Biofilms of MDR K. pneumoniae (hvKp) Strains Can be Destroyed by Free Fatty Acids Interactions with Bacterial Cell Wall Membranes

Hypervirulent mucoviscus Klebsiella pneumoniae (hvKp) is rapidly emerging as opportunistic pathogens that have a global impact leading to a significant increase in mortality rates among clinical patients. Anti-virulence strategies that target bacterial adhesion and biofilm formation, proposed as alternatives to antibiotic treatments for reducing the rapid emergence of bacterial resistance. The main objective of this study was to examine the efficacy of fatty acid-enriched extract (AWME3) derived from the fat of Hermetia illucens fly larvae to combat biofilms formed by multidrug-resistant (MDR) and highly virulent hvKp pathogens. To reach these goals we used crystal violet (CV) and ethidium bromide (EtBr) assays on the mature biofilms of K. pneumoniae KPi1627, KPM9 and ATCC BAA-2473 strains. We found that exposure of hvKp strains to AWME3 at a concentration of 500 µg/mL (corresponding to 2× minimum inhibitory concentration, MIC) significantly affects the membrane permeability (p < 0.0001), causing serious disturbances and changes in the composition of membrane phospholipids, as confirmed by the detected increase in CV and EtBr uptake by 70 and 80%, respectively, compared to the control group. We used scanning electron microscopy (SEM) as a direct microscopic method to collect evidence of bactericidal action of AWME3 extract and the destruction of hvKp biofilms. In conclusion, our study demonstrates the exceptional capability of natural AWME3 extract, enriched with a unique combination of fatty acids, to effectively eliminate biofilms formed by highly drug-resistant and highly virulent pathogens K. pneumoniae (hvKp). Our results highlight the potential to control and minimize the rapid emergence of bacterial resistance by treating biofilm-associated infections caused by hvK pathogens with AWME3.