Efflux pump inhibitors reduce the invasiveness of Pseudomonas aeruginosa

Abstract number: 1733_315

Hirakata Y., Kondo A., Hoshino K., Miyazaki T., Kurihara S., Izumikawa K., Seki M., Yanagihara K., Miyazaki Y., Kamihira S., Kohno S.

Objectives: We have recently shown a mexAB-oprM deletion strain (delta-ABM) derived from P. aeruginosa PAO1 was compromised in its capacity to invade or transmigrate into MDCK cells (Hirakata Y, et al. J Exp Med 2002; 196: 109). These data suggest that P. aeruginosa exports invasion determinants predominantly using MexAB-OprM efflux system. On the other hand, multi-drug efflux systems are thought to contribute to the intrinsic resistance of a number of the antimicrobials. MexAB-OprM is known to be constitutively expressed in P. aeruginosa PAO1. We studied the influence of efflux pump inhibitors (EPIs), broad-spectrum efflux inhibitor MC-207,110 and MexAB-OprM specific efflux pump inhibitor (ABS-EPI) D13–9001, on the P. aeruginosa invasion using the Madin-Darby canine kidney (MDCK) epithelial cell monolayer penetration assay model.

Methods:P. aeruginosa PAO1, its delta-ABM mutant, nalB (MexAB-OprM overproducing strain) mutant, and nfxB (MexCD-OprJ overproducing strain) mutant were used in this study. Broad-spectrum EPI, Phe-Arg b-naphthylamide (MC-207,110) and MexAB-OprM-specific efflux pump inhibitor (ABS-EPI) D13–9001 were used. MDCK cell monolayer penetration assay was performed as reported previously (Hirakata Y, et al. J Infect Dis 2000; 181: 765). Bacterial strains were cultured together with several concentrations of EPIs in LB broth overnight at 37°C with vigorous shaking. The bacteria in the baso-lateral medium were counted by plating at timed intervals.

Results: The invasiveness of PAO1 wild-type (WT) and nalB (MexAB-OprM overproducing strain) was concentration-dependently inhibited in the presence of EPIs. However, the invasiveness of nfxB (MexCD-OprJ overproducing strain) was not reduced in the presence of EPIs.

Conclusion: The findings support that invasion determinant(s) are predominantly exported by P. aeruginosa via MexAB-OprM, and that the EPIs are useful to reduce not only antimicrobial resistance but also the invasiveness of P. aeruginosa.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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