Staphylococcus Aureus: Methicillin Resistance and Small Colony Variants from Pyogenic Infections of Skin, Soft Tissue and Bone

Abstract

Background: Staphylococcus aureus (S. aureus) colonizing the nares, is the leading cause of hospital as well as community acquired infections. The aim of this study was to identify the S. aureus from skin, soft tissue and bone related  infections and typing them on the basis of antimicrobial susceptibility profile.

Methods: Clinical samples were collected from patients with skin, soft tissue and bone related infections from January  to October 2013 at Chitwan Medical College Teaching Hospital, Bharatpur. The S. aureus, small colony variants and  methicillin resistant strains were identified by standard microbiological methods recommended by  American Society for Microbiology. Antimicrobial susceptibility testing was performed by modified Kirby-Bauer disk diffusion method.

Results: Among 333 samples processed, there was positive growth of S. aureus in 66 (19.8%) samples. Among the isolated S. aureus, 10 isolates were small colony variants of S. aureus and all the strains recovered were thymidine independent in this study. Amikacin, vancomycin and teicoplanin were found to be the most effective antibiotics. Methicillin resistance was found in 34.8% isolates of S. aureus.

Conclusions: It can be concluded that, S. aureus is one of the  causative agent of pyogenic infections and the trend of antibiotic resistant is alarmingly high and also the rate of methicillin resistant S. aureus is comparably high in this study.

Keywords: Methicillin resistant Staphylococcus aureus (MRSA); small colony variants; staphylococcus aureus; thymidine dependent strains