Characterization of methicillin resistant Staphylococcus aureus (MRSA) isolates using oxacillin-cefoxitin disk diffusion test (OCDDT)


Characterization of methicillin resistant Staphylococcus aureus (MRSA) isolates using oxacillin-cefoxitin disk diffusion test (OCDDT)

Chika Ejikeugwu1*, Chiwendu E. Okike1, Chijioke Edeh1, Felix Nwezeagu1, Malachy Ugwu2

1Department of Applied Microbiology, Faculty of Science, Ebonyi State University, P.M.B. 053, Abakaliki, Ebonyi State, Nigeria; 2Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria

International Research Journal of Public Health-2D code

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) still remains an important nosocomial and community-acquired pathogen because of its multidrug resistant nature which gives them the innate/acquired ability to evade the onslaught of antibiotics. MRSA infection now occurs globally; and it is important to be on the lookout for these resistant pathogens in clinical samples in order to effectively guide therapy for patients.

Objective: This study was aimed at evaluating the frequency of MRSA strains from urine samples of out-going patients in a tertiary hospital using oxacillin-cefoxitin disk diffusion test (OCDDT).

Materials and methods: In this study, a total of thirty nine (39) non-duplicate isolates of S. aureus from urine samples of out-going patients who attended a tertiary hospital in Abakaliki, Nigeria for medical attention was bacteriologically investigated for methicillin resistance. All the S. aureus isolates was re-characterized using standard microbiology techniques. The modified Kirby-Bauer disk diffusion technique was used to evaluate the antibiogram of the S. aureus clinical isolates while MRSA positive isolates was phenotypically confirmed using the oxacillin-cefoxitin disk diffusion technique (OCDDT). Multiple antibiotic resistance index (MARI) was used to calculate the multidrug resistant nature of the MRSA positive S. aureus isolates.

Results: Our result shows that the S. aureus isolates showed varying rates of susceptibility and resistance to the tested antibiotics which are usually used in hospitals for treating infections caused by the organism. The S. aureus isolates was highly resistant or intermediately resistant to cefoxitin (56.4 %), bacitracin (89.7 %), oxacillin (89.7 %), and mupirocin (71.7 %). Clindamycin which is usually used for the treatment of S. aureus infections had no inhibitory activity on the S. aureus isolates evaluated in this study. Out of the 39 isolates of S. aureus, the detection of MRSA positive isolates was recorded at 35.8 % (n=14). All the MRSA positive isolates had MARI of 0.5 on average; and this indicates the multiple antibiotic resistance nature of the MRSA positive isolates recovered in this study. Conclusively, this study has presumptively shown that S. aureus isolates of clinical origin in this region are methicillin resistant. Further studies are required to characterize the genetic factors of the MRSA isolates. The worldwide problem of antibiotic resistance especially those caused by MRSA isolates warrants the need for accurate and prompt detection of MRSA from clinically important samples in order to ensure proper antibiotic therapy in infected individuals as well as to stop any disease outbreak that may be due to them.


Keywords: MRSA, Staphylococcus aureus, Antimicrobial Resistance, Gram positive bacteria, Nigeria

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How to cite this article:
Chika Ejikeugwu, Chiwendu E. Okike, Chijioke Edeh, Felix Nwezeagu, Malachy Ugwu.Characterization of methicillin resistant Staphylococcus aureus (MRSA) isolates using oxacillin-cefoxitin disk diffusion test (OCDDT) .International Research Journal of Public Health, 2018; 2:22. DOI:10.28933/irjph-2018-11-1801


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