Evaluation of the Phenotypic and Molecular Pattern of Efflux Pumps in Clinical Isolates of Methicillin-resistant Staphylococcus aureus

Efflux pumps are regarded as one of the most important mechanisms of antibiotic resistance in this era. Staphylococcus aureus is one of the bacterial groups with efflux pumps. The pumps’ activity is coded by specific genes. The aim of this study was to determine the phenotypic and molecular pattern of efflux pumps in the clinical isolates of methicillin-resistant S. aureus.
This study was conducted on 302 S. aureus bacteria collected from different clinical specimens. We detected 145 isolates of methicillin-resistant using disk diffusion method with cefoxitin (30 µg) as well as minimum inhibitory concentration with E-test strips and cefoxitin disks. In addition, multiplex polymerase chain reaction method was employed to identify the genes responsible for resistance to efflux pump and gyrase. The data were analyzed using SPSS software version 16.
Among the 145 isolates of methicillin-resistant S. aureus, norfloxacin and ciprofloxacin had the highest frequency. Furthermore, norA, norB, norC, grlA, grlB, gyrA, and gyrB genes were positive in 39 (25.825%), 12 (9.97%), 41 (49.15%), 75 (49.66%), 37 (26.50%), 58 (38.41%), and 19 clinical isolates (12.58%), respectively.
As the findings indicated, the presence of efflux pumps in the strains of methicillin-resistant Staphylococcus aureus provided the ground for the emergence of multi-drug resistant bacteria.