Quorum sensing inhibitory activity of sub-inhibitory concentrations of β-lactams

Introduction: The virulence factors of Pseudomonas aeruginosa are under the control of quorum sensing (QS) signals. Hence, interference with QS prevents its pathogenesis.

Objective: The aim of the present research is to assess the influence of some β-lactam antibiotics on cell communication and the release of different virulence factors.

Methods: The minimal inhibitory concentrations of ceftazidime, cefepime and imipenem were evaluated by microbroth dilution method. The effect of sub-inhibitory concentration of the tested antibiotics on QS signals was investigated using reporter strain assay. In addition, different virulence factors (elastase, protease, pyocyanin and hemolysin) were estimated in the presence of their sub-inhibitory concentrations.

Results: Low concentrations of ceftazidime, cefepime and imipenem caused significant elimination of the QS signals 3OHC12- HSL and C4-HSL up to 1/20 MIC. Furthermore, low concentrations of the tested antimicrobials suppressed virulence factors elastase and hemolysin. Moreover, 1/20 of their MICs reduced elastase, protease, pyocyanin and hemolysin.

Conclusion: Utilization of β-lactam antibiotics at low concentrations could be an effective approach for prevention and treatment of P. aeruginosa infection.

Keywords: Quorum sensing inhibition, β-lactams, Pseudomonas aeruginosa

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