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

Abstract

BackgroundStaphylococcus aureus is one of the foodborne gram-positive bacterial pathogens that cause staphylococcal food poisoning worldwide and can contaminate foods of animal origin. The current study was conducted in Ambo and Bako towns, Ethiopia to estimate the prevalence, associated risk factors, hygienic quality, and antibiogram of Staphylococcus aureus (S. aureus) in cow's raw milk and milk products. ResultsThe overall prevalence of S. aureus from milk and milk products was 15.6% (94/601) with the highest prevalence detected in bulk tank raw milk at 17.50% (14/80) and the lowest in 'Ergo' at 13.11% (8/61). Age of cows, previous history of treatment, stage of lactation, udder washing, use of towel for individual cow, tick infestation, hygiene of the milker and utensils, and use of disinfectant were found to be statistically signi cant (P < 0.05) risk factors for S. aureus isolation at the individual cow level. Accordingly, a higher probability of getting infected with S. aureus was detected in cows aged 5 years old, crossbreeds, had a history of previous treatment, mid-lactation stage, no udder washing practiced, no individual towel used, tick infestation, and poor milking hygiene. Personnel hygiene, container hygiene, and use of disinfectants were the major risk factors that had a statistically signi cant association (p < 0.05) with bulk tank milk contamination with S. aureus. The maximum S. aureus counts at the farm and restaurant levels were 1.92x10 4 CFU/mL and 1.86x10 4 CFU/mL, respectively. The antimicrobial susceptibility test showed a higher resistance of S. aureus against amoxicillin (98.48%), oxacillin (98.48%), ampicillin (98.48%), cefoxitin (92.42%), and tetracycline (83.33%), of which 43.94% of isolates showed multidrug resistance. The high prevalence of oxacillin and cefoxitin-resistant isolates, which is indicative of the existence of Methicillin-Resistant Staphylococcus aureus (MRSA), was also detected in the current study.

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

“…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%. The variation in tetracycline resistance levels between the current study and previous research likely arise from differences in antibiotic usage practices.…”

“…Similar resistance rates for penicillin, ranging from 69.9 to 98.5%, have been documented in various regions of Ethiopia [ 22 , 70 , 71 ], while rates of 76–91.3% have been reported in Algeria [ 2 ], Egypt [ 46 ], and China [ 5 ]. Consistent with our findings, previous studies have reported proportions of ampicillin-resistant S. aureus ranging from 70.9 to 98.5% in different regions of Ethiopia [ 11 , 48 , 53 , 71 ], and rates ranging from 72.94 to 90.3% in Egypt [ 46 ], Turkey [ 56 ], Uganda [ 72 ], and China [ 5 ]. Supporting these observations, a global meta-analysis reported similarly high resistance levels, with penicillin resistance at 73.85% and ampicillin resistance at 59.63% [ 59 ].…”

“…In this study, 71.8% of the isolates exhibited multidrug resistance, defined as resistance to three or more antimicrobial classes, signaling a notable prevalence of antimicrobial resistance in the area. Our findings are consistent with elevated levels of MDR reported in other parts of the country, such as 65% in Holeta [ 11 ] and 61% in West Shewa [ 48 ]. Similarly, a study in Malaysia documented a comparable prevalence of multidrug resistance at 65.6% [ 75 ].…”

“…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 ]. A global meta-analysis documented a pooled prevalence of 33.5% in raw cow milk sampled from farms, retailers, and processing companies, which agrees with our findings [ 49 ].…”

“…Prevalence of 17.5% in Addis Ababa [ 52 ], 24.14% in Holeta [ 11 ], and 25.5% in Tigray [ 43 ] have been documented. Conversely, other studies within the country have reported relatively lower prevalence, such as 3% in Jimma zone [ 53 ], 10.8% in Borena pastoral areas [ 23 ], and 13.11% in Ambo and Bako towns [ 48 ]. In Southwest Uganda, S. aureus was identified in 12.1% of fermented milk samples [ 54 ].…”