An Investigation of Resistance to Macrolide-Lincosamide-Streptogramine B (MLSB), Ketolid and Linezolid in Methicillin-Susceptibile Staphylococcus aureus Strains

Introduction: Macrolide-lincosamide-streptogramine-B (MLSB) phenotype resistance has been increasingly detected in Staphylococcus aureus. The aim of this study was to investigate MLSB, ketolid and linezolid resistance in methicillin susceptible S. aureus strains. Materials and Methods: In the study, macrolide-lincosamide-streptogramin B (MLSB) phenotype resistance of 100 methicillin-susceptible Staphylococcus aureus (MSSA) strains isolated from various clinical specimens was investigated by using D-test. Disk diffusion method was used to determine the susceptibility of the strains to azithromycin, spiramycin, quinupristin/dalfopristin (Q/D), telithromycin, and linezolid. Results: It was found that the inducible MLSB resistance was the most common resistance phenotype (11%) followed by antibiotic inactivation (9%), constitutive MLSB resistance (4%), and M/MSB phenotype resistance (3%). The susceptiblity of the strains to both erythromycin and clindamycin was found to be very high (73%). The results were also shown that the linezolid (100%), Q/D (98%), and telithromycin (95%) were the most three efficient antibiotics. Conclusion: Constitutive MLSB resistance rate was found low when it is compared with other studies