Molecular Typing of Staphylococcus aureus Isolated From Clinical Specimens During an Eight-Year Period (2005 - 2012) in Tabriz, Iran

Abstract

Background: Antibiotic resistant Staphylococcus aureus is a serious public health problem worldwide. Objectives: This study aimed to investigate the susceptibility pattern and molecular typing of S. aureus isolated from clinical specimens of hospitalized patients during eight years, from 2005 to 2012. Materials and Methods: A total of 151 randomly selected S. aureus isolates, identified with phenotypic tests and detection of nuc gene, were subjected to antimicrobial susceptibility testing using the disk diffusion method. Moreover, molecular typing of the isolates was carried out by PCR-RFLP based on coa and spa genes. Results: All isolates were susceptible to vancomycin and teicoplanin. High rates of susceptibility were also observed with rifampin (98.1%), imipenem (94.7%), and linezolid (94.1%). On the other hand, most of the isolates were resistant against penicillin (95.4%), erythromycin (68.9%) and clindamycin (57.6%). Four types of spa and coa were distinguished among the isolates based on PCR results; however, the HaeII digestion resulted in a total of sixteen and nine RFLP patterns for spa and coa genes, respectively. Conclusions: The outcome of this study indicates a higher discriminatory power of the RFLP analysis based on the spa gene compared to the coa gene. Moreover, the results of our study reveal that the resistance rate of S. aureus to some antimicrobial agents including linezolid is a growing concern.