Single
and Double Mutations in gyrA but Not in gyrB Are
Associated with Low- and High-Level Fluoroquinolone Resistance in
Helicobacter
pylori

ABSTRACT In one French hospital the rate of resistance to ciprofloxacin in Helicobacter pylori was 3.3% (2 of 60 strains) in 1999. The six resistant clinical strains (four from 1996 and two from 1999) and three ciprofloxacin-selected single-step mutants studied carried one gyrA mutation but none in gyrB. Clinafloxacin and garenoxacin were the most active fluoroquinolones against these mutants. Occurrence of a second gyrA mutation was associated with high MICs of all fluoroquinolones tested.

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Development of fluoroquinolone resistance in Enterococcus faecalis and role of mutations in the DNA gyrase gyrA gene.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.11.2558 ◽

1996 ◽

Vol 40 (11) ◽

pp. 2558-2561 ◽

Cited By ~ 30

Author(s):

J Tankovic ◽

F Mahjoubi ◽

P Courvalin ◽

J Duval ◽

R Leclerco

Keyword(s):

Enterococcus Faecalis ◽

Resistant Isolate ◽

Fluoroquinolone Resistance ◽

Gyra Gene ◽

Single Clone ◽

Total Dna ◽

Resistant Strains ◽

French Hospital ◽

High Level

We have analyzed the development of fluoroquinolone resistance between 1986 and 1993 among clinical isolates of Enterococcus faecalis from a French hospital. One hundred randomly selected isolates per year were screened for resistance to ciprofloxacin (MIC > 2 micrograms/ml) and for high-level resistance to gentamicin (MIC > 1,000 micrograms/ml). The percentages of ciprofloxacin-resistant strains for these years were as follows: 1986, 0; 1987, 1; 1988 to 1989, 2; 1990, 6; 1991, 16; 1992, 24; and 1993, 14. Eighty-three percent of the ciprofloxacin-resistant isolates were coresistant to high levels of gentamicin. Forty-eight high-level gentamicin-resistant E. faecalis strains, which were resistant (24 strains) or susceptible (24 strains) to ciprofloxacin, were examined by pulsed-field gel electrophoresis (PFGE) of SmaI-digested total DNA. Numerous PFGE types were observed among the ciprofloxacin-susceptible isolates, whereas one type was largely predominant among the ciprofloxacin-resistant strains, which suggests that the increase in fluoroquinolone resistance was due to the spread of a single clone. A 241-bp fragment of gyrA, corresponding to the quinolone resistance-determining region, was amplified and sequenced for seven ciprofloxacin-resistant isolates. Six strains had high levels of resistance (MICs, 32 to 64 micrograms/ml) and had a mutation at position 83 (Escherichia coli coordinates) from Ser to Arg (three strains) or to Ile (two strains) or at position 87 from Glu to Gly (one strain), whereas the low-level-resistant isolate (MIC, 8 micrograms/ml) had no mutations.

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Acquisition of double mutation in gyrA caused high resistance to sitafloxacin in Helicobacter pylori after unsuccessful eradication with sitafloxacin-containing regimens

United European Gastroenterology Journal ◽

10.1177/2050640617737215 ◽

2017 ◽

Vol 6 (3) ◽

pp. 391-397 ◽

Cited By ~ 12

Author(s):

Hideki Mori ◽

Hidekazu Suzuki ◽

Juntaro Matsuzaki ◽

Tatsuhiro Masaoka ◽

Takanori Kanai

Keyword(s):

Helicobacter Pylori ◽

Randomized Study ◽

University Hospital ◽

Fluoroquinolone Resistance ◽

Infection Prevalence ◽

Double Mutation ◽

Before And After ◽

Pre Treatment ◽

H Pylori ◽

High Level

Background and aim Although sitafloxacin (STFX)-containing regimens are effective rescue treatments for Helicobacter pylori infection, prevalence of fluoroquinolone resistance in H. pylori has increased rapidly worldwide. The change in resistance levels and gyrA mutations, a major cause of fluoroquinolone resistance, after unsuccessful STFX-containing treatment has not been investigated. Methods We conducted a retrospective, non-randomized study to compare the minimum inhibitory concentrations (MICs) of STFX and the location of gyrA mutations in H. pylori before and after unsuccessful eradication with STFX-containing regimens at Keio University Hospital between December 2011 and March 2015. Results A total of 266 patients treated with STFX-containing regimens for third-line H. pylori eradication were evaluated. Double mutations in gyrA were acquired by 20.8% of strains that exhibited seven-fold increased STFX MICs, compared to pre-treatment MICs. The STFX MICs did not increase, however, when the location of the gyrA mutations did not change after treatment. Double mutations in gyrA developed in 60.0% of the strains in which eradication failed, which exhibited a baseline mutation at position D91, and in 11.1% of strains with baseline mutations at position N87. Conclusion Acquisition of double mutations in gyrA evoked high-level resistance to STFX in H. pylori after unsuccessful eradication with STFX-containing regimens.

