Macrolide-Lincosamide-Streptogramin B (Mlsb) Resistance Phenotype in Staphylococcal Isolates

Aim: The aim of this study was to determine the incidence of macrolide-lincosamide-streptogramin B (MLSB) resistance in staphylococcal isolates from various clinical samples. Methods: In this study, we included a total of 100 staphylococcal isolates, 35 Staphylococcus aureus and 65 coagulase-negative staphylococci (CNS), from specimens obtained from patients followed up in our hospital between 2009 and 2010. Methicillin resistance of these isolates was determined using cefoxitin disc diffusion method. MLSB resistance was investigated by D-test method using erythromycin and clindamycin disks. Results: Of 35 S. aureus isolates, 14 were methicillin-resistant (MRSA) and 21 were methicillin-sensitive (MSSA). Of 65 CNS isolates, 41 were methicillin-resistant (MRCNS) and 24 were methicillin-sensitive (MSCNS). In 79 strains, there was at least one MLSB resistance phenotype. The most frequent resistance phenotypes were inducible (35%) and constitutive (30%) among all isolates, while the constitutive one was more common in S. aureus strains (62%). Conclusion: Since the resistant community-and hospital-acquired staphylococcal infections have become a therapeutic problem, it is very important to detect MLSB resistance routinely in microbiology laboratories. D-test is a cheap and reliable diagnostic method which can be performed in every laboratory. In order to prevent treatment failure, D-test should be routinely used and the results should be reported to the clinician before starting a therapy with MLSB group of antibiotics.