Effect of Kaempferol against Biofilm Formation by Klebsiella pneumoniae Clinical Isolates

Biofilm production is a key factor in the development of antibiotic resistance in multidrug-resistant Klebsiella pneumoniae (K. pneumoniae), a significant contributor to healthcare-associated infections (HAIs). Kaempferol, a flavonoid, is widely recognized for its ability to combat various microorganisms.

Our goal is to assess the impact of kaempferol on K. pneumoniae biofilms by determining the level of gene expression for the biofilm-forming genes.

Fifty K. pneumoniae isolates were studied. Different doses of kaempferol with a concentration range of 0.04 to 100% in Luria Bertani broth (LB) medium were incubated at 37°C for 24 h with forty-three K. pneumoniae strong and intermediate biofilm producers. The minimum inhibitory concentration (MIC) of kaempferol was determined. Molecular detection of the biofilm-forming genes (mrkA, pgaA, wbbM, and wzm) was performed on all isolates before and after kaempferol treatment at 0.5 x MIC.

Seven isolates out of 50 (14%) exhibited weak biofilm formation ability, 6 out of 50 (12%) were moderate producers, and 37 out of 50 (74%) were strong producers. The MIC values of kaempferol for K. pneumoniae ranged from 50% to 6.25% (p = 0.0003). The levels of expression of the studied genes were slightly decreased after treatment compared with their corresponding values before treatment.

Kaempferol has shown potential in disrupting biofilms by inhibiting key genes (mrkA, pgaA, wbbM, wzm) involved in adhesion and biofilm matrix synthesis, although its effect is moderate. In vitro testing revealed that kaempferol inhibits biofilm formation at varying concentrations depending on the bacterial strain, with gene expression downregulation indicating its interference in biofilm-related pathways. Patent related to this topic has been mentioned along the text.

Based on current knowledge, few research studies have investigated the impact of kaempferol on K. pneumoniae biofilms. Our results show that its effect on the biofilms of this bacterium is moderate to weak. Further research is necessary to determine potential synergies with other treatments.