ABSTRACT
Burkholderia cepacia complex (Bcc) are opportunistic pathogens implicated with nosocomial infections, and high rates of morbidity and mortality, especially in individuals with cystic fibrosis (CF). B. cepacia are naturally resistant to different classes of antibiotics, and can subvert the host innate immune responses by producing quorum sensing (QS) controlled virulence factors and biofilms. It still remains a conundrum as to how exactly the bacterium survives the intracellular environment within the host cells of CF patients and immunocompromised individuals although the bacterium can invade human lung epithelial cells, neutrophils, and murine macrophages. The mechanisms associated with intracellular survival in the airway epithelial cells and the role of QS and virulence factors in B. cepacia infections in cystic fibrosis remain largely unclear. The current review focuses on understanding the role of QS-controlled virulence factors and biofilms, and provides additional impetus to understanding the potentials of QS-inhibitory strategies against B. cepacia.
Subject(s)
Biofilms , Burkholderia Infections , Burkholderia cepacia/pathogenicity , Cystic Fibrosis/microbiology , Quorum Sensing/immunology , Animals , Biofilms/drug effects , Biofilms/growth & development , Burkholderia Infections/etiology , Burkholderia Infections/immunology , Burkholderia cepacia/growth & development , Burkholderia cepacia complex/pathogenicity , Communicable Diseases, Emerging , Cross Infection/immunology , Cystic Fibrosis/complications , Cystic Fibrosis/immunology , Cytokine Release Syndrome , Drug Resistance, Multiple, Bacterial , Humans , Immune Evasion , Immunocompromised Host , Inflammation , Lipase/metabolism , Lipopolysaccharides/metabolism , Lung/microbiology , Macrophages/microbiology , Metalloendopeptidases/metabolism , Mice , Neutrophils/immunology , Siderophores/metabolism , Virulence Factors/metabolismABSTRACT
In a preliminary screening, the methanol extract of Cinnamomum tamala leaves was found to inhibit the swarming motility of Pseudomonas aeruginosa. Bioassay-guided fractionation by silica gel column chromatography led to the identification of cinnamtannin B1 (1) as one of the active components of the extract. It inhibited the swarming motility (at 12.5 µg/mL) and biofilm formation (at 25 µg/mL) ofP. aeruginosa. Comparative gene expression analysis revealed downregulation of rhlA and fliC genes upon treatment with the tannin. The tannin may be affecting rhamnolipid and flagellin production. Thus, cinnamtannin B1 is an active component of C. tamala responsible for inhibiting the swarming motility of P. aeruginosa.
