Detection of methicillin resistant staphylococcus aureus using mec a, ribotyping and antibiogram profile of Pakistani clinical isolates

Abstract

Background: The objective of this study was to determine the incidence of MRSA with their antibiotic susceptibility pattern and molecular characterization of these strains. Study Design: Cross sectional study. Setting: Microbiology section of Citilab and Research Centre, Lahore. Period: March 2014 to June 2016. Materials and Methods: Bacterial isolates were retrieved from different specimens of pus/wound, blood and other body fluids. These were characterized using conventional (catalase, DNase, coagulase etc), phenotypic and molecular techniques (oxacillin and cefoxitin susceptibility, 16S rRNA gene sequencing and mec-A gene) methods of identification. Antibiotic sensitivity pattern was also detected by applying standard Kirby Bauer disc diffusion method. Results: Out of all the isolated strains, the frequency of MSSA (methicillin sensitive Staphylococcu saureus) was more than the MRSA and it was found that the male patients were more affected than the female patients. All of the isolates were resistant to cefoxitin and oxacillin while most of them showed positive band of mec-A gene. All of the MRSA isolates showed resistant to penicillin followed by azithromycin, erythromycin, co-trimoxazole and ciprofloxacin, while these strains were sensitive to linezolid and vancomycin, followed by teicoplanin, fosfomycin and fusidic acid. Conclusion: In conclusion, proper diagnosis of MRSA required conventional, phenotypic molecular techniques in our hospital diagnostic settings. This will help in choosing the effective antibiotics combat the infection.