Antibacterial and Anti-Biofilm Activities of Essential Oil Compounds against New Delhi Metallo-β-Lactamase-1-Producing Uropathogenic Klebsiella pneumoniae Strains

Abstract

The World Health Organization points out that the opportunistic pathogen <i>Klebsiella pneumoniae</i> that causes various infections among others, urinary tract infections (UTIs), is one of the high-priority species due to a global problem of antimicrobial resistance. The aim of this study was to investigate antibacterial and anti-biofilm activities of chosen constituents of essential oils against NDM-1-producing, uropathogenic <i>K. pneumoniae</i> strains. The genes encoding lipopolysaccharide (<i>uge</i>, <i>wabG</i>), adhesin gene <i>fimH</i> (type I fimbriae) and gene encoding carbapenemase (<i>bla</i>_NDM-1) for all tested strains were detected by PCR amplification. The <i>K. pneumoniae</i> ATCC BAA-2473 reference strain was <i>uge</i>- and <i>bla</i>_NDM-1-positive. The effectiveness of fifteen essential oil compounds (EOCs) (linalool, β-citronellol, linalyl acetate, menthone, (-)-menthol, (+)-menthol, geraniol, eugenol, thymol, <i>trans</i>-anethole, farnesol, β-caryophyllene, (R)-(+)-limonene, 1,8-cineole, and carvacrol) was assessed by determining the MIC, MBC, MBC/MIC ratio against <i>K. pneumoniae</i> strains by the microdilution method. Anti-biofilm properties of these compounds were also investigated. Thymol, carvacrol and geraniol exhibited the best antibacterial and anti-biofilm activities against uropathogenic NDM-1-producing <i>K. pneumoniae</i> isolates. Results of our investigations provide a basis for more detailed studies of these phytochemicals on their application against uropathogenic <i>K. pneumoniae</i>.