Introduction: Antibiotic resistance, largely driven by Gram-negative bacteria, is a global public health problem aggravated by biofilm formation, which limits antibiotic access and effectiveness. These problems call for novel antibiotics including those targeting BamA, a key component of β-barrel assembly machinery (BAM) complex, present in the outer membrane of all Gram-negative bacteria. BamA catalyses the insertion of outer membrane proteins essential for bacterial growth and biofilm formation. The BamA inhibitor, polyphor 7 is bactericidal against many Gram-negative species but its ability to suppress virulence activities such as biofilm formation remains untested.
Objective: The study aimed to determine whether sublethal concentrations of polyphor 7 can inhibit activities associated with biofilm formation such as motility, exopolysaccharide export pores, and adhesion.
Methods: Polyphor 7 was tested at different concentrations in three types of experiments: swarming motility, and mucoid assay using clinical strains of Pseudomonas aeruginosa, and bacterial sedimentation assay using Escherichia coli K-12. The procedures included the preparation of polyphor 7-containing culture media at various concentrations, bacterial resuspension and inoculation, incubation, and phenotypic evaluation. Sedimentation was monitored by measuring OD_{600 every} 15 minutes, and the data were analysed using GraphPad Prism version 10.2.1.
Results: A reduction in motility and siderophore-associated pigment release was observed in P. aeruginosa strains. Additionally, aggregative E. coli showed decreased biofilm sedimentation in a concentration-dependent manner.
Conclusion: The data strongly suggest that polyphor 7 reduces virulence activities associated with biofilm formation. Further sedimentation assays using clinical E. coli isolates are recommended, particularly due to their frequent involvement in chronic urinary tract infections related to catheter use.
Keywords: BamA , BAM inhibitor, Polyphor 7, Biofilm formation.