Detection of linezolid resistance cfr gene among MRSA isolates

Background: Linezolid (Oxazolidinones) is commonly used against a variety of Gram-positive infections, especially methicillin-resistant Staphylococcus aureus (MRSA). The emerging resistance to linezolid curtail the treatment of infections caused by MRSA and other Gram-positive bacteria. Presence of cfr gene plays a crucial role in Linezolid resistance. Objective: Present study was aimed to detect cfr gene among clinical MRSA isolates. Materials and methods: The suspected Staphylococcus aureus isolates were processed through Kirby Bauer disc diffusion methods for the confirmation of MRSA strains. Phenotypic Linezolid resistance was de-termined through broth micro-dilution method. The plasmid and DNA of Linezolid resistant isolates were subjected to molecular characterization for the presence of cfr gene. Results: Among 100 Staphylococcus aureus isolates, 85 of them were confirmed as MRSA isolates. Categorically, 65% MRSA isolates were sensitive to linezolid with MIC lower than 8 lig/ml, whereas, 35% of them were resistant to linezolid having MIC greater than 8 lig/ml. MIC level of 128 lig/ml was observed among 3.5% of the resistant isolates. Similarly, MIC level of 64 lig/ml, 32 lig/ml, 16 lig/ml and 8 lig/ml were noted for 3.5%, 4.7%, 8.2% and 15.3% isolates respectively. Linezolid resistance cfr gene was detected only in 9.4% of the resistant isolates. Conclusion: Multi drug resistance among MRSA isolates is keenly attributed to the presence of cfr gene as evident in the present study, and horizontal dissemination of cfr gene among MRSA strains is accredited to cfr-carrying transposons and plasmids. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/li-censes/by-nc-nd/4.0/).

Automated summary

The present study aimed to detect the presence of the cfr gene in clinical MRSA isolates. The results showed that multi-drug resistance among resistant MRSA isolates is largely attributed to the presence of the cfr gene, and the horizontal dissemination of the cfr gene among MRSA strains is facilitated by cfr-carrying transposons and plasmids.