Antibiotic Profiling of Staphylococcus Aureus and Genotypic Detection of Ermgene Causing Inducible Resistance to Clindamycin Isolated From All Clinical Samples in a Tertiary Care Center

Abstract

Objective The objective of this investigation is to ascertain the phenotypic and genotypic expression of inducible clindamycin resistance in clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) as a result of the expression of ermA, ermB, and ermC genes using and double disc diffusion method and RT-PCR. Method This cross-sectional study was conducted at department of Microbiology, SRM Medical College Hospital & Research Centre. Total of 150 isolates of S. aureus were collected. All these isolates were cultured aerobically. Staphylococcus aureus was identified and Antimicrobial Susceptibility Testing (AST) was done using Kirby-Bauer disk diffusion method and inducible resistance to clindamycin is detected by “D-test”. All clinical isolates of MRSA during the study period were included Result Analysis of 150 S. aureus isolates revealed 60 MRSA. Out of which 31 were detected as inducible clindamycin by double disk diffusion method. These 31 isolates were subjected to RT-PCR for genotypic detection of erm gene. 13 were found to be ermC, 5 were found to be ermB and 3 were found to be ermA positive isolates. Conclusion Clindamycin may be a viable alternative and should be recommended for severe MRSA infections, as indicated by its susceptibility pattern. We observed the D test as a mandatory method for the detection of inducible clindamycin-resistant Staphylococcus. It is crucial to note that the ermC gene is a significant determinant of macrolide resistance in MRSA.