Oxidative stress response in reference and clinical Staphylococcus aureus strains under Linezolid exposure

Abstract

BACKGROUND:Methicillin-resistant Staphylococcus aureus (MRSA) strains are some of the most widespread pathogens multi-resistant to antimicrobial agents (AA). The AA provoke several changes inside bacteria, which cannot be solely explained by the main mechanisms of action reported. OBJECTIVE:The role of the oxidative stress in bacteria exposed to bacteriostatic AA has not been widely studied; hence, the aim of our work was to investigate the effect of Linezolid (LZD) on S. aureus strains. METHODS:Oxidative stress markers, such as superoxide dismutase enzyme (SOD) activity, the global antioxidant response, the advanced oxidation protein products (AOPP) and the basal levels of glutathione in 28 clinical and 2 reference strains were performed. RESULTS AND CONCLUSIONS:We identified 10 of 30 strains showing a slightly increase in reactive species under LZD treatment with respect to the untreated control (between 22 to 56%). The higher generation was detected in the clinical strains compared to the reference ones, however the impact in the antioxidant response was not significant, and the oxidized protein levels were almost undetectable. The strains exposed to this oxazolidinone did not suffer acute oxidative stress. This is the first work reporting the behavior of S. aureus clinical and reference strains exposed to LZD, being the oxidative stress negligible.