Quorum sensing and virulence of Pseudomonas aeruginosa during urinary tract infections

Sezgi Senturk,Seyhan Ulusoy,Aysegul Yagci,Gulgun Bosgelmez-Tinaz

doi:10.3855/jidc.2543

Sezgi Senturk, Seyhan Ulusoy + Show 2 more

Open Access

https://doi.org/10.3855/jidc.2543

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Abstract

In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules. In vitro studies have suggested that the QS system is crucial in the pathogenesis of P. aeruginosa. However, it is unclear whether QS systems of P. aeruginosa play the same role during infections. In this study, to explore the contribution of QS systems to the pathogenesis of P. aeruginosa during urinary tract infections, we collected 82 clinical isolates. Detection of N-acyl-homoserine lactones (C12-HSL and C4-HSL) was performed on agar plates employing biosensor strains C. violaceum. Elastase and biofilm production were determined spectrophotometrically. QS genes were detected by PCR and subsequently underwent sequencing. Six isolates were found to be negative in the production of both C12-HSL and C4-HSL and all virulence factors tested. PCR analysis of these isolates revealed that four isolates contained all four QS genes while one isolate was negative for lasR gene, and one isolate negative for lasI, lasR and rhlR genes. Sequence analyses of these isolates showed that the lasR, lasI, rhlR and rhlI genes had point mutations. The combination of these mutations probably explains their C12-HSL, C4-HSL and virulence factor deficiencies. Results of this study suggest that QS deficient clinical isolates occur and are still capable of causing clinical infections in humans.

Highlights

In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules
To determine the contribution of QS systems to the pathogenesis of P. aeruginosa during urinary tract infections, 82 isolates were obtained from patients with urinary tract infections at Marmara University Hospital
In vitro levels of elastase produced by the 82 clinical isolates were compared with those produced by the lasR mutant strain (PAO-JP3) and QS wild-type strain (PAO1)

Summary

Introduction

In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules. Sequence analyses of these isolates showed that the lasR, lasI, rhlR and rhlI genes had point mutations The combination of these mutations probably explains their C12-HSL, C4-HSL and virulence factor deficiencies. Pseudomonas aeruginosa is an opportunistic human pathogen that preferentially infects patients with cancer or AIDS, patients immunocompromised by surgery, cytotoxic drugs or burn wounds, people with cystic fibrosis or blood, skin, eye and genitourinary tract infections 1,2. One of the reasons that P. aeruginosa is a successful opportunistic pathogen is that it produces an array of virulence factors, including elastases (LasB and LasA), alkaline protease, pyocyanin and rhamnolipids 5 The genes encoding these virulence factors are often controlled in a cell-dependent fashion through a mechanism known as quorum sensing (QS). The las system comprises LasI, which is responsible for the synthesis of N-(3oxododecanoyl)-L-homoserine lactone

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