Impact of antibiotics on biofilm and some other properties of Klebsiella pneumoniae in vitro

Abstract number: P710

Hostacka A., Ciznar I.

Objectives:K. pneumoniae is a pathogen responsible for different human infections and it is also involved in outbreaks of nosocomial infections. Antibiotic resistance of these bacteria have become a serious clinical problem. The effects of subinhibitory concentrations (sub-MICs) of ciprofloxacin, enoxacin, norfloxacin, gentamicin and netilmicin on biofilm formation, hydrophobicity, lipase and response to oxidative stress in two clinical K. pneumoniae strains (39, 61/P) were evaluated.

Methods: Microtiter plate assay for biofilm formation, adherence to xylene for hydrophobicity, spectrophotometric method with Tween 20 for lipase activity and effect of H2O2 for response to oxidative stress were applied.

Results: Biofilm production by the strain 39 treated with quinolones and aminoglycosides and by the strain 61/P with aminoglycosides was markedly decreased. The most effective concentrations (1/2 of the MICs) suppressed biofilm formation to 28.7–56.9% of the control levels. Quinolones to the lesser extent altered biofilm in strain 61/P. Though antibiotics in the most cases enhanced bacterial adherence to xylene, the strains remained in the hydrophilic state. Decreased lipase activity to the different range in the strains treated with all concentrations of quinolones (with the exception of norfloxacin and enoxacin in strain 39) and netilmicin and with some concentrations of gentamicin was found. Antibiotic treated bacteria in most of the cases showed higher sensitivity to oxidative stress (with the exception of norfloxacin), but in case of netilmicin in strain 39 no changes were observed.

Conclusion:K. pneumoniae treated with antibiotics manifested suppressed biofilm production and also altered adherence to xylene, lipase and response to oxidative stress in dependence on strain, type and concentration of antibiotic.

This work was supported by Ministry of Health of the Slovak Republic under the project Analysis of biofilm production in nosocomial strains as a basis to prevent infections in healthcare institutions 2005/24-SMU-02.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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