Study of antibiotic resistance pattern in methicillin-resistant Staphylococcus aureus isolated from clinical samples of hospitals in Tabriz – Iran

Introduction:Methicillin-resistant Staphylococcus aureus (S. aureus) is commonly a cause of nosocomial infections. The increase in infection rates caused by this bacteriain developing countries has led to many problems. The aim of this study is to determine the antibiotic resistance pattern in methicillin-resistant S. aureus strains isolated from clinical specimens. Methods: In this cross-sectional study, 256 isolates of S. aureus were collected from Tabriz hospitals and treatment centers. The isolates were identified by standard laboratory methods and cultured in a specific environment. Identification of Methicillin-Resistant Staphylococcus aureus (MRSA) strains was made through phenotypic method. In order to evaluate antibiotic susceptibility patterns of strains, a disk diffusion method based on CLSI protocol was also performed. Data was analyzed by Chi-square test and SPSS 16 software. Results:Out of 256 examined samples, 197 (76.95%) of them were methicillin-resistant Staphylococcus aureus. The phenotypic evaluation of the antibiotic resistance pattern of methicillin-resistant S. aureus showed that the highest resistance was for 100% penicillin antibiotics, 94.22% co-amoxiclav and 81.22% gentamicin antibiotics and the lowest resistance was observed as chloramphenicol (16.75%). There was no significant relationship between age, sex, and MRSA infections (P> 0.05). Conclusion: High resistance S. aureus to penicillin, co-amoxiclav, gentamicin and also the high frequency of isolation of MRSA of hospital studied samples are remarkable. The present study demonstrates the need for continuous monitoring of antimicrobial susceptibility in S. aureus in order to determine the optimal drug regimens.