Sensitivity Pattern of Staphylococcus aureus Isolates from Different Sources for Methicillin, Vancomycin, β-lactamase and ESBL Production

Abstract

Background: Staphylococcus aureus has the ability to develop many efficient mechanisms to neutralize them and it has become difficult to control the virulent strains of S. aureus from causing staphylococcal diseases in animals and humans. Mostly Staphylococcal strains have become resistant to methicillin, β-lactamase and ESBL activity and sometime to vancomycin also. The present study investigated the phenotypic and genotypic characteristics of all the 62 S. aureus isolates for sensitivity towards methicillin, b-lactamase, ESBL production and vancomycin. Methods: The isolates were obtained by conventional microbiological methods, confirmed genotypically by 23S rRNA ribotyping and Maldi-Tof MS. Methicillin resistance activity among S. aureus isolates was detected by culturing them on MeReSa Agar. Extended-spectrum b-lactamase activity among S. aureus isolates was detected by the combined disc method. Result: On MeReSa agar, 53(85.48%) isolates were detected as methicillin resistant S. aureus (MRSA), but none of the isolates from any source or place of sampling was detected positive by the methicillin disk method. Extended-spectrum b-lactamase (ESBL) activity was exhibited by 51 (82.25%) isolates with 100% (maximum) isolates from human pus showing activity and 66.66% (least activity) was seen in isolates from unprocessed meat. All the isolates were susceptible to vancomycin.