Phenotypic detection and prevalence of erythromycin induced resistance to clindamycin in methicillin resistant staphylococcus aureus mrsa and methicillin sensitive staphylococcus aureus mssa isolates from various clinical samples

Abstract

newline Staphylococcus aureus (S. aureus) is one of the most important cause of hospital and community acquired infections. The determination of antimicrobial susceptibility of a clinical isolate is crucial for optimal antimicrobial therapy of infected patients. newline newlineA total of 3540 samples (pus, urine, HVS, blood, devices, sputum and various body fluids) were processed, out of which 800 (22.59%) were S. aureus isolates. The maximum number of S. aureus strains were isolated from pus samples. The isolates of S. aureus (n=800) were subjected to antibiotic sensitivity testing by Kirby Bauer disk diffusion method and maximum resistance was observed in penicillin (83.62%) followed by chloramphenicol (72.75%), ciprofloxacin (70.12%), doxycycline newline(56.37%), cefoxitin (43.12%), gentamicin (38.87%), erythromycin newline newline(30%), azithromycin (27.37%) and clindamycin (18.50%). None of the strains of S. aureus was found to be resistant to vancomycin, teicoplanin and linezolid whereas in case of urine samples, the resistance against nitrofurantoin was reported as 2.65% in the present study. newline newlineMethicillin resistant Staphylococcus aureus (43.12%) and methicillin sensitive Staphylococcus aureus (56.87%) were detected by using Cefoxitin disk. The strains were further tested for detection of inducible clindamycin resistance. The prevalence of iMLSB, cMLSB and MSB phenotypes were 9%, 9.5% and 11.5% respectively among 800 S. aureus isolates. Out of 72 iMLSB phenotypic strains of S. aureus, 40 strains were randomly selected for detecting ermA and ermC genes. The gene ermC was identified in 27 (67%) strains whereas no strain was positive for ermA. newline newline newline