Major Transcriptome Changes Accompany the Growth of Pseudomonas aeruginosa in Blood from Patients with Severe Thermal Injuries

Abstract

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes serious infections in immunocompromised hosts including severely burned patients. After multiplying within the burn wound, P. aeruginosa translocate into the bloodstream causing bacterial sepsis frequently leading to organ dysfunction and septic shock. Although the pathogenesis of P. aeruginosa infection of thermally-injured wounds has been extensively analyzed, little is known regarding the ability of P. aeruginosa to adapt and survive within the blood of severely burned patients during systemic infection. To identify such adaptations, transcriptome analyses (RNA-seq) were conducted on P. aeruginosa strain PA14 that was grown in whole blood from a healthy volunteer or three severely burned patients. Compared with growth in blood from healthy volunteers, growth of PA14 in the blood from severely burned patients significantly altered the expression of 2596 genes, with expression of 1060 genes enhanced, while that of 1536 genes was reduced. Genes whose expression was significantly reduced included genes related to quorum sensing, quorum sensing-controlled virulence factors and transport of heme, phosphate, and phosphonate. Genes whose expression was significantly enhanced were related to the type III secretion system, the pyochelin iron-acquisition system, flagellum synthesis, and pyocyanin production. We confirmed changes in expression of many of these genes using qRT-PCR. Although severe burns altered the levels of different blood components in each patient, the growth of PA14 in their blood produced similar changes in the expression of each gene. These results suggest that, in response to changes in the blood of severely burned patients and as part of its survival strategy, P. aeruginosa enhances the expression of certain virulence genes and reduces the expression of others.

Lactobacilli spp.: real-time evaluation of biofilm growth

“…Previous study of L. plantarum found several global regulators of gene expression, such as CtsR, HrcA, and CcpA, which upregulate the expression of various gene networks in response to stressors such as acidic or alkaline environments, high temperatures, and caloric restriction [36,37]. These studies have indicated that, in response to stressors, L. plantarum changes its energy metabolism as well as its production of fatty acids and exopolysaccharides incorporated into biofilms [38,39]. Our data agrees with these observations, demonstrating changes in oligosaccharide and fatty acid transports between attached (original place of biofilm formation) and detached phases after 24 h. in flow culture.…”

“…Biofilm was collected separately from A and D phases after 24 (n = 3 each) and 48 h. (n = 3 each) of culture flash frozen in liquid nitrogen and stored at − 80°C for future analyses. RNA was extracted, using TRIzol™ reagent [37] and Next Generation sequencing (NGS) was performed as previously described [38], utilizing the Illumina MiSeq platform (San Diego, CA). We compared whole genome expression of biofilms from the A and D phases at the bottom of the fermenter as validation of biofilm formation/maturation capacities as well as of biofilm growth by measuring both bacterial biomass from the spatula and from the bottom of the microfermenter in a time-dependent manner (24 and 48 h.).…”

Pseudomonas aeruginosa serA Gene Is Required for Bacterial Translocation through Caco-2 Cell Monolayers

“…P . aeruginosa utilizes numerous cell-associated and extracellular virulence factors including lipopolysaccharides, flagella, pili, exotoxin A, elastases, proteases, type III secretion effectors (ExoS, ExoT, ExoY, and ExoU), pyocyanin, catalase, alginate, and LasR/RhlR quorum-sensing molecules [15,16]. However, critical factors that play a key role in penetration through the Caco-2 epithelial barrier are still largely unknown.…”

Heparinase Is Essential for Pseudomonas aeruginosa Virulence during Thermal Injury and Infection

“…Despite numerous studies, the pathogenesis of P. aeruginosa infection during trauma-induced sepsis has not been defined. In an attempt to understand bacterial pathogenesis during sepsis following burn injury, we recently initiated a new approach, in which we grew P. aeruginosa in whole blood and examined the changes in expression of the transcriptome (13). The growth of P. aeruginosa in whole blood from severely burned patients significantly enhanced the expression of specific sets of virulence genes, such as iron-regulated genes, quorum sensing-related genes, and type III secretion genes, as well as numerous previously uncharacterized genes, compared with their expression when P. aeruginosa was grown in whole blood from healthy volunteers (13).…”

“…In an attempt to understand bacterial pathogenesis during sepsis following burn injury, we recently initiated a new approach, in which we grew P. aeruginosa in whole blood and examined the changes in expression of the transcriptome (13). The growth of P. aeruginosa in whole blood from severely burned patients significantly enhanced the expression of specific sets of virulence genes, such as iron-regulated genes, quorum sensing-related genes, and type III secretion genes, as well as numerous previously uncharacterized genes, compared with their expression when P. aeruginosa was grown in whole blood from healthy volunteers (13). One of the genes whose expression was significantly enhanced upon the growth of P. aeruginosa strain UCBPP_PA14 (PA14) in whole blood from severely burned patients was hepP, a previously uncharacterized gene encoding a heparinase enzyme.…”