Genotypic Investigation of Methicillin Resistant Staphylococcus aureus Strains Isolated from Urinary Tract Infection

Methicillin resistant Staphylococcus aureus (MRSA) have recently emerged as major causes of urinary tract infection (UTI). The aims of this study were to determine antibiotic susceptibility of S. aureus isolated from UTI and to detect the presence of mecA (causing resistance to methicillin) and SCCmec types.

In this cross sectional study, 44 S. aureus isolates were collected in autumn 2017 from patients with UTI in two hospitals in Sanandaj, west of Iran. Susceptibility rates to nine antibiotics and vancomycin were determined by disk diffusion method and E test, respectively. The mecA and SCCmec types were detected by polymerase chain reaction (PCR). Descriptive statistics were used to evaluate the data.

Vancomycin, linezolid, and trimethoprim-sulfamethoxazole showed the highest susceptibility rates (more than 90%), followed by gentamicin (86.4%), cefoxitin (79.5%), tetracycline (77.3%), clindamycin (75%), ciprofloxacin (70.4%), erythromycin (52.3%), and penicillin (6.8%). The isolates from inpatients were more susceptible to antibiotics compared to those from outpatients. Of the 44 isolates, 9 (20.5%) were MRSA, of which 6 were isolated from outpatients. Five of 9 MRSA isolates carried the mecA gene, and of these, two isolates harbored SCCmec V while three were nontypeable.

Our study suggests that trimethoprim-sulfamethoxazole, vancomycin or linezolid would be suitable agents in treatment of UTI caused by MRSA. Identification of an MRSA isolate in urine is a serious concern and highlights the need for monitoring drug resistance in S. aureus.