Progesterone and Estradiol alter the growth, virulence and antibiotic susceptibilities of Staphylococcus aureus.

In the present study, the effects of progesterone (PRO) and estradiol (EST) on the growth, adhesion, invasion, biofilm and antibiotic susceptibilities of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) were examined. We also investigated effects of S. aureus infections on the viability of human breast adenocarcinoma (MCF-7) cells in the presence/ absence of hormones. The effects of hormones on the growth, adhesion and invasion of S. aureus were investigated in MCF-7 cells. Growths were assessed spectrophotometrically. Adhesive/invasive bacterial counts were examined by colony counting method. Biofilm was determined using microtiter plate assay. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of ciprofloxacin (CIP) and gentamicin (GN) were examined by the microdilution method. Cell viabilities were detected via methylthiazolyldiphenyl-tetrazolium bromide assay. Growths of bacteria were decreased by hormones (p<0.0001). Adhesion was affected differently depending on hormones and strains tested. Hormones reduced the invasion (p≤0.0001) and biofilm (p<0.0001) of both strains. Progesterone increased and estradiol decreased MIC and MBC of CIP for MRSA; however, MICs of MSSA were not affected. S. aureus infected-MCF-7 viabilities were decreased in the presence of hormones except for high-level PRO (p<0.05). Our results showed that these two hormones have different effects on behaviors of S. aureus strains.