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Gyrase mutations in laboratory-selected, fluoroquinolone-resistant mutants of Mycobacterium tuberculosis H37Ra.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.8.1768 ◽

1996 ◽

Vol 40 (8) ◽

pp. 1768-1774 ◽

Cited By ~ 72

Author(s):

T Kocagöz ◽

C J Hackbarth ◽

I Unsal ◽

E Y Rosenberg ◽

H Nikaido ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Fold Increase ◽

Single Step ◽

Fluoroquinolone Resistance ◽

Missense Mutations ◽

Gyrase A ◽

Gyra Mutation ◽

High Level ◽

Selection Of

To characterize mechanisms of resistance to fluoroquinolones by Mycobacterium tuberculosis, mutants of strain H37Ra were selected in vitro with ofloxacin. Their quinolone resistance-determining regions for gyrA and gyrB were amplified and sequenced to identify mutations in gyrase A or B. Three types of mutants were obtained: (i) one mutant (TKp1) had no mutations in gyrA or gyrB; (ii) mutants that had single missense mutations in gyrA, and (iii) mutants that had two missense mutations resulting in either two altered gyrase A residues or an altered residue in both gyrases A and B. The TKp1 mutant had slightly reduced levels of uptake of [14C]norfloxacin, which was associated with two- to fourfold increases in the MICs of ofloxacin, ciprofloxacin, and sparfloxacin. Gyrase mutations caused a much greater increase in the MICs of fluoroquinolones. For mutants with single gyrA mutations, the increases in the MICs were 4- to 16-fold, and for mutants with double gyrase mutations, the MICs were increased 32-fold or more compared with those for the parent. A gyrA mutation in TKp1 secondary mutants was associated with 32- to 128-fold increases in the MICs of ofloxacin and ciprofloxacin compared with the MICs for H37Ra and an eight-fold increase in the MIC of sparfloxacin. Sparfloxacin was the most active fluoroquinolone tested. No sparfloxacin-resistant single-step mutants were selected at concentrations of > 2.5 micrograms/ml, and high-level resistance (i.e., MIC, > and = 5 micrograms/ml) was associated with two gyrase mutations. Mutations in gyrB and possibly altered levels of intracellular accumulation of drug are two additional mechanisms that may be used by M. tuberculosis in the development of fluoroquinolone resistance. Because sparfloxacin is more active in vitro and selection of resistance appears to be less likely to occur, it may have important advantage over ofloxacin or ciprofloxacin for the treatment of tuberculosis.

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Type II topoisomerase mutations in Bacillus anthracis associated with high-level fluoroquinolone resistance

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkh294 ◽

2004 ◽

Vol 54 (1) ◽

pp. 90-94 ◽

Cited By ~ 26

Author(s):

D. J. Bast

Keyword(s):

Bacillus Anthracis ◽

Fluoroquinolone Resistance ◽

Type Ii ◽

High Level

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Distribution of SpontaneousgyrAMutations in 97 Fluoroquinolone-Resistant Helicobacter pylori Isolates Collected in France

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05243-11 ◽

2011 ◽

Vol 56 (1) ◽

pp. 550-551 ◽

Cited By ~ 30

Author(s):

Magali Garcia ◽

Josette Raymond ◽

Martine Garnier ◽

Julie Cremniter ◽

Christophe Burucoa

Keyword(s):

Helicobacter Pylori ◽

Quinolone Resistance ◽

Fluoroquinolone Resistance ◽

Content Type

ABSTRACTWe determined the prevalence ofgyrAmutations conferring fluoroquinolone resistance in 97Helicobacter pyloriisolates collected in France from 2007 to 2010. Ninety-four harbored one or two mutations already found in the quinolone resistance determining region (QRDR) ofgyrA(for T87I,n= 23; for N87K,n= 32; for D91N,n= 30; for D91G,n= 7; for D91Y,n= 6), 2 harbored a mutation never previously described (D91H and A88P), and one strain was resistant (ciprofloxacin MIC of 8 mg/liter) without a detected mutation conferring this resistance ingyrAorgyrBgenes.

