Prevalence and antimicrobial drug resistance of isolated from cow milk samples.

BACKGROUND AND AIM

infections and antimicrobial resistance (AMR) in mastitis cases are both of clinical and economic importance. This study investigated the prevalence and AMR patterns of isolated from composite milk samples of dairy cows submitted to the Onderstepoort Milk Laboratory for routine diagnosis.

MATERIALS AND METHODS

A total of 2862 cow milk samples randomly selected from submitted samples were tested for the presence of using microbiological and biochemical tests. Confirmation of isolates was done using the analytical profile index. Antimicrobial susceptibility of isolates against 12 antimicrobial agents was determined using the disk diffusion method.

RESULTS

was isolated from 1.7% (50/2862) of the samples tested. All (100%) isolates were resistant to at least one antimicrobial, while 62% (31/50) were resistant to three or more categories of antimicrobials (multidrug-resistant [MDR]). Most isolates were resistant to erythromycin (62%; 31/50) and ampicillin (62%; 31/50). Almost half of isolates were resistant to oxacillin (46%; 23/50) and only 8% (4/50) were resistant to cefoxitin.

CONCLUSION

Although the prevalence of among mastitis cases in this study was low, isolates exhibited high resistance to aminoglycosides, macrolides, and penicillins, all of which are important drugs in human medicine. The high prevalence of MDR and the presence of methicillin resistance among observed in this study are of both clinical and public health concerns.