Oxidative stress resistance mediated by SigB increases the emergence of Staphylococcus aureus persister cells

SULIGOY S; CÁCERES ME; ROMERO R; SORDELLI DO; SULIGOY CM; BUZZOLA FR

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Staphylococcus aureus HU-14 from a patient with chronic osteomyelitis was passed through the bloodstream using a bacteriemia mouse model and derivative P3.1 was obtained. Reacquisition of capsule expression with parallel increase of SigB expression and staphyloxanthin production was previously demonstrated in the P3.1 variant. The SigB regulon is known to respond to different stress signals and accordingly regulates stress responses. This study aimed to determine the response to the oxidative stress of HU14 and P3.1 variant strains and whether SigB mediates such response. S. aureus SH1000 (sigB positive) and the isogenic sigB mutant (SH1000 ΔsigB) strains were also included. The bacteria suspensions were exposed to 1.5 % hydrogen peroxide (H2O2) for 1 h at 37oC. Then, serial dilutions were done to take aliquots for plating in TSA plates. After 24 h of incubation at 37oC, the CFU/ml was calculated. The P3.1 variant presented higher oxidative stress resistance compared with HU14 strain (2.1x104 CFU/ml vs 4.2x103 CFU/ml, p=0.017 t-test). When sigB operon was deleted, the number of surviving bacteria was significantly lower (2.2x102 CFU/ml) in comparison to that observed in the wild-type (6.5x103 CFU/ml, p