considered the major etiologic pathogen of mastitis in cattle and buffaloes ( 11 ). The infection of S. aureus in dairy cows not only harms the health of animals and milk production or quality ( 2 ) but also potentially transmits this pathogen to herdsmen or citizens ( 9 ).…”