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Characterization of high-level fluoroquinolone resistance in Escherichia coli O78:K80 isolated from turkeys

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/47.3.341 ◽

2001 ◽

Vol 47 (3) ◽

pp. 341-343 ◽

Cited By ~ 30

Author(s):

E. Giraud

Keyword(s):

Escherichia Coli ◽

Fluoroquinolone Resistance ◽

High Level

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E-Test or Agar Dilution for Metronidazole Susceptibility Testing of Helicobacter Pylori: Importance of the Prevalence of Metronidazole Resistance

10.21203/rs.3.rs-677597/v1 ◽

2021 ◽

Author(s):

Jinnan Chen ◽

Yu Huang ◽

Zhaohui Ding ◽

Xiao Liang ◽

Hong Lu

Keyword(s):

Helicobacter Pylori ◽

Susceptibility Testing ◽

Resistance Rate ◽

Test Method ◽

Major Error ◽

Metronidazole Resistance ◽

Agar Dilution ◽

H Pylori ◽

High Level ◽

Level Resistance

Abstract Background: A number of studies have shown that E-test overestimated the presence of Helicobacter pylori (H. pylori) resistance compared to agar dilution.Objective: The purpose of this study was to explore whether E-test could be an alternative for agar dilution to detect the metronidazole susceptibility of H. pylori.Method: E-test and agar dilution were used to assess susceptibility of H. pylori to metronidazole, clarithromycin and levofloxacin in 281 clinical isolates obtained from China where resistance was high. Cohen kappa analysis, McNemar test, essential and categorical agreement analysis were performed for these two methods. Results: Overall, the result of E-test showed similar prevalence of resistance rate to all antibiotics compared with agar dilution. The essential agreement (EA) of E-test method and agar dilution in the evaluation susceptibility of H. pylori to clarithromycin and levofloxacin were moderate, with 89.0% and 79.7% respectively, but only 45.9% for metronidazole. Results showed categorical agreement (CA) between E-test and agar dilution were 100% for both clarithromycin and levofloxacin. As for metronidazole, the CA was 98.7%, no major error was identified, and rate of very major error was 1.8%.Conclusion: E-test can be an alternative method to detect the metronidazole susceptibility of H. pylori in regions where high-level resistance is common.

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Contributions of individual mechanisms to fluoroquinolone resistance in 36 Escherichia coli strains isolated from humans and animals.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.10.2380 ◽

1996 ◽

Vol 40 (10) ◽

pp. 2380-2386 ◽

Cited By ~ 217

Author(s):

M J Everett ◽

Y F Jin ◽

V Ricci ◽

L J Piddock

Keyword(s):

Escherichia Coli ◽

Dna Sequences ◽

Quinolone Resistance ◽

Fluoroquinolone Resistance ◽

Polymorphism Analysis ◽

Single Mutation ◽

Wild Type ◽

Single Strand Conformational Polymorphism ◽

E Coli ◽

High Level

Twenty-eight human isolates of Escherichia coli from Argentina and Spain and eight veterinary isolates received from the Ministry of Agriculture Fisheries and Foods in the United Kingdom required 2 to > 128 micrograms of ciprofloxacin per ml for inhibition. Fragments of gyrA and parC encompassing the quinolone resistance-determining region were amplified by PCR, and the DNA sequences of the fragments were determined. All isolates contained a mutation in gyrA of a serine at position 83 (Ser83) to an Leu, and 26 isolates also contained a mutation of Asp87 to one of four amino acids: Asn (n = 14), Tyr (n = 6), Gly (n = 5), or His (n = 1). Twenty-four isolates contained a single mutation in parC, either a Ser80 to Ile (n = 17) or Arg (n = 2) or a Glu84 to Lys (n = 3). The role of a mutation in gyrB was investigated by introducing wild-type gyrB (pBP548) into all isolates; for three transformants MICs of ciprofloxacin were reduced; however, sequencing of PCR-derived fragments containing the gyrB quinolone resistance-determining region revealed no changes. The analogous region of parE was analyzed in 34 of 36 isolates by single-strand conformational polymorphism analysis and sequencing; however, no amino acid substitutions were discovered. The outer membrane protein and lipopolysaccharide profiles of all isolates were compared with those of reference strains, and the concentration of ciprofloxacin accumulated (with or without 100 microM carbony cyanide m-chlorophenylhydrazone [CCCP] was determined. Twenty-two isolates accumulated significantly lower concentrations of ciprofloxacin than the wild-type E. coli isolate; nine isolates accumulated less then half the concentration. The addition of CCCP increased the concentration of ciprofloxacin accumulated, and in all but one isolate the percent increase was greater than that in the control strains. The data indicate that high-level fluoroquinolone resistance in E. coli involves the acquisition of mutations at multiple loci.

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