Molecular Characteristics and Antimicrobial Resistance of Linezolid-Resistant in Osteoarticular Infections: A 11-Year Study From a Hospital in Xi'an.

PURPOSE

This study examines the distribution of pathogens and the characteristics of linezolid-resistant (LRSA) in osteoarticular infections (OAIs) over an 11-year period.

METHODS

Identification and initial antimicrobial susceptibility testing were conducted using the VITEK2 compact system. Broth microdilution method (BMD) to confirm linezolid-resistant isolates. The results were interpreted according to the Clinical and Laboratory Standards Institute (CLSI) guideline. Polymerase chain reaction (PCR) screening identified linezolid-resistance-related genes and molecular typing loci.

RESULTS

From 2012 to 2022, 2049 clinical isolates were collected, with identified as the leading pathogen, constituting 38.90% (797/2049) of cases. Among the 797 isolates, eight strains were initially identified as LRSA through VITEK2; however, only one isolate was confirmed as LRSA by BMD. For the eight strains, molecular typing revealed four spa types (t030, t037, t002, t437) and three MLST types, with ST239-t030 as the dominant clone. No transferable resistance genes () were detected, but a G2576T mutation, associated with reduced linezolid sensitivity, was identified in two isolates (included the isolate confirmed as LRSA by BMD) subjected to extended linezolid therapy.

CONCLUSION

Our findings highlight the importance of accurate susceptibility testing and proactive monitoring of LRSA in the treatment of chronic OAIs to mitigate potential therapeutic challenges.