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Pathogens 2017, 6(4), 52;

Characterization of Three Ocular Clinical Isolates of P. aeruginosa: Viability, Biofilm Formation, Adherence, Infectivity, and Effects of Glycyrrhizin

Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201, USA
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266071, China
Author to whom correspondence should be addressed.
Received: 30 September 2017 / Revised: 15 October 2017 / Accepted: 19 October 2017 / Published: 24 October 2017
(This article belongs to the Special Issue Signaling Systems in Pseudomonas aeruginosa Biofilm)
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We selectively characterized three isolates from Pseudomonas aeruginosa keratitis patients and how glycyrrhizin (GLY) affected them. Type III toxins were determined using polymerase chain reaction (PCR). Minimum Inhibitory Concentration (MIC) of GLY and assays for its effects on: time kill, bacterial permeability, and biofilm/adhesion were done. In vivo, C57BL/6 (B6) mice were treated topically with GLY after G81007 infection. Clinical score, photography with a slit lamp and RT-PCR were used to assess treatment effects. Isolates expressed exoS and exoT, but not exoU. MIC for all isolates was 40 mg/mL GLY and bacteriostatic effects were seen for G81007 after treatment using time kill assays. From viability testing, GLY treatment significantly increased the number of permeabilized bacteria (live/dead assay). Isolates 070490 and G81007 formed more biofilms compared with R59733 and PAO1 (control). GLY-treated bacteria had diminished biofilm compared with controls for all isolates. GLY reduced adherence of the G81007 isolate to cultured cells and affected specific biofilm associated systems tested by reverse transcription PCR (RT-PCR). In vivo, after G81007 infection, GLY treatment reduced clinical score and messenger RNA (mRNA) expression of IL-1β, TNF-α, CXCL2 and HMGB1. This study provides evidence that GLY is bacteriostatic for G81007. It also affects biofilm production, adherence to cultured cells, and an improved keratitis outcome. View Full-Text
Keywords: Pseudomonas aeruginosa; keratitis; mice; glycyrrhizin Pseudomonas aeruginosa; keratitis; mice; glycyrrhizin

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Peng, X.; Ekanayaka, S.A.; McClellan, S.A.; Barrett, R.P.; Vistisen, K.; Hazlett, L.D. Characterization of Three Ocular Clinical Isolates of P. aeruginosa: Viability, Biofilm Formation, Adherence, Infectivity, and Effects of Glycyrrhizin. Pathogens 2017, 6, 52.

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