scholarly journals Prevalence and Characteristic of Swine-Origin mcr-1-Positive Escherichia coli in Northeastern China

2021 ◽  
Vol 12 ◽  
Author(s):  
Ping Cheng ◽  
Yuqi Yang ◽  
Sai Cao ◽  
Haibin Liu ◽  
Xiaoting Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Plasmid Stability ◽  
Horizontal Transmission ◽  
Northeastern China ◽  
Public Attention ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Food Animal ◽  
Potential Possibility

The emergence of the plasmid-mediated colistin resistance gene mcr-1 is threatening the last-line role of colistin in human medicine. With mcr-1-positive Escherichia coli (E. coli) isolated from food animal being frequently reported in China, the prevalence of mcr-1 in food animal has attracted public attention. In the present study, a total of 105 colistin-resistant E. coli strains were isolated from 200 fecal samples collected from six swine farms in northeastern China. mcr-PCR revealed that the prevalence of mcr-1 in colistin-resistant E. coli was 53.33% (56/105). mcr-1-positive E. coli showed extensive antimicrobial resistance profiles with the presence of additional resistance genes, increased expression of multidrug efflux pump-associated genes, and increased biofilm formation ability. MLST differentiated all the mcr-1-positive E. coli into 25 sequence types (STs) and five unknown ST, and the most common ST was ST10 (n = 11). By phylogenetic group classification, the distribution of all mcr-1-positive E. coli belonging to groups A, B1, B2, and D was 46.43, 35.71, 5.36, and 5.36%, respectively. Conjugation experiment demonstrated that most of the mcr-1 were transferable at frequencies of 2.68 × 10–6–3.73 × 10–3 among 30 representative mcr-1-positive E. coli. The plasmid replicon types IncI2 (n = 9), IncX4 (n = 5), IncHI2 (n = 3), IncN (n = 3), and IncP (n = 1) were detected in the transconjugants. The results of growth assay, competition experiment, and plasmid stability testing showed that acquisition of mcr-1-harboring plasmids could reduce the fitness of bacterial hosts, but mcr-1 remained stable in the recipient strain. Due to the potential possibility of these mcr-1-positive E. coli being transmitted to humans through the food chain or through horizontal transmission, therefore, it is necessary to continuously monitor the prevalence and dissemination of mcr-1 in food animal, particularly in swine.

scholarly journals Genetic Characterization of Highly Fluoroquinolone-Resistant Clinical Escherichia coli Strains from China: Role ofacrR Mutations

2001 ◽  
Vol 45 (5) ◽  
pp. 1515-1521 ◽  
Author(s):  
Hui Wang ◽  
Joann L. Dzink-Fox ◽  
Minjun Chen ◽  
Stuart B. Levy
Keyword(s):  
Escherichia Coli ◽  
Blot Analysis ◽  
Genetic Basis ◽  
Efflux Pump ◽  
Pcr Amplification ◽  
Fluoroquinolone Resistance ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
High Level

ABSTRACT The genetic basis for fluoroquinolone resistance was examined in 30 high-level fluoroquinolone-resistant Escherichia coliclinical isolates from Beijing, China. Each strain also demonstrated resistance to a variety of other antibiotics. PCR sequence analysis of the quinolone resistance-determining region of the topoisomerase genes (gyrA/B, parC) revealed three to five mutations known to be associated with fluoroquinolone resistance. Western blot analysis failed to demonstrate overexpression of MarA, and Northern blot analysis did not detect overexpression of soxS RNA in any of the clinical strains. The AcrA protein of the AcrAB multidrug efflux pump was overexpressed in 19 of 30 strains of E. colitested, and all 19 strains were tolerant to organic solvents. PCR amplification of the complete acrR (regulator/repressor) gene of eight isolates revealed amino acid changes in four isolates, a 9-bp deletion in another, and a 22-bp duplication in a sixth strain. Complementation with a plasmid-borne wild-type acrR gene reduced the level of AcrA in the mutants and partially restored antibiotic susceptibility 1.5- to 6-fold. This study shows that mutations in acrR are an additional genetic basis for fluoroquinolone resistance.

scholarly journals Expression in Escherichia coli of a New Multidrug Efflux Pump, MexXY, from Pseudomonas aeruginosa

1999 ◽  
Vol 43 (2) ◽  
pp. 415-417 ◽  
Author(s):  
Tomoyuki Mine ◽  
Yuji Morita ◽  
Atsuko Kataoka ◽  
Tohru Mizushima ◽  
Tomofusa Tsuchiya
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Multidrug Resistance ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Expression In Escherichia Coli ◽  
New Genes

ABSTRACT Two new genes (mexXY) similar to mexAB,mexCD, and mexEF and mediating multidrug resistance were cloned from the chromosome of Pseudomonas aeruginosa. Elevated ethidium extrusion was observed withEscherichia coli cells harboring the plasmid carryingmexXY. This MexXY system confers higher resistance to fluoroquinolones than the MexAB and MexCD systems, and E. coli TolC or P. aeruginosa OprM is necessary for the function of the MexXY system.

