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Efficacy of chlorhexidine gluconate against Staphylococcus aureus in a respiratory epithelial infection model

Abstract number: P1906

Anderson M.J., Lin Y.C., Parks P.J., Peterson M.L.

Background:Staphylococcus aureus, a significant pathogen, can invade via skin or mucosal epithelium. Chlorhexidine gluconate (CHG) is a common antiseptic agent used at concentrations from 0.12% (oral rinses) to 4% (surgical site preparations) to minimise the risk of nosocomial infections. This study evaluated the efficacy of CHG against a clinical isolate of Staphylococcus aureus, MN8, using two in vitro respiratory epithelial infection models.

Methods:S. aureus MN8 invasion of lung epithelial cells (A549) was characterised using fluorescently labeled bacteria (BacLight, Molecular Probes), and flow cytometry. Extracellular fluorescence (bound but not internalised bacteria) was quenched using trypan blue. Confluent nasal (RPMI 2650) and lung (A549) epithelial cells were infected with S. aureus MN8 1×106 CFU/mL for 15 min prior to treatment with CHG (2.0–128 ug/mL; 0.0002 to 0.0128%) for 2 h. Antiseptic efficacy was evaluated by serial diluting and plating supernatants. Intracellular bacteria were enumerated by washing the adherent cells with PBS, resuspending in Triton X-100, serial dilution and plating. Cytotoxicity was evaluated by Cell Titer Aqueous One (Promega).

Results:S. aureus were bound to A549 within 10 min (16% of fluorescence) with approximately 50% being internal; therefore, we determined the ability of CHG to kill intra and extra-cellular S. aureus. At 2 h, complete S. aureus killing was observed in the supernatant at CHG geqslant R: gt-or-equal, slanted 64 ug/mL; and cell associated was achieved at CHG geqslant R: gt-or-equal, slanted 128 ug/mL.

Epithelial cell lineChlorhexidine gluconate
 S. aureus
geqslant R: gt-or-equal, slanted2 1og10 CFU/mL kill supernatant
S. aureus
geqslant R: gt-or-equal, slanted2 1og10 CFU/mL kill epithelial cell-associated
Epithelial cytotoxicity (LD50)
Nasal (RPMI 2650)geqslant R: gt-or-equal, slanted2 ug/mL (0.0002%)geqslant R: gt-or-equal, slanted16 ug/mL (0.0016%)geqslant R: gt-or-equal, slanted64 ug/mL (0.0064%)
Lung (A549)geqslant R: gt-or-equal, slanted4 ug/mL (0.0004%)geqslant R: gt-or-equal, slanted16 ug/mL (0.0016%)geqslant R: gt-or-equal, slanted128 ug/mL (0.0128%)

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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