Corchorus olitorius aqueous extract attenuates quorum sensing-regulated virulence factor production and biofilm formation

ABSTRACT The administration of macrolides such as azithromycin for chronic pulmonary infection of cystic fibrosis patients has been reported to be of benefit. Although the mechanisms of action remain obscure, anti-inflammatory effects as well as interference of the macrolide with Pseudomonas aeruginosa virulence factor production have been suggested to contribute to an improved clinical outcome. In this study we used a systematic approach and analyzed the impact of azithromycin on the global transcriptional pattern and the protein expression profile of P. aeruginosa PAO1 cultures versus those in untreated controls. The most remarkable result of this study is the finding that azithromycin exhibited extensive quorum-sensing antagonistic activities. In accordance with the inhibition of the quorum-sensing systems, virulence factor production was diminished and the oxidative stress response was impaired, whereas the type III secretion system was strongly induced. Moreover, P. aeruginosa motility was reduced, which probably accounts for the previously observed impaired biofilm formation capabilities of azithromycin-treated cultures. The interference of azithromycin with quorum-sensing-dependent virulence factor production, biofilm formation, and oxidative stress resistance in P. aeruginosa holds great promise for macrolide therapy in cystic fibrosis. Clearly quorum-sensing antagonist macrolides should be paid more attention in the management of chronic P. aeruginosa infections, and as quorum-sensing antagonists, macrolides might gain vital importance for more general application against chronic infections.

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Quorum sensing-regulated functions of Serratia marcescens are reduced by eugenol

Iranian Journal of Microbiology ◽

10.18502/ijm.v12i5.4607 ◽

2020 ◽

Author(s):

Zahra Fekrirad ◽

Basira Gattali ◽

Nasim Kashef

Keyword(s):

Quorum Sensing ◽

Serratia Marcescens ◽

Virulence Factor ◽

Biofilm Formation ◽

Protease Production ◽

Resistant Bacteria ◽

Pigment Formation ◽

Factor Production ◽

Regulated Functions ◽

Virulence Factor Production

Background and Objectives: Serratia marcescens has emerged as a nosocomial pathogen responsible for human infections, where antibiotic resistance further complicates the treatments. In S. marcescens, biofilm formation and virulence factor production are controlled via quorum sensing (QS) system. QS is a signaling system that enables gene regulation to control diverse physiological functions in bacteria. Essential oils have shown to be potential in diminishing the pathogenicity and virulence of drug-resistant bacteria. This study was performed to determine whether eugenol would affect QS system, biofilm formation and virulence factor production of S. marcescens. Materials and Methods: Biofilm formation, extracellular virulence factor production (hemolysin and protease), swarming motility and pigment formation of S. marcescens ATCC 13880 and S. marcescens Sm2 were assessed after eugenol exposure at 1.25 and 2.5 µg/ml concentrations. The expression of genes involved in motility (flhD), attachment (fimC), biofilm formation (bsmB, bsmA), and QS regulatory (swrR) were also evaluated. Results: Eugenol treatment at 1.25 and 2.5 µg/ml concentrations caused a significant reduction in biofilm formation. The pigment, hemolysin and protease production of two studied S. marcescens strains, also reduced significantly by eugenol treatments (p<0.05). The bsmA, bsmB, flhD and fimC genes were down-regulated after eugenol treatment. The swrR gene expression was also reduced significantly by eugenol in both S. marcescens strains (p<0.05). Conclusion: Eugenol inhibited quorum sensing-regulated functions of two studied S. marcescens strains.

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