Qekwana, Daniel Nenene2026-01-282026-01-282019-02-042018-03*A2019http://hdl.handle.net/2263/107656Dissertation (MSc)--University of Pretoria, 2018.BACKGROUND : Coagulase positive Staphylococcus (CoPS) species are commensal of the skin and the mucosal surface of animals, including dairy cattle. However, they have also been implicated in sub-clinical and clinical mastitis in dairy cattle. In South Africa, information on the prevalence and antimicrobial drug resistance of CoPS from clinical mastitis cases of dairy cattle is limited. Therefore, the aim of this study was to investigate the prevalence and antimicrobial resistance patterns of CoPS isolated from dairy cow milk samples submitted to the Onderstepoort milk laboratory for routine clinical diagnosis. METHODOLOGY : A multistage sampling technique was used to obtain a representative sample of 2862 randomly selected cow milk samples. Coagulase-positive Staphylococcus species were identified based on morphology and biochemical tests and confirmation was done using the Analytical Profile Index (API). Antimicrobial susceptibility to twelve antimicrobial agents was determined using the disk diffusion method and interpreted according to the Clinial Laboratory Standard International guidelines. RESULTS : Twenty-three percent (23.2%; 665/2862) of samples tested positive for Staphylococcus species. Of these, 21.1% (605/2862) were coagulase negative Staphylococcus species (CoNS) and 2.0% (58/2862) CoPS. Among CoPS, Staphylococcus aureus (S. aureus, 86.2%, 50/58) was more prevalent than Staphylococcus hyicus (S. hyicus, 13.8%; 8/58). All (100%) S. aureus isolates exhibited antimicrobial resistance (AMR) to at least one category of antimicrobials, while 92.0% (46/50) were multidrug resistant (MDR). The highest proportion of S. aureus isolates were resistant to streptomycin (92.0%; 42/50) followed by erythromycin (62.0%; 31/50) and ampicillin (62.0%; 31/50). Almost half of S. aureus isolates were resistant to oxacillin (46.0%; 23/50) and only 8.0% (4/50) resistant to cefoxitin. Staphylococcus hyicus exhibited a high prevalence of resistance to streptomycin (100%; n=8) followed by erythromycin (75.0%; n=6) and ampicillin (75.0%; n=6). CONCLUSION : Staphylococcus aureus is the predominant CoPS species associated with infectious mastitis among dairy herds in this study. Staphylococcus aureus and Staphylococcus hyicus exhibited high prevalence of resistance to aminoglycosides, macrolides and penicillins. In addition, several S. aureus isolates from milk samples submitted to the Onderstepoort milk laboratory exhibited multidrug and methicillin resistance.en© 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.UCTDMastitisCoagulase positive StaphylococcusAntimicrobial resistanceOnderstepoortDissertation11262436N/A