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. 2017 Jul 19:8:1370.
doi: 10.3389/fmicb.2017.01370. eCollection 2017.

Cellular Response to Ciprofloxacin in Low-Level Quinolone-Resistant Escherichia coli

Jesús Machuca  1   2 , Esther Recacha  1   2 , Alejandra Briales  3   4 , Paula Díaz-de-Alba  1 , Jesús Blazquez  2   3   5 , Álvaro Pascual  1   2   3 , José-Manuel Rodríguez-Martínez  2   3   4
Affiliations

Cellular Response to Ciprofloxacin in Low-Level Quinolone-Resistant Escherichia coli

Jesús Machuca et al. Front Microbiol. .

Abstract

Bactericidal activity of quinolones has been related to a combination of DNA fragmentation, reactive oxygen species (ROS) production and programmed cell death (PCD) systems. The underlying molecular systems responsible for reducing bactericidal effect during antimicrobial therapy in low-level quinolone resistance (LLQR) phenotypes need to be clarified. To do this and also define possible new antimicrobial targets, the transcriptome profile of isogenic Escherichia coli harboring quinolone resistance mechanisms in the presence of a clinical relevant concentration of ciprofloxacin was evaluated. A marked differential response to ciprofloxacin of either up- or downregulation was observed in LLQR strains. Multiple genes implicated in ROS modulation (related to the TCA cycle, aerobic respiration and detoxification systems) were upregulated (sdhC up to 63.5-fold) in mutants with LLQR. SOS system components were downregulated (recA up to 30.7-fold). yihE, a protective kinase coding for PCD, was also upregulated (up to 5.2-fold). SdhC inhibition sensitized LLQR phenotypes (up to ΔLog = 2.3 after 24 h). At clinically relevant concentrations of ciprofloxacin, gene expression patterns in critical systems to bacterial survival and mutant development were significantly modified in LLQR phenotypes. Chemical inhibition of SdhC (succinate dehydrogenase) validated modulation of ROS as an interesting target for bacterial sensitization.

Keywords: ciprofloxacin; global response; low-level quinolone resistance; sensitization; survival; transcriptomic.

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Figures

FIGURE 1
FIGURE 1
Global expression profiles of cells with low-level quinolone resistance (LLQR) exposed to 1 μg/mL of ciprofloxacin and compared with the wild-type cells in the same conditions. (A) Number of differentially up- and downregulated genes (≥ or ≤5-fold) in the presence of ciprofloxacin (1 μg/mL) in LLQR cells compared to wild-type cells in the same conditions. (B) Number of genes up- or downregulated, grouped according to the factor of differential expression in LLQR cells compared to the wild-type cells in the same conditions. Genes were included when differences were significant (p < 0.05). EC14 means E. coli ATCC 25922 pBK-QnrS1; EC19 means E. coli ATCC 25922 ΔmarR pBK-QnrS1; and EC24 means E. coli ATCC 25922 S83L pBK-QnrS1.
FIGURE 2
FIGURE 2
Gene expression classified by COG (Cluster of Orthologous Groups) (Tatusov et al., 2000) for functional categories (greater than or equal to 30-fold, p-value < 0.05).
FIGURE 3
FIGURE 3
Overlap between differently expressed genes (greater than or equal to 30-fold, p-value < 0.05) on exposure to ciprofloxacin (1 μg/mL) between low-level quinolone resistant (LLQR) cells compared to the wild-type cells in the same conditions. Venn diagram shows the overlap. The numbers indicated on the diagram refer to the number of genes with significantly altered expression levels in one or both conditions. LLQR phenotypes: EC14 means E. coli ATCC 25922 pBK-QnrS1; EC19 means E. coli ATCC 25922 ΔmarR pBK-QnrS1; and EC24 means E. coli ATCC 25922 S83L pBK-QnrS1.
FIGURE 4
FIGURE 4
Impact on ROS response of low-level quinolone-resistant (LLQR) cells exposed to 1 μg/mL of ciprofloxacin compared to wild-type cells in the same conditions. LLQR phenotypes: EC14 means E. coli ATCC 25922 pBK-QnrS1; EC19 means E. coli ATCC 25922 ΔmarR pBK-QnrS1; and EC24 means E. coli ATCC 25922 S83L pBK-QnrS1. All indicated genes show a significantly different pattern of expression between LLQR strains and wild-type E. coli (p-value < 0.05). Standard deviations were within 10% of the means.
FIGURE 5
FIGURE 5
Impact on SOS response of low-level quinolone-resistant (LLQR) cells exposed to 1 μg/mL of ciprofloxacin, compared to wild-type cells in the same conditions. LLQR phenotypes: EC14 means E. coli ATCC 25922 pBK-QnrS1; EC19 means E. coli ATCC 25922 ΔmarR pBK-QnrS1; and EC24 means E. coli ATCC 25922 S83L pBK-QnrS1. All indicated genes shown a pattern of expression significantly different among LLQR strains and wild-type E. coli (p-value < 0.05). Standard deviations were within 10% of the means.
FIGURE 6
FIGURE 6
Evaluation of susceptibility to killing by ciprofloxacin (A–C), ofloxacin (D–F), and combination treatments with carboxin (500 μM). Fluoroquinolone concentrations tested were equivalent to 2xMIC values. Data are plotted as mean ± standard deviation.
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References

    1. Baharoglu Z., Mazel D. (2014). SOS, the formidable strategy of bacteria against aggressions. FEMS Microbiol. Rev. 38 1126–1145. 10.1111/1574-6976.12077 - DOI - PubMed
    1. Baym M., Stone L. K., Kishony R. (2016). Multidrug evolutionary strategies to reverse antibiotic resistance. Science 351:aad3292 10.1126/science.aad3292 - DOI - PMC - PubMed
    1. Blair J. M. A., Webber M. A., Baylay A. J., Ogbolu D. O., Piddock L. J. V. (2015). Molecular mechanisms of antibiotic resistance. Nat. Rev. Microbiol. 13 42–51. 10.1038/nrmicro3380 - DOI - PubMed
    1. Briales A., Rodriguez-Martinez J. M., Velasco C., Diaz de Alba P., Dominguez-Herrera J., Pachon J., et al. (2011). In vitro effect of qnrA1, qnrB1, and qnrS1 genes on fluoroquinolone activity against isogenic Escherichia coli isolates with mutations in gyrA and parC. Antimicrob. Agents Chemother. 55 1266–1269. 10.1128/AAC.00927-10 - DOI - PMC - PubMed
    1. Brynildsen M. P., Winkler J. A., Spina C. S., MacDonald I. C., Collins J. J. (2013). Potentiating antibacterial activity by predictably enhancing endogenous microbial ROS production. Nat. Biotechnol. 31 160–165. 10.1038/nbt.2458 - DOI - PMC - PubMed