Prevalence and antimicrobial drug resistance of Staphylococcus aureus isolated from cow milk samples

Abstract

Background and Aim: Staphylococcus aureus infections and antimicrobial resistance (AMR) in mastitis cases are both of clinical and economic importance. This study investigated the prevalence and AMR patterns of S. aureus 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 S. aureus using microbiological and biochemical tests. Confirmation of isolates was done using the analytical profile index. Antimicrobial susceptibility of S. aureus isolates against 12 antimicrobial agents was determined using the disk diffusion method. Results: S. aureus was isolated from 1.7% (50/2862) of the samples tested. All (100%) S. aureus 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 S. aureus isolates were resistant to erythromycin (62%; 31/50) and ampicillin (62%; 31/50). Almost half of S. aureus isolates were resistant to oxacillin (46%; 23/50) and only 8% (4/50) were resistant to cefoxitin. Conclusion: Although the prevalence of S. aureus 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 S. aureus and the presence of methicillin resistance among S. aureus observed in this study are of both clinical and public health concerns.

Molecular characterization of multi-drug-resistant Staphylococcus aureus in mastitis bovine milk from a dairy farm in Anhui, China

“…For the prevention and control of mastitis in cattle, a wide range of antimicrobials are commonly used ( 51 ), however inappropriate and excessive use of antibiotics leads to resistant bacteria. In the present results, a high antibiotic resistance rate was found, which is in line with previous studies of drug resistant S. aureus in South Africa and Turkey ( 4 , 42 ). The resistance of S. aureus to penicillin G, SXT, ciprofloxacin, norfloxacin, polymyxin B, clindamycin, clarithromycin, and erythromycin was significant, which indicates that it is unsuitable to employ those antibiotics in this region.…”

“…The prevalence of S. aureus isolated from milk samples was 24.8% (31/125), which is in line with the prevalence of S. aureus in cow bulk tank milk samples in the region of Balikesir in Turkey (28%) ( 4 ) and milk samples obtained from acute mastitis cases in Jordan ( 23 ). The prevalence was lower than in bovine mastitis milk samples in the US (46.6%), Indonesia (57%), and Bangladesh (72.7%) ( 11 , 32 , 41 ), but higher than in milk samples obtained from culled cows in Jordan (13.7%) ( 23 ), milk samples in cows in Ethiopia (12.5%) ( 10 ), and composite milk samples in dairy cows in South Africa ( 42 ). This variability between different study results could be attributed to the differences in geographical, study population, farm hygienic and management practices (such as breeds, farm size, the practice of hand milking, and absence of dry cow therapy), milking methods, and instruments employed ( 11 , 42 ).…”

Ecological Distribution of Virulent Multidrug-Resistant Staphylococcus aureus in Livestock, Environment, and Dairy Products

“…The presence of high percentages of MAR S. aureus from dairy cattle has been reported worldwide, 100% MAR from Egypt [ 11 ], 98.3%, 50%, and 62% from Ethiopia, Italy, and South Africa, respectively [ 52 ]. The difference in the MAR index may be attributable to the difference in the prevalence of antimicrobial-resistant genes that are responsible for MDR [ 53 ].…”

Properties of coagulase-positive staphylococcal cells that make it difficult to diagnose and treat mastitis in cows

“…In contrast, 62% were resistant to three or more categories of antibiotics. They were most often resistant to erythromycin (62%), ampicillin (62%) and oxacillin (46%) [15]. On the other hand, Bissong MAE (2020), analyzing the resistance of staphylococcus aureus, showed 39 isolates S. aureus from 289 microorganisms [16].…”