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

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).

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.

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.

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.

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.