Resistance to linezolid observed in clinical isolates of Staphylococcus aureus obtained from a tertiary care facility in Hyderabad, India

Abstract

Background: Staphylococcus aureus has become increasingly prevalent in recent decades, serving as a primary source of infections acquired in both hospital and community settings. Severe MRSA (Methicillin resistant Staphylococcus aureus) infections pose a challenge in terms of therapeutic options, as they are limited. Linezolid, due to its antimicrobial spectrum, favorable short-term safety profile, and effectiveness, is extensively utilized in critical care settings.Methods: The study was conducted within the microbiology department of a tertiary care hospital located in Hyderabad from December 2021 to December 2023.The identification of MRSA was carried out using the cefoxitin disk diffusion technique. The detection of LRSA (Linezolid resistant Staphylococcus aureus) was carried out using the Kirby Bauer disc diffusion method, while the detection of MIC (Minimum Inhibitory Concentration) was conducted through the E-strip method and broth dilution methods for all the MRSA samples.Results: Among the 221 S.aureusisolates examined, the cefoxitin method revealed that 100 samples were determined to be MRSA, whereas the remaining 121 samples were categorized as MSSA. Six out of the 100 MRSA isolates were determined to be LRSA using the Kirby Bauer disc diffusion method. Three isolates were termed as LRSA using the E-strip method, whereas the broth dilution method identified four isolates as LRSA.Conclusion: This study show's both the E-strip method and broth dilution method exhibited a sensitivity rate of 96% and 97% respectively. The determination of MIC can be accomplished using either of these methods. In order to halt the dissemination of resistant strains, healthcare facilities should enhance the Standard Operating Procedures (SOPs) of Hospital Infection Control Committees (HICC) to mitigate the impact of antibiotic resistance and nosocomial infections.