scholarly journals The channel-tunnel HI1462 of Haemophilus influenzae reveals differences to Escherichia coli TolC

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1639-1647 ◽  
Author(s):  
Georg Polleichtner ◽  
Christian Andersen
Keyword(s):  
Escherichia Coli ◽  
Single Channel ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Tunnel Entrance

Efflux pumps play a major role in multidrug resistance of pathogenic bacteria. The TolC homologue HI1462 was identified as the single channel-tunnel in Haemophilus influenzae required to form a functional multidrug efflux pump. The outer-membrane protein was expressed in Escherichia coli, purified and reconstituted in black lipid membranes. It exhibited a comparatively small single-channel conductance of 43 pS in 1 M KCl and is the first known TolC homologue which is anion-selective. The HI1462 structure was modelled and an arginine residue lining the tunnel entrance was identified. The channel-tunnel of a mutant with the arginine substituted by an alanine residue was cation-selective and had a sevenfold higher single-channel conductance compared to wild-type. These results confirm that the arginine is responsible for anion selectivity and forms a salt bridge with a glutamate residue of the adjacent monomer, establishing a circular network, which keeps the tunnel entrance in a tightly closed conformation. In in vivo experiments, both the wild-type HI1462 and the mutant were able to substitute for E. coli TolC in the haemolysin secretion system, but not in the AcrAB/TolC multidrug efflux pump. The structure–function relationship of HI1462 is discussed in the context of the well-studied TolC channel-tunnel of E. coli.

scholarly journals MarA-Like Regulator of Multidrug Resistance in Yersinia pestis

2006 ◽  
Vol 50 (9) ◽  
pp. 2971-2975 ◽  
Author(s):  
Rupa A. Udani ◽  
Stuart B. Levy
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistance ◽  
Yersinia Pestis ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
N Terminus ◽  
Resistant Mutants

ABSTRACT MarA47Yp from Yersinia pestis, showing 47% identity to Escherichia coli MarA in its N terminus, caused resistance to antibiotics and to organic solvents when expressed in both E. coli and Y. pestis. Resistance was linked to increased expression of the AcrAB multidrug efflux pump. In four of five spontaneous multidrug-resistant mutants of Y. pestis independently selected by growth on tetracycline, the marA47 Yp gene was overexpressed. The findings suggest that marA47 Yp is a marA ortholog in Y. pestis.

scholarly journals The eefABC Multidrug Efflux Pump Operon Is Repressed by H-NS in Enterobacter aerogenes

2005 ◽  
Vol 187 (11) ◽  
pp. 3894-3897 ◽  
Author(s):  
Muriel Masi ◽  
Jean-Marie Pagès ◽  
Claude Villard ◽  
Elizabeth Pradel
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Enterobacter Aerogenes ◽  
Dominant Negative ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Laboratory Conditions ◽  
Wide Range

ABSTRACT The Enterobacter aerogenes eefABC locus, which encodes a tripartite efflux pump, was cloned by complementation of an Escherichia coli tolC mutant. E. aerogenes ΔacrA expressing EefABC became less susceptible to a wide range of antibiotics. Data from eef::lacZ fusions showed that eefABC was not transcribed in the various laboratory conditions tested. However, increased transcription from Peef was observed in an E. coli hns mutant. In addition, EefA was detected in E. aerogenes expressing a dominant negative E. coli hns allele.

Novel mechanisms of TolC-independent decreased bile-salt susceptibility in Escherichia coli

2020 ◽  
Vol 367 (10) ◽  
Author(s):  
Vuong Van Hung Le ◽  
Patrick J Biggs ◽  
David Wheeler ◽  
Ieuan G Davies ◽  
Jasna Rakonjac
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Sodium Deoxycholate ◽  
Coli Strain ◽  
Receptor Protein ◽  
Phosphotransferase System ◽  
Multidrug Efflux Pump ◽  
Knock Out ◽  
E Coli ◽  
Camp Receptor

ABSTRACT Bile salts, including sodium deoxycholate (DOC), are secreted into the intestine to aid fat digestion and contribute to antimicrobial protection. Gram-negative pathogens such as Escherichia coli, however, are highly resistant to DOC, using multiple mechanisms of which the multidrug efflux pump AcrAB-TolC is the dominant one. Given that TolC-mediated efflux masks the interaction of DOC with potential targets, we sought to identify those targets by identifying genes whose mutations cause an increase in the MIC to DOC relative to the ∆tolC parental strain, that lacks TolC-associated functional efflux pumps. Using a mutant screen, we isolated twenty independent spontaneous mutants that had a higher MICDOC than the E. coli parental ∆tolC strain. Whole genome sequencing of these mutants mapped most mutations to the ptsI or cyaA gene. Analysis of knock-out mutants and complementation showed that elimination of PtsI, a component of the carbohydrate phosphotransferase system, or one of the two key proteins involved in cAMP synthesis and signaling, adenylate cyclase (CyaA) or cAMP receptor protein (Crp) causes low-level increased resistance of a ∆tolC E. coli strain to DOC.

