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, it 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 isolates and reference
strain of Klebsiella pneumoniae.
Methods: The efficacy of Lactobacillus supernatants and antibiotics in the prevention and elimination
of K. pneumoniae biofilms was determined using a quantitative adherence assay. A rapid colorimetric
microplate bioassay was applied for the detection of survived bacterial cells after treatment
with antibacterial agents. Biofilm phenotypes were studied by scanning electron microscopy
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 a strong biofilm producer
isolate. Supra-MIC levels of antibiotics had a 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 lower concentrations of 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.