Exogenous fatty acids alter phospholipid composition, membrane permeability, capacity for biofilm formation, and antimicrobial peptide susceptibility in Klebsiella pneumoniae

Abstract

Klebsiella pneumoniae represents a major threat to human health due to a combination of its nosocomial emergence and a propensity for acquiring antibiotic resistance. Dissemination of the bacteria from its native intestinal location creates severe, complicated infections that are particularly problematic in healthcare settings. Thus, there is an urgency for identifying novel treatment regimens as the incidence of highly antibiotic-resistant bacteria rises. Recent findings have highlighted the ability of some Gram-negative bacteria to utilize exogenous fatty acids in ways that modify membrane phospholipids and influence virulence phenotypes, such as biofilm formation and antibiotic resistance. This study explores the ability of K. pneumoniae to assimilate and respond to exogenous fatty acids. The combination of thin-layer chromatography liquid chromatography-mass spectrometry confirmed adoption of numerous exogenous polyunsaturated fatty acids (PUFAs) into the phospholipid species of K. pneumoniae. Membrane permeability was variably affected as determined by two dye uptake assays. Furthermore, the availability of many PUFAs lowered the MICs to the antimicrobial peptides polymyxin B and colistin. Biofilm formation was significantly affected depending upon the supplemented fatty acid.

Establishment of an induced memory response in Pseudomonas aeruginosa during infection of a eukaryotic host

“…Host-and in vitro-derived exogenous fatty acids were demonstrated to influence bacterial membrane physiology. This resulted in altered phenotypes such as virulence, motility, antimicrobial peptide susceptibility, or biofilm formation [47][48][49][50][51][52]. It was proposed that exogenous polyunsaturated fatty acids were directly incorporated into the bacterial membrane and thus to affect membrane permeability.…”

Exogenous polyunsaturated fatty acids (PUFAs) promote changes in growth, phospholipid composition, membrane permeability and virulence phenotypes in Escherichia coli

“…Permeability Assays. Three different membrane permeability assays were carried out to determine the effects of phospholipid remodeling in E. coli by following previously established procedures [2,3]. The rst assay monitored bacterial uptake of the hydrophobic compound crystal violet (CV).…”

“…Antimicrobial Peptide Susceptibility Assay. A previously established protocol was used to determine the effect that PUFA exposure has on antimicrobial peptide susceptibility in E. coli [2,4]. Cultures were grown to logarithmic phase in CM9 minimal medium in the presence or absence of one of the seven PUFAs at a concentration of 300 µM.…”

“…The observed alteration to membrane permeability led to an investigation of the impact of fatty acids on antimicrobial peptide susceptibility, a phenomenon previous documented for several Gram-negative bacteria [1][2][3][4]. For these experiments, two antimicrobials (polymyxin B and colistin) with mechanisms of action that target membrane bilayers via biophysical intercalation were chosen to compare with an antibiotic (ampicillin) that relies on protein-mediated uptake for activity.…”

“…An emerging body of evidence has highlighted the expanded fatty acid handling characteristics of Gramnegative bacteria. The impacts of fatty acids acquired from growth media include phospholipid remodeling and phenotypes affecting growth and virulence [1][2][3][4]. The expanded utility of fatty acids magni es the relevance of environmental adaptation for bacteria, especially those that oscillate between host and aquatic niches.…”