Alongitudinal Study on Occurrence of Staphylococcus aureus and its Drug Resistance Pattern in Raw Bovine Milk Originated from Alage TVET College Dairy Farm, Ethiopia
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2012-06
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Addis Ababa University
Abstract
A longitudinal study was conducted from November 2011 to April 2012 to investigate the contamination rate of Staphylococcus aureus in raw and processed bovine milk in Algae ATVET College. The rate of raw milk contamination along lactation length, the role of some potential risk factors, and degree of antibiotic resistance to the study organism was also addressed. A total of 316 (265 udder and 51 raw processed) milk samples were analyzed and 20.3% (64/316) were found contaminated with S. aureus. The rate of contamination in udder milk and raw processed milk was 20.8% (55/265) and 17.6% (9/51), respectively. The longitudinal study done indicated that the rate of contamination at early, mid and late stage of lactation was, 40.5% (30174), 11.2% (10/89) and 14.7% (15/ 102) respectively. There was statistically significant difference (P<0.05) in rate of contamination between early and late lactation stages. The calculated odd ratio for early and late lactation stage was 3.955 (CI= 1.929, 8.101 ). Udder milk from cows with two or more parity number and high milk yielders also revealed significant (P<0.05) contamination rate with S. aureus when compared with cows having less than two parity number (OR= 5.81, CI= 2.898, 11.765) and low milk yielders (OR= 4.83 , CI= 1.88, 12.35), respectively. From the raw processed milk samples, the higher percentage of occurrence was at milk destination sites 'B' and 'C', 33.3% each. The antibiotic susceptibility test indicated the study microorganism was highly susceptible to chloramphenicol (76.9%) followed by erythromycin (71.8%) and trimethoprim sulfamethoxazole (64. 1%). However, these isolates were equally resistant to doxycycline and nalidixic acid (36.1 %) following ampicillin for which they were highly resistant (94.9%). From the 39 pure isolates, 82.1 % were resistant for two or more drugs. The multidrug resistance pattern done for isolates from different parity group was statistically insignificant (P>0.05) In conclusion, this study indicated the importance of S. aureus in milk contamination in the study area. It also indicated lactation stage, milk yield and parity number of lactating cows were the potential risk factors for the contamination of udder milk. Measure should be taken to address the antibiotic resistance in the study farm . Keywords: Occurrence, Raw processed milk, Staphylococcus aureus, Udder milk.
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Keywords
Occurrence, Raw processed milk, Staphylococcus aureus, Udder milk.