Article

Rapid detection of clarithromycin resistant Helicobacter pylori strains in Spanish patients by polymerase chain reaction-restriction fragment length polymorphism

Hospital de la Princesa, Madrid, Spain.
Revista espanola de quimioterapia: publicacion oficial de la Sociedad Espanola de Quimioterapia (Impact Factor: 0.8). 03/2011; 24(1):32-6.
Source: PubMed

ABSTRACT

The aim of this study was to characterize the mutations types present in the 23S rRNA gene related to H. pylori clarithromycin-resistance strains in Spain and evaluate a novel PCR-RFLP method for detection of the most frequent point mutation in our population.
Gastric biopsies were obtained by endoscopy from patients with gastric symptoms. H. pylori was cultured according to standard microbiological procedures and clarithromycin resistance was determined by E-test. DNA extraction was performed by NucliSens platform with the NucliSens magnetic extraction reagents (bioMérieux) according to the manufacturer instructions. Analyses for point mutations in 23S rRNA gene strains were performed by sequence analysis of amplified polymerase chain reaction products. Restriction fragment length polymorphism was performed using BsaI enzyme to detect restriction sites that correspond to the mutation (A2143G).
We found 42 out of 118 (35.6%) strains resistant to clarithromycin by E-test. E-test results were confirmed for the presence of point mutation in 34 (88.1%) of these strains. Mutation A2143G was found in 85.3% of the strains. Analyses with the restriction enzyme BsaI was able to confirm the presence of A2143G mutation. There were 8 H. pylori strains resistant to clarithromycin by E-test but without any point mutation in the 23 rRNA gene.
We conclude that PCR-RFLP is a reliable method to detect clarithromycin-resistance H. pylori strains in countries with a high prevalence of clarithromycin-resistance as Spain. It may be useful before choosing regimens of H. pylori eradication.

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    Full-text · Article · Jul 2014 · PLoS ONE
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    • ". pylori ATCC 700684; M — Molecular Weