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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #394038

Research Project: Developing Agronomically and Environmentally Beneficial Management Practices to Increase the Sustainability and Safety of Animal Manure Utilization

Location: Food Animal Environmental Systems Research

Title: Antimicrobial resistance of staphylococci at animal human interface in smallholder dairy farms in Central Oromia, Ethiopia

item MARAMI, LENCHO - Ambo University
item BERHANU, GEMECHU - Dambi Dollo University
item TEKLE, MULUKEN - Addis Ababa University
item Agga, Getahun
item BEYENE, TARIKU - Nationwide Children'S Hospital
item TUFA, TAKELE - Addis Ababa University
item BEYI, ASHENAFI - Iowa State University
item EDAO, BEDASO - Addis Ababa University

Submitted to: Infection and Drug Resistance
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2022
Publication Date: 7/14/2022
Citation: Marami, L.M., Berhanu, G., Tekle, M., Agga, G.E., Beyene, T.J., Tufa, T.B., Beyi, A.F., Edao, B.M. 2022. Antimicrobial resistance of staphylococci at animal human interface in smallholder dairy farms in Central Oromia, Ethiopia. Infection and Drug Resistance. 15:3767-3777.

Interpretive Summary: Staphylococcus bacteria are the major causes of mastitis, an udder infection, in dairy cows. Mastitis causes significant economic losses to dairy cattle producers such as through reduced milk production, and discarded milk. In addition to its economic losses, mastitis is also an important public health issue. Unpasteurized or raw milk from infected udder can cause infections and food poisoning in humans. Therefore, it is important to investigate the burden of infection in the cows, monitor antibiotic susceptibility testing for treatment choice to reduce its economic burden and protect the public. Raw milk samples, udder swabs, milking utensil swabs, and milkers’ hand swabs were collected and cultured for the isolation and identification of Staphylococcus species. Approximately, over 70 percent of the sample types were positive for Staphylococcus suggesting that it is widespread with potential contamination of milk. Antibiotic resistance was also very common among the Staphylococcus isolates tested with high multidrug resistance. Infection control, antimicrobial stewardship, and milk hygiene practices at the dairy farms, together with milk pasteurization and boiling before consumption will ensure milk safety.

Technical Abstract: Purpose: Staphylococcus species come from a variety of sources and can contaminate milk during milking, cause mastitis and other diseases in animals and humans. The enterotoxins produced by these species are known to cause food poisoning. This study was aimed to isolate, biochemically characterize, and determine antimicrobial susceptibility profiles of Staphylococcus species from dairy farms in central Ethiopia. Methods: A total of 339 samples (n = 135 (raw milk), n = 135 (udders’ swabs), n = 25 (milkers’ swabs), n = 44 (pooled milking utensils’ swabs)) were collected from smallholders and dairy farms. Bacteriological culture techniques and biochemical tests were performed to isolate and identify Staphylococcus species, and the Kirby Bauer disk diffusion test was used to assess antimicrobial susceptibility tests. Results: A total of 247 (72.9%) Staphylococcus species were identified and classified into 101 (74.8%) isolates from raw milk; 98 (72.6%) from udders’ swabs; 30 (68.2%) from pooled utensils swabs; and 18 (72%) from milkers’ hands' swabs. Fifty coagulase positive Staphylococcus species (20 S. aureus, 20 S. hyicus and 10 S. intermedius) subjected to antimicrobial susceptibility tests have shown various degree of resistance. All S. aureus isolates were 100 % resistant to ampicillin and penicillin. Out of 20 S. hyicus isolates, 90% were resistant to ampicillin and 85% to penicillin. S. intermedius isolates (n=10) were 70 % resistant to Nalidixic Acid and penicillin whilst remaining 100 % resistant to ampicillin. Five S. aureus, three S. intermedius and two S. hyicus isolated from raw milk, milk utensil swabs and milkers’ hands swab were resistant to at least three classes of antibiotics (multidrug-resistant). Conclusions: This study revealed a high contamination rate of raw milk with multidrug-resistant Coagulase Positive Staphylococcus species suggesting the significance of pasteurization. Further research is encouraged on the factors leading to antibiotic resistance in Staphylococcus species.