Isolation, Detection and Molecular Characterization of Staphylococcus aureus from Postoperative Infections

Post operative infections that occur after surgical procedures can cause a lot of complications like sepsis, organ failure or even death. These are the third most commonly reported healthcare associated infection. The most common cause of wound infection regardless of procedure performed remains gram-positive cocci which comprise more than 50% of all infections. Specifically, Staphylococcus aureus and coagulase-negative staphylococci are the most frequent organisms isolated from a wound infection. There has been an increasing incidence of MRSA strains reported in hospitals across the globe. The main aim of our study is isolation, detection and molecular characterization of Staphylococcus aureus from postoperative infections. Samples were collected from post operative patients with infected wounds. The area around the wound was cleaned. Exudates were collected from the wound with a sterile swab stick. The samples were inoculated on different solid culture mediums and the plates were incubated in the presence of oxygen at 37°C overnight. There were many standard procedures done in which tube coagulase was taken as the main criteria. Antibiotic susceptibility testing was done by Kirby Bauer method following Clinical and Laboratory Standards Institute (CLSI) guidelines using commercially available cefoxitin (30 μg) disc (HiMedia) and the results were compared with Staphylococcus aureus ATCC 25923 and MRSA ATCC 43300 control strains. The MRSA strains were identified and detection of Mec A gene that codes for methicillin resistance is done using PCR technique.