Background: HIV is a well established risk factor for nasal colonization of staphylococcus aureus. MRSA is substantial cause of morbidity and mortality among HIV infected patients worldwide. Hence, Rapid and accurate method for detection of Methicillin resistant Staphylococcus aureus (MRSA) is an important role of clinical microbiology laboratories to avoid treatment failure and to control the endemicity of MRSA. The aim of this study was to compare three conventional methods against the molecular method to evaluate the best phenotypic method for route laboratory. Methods: A total of 440 nasal swab samples from 220 HIV positive cases and 220 HIV negative controls were processed, among which 144 isolates of S. aureus were obtained. Methicillin resistance was determined by oxacillin disc diffusion, cefoxitin disc diffusion the Oxacillin screen agar test and mecA gene detection by PCR. Result: Out of 144 nasal isolates of S. aureus, 16, 20 and 21 isolates were identified as MRSA based on Oxacillin disc diffusion method, Oxacillin screen agar method, Cefoxitin disc diffusion method respectively. In all phenotypic methods, Cefoxitin disc diffusion test better correlates with gold standard mecA gene PCR method for detection of MRSA having 100% specificity (95% CI; 97.05% -100.00%), 100% sensitivity (95% CI; 83.89% -100.00%) and 100% accuracy (95% CI; 97.47%- 100.00%). Conclusion: - Our study revealed that cefoxitin disk diffusion method had a high sensitivity, specificity and accuracy comparative to other phenotypic methods for detection of MRSA. It is also easy to perform and cost effective as compared to other method.
Keywords: Nasal isolates, S. aureus, MRSA, Cefoxitin disc diffusion.
Received: 12 September 2018 Revised: 23 September 2018 Accepted: 25 September 2018
Corresponding author: Dr Prasanna Gupta, Professor & Head, Dept of Microbiology, NIMS Medical college, Jaipur (Rajasthan), India
This article may be cited as: Diwakar MK, Gupta P, Goyal A. Detection of Methicillin resistance among nasal isolates of staphylococcus aureus in HIV patients: An evaluation of three different screening methods. J Adv Med Dent Scie Res 2018;6(10):1-5.