Prevalence of blaOXA-1 and blaDHA-1 AmpC -Lactamase-Producing and Methicillin-Resistant Staphylococcus aureus in Iran

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to most antibiotics and can transfer resistance to other bacteria, which is a significant problems among hospitalized children with MRSA infections. Objectives: The aim of this study was to detect blaOXA-1 and blaDHA-1 AmpC -lactamase-producing MRSA in hospitals. Materials and Methods: In this descriptive study, 21 MRSA samples isolated from healthcare providers’ nostrils and 35 samples isolated from clinical cases, obtained between August 2012 and July 2013, were examined. Antimicrobial susceptibility testing was performed using agar disc diffusion (i.e., the Kirby-Bauer method). Polymerase chain reaction (PCR) approaches were used to examine MRSA molecularly for blaOXA-1 and blaDHA-1 AmpC -lactamase genes. Results: From the 56 MRSA samples, the highest antibiotic resistance was to penicillin (92.29%) and ceftazidime (82.98%). All isolates were sensitive to linezolid and vancomycin. Only one clinical MRSA sample carried both blaOXA-1 and blaDHA-1 AmpC -lactamaseencoding genes Conclusions: Improper consumption of antibiotics and environmental factors play important roles in the emergence and spread of antibiotic-resistant MRSA. Thus, the significance of the isolates from this study was that they were assayed for the presence of resistant genes, such as blaOXA-1 and blaDHA-1 AmpC -lactamase, in healthcare worker and patient samples, and decolonized to reduce transmission of antibiotic-resistant microorganisms in hospitals.