Antimicrobial susceptibility of staphylococci species from cow foremilk originating from dairy farms around Gaborone, Botswana

Abstract

Objective: To determine the prevalence of antibiotic susceptibility of Staphylococcus species isolated from foremilk samples. Setting: Milk was collected from five farms within a 70 km radius of Gaborone, Botswana. Subjects: Two hundred and twenty five staphylococci isolates from foremilk samples. Main outcome measures: Antibiotic susceptibility tests to penicillin G, ampicillin, tetracycline, erythromycin, cephalothin, chloramphenicol, methicillin, gentamicin and vancomycin. Results: The susceptibility patterns of the staphylococcal strains to the antibiotics were as follows: penicillin G (47.1%), ampicillin (58.7%), tetracycline (62.7%), erythromycin (72%), cephalothin (72.9%), chloramphenicol (79.1%), methicillin (86.2%), gentamicin (88.9%) and vancomycin (100%). Lower susceptibility to chloramphenicol, methicillin and gentamicin was displayed by Staphylococcus epidermidis, S. haemolyticus and S. saprophyticus. Only 19 (8.5%) of the isolates were susceptible to all the antibiotics tested. The most common multiple resistance patterns encountered were penicillin-ampicillin (9.3%), penicillin-erythromycin-ampicillin (6.1%) and erythromycin-tetracycline - ampicillin (3.6%). Conclusion: Most of the Staphylococcus isolates were resistant to one or more of the antimicrobial agents, with none being resistant to vancomycin. Inappropriate use of antibiotics is suspected to be a major contributory factor in the relatively high level of resistance to antimicrobial agents observed in this study. Therefore, milk can act as a very good source of antibiotic resistant Staphylococcus species posing a threat to consumers.