Investigation of Antibiotic Resistance Pattern and Detection of Methicillin- Resistant Strains (Mrsa) in Staphylococcus Aureus Isolates Associated With Bovine Mastitis



Havaei SA^{1, 2} ; Esfahani BN^{1, 2} ; Hoseini N^{1, 2} ; Assadbeigi B³ Show Affiliations
Source: Journal of Isfahan Medical School Published:2014

Abstract

Background: Staphylococcus aureus is one of the main causative agents in bovine mastitis. Resistance of some Staphylococcus aureus strains to antibiotics, particularly methicillin, can complicate the treatment of its infections. Moreover, the transmission of resistant strains into human is also important. Thus, the aim of this study was to investigate the prevalence of mastitis caused by Staphylococcus aureus in Isfahan dairy herds, Iran, and to determine the antimicrobial susceptibility pattern of the isolates. Methods: A total of 450 milk samples were collected. After inoculation and applying the relevant tests, antibiotic resistance was determined via disk diffusion method in isolates. D-test method was performed for the detection of inducible clindamycin resistance (ICR). Then, methicillin-resistant strains (MRSA) were detected using oxacillin agar screening and cefoxitin disc diffusion methods. Findings: Fifty-four Staphylococcus aureus were isolated. All isolates were sensitive to ciprofloxacin and gentamicin. Furthermore, 31, 25, 8, 7 and 2 isolates were resistant to erythromycin, clindamycin, tetracycline, oxacillin and cotrimoxazole, respectively. D-test was negative for all isolates. Nine methicillin-resistant strains were identified using oxacillin agar screening and ten methicillin-resistant strains were detected using cefoxitin disc diffusion methods. Conclusion: Since it is expected that the prevalence of Staphylococcus aureus, especially antibiotic resistant strains in herds, be too negligible, even the low incidence reported in this study can lead to many problems. Therefore, applying an appropriate antimicrobial susceptibility test before the beginning of antibiotic therapy in bovine mastitis cases is of primary importance. © 2014, Isfahan University of Medical Sciences(IUMS). All rights reserved.