Correlation of quorum sensing and virulence factors in Pseudomonas aeruginosa isolates in Egypt

Abstract

Introduction: Pseudomonas aeruginosa is one of the most virulent nosocomial pathogens worldwide. Quorum sensing (QS) regulates the production of pathogenic virulence factors and biofilm formation in P. aeruginosa. The four genes lasR, lasI, rhlR,and rhlI were found to regulate this QS system. In this study, we aimed to assess the correlation between these four genes and QS-dependent virulence factors and to detect the inhibitory effect of clove oil on QS. Methodology: Fifty P. aeruginosa clinical isolates were collected. Susceptibility to different antibiotics was tested. Virulence factors including biofilm formation, pyocyanin production, and twitching motility were phenotypically detected. QS genes were amplified by polymerase chain reaction (PCR), and one strain subsequently underwent sequencing. The inhibitory effect of clove oil on virulence factors was also tested. Results: A positive correlation was found between biofilm formation and the presence of lasR and rhlI genes. Twitching motility was positively correlated with the presence of lasR, lasI, and rhlI genes. On the other hand, no correlation was found between pyocyanin production and any of the studied genes. Only one isolate amplified all the tested QS gene primers, but it did not express any of the tested virulence factors phenotypically. Sequence analyses of this isolate showed that the four genes had point mutations. Conclusions: Results emphasize the importance of QS in P. aeruginosa virulence; however, QS-deficient clinical isolates occur and are still capable of causing clinical infections in humans. Also, clove oil has an obvious inhibitory effect on QS, which should be clinically exploited.

High prevalence of atypical virulotype and genetically diverse background among Pseudomonas aeruginosa isolates from a referral hospital in the Brazilian Amazon

“…aeruginosa is coordinated by the las and rhl systems that function hierarchically for bacterial survival in the face of environmental changes, biofilm formation and control of several other virulence factors [ 10 , 12 ]. Although a decrease in the ability to express virulence factors has been reported due to the absence and/or mutations in genes related to such QS, this does not necessarily compromise the ability to cause infection due to regulation mediated by the rhl system [ 12 , 68 , 69 ] Our results are in agreement with a study carried out by Senturk et al [ 12 ] and Ruiz-Roldán et al [ 56 ]; however, disagreeing with Aboushleib et al [ 69 ], who reported gene deficiency in more than 60% in clinical isolates.…”

Quorum Sensing: A Prospective Therapeutic Target for Bacterial Diseases

“…For example, Gram-negative Pseudomonas aeruginosa produces virulence factors, such as pyocyanin, elastase, lectin, and exotoxin A [47,48], and Gram-positive Staphylococcus aureus produces virulence factors such as fibronectin binding protein, hemolysin, protein A, lipase, and enterotoxin [49,50]. Studies have shown that the production of these virulence factors is regulated by the bacterial QS signaling systems [51,52]. Disruption of QS to control the production of virulence factors seems to be an attractive broad-spectrum therapeutic strategy.…”

Study of quorum-sensing LasR and RhlR genes and their dependent virulence factors in Pseudomonas aeruginosa isolates from infected burn wounds

“…Certainly, pyocyanin secretion is under the control of the rhl systems. As well, PQS controls rhl-dependent virulence-factor production such as pyocyanin [ 34 ] , as regards lasR , the study done by Abou shleib and his colleagues found that there was no statistical significant value between pyocyanin production and the studied lasR gene [ 35 ]. In contrast, in our study we found a statistically significant difference between lasR -positive isolates and lasR -negative isolates regarding pyocyanin production ( P value=0.035).…”