The AcrAB-TolC Efflux Pump Impacts Persistence and Resistance Development in Stationary-Phase Escherichia coli following Delafloxacin Treatment

Abstract

Bacteria have a repertoire of strategies to overcome antibiotics in clinical use, complicating our ability to treat and cure infectious diseases. In addition to evolving resistance, bacteria within genetically clonal cultures can undergo transient phenotypic changes and tolerate high doses of antibiotics. These cells, termed persisters, exhibit heterogeneous phenotypes: the strategies that a bacterial population deploys to overcome one class of antibiotics can be distinct from those needed to survive treatment with drugs with another mode of action. It was previously reported that fluoroquinolones, which target DNA topoisomerases, retain the capacity to kill non-growing bacteria that tolerate other classes of antibiotics. Here, we show that in Escherichia coli stationary-phase cultures and colony biofilms, persisters that survive treatment with the anionic fluoroquinolone Delafloxacin depend on the AcrAB-TolC efflux pump. In contrast, we did not detect this dependence on AcrAB-TolC in E. coli persisters that survive treatment with three other fluroquinolone compounds. We found that the loss of AcrAB-TolC activity via genetic mutations or chemical inhibition not only reduces Delafloxacin persistence in non-growing E. coli MG1655 or EDL933 (an E. coli O157:H7 strain), it limits resistance development in progenies derived from Delafloxacin persisters that were given the opportunity to recover in nutritive media following antibiotic treatment. Our findings highlight the heterogeneity in defense mechanisms that persisters use to overcome different compounds within the same class of antibiotics. They further indicate that efflux pump inhibitors can potentiate the activity of Delafloxacin against stationary-phase E. coli and block resistance development in Delafloxacin persister progenies.

Comparative Metagenomic Study of Rhizospheric and Bulk Mercury-Contaminated Soils in the Mining District of Almadén

“…Among these, there is a large representation of MexAB-OprM and MexEF-OprN, along with MexCD-OprJ antibiotic transporters, related not only to antibiotic resistance but also mediate processes of quorum sensing ( Alcalde-Rico et al, 2018 ). Other antibiotic resistance predicted proteins found were those from AcrAB-TolC, a system responsible for the expulsion of antibiotics, such as penicillin G, cloxacillin, naphthyllin, macrolides, novobiocin, linezolid, and fusidic acid derivatives; this system is commonly associated with E. coli ( Anes et al, 2015 ; Byrd et al, 2021 ). Proteins from MdtABC genes have also been predicted in SEED, related TolC, which give resistance to novobiocin, quinolones and phosphomycin, among others ( Anes et al, 2015 ).…”

Probiotic Escherichia coli Nissle 1917 inhibits bacterial persisters that survive fluoroquinolone treatment

“…The precise molecular basis underlying the interaction between Levo-treated cells and E. coli Nissle will be the subject of future investigations. Nevertheless, as survival of persisters treated with certain antibiotics depends on the action of TolC-associated RND efflux pumps, our findings suggest that targeting efflux pump action can have dual function in bolstering the activities of certain antibiotics and probiotics like E. coli Nissle (Byrd et al, 2021;El Meouche & Dunlop, 2018;Pu et al, 2016).…”

“…Once antibiotic therapy ceases, these persisters can resume growth and potentially contribute to infection relapse (Fauvart et al, 2011; Van den Bergh et al, 2017). As progenies derived from surviving persisters can adapt to antibiotic exposure, antibiotic persistence has also been shown to accelerate the evolution towards heritable resistance (Barrett et al, 2019; Byrd et al, 2021; Levin‐Reisman et al, 2017; Liu et al, 2020).…”

“…These stresses can also enrich persisters that form in response to environmental triggers (Balaban et al, 2019; Brauner et al, 2016). Previously, our group and others demonstrated that some fluoroquinolones—a class of antibiotics that inhibits type II topoisomerases in bacteria and encompasses a number of compounds on the World Health Organizations list of essential medicines—can kill over 90% of slow−/non‐growing bacteria (Barrett et al, 2019; Byrd et al, 2021; Drlica & Zhao, 1997; Mok & Brynildsen, 2018; Völzing & Brynildsen, 2015; WHO, 2019). Persisters from non‐replicating cultures are not exempt from fluoroquinolone‐induced DNA damage (Völzing & Brynildsen, 2015).…”

Single-Cell Technologies to Study Phenotypic Heterogeneity and Bacterial Persisters

“…As a cell secretes metabolites and enzymes into its surroundings, the analytes will remain associated with that cell due to encapsulation within the same droplet [102]. Therefore, this offers a way to investigate the molecular identities of secreted or excreted products from a single cell and could be relevant to studying the role of antibiotic efflux in persistence [103][104][105].…”