PHENOTYPIC DETECTION OF INDUCIBLE CLINDAMYCIN RESISTANCE IN STAPHYLOCOCCUS SPECIES ISOLATED FROM CLINICAL SAMPLES IN A TERTIARY CARE HOSPITAL

Introduction: Clindamycin is an effective drug used as an alternative to Vancomycin to treat skin and soft tissue infections caused by Staphylococcus spp. Reporting Staphylococcus as susceptible to Clindamycin without checking for inducible Clindamycin resistance may lead to therapeutic failure.

Aim: To detect inducible Clindamycin resistance (MLSBi) among clinical isolates of Staphylococci by using a simple double-disc diffusion test (D-test). Methods: It was a prospective study conducted for 6 months from June 2022 to November 2022. All the Staphylococcal isolates from various samples were taken . Inducible clindamycin resistance (MLSBi) was detected by Erythromycin and Clindamycin disc approximation test (D-test) following CLSI guidelines.

Results: A total of 216 Staphylococcus species were isolated from different samples. Out of the total samples Staphylococcus aureus were 42% and Coagulase negative Staphylococcus (CoNS) were 58%. Sensitivity to vancomycin, linezolid and teicoplanin were 100%. Methicillin resistance is seen in 21% of Staphylococcus aureus and 23% of CoNS. The different susceptibility patterns to clindamycin in both Staphylococcus aureus and CoNS were noted. Constitutive (MLSBc) phenotype was most prevalent (48%) followed by MS phenotype (43%) and inducible (MLSBi) phenotype (9%) among Erythromycin resistant Staphylococcus isolates. Sensitive phenotype (S) is detected in 27%. MLSBi was more frequent in Methicillin Resistant Staphylococcus aureus (MRSA) (28%) and MRCoNS (10%) than in MSSA (4%) and MSCoNS (2%).

Conclusion: D-test should be included as a mandatory method in routine disc diffusion antimicrobial testing to detect inducible Clindamycin resistance in Staphylococci for the optimum treatment of patients.