MAO W, LEE A, WARREN M, CHO D, LOFLAND D, BLAIS J, HOSHINO K, ISHIDA Y, DUDLEY M, LOMOVSKAYA O; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. F-343.
Microcide Pharmaceuticals, Inc., Mountain View, CA
At least three multidrug resistance (MDR) efflux pumps (MexAB-OprM, MexCD-OprJ and MexEF-OprN), all belonging to the RND-family of transporters, contribute to fluoroquinolone resistance in clinical isolates of P. aeruginosa. We recently described a series of broad-spectrum efflux pump inhibitors (EPIs), exemplified by MC-207110, with activity against all three Mex pumps as well as RND pumps from E. coli and H. influenzae. Here we report the discovery of pump-selective EPIs (PS-EPIs) through high-throughput screening of our small molecule libraries. EPIs that selectively inhibit each one of the three Mex pumps were identified. The mode of action of these efflux pump inhibitors was confirmed using whole-cell accumulation assays. As a consequence of being pump-selective, these compounds potentiated the activity of levofloxacin only against strains of P. aeruginosa overexpressing the corresponding efflux pump. We hypothesized that using PS-EPIs singly or in combination may help to discriminate between the different efflux-mediated mechanisms of levofloxacin resistance, including simultaneous overexpression of multiple efflux pumps. To test this hypothesis we constructed a series of isogenic strains simultaneously overexpressing various combinations of the Mex pumps, including a strain overexpressing all three. Overexpression was confirmed using antibodies specific to the outer membrane components of the pumps. Levofloxacin MICs for these strains alone and in the presence of various PS-EPI cocktails were determined. Based on the levofloxacin potentiating activity of combinations of PS-EPIs, we were able to correctly predict, without exception, the involvement of each particular pump in levofloxacin resistance.
Publication Types:
Keywords:
- Dipeptides
- Drug Resistance, Multiple
- Fluoroquinolones
- Membrane Transport Proteins
- Microbial Sensitivity Tests
- Ofloxacin
- Pseudomonas aeruginosa
- phenylalanine arginine beta-naphthylamide
Other ID:
UI: 102269890
From Meeting Abstracts