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


1. Yves G, Philippe V, Gerard L, Miche`le B, Francois V, Daniel F, and Jerome E (2007). Factors Predicting Mortality in Necrotizing Community-Acquired Pneumonia Caused by Staphylococcus aureus Containing Panton-Valentine Leukocidin. Clinical Infectious Diseases, 45:315–21.
2. Venubabu T., Channappa T.S and Subhaschandra M.G (2011). Vancomycin resistance among methicillin resistant Staphylococcus aureus isolates form intensive care units of tertiary care hospitals in Hyderabad. Indian J Med Res, 134:704-708.
3. Nakou A, Woodhead M, and Torres A (2009). MRSA as a cause of community-acquired pneumonia. Eur Respir J, 34: 1013–1014.
4. Boucher H., Miller L.G. and Razonable R.R (2010). Serious infections caused by methicillin resistant Staphylococcus aureus. Clin Infect Dis, 51 Suppl 2:S183-97.
5. Mongkolrattanothai K, Boyle S, Kahana M.D and Daum R.S (2003). Severe Staphylococcus aureus Infections Caused by Clonally Related Community-Acquired Methicillin-Susceptible and Methicillin-Resistant Isolates. Clinical Infectious Diseases, 37:1050–1058.
6. Denyer S.P., Hodges N.A and Gorman S.P (2004). Hugo & Russell’s Pharmaceutical Microbiology. 7th ed. Blackwell Publishing Company, USA. Pp.152-172.
7. Michael Z.D and Robert S.D (2010). Community-Associated Methicillin Resistant Staphylococcus aureus: Epidemiology and Clinical Consequences of Emerging Epidemic. Clinical Microbiology Review, 23(3):616-687.
8. Terry A.O.A., Ogbolu D.O., Akorede E., Onemu O.M and Okanlawon B.M (2011). Distribution of mecA gene amongst Staphylococcus aureus isolates from southwestern Nigeria. Afr. J. Biomed. Res, 9-16.
9. Ike B, Ugwu M.C, Ikegbunam N.M, Nwobodo D, Ejikeugwu C, Gugu T and Esimone C.O (2016). Prevalence, Antibiogram and Molecular Characterization of Comunity-Acquired Methicillin-Resistant Staphylococcus aureus in Awka, Anambra Nigeria. The Open Microbiology Journal, 10, 211-221.
10. Sae T., Kyoko K.A., Takashi S and Keiichi H (2010). Origin and Molecular Evolution of the Determinant of Methicillin Resistance in Staphylococci. Antimicrobial Agents Chemotherapy, 54(10):4352-4359.
11. Brooks G.F., Butel J.S and Morse S.A (2010). Medical Microbiology, 23rd edition. McGraw Hill Publishers. USA. Pp. 248-260.
12. Otter J.A and French G.L (2010). Molecular epidemiology of community-associated methicillin-resistant Staphylococcus aureus in Europe. Lancet Infect Dis, 10(4):227-329.
13. Pinho M.G., de Lencastre H and Tomasz A (2001). An acquired and native penicillin-binding protein cooperate in building the cell wall of drug-resistant Staphylococci. Proc Natl Acad Sci USA, 98(19):10886-91.
14. Cheesbrough M (2006). District Laboratory Practice in Tropical Countries. 2nd edition. Cambridge University Press, UK. Pp. 178-187.
15. Ejikeugwu C., Iroha O., Amaechi C., Ugwu M., Eze P., Iroha C., Ogene L., Orinya C. (2017). Multiple Antibiotic Resistance, Antibiogram and phenotypic Detection of Metallo-Beta-lactamase (MBL) from Escherichia coli of poultry origin. Journal of Apply Microbiology & Biotechnology, 1:4:5.
16. Clinical Laboratory Standard Institute, CLSI. Performance standards for antimicrobial disk susceptibility test. Fifteenth informational supplement, CLSI document M100-S15. 2011; CLSI, Wayne, PA. USA.
17. Urbaskova, P., O. Melter, B. Mackova, V. Jakubu, and M. Wunschova (2004). Detection of MRSA in a group of 752 strains of S. aureus using a cefoxitin disk. Epidemiol. Mikrobiol. Immunol. 53:62–65.
18. Swenson J.M, Tenover F.C, and the Cefoxitin Study Group (2005). Results of disk diffusion testing with cefoxitin correlates with presence of mecA in Staphylococcus spp. Journal of Clinical Microbiology, 43(8):3818-3823.
19. Wang W.Y., Chiueh T.S., Sun J.R., Tsao S.M and Lu J.J (2012). Molecular Typing and Phenotypic Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Blood in Taiwan. PloS ONE, 7(1):e30394.
20. Adriana C., Michael Z.D., Robert S.D and Susan B.V (2011). Association of High Mupirocin Resistance and Multidrug-Resistant Staphylococcus aureus at an Academic Center in the Midwestern United States. Journal of Clinical Microbiology, 40(1):95-100.