Antisense yycG Regulation of Antibiotic Sensitivity of Methicillin-Resistant Staphylococcus aureus in Chronic Osteomyelitis.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an urgent medical problem in osteomyelitis. The YycFG two-component regulatory system (TCS) allows bacteria to adapt rapidly to physical, chemical, and biological stresses. The recombinant plasmid shuttle vector was used to overexpress an antisense RNA (asRNA) to inhibit target gene expression by sequence-specific double-stranded RNA complex degradation. In the current study, antisense yycG RNA (AS yycG ) - overexpression MRSA clinical isolates were constructed. Methods: Bacterial growth was monitored, and biofilm biomass was determined by crystal violet microtiter assay. Quantitative reverse transcription polymerase chain reaction analysis was used to identify expression of yycF/G/H and icaA/D in MRSA and AS yycG strains. The expression of YycG protein was quantified by Western blot assays. The antibiotic resistance of AS yycG strains was compared with that of the MRSA strains. Results: The AS yycG strains showed a decrease in growth rate compared with the MRSA strains. Of note, overexpression of AS yycG led to a reduction in biofilm formation and adhesion force. AS yycG strains had decreased expressions of the yycF/G/H and icaA/D . Furthermore, Western blot data showed that expression of the YycG protein decreased by 40% in AS yycG strains compared with MRSA strains. In addition, the effect of yycG asRNA improved the susceptibility of AS yycG strains to cefoxitin. Conclusions: The AS yycG strains inhibited biofilm organization and increased antibiotic sensitivity, which may be attributed to altered intracellular polysaccharide construction.