Alternative sigma factor B (σB) and catalase enzyme contribute to Staphylococcus epidermidis bioflm’s tolerance against physicochemical disinfection

Abstract

Staphylococcus epidermidis is the predominant cause of recalcitrant bioflm-associated infections, which are often highly resistant to antibiotics. Thus, the use of physico-chemical agents for disinfection ofers a more efective approach to the control of S. epidermidis bioflm infections. However, the underlying tolerance mechanisms employed by S. epidermidis bioflm against these physico-chemical disinfectants remain largely unknown. The expression of a σB-dependent gene, alkaline shock protein 23 (asp23) and catalase activity by S. epidermidis bioflm and planktonic cells exposed to heat (50°C), 0.8M sodium chloride (NaCl), 5mM sodium hypochlorite (NaOCl) or 50μM hydrogen peroxide (H2O2) for 60minutes were compared. Signifcantly higher asp23 expression levels were observed in bioflms exposed to 50°C, 5mM NaOCl or 50μM H2O2 compared to the corresponding planktonic cells (p<0.05). Conversely, asp23 expression levels in bioflm and planktonic cells exposed to 0.8M NaCl were not signifcantly diferent (p>0.05). Further, bioflms exposed to 50°C, 0.8M NaCl, 5mM NaOCl or 50μM H2O2 exhibited signifcantly higher catalase activity than the planktonic cells (p<0.05). These results suggest that activities of σB and catalase may be involved in the tolerance of S. epidermidis bioflm against physicochemical disinfectio