scholarly journals Mechanisms Accounting for Fluoroquinolone Resistance in Escherichia coli Clinical Isolates

2008 ◽  
Vol 53 (1) ◽  
pp. 235-241 ◽  
Author(s):  
Sonia K. Morgan-Linnell ◽  
Lauren Becnel Boyd ◽  
David Steffen ◽  
Lynn Zechiedrich
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Multidrug Efflux Pump ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Genes Encoding

ABSTRACT Fluoroquinolone MICs are increased through the acquisition of chromosomal mutations in the genes encoding gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE), increased levels of the multidrug efflux pump AcrAB, and the plasmid-borne genes aac(6′)-Ib-cr and the qnr variants in Escherichia coli. In the accompanying report, we found that ciprofloxacin, gatifloxacin, levofloxacin, and norfloxacin MICs for fluoroquinolone-resistant E. coli clinical isolates were very high and widely varied (L. Becnel Boyd, M. J. Maynard, S. K. Morgan-Linnell, L. B. Horton, R. Sucgang, R. J. Hamill, J. Rojo Jimenez, J. Versalovic, D. Steffen, and L. Zechiedrich, Antimicrob. Agents Chemother. 53:229-234, 2009). Here, we sequenced gyrA, gyrB, parC, and parE; screened for aac(6′)-Ib-cr and qnrA; and quantified AcrA levels in E. coli isolates for which patient sex, age, location, and site of infection were known. We found that (i) all fluoroquinolone-resistant isolates had gyrA mutations; (ii) ∼85% of gyrA mutants also had parC mutations; (iii) the ciprofloxacin and norfloxacin MICs for isolates harboring aac(6′)-Ib-cr (∼23%) were significantly higher, but the gatifloxacin and levofloxacin MICs were not; (iv) no isolate had qnrA; and (v) ∼33% of the fluoroquinolone-resistant isolates had increased AcrA levels. Increased AcrA correlated with nonsusceptibility to the fluoroquinolones but did not correlate with nonsusceptibility to any other antimicrobial agents reported from hospital antibiograms. Known mechanisms accounted for the fluoroquinolone MICs of 50 to 70% of the isolates; the remaining included isolates for which the MICs were up to 1,500-fold higher than expected. Thus, additional, unknown fluoroquinolone resistance mechanisms must be present in some clinical isolates.

scholarly journals Plasmid-Encoded Multidrug Efflux Pump Conferring Resistance to Olaquindox in Escherichia coli

2004 ◽  
Vol 48 (9) ◽  
pp. 3332-3337 ◽  
Author(s):  
Lars Hestbjerg Hansen ◽  
Elsebetta Johannesen ◽  
Mette Burmølle ◽  
Anders Hay Sørensen ◽  
Søren J. Sørensen
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Open Reading Frames ◽  
Conjugative Plasmid ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Control Plasmid ◽  
Reading Frames

ABSTRACT We report here the first gene-encoded resistance mechanism to the swine growth enhancer olaquindox. The genetic elements involved in resistance to olaquindox were subcloned and sequenced from a conjugative plasmid isolated from Escherichia coli. The subcloned fragment contained two open reading frames, oqxA and oqxB, that are homologous to several resistance-nodulation-cell-division family efflux systems from different species. The putative protein sequences were aligned to both experimentally verified and putative efflux pumps. We show that oqxA and oqxB are expressed in E. coli. Plasmids containing the oqxAB genes yielded high (>128 μg/ml) resistance to olaquindox in E. coli, whereas strains containing the control plasmid showed low resistance to the drug (8 μg/ml). The oqxAB-encoded pump also conferred high (>64 μg/ml) resistance to chloramphenicol. We demonstrate that the subcloned fragment conferred H+-dependent ethidium efflux abilities to E. coli strain N43. In addition, we show that the efflux system is dependent on the host TolC outer membrane protein when expressed in E. coli.

The assembly and disassembly of the AcrAB-TolC three-component multidrug efflux pump

2015 ◽  
Vol 396 (9-10) ◽  
pp. 1083-1089 ◽  
Author(s):  
Reinke Tobias Müller ◽  
Klaas Martinus Pos
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Electrochemical Gradient ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Gram Negative ◽  
E Coli ◽  
Pump Assembly ◽  
Multiple Antibiotics

Abstract In Gram-negative bacteria, tripartite efflux pumps, like AcrAB-TolC from Escherichia coli, play a prominent role in the resistance against multiple antibiotics. Transport of the drugs across the outer membrane and its coupling to the electrochemical gradient is dependent on the presence of all three components. As the activity of the E. coli AcrAB-TolC efflux pump is dependent on both the concentration of substrates and the extent of the electrochemical gradient across the inner membrane, the dynamics of tripartite pump assembly and disassembly might be crucial for effective net transport of drugs towards the outside of the cell.

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