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The Inhibitory Effects of Lactobacillus Supernatants and Their Metabolites on the Growth and Biofilm Formation of Klebsiella pneumoniae


Fatemeh Kheiri*, Rouha Kasra Kermanshahi and Mohammad Mehdi Feizabadi   Pages 1 - 11 ( 11 )


Background: Klebsiella pneumoniae is a common cause of hospital acquired infections including urinary tract infection (UTI). Biofilm formation makes the K. pneumoniae infection more complicated and carrying extended spectrum beta-lactamases (ESBLs) genes limits antibiotic choices for treatment. Lactobacillus strains are known as natural protective barriers against UTIs.

Objectives: This is a small in-vitro study aimed to determine the effect of probiotic Lactobacillus strains and some types of their metabolites on the growth and biofilm of UTI isolated and reference strain of Klebsiella pneumoniae.

Methods: The efficacy of Lactobacillus supernatants and antibiotics in prevention and elimination of K. pneumoniae biofilms was determined using a quantitative adherence assay. A rapid colorimetric microplate bioassay was applied for detection of survived bacterial cells after treatment with antibacterial agents. Biofilm phenotypes were studied by scanning electron microscopy (SEM).

Results: The results showed that seven out of eight ESBL producing uropathogenic K. pneumoniae isolates in this study were able to produce biofilm. Lactobacillus supernatants at 1:1 to 1:16 dilutions, had more than 95% biofilm-inhibitory and biofilm-killing properties on strong biofilm producer isolate. Supra-MIC levels of antibiotics had much lower anti-biofilm effect than Lactobacillus supernatant and left considerable alive biofilm cells.

Conclusions: Although antibiotic resistance increases in biofilm forms of Klebsiella pneumoniae, Lactobacillus supernatants have strong antibiofilm efficacy even in concentrations lower than MIC. Biofilm formation decreases considerably in the presence of Lactobacillus supernatants. Hydrogen peroxide is an effective product against growth and biofilm formation of Klebsiella pneumoniae.


Biofilms, K. pneumoniae, Lactobacillus, probiotics, Biological Assay, Urinary Tract Infections


Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran

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