The effect of subinhibitory concentrations of satureja spp. essential oils on the biofilm formation and urease activity of Klebsiella pneumoniae

Background: Klebsiella pneumoniae is one of the most important bacteria that cause nosocomial infections. This opportunistic pathogen has a high potential for antibiotic resistance and can generate a thick layer of biofilm. Nowadays, antibiotic resistant strains are emerging and widely spreading worldwide. Thus, it is necessary to combat drug-resistant strains through the use of novel drugs (such as medicinal plants). Objective: This study aimed to evaluate the in vitro antibacterial activity of Satureja rechingeri Jamzad, S. khuzestanica Jamzad, S. bachtiarica Bunge, and S. mutica Fisch. & C.A.Mey. essential oils against K. pneumonia ATCC 700603. Methods: For evaluation of the minimal inhibitory concentration (MIC) of essential oils, broth microdilution method was used. The microtiter plate assay method was used for the assessment of anti-biofilm activities of sub-MIC value of essential oils. Colorimetric and Iodometric assays were used for determination of urease and beta-lactamase activity. Results: According to data collected, the MIC value of essential oils was 4096 µg/mL. sub-MIC value of essential oils inhibited biofilm formation and urease activity of K. pneumoniae. However, S. khuzestanica had more activity. None of the essential oils caused a significant decrease in beta-lactamase activity of K. pneumoniae. Conclusion: Based on our analysis S. khuzestanica had a good antibacterial, anti-biofilm activities and urease inhibitory effects against K. pneumoniae, but additional studies are required to investigate the exact mechanisms of the antibacterial action and functions of this phytocompound.