Occurrence of Inducible Clindamycin Resistance in Staphylococcus aureus Isolates in Uttar Pradesh, India

Abstract

The development of methicillin-resistant Staphylococcus aureus (MRSA) and its ability to confer cross-resistance to MLSB group of antibiotics, i.e. macrolide-lincosamide-streptogramin B, have made difficult to treat MRSA infections. Routine use of clindamycin susceptibility testing is unable to identify inducible MLSB (iMLSB) phenotype which frequently leads to treatment failure and requires the use of a simple D-test for detection of this type of resistance. This cross-sectional observational study was performed in the Department of Microbiology, TMMC & RC Moradabad, India. Two hundred S. aureus strains have been identified in various clinical samples, including blood, pus, body fluids, and respiratory samples. S. aureus strains were subjected to antibiotic susceptibility testing using the Kirby–Bauer disc diffusion (D-test) technique. Cefoxitin-resistant S. aureus (MRSA) isolates were subjected to mecA gene detection using polymerase chain reaction. A total of 200 S. aureus isolates were obtained from various specimens, of which 134 (67%) were MRSA and 66 (33%) were MSSA. All MRSA strains possessed mecA. The constitutive MLSB (cMLSB), iMLSB, and MS phenotype prevalence was found to be 37.3%, 22.4%, and 40.3% in MRSA and 27.7%, 12.1%, and 65.2% in MSSA, respectively. In this study, S. aureus isolates exhibited a significant frequency of iMLSB in this region. Therefore, the D-test can be regularly used for clinical isolates to prevent clindamycin treatment failure.