The dangers of sublethal carvacrol exposure: increases in virulence of during endophthalmitis.

can cause endophthalmitis through secretion of virulence factors, including hemolysin BL (Hbl) and nonhemolytic entertoxin (Nhe). Carvacrol is an extract from oregano oil, with potential for curtailing endophthalmitis, due to antimicrobial and anti-inflammatory qualities. However, sublethal levels of carvacrol increases virulence. The goal of this study was to investigate the increase in virulence potential in response stress induced by a subinhibitory concentration (SIC) of carvacrol. Enterotoxin production and tissue damage were examined during ocular infections and . We hypothesized that the SIC of carvacrol would significantly increase toxin production in without progressing systemically. RT-PCR determined SIC carvacrol-treated had significantly higher and mRNA expression levels than controls . ELISA and RPLA analysis revealed a 46.8% and 50% increase in NheA and HblC toxin levels, respectively, in SIC-treated cultures. -fed SIC carvacrol-treated had a significantly higher mean mortality rate than nematodes fed untreated . Significantly higher TNF-α levels were observed in SIC carvacrol-treated mice compared to other treatment groups except for mice infected with alone. Significantly higher IL-6 levels were also found in SIC- mice. Histological analysis using Rose-Bengal and DAPI determined that the eyes of mice infected with SIC carvacrol-treated had significantly more damage than eyes treated with alone. The SIC of carvacrol increased virulence and , with a mild systemic infection noted.