,8-Cineol inhibe biofilms y células planctónicas de Klebsiella pneumoniae multiresistente a drogas

ESTELA M GALVÁN; NICOLÁS VÁZQUEZ; SILVIA MORENO

Cordoba

Congreso; XI Congreso Argentino de Microbiología General; 2015

Sociedad Argentina de Microbiología

Active compounds produced during secondary vegetal metabolism are usually responsible for the biological properties of some plant species used throughout the globe for various purposes, including treatment of infectious diseases. In the last years, the emergence of bacterial resistance to antibiotics encourages the research of new antimicrobials from the reservoir of medicinal plants and special attention has been paid towards plant essential oils and polyphenols (Nature 2012, 485:439?40; Current Opinion Biotechnology 2012, 23:168?173). Earlier we reported the antibacterial activity of Rosmarinus officinalis (rosemary) polyphenols which inhibited the human pathogen Klebsiella pneumoniae (Free Radical Research 2006, 40:223-231; Food Control 2013, 31:189-195). Most studies focused on the antimicrobial properties of phytochemicals against planktonic cells, but there are limited reports evaluating their efficacy against biofilms (Antimicrobial Agents and Chemotherapy 2014, 58:1192-1194).Here, we evaluate the efficacy of 1,8-cineole (main monoterpene of rosemary essential oil) against biofilm and planktonic cells of several carbapenem-resistant Klebsiella pneumoniae, which is an emerging multidrug-resistant nosocomial pathogen. The antibacterial activity against planktonic cells was studied by broth microdilution technique. The SYTOX green assay, a fluorescent nucleic acid stain, was used to assess the integrity of the bacterial plasma membranes. Biofilms were developed in vitro on microtiter plates and quantified by crystal violet stain. Results showed that 1,8-cineole inhibited planktonic nosocomial multidrug resistant-K. pneumoniae strains at 1-4% (v/v). A strong permeabilization effect on the plasma membrane of both non-nosocomial K. pneumoniae strain (increment in the fluorescence of 50-60%) and multidrug resistant K. pneumoniae strains (an increment of 30-35% in the fluorescence) was observed after treatment with 1,8-cineole at 4% (v/v) for 24 h. In order to study the effect of 1,8-cineole on biofilm disruption, biofilms were allowed to form in M9 minimal medium for 24 h and then treated with the compound another 24 h. Our data indicated that K. pneumoniae strains were good biofilm producers. Interestingly, a clear anti-biofilm effect was observed with 1,8-cineole in a concentration-dependent manner (0.003 to 4%, v/v), disrupting both susceptible and multidrug-resistant K. pneumoniae strains at least in a 30-50%. In conclusion: our in vitro findings suggest that 1,8-cineole may be useful for the prevention and/or treatment of health care-associated K. pneumoniae infections. In-vivo studies using animal models and clinical trials are needed to further evaluate its potential as antibacterial agent.