Synergistic effects of silybin and curcumin on virulence and carbapenemase genes expression in multidrug resistant Klebsiella oxytoca

Objective Silybin and curcumin have potential antimicrobial effects. This study aimed to evaluate the synergistic antimicrobial effects of silybin and curcumin on virulence and carbapenemase genes expression among multidrug-resistant (MDR) Klebsiella oxytoca . Results A total of 70 MDR K. oxytoca (carrying bla IMP and bla OXA-48-like genes) were included. The antibiotic susceptibility and biofilm production of isolates were determined. The silybin and curcumin at concentrations 10–500 mg/mL alone and in combination were exposed to bacterial isolates in Mueller Hinton broth medium for 24 h. The expression of bla IMP , bla OXA-48-like , mrkA , pilQ , matB and fimA genes was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). The mean minimum inhibitory concentration (MIC) of curcumin and silybin were 250 mg/mL and 500 mg/mL, respectively. The anti-virulent effect of 100 mg/mL of silybin and curcumin was shown by significant reduction in the expression of fimA (2.1-fold, P < 0.0001) and mrkA (2.1 fold, P < 0.0001) genes. Moreover, these compounds significantly decreased the expression of bla IMP1 (3.2-fold, P < 0.0001) gene. Notably, there was no significant effect on pilQ , matB and bla OXA-48-like genes. The results showed that silybin and curcumin can be candidate as natural way for control the MDR virulent strains of K. oxytoca .