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A cell-based infection assay identifies efflux pump modulators that reduce bacterial intracellular load.

Authors :
Reens, Abigail L.
Crooks, Amy L.
Su, Chih-Chia
Nagy, Toni A.
Reens, David L.
Podoll, Jessica D.
Edwards, Madeline E.
Yu, Edward W.
Detweiler, Corrella S.
Source :
PLoS Pathogens; 6/7/2018, Vol. 14 Issue 6, p1-29, 29p
Publication Year :
2018

Abstract

Bacterial efflux pumps transport small molecules from the cytoplasm or periplasm outside the cell. Efflux pump activity is typically increased in multi-drug resistant (MDR) pathogens; chemicals that inhibit efflux pumps may have potential for antibiotic development. Using an in-cell screen, we identified three efflux pump modulators (EPMs) from a drug diversity library. The screening platform uses macrophages infected with the human Gram-negative pathogen Salmonella enterica (Salmonella) to identify small molecules that prevent bacterial replication or survival within the host environment. A secondary screen for hit compounds that increase the accumulation of an efflux pump substrate, Hoechst 33342, identified three small molecules with activity comparable to the known efflux pump inhibitor PAβN (Phe-Arg β-naphthylamide). The three putative EPMs demonstrated significant antibacterial activity against Salmonella within primary and cell culture macrophages and within a human epithelial cell line. Unlike traditional antibiotics, the three compounds did not inhibit bacterial growth in standard microbiological media. The three compounds prevented energy-dependent efflux pump activity in Salmonella and bound the AcrB subunit of the AcrAB-TolC efflux system with K<subscript>D</subscript>s in the micromolar range. Moreover, the EPMs display antibacterial synergy with antimicrobial peptides, a class of host innate immune defense molecules present in body fluids and cells. The EPMs also had synergistic activity with antibiotics exported by AcrAB-TolC in broth and in macrophages and inhibited efflux pump activity in MDR Gram-negative ESKAPE clinical isolates. Thus, an in-cell screening approach identified EPMs that synergize with innate immunity to kill bacteria and have potential for development as adjuvants to antibiotics. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
15537366
Volume :
14
Issue :
6
Database :
Complementary Index
Journal :
PLoS Pathogens
Publication Type :
Academic Journal
Accession number :
130008453
Full Text :
https://doi.org/10.1371/journal.ppat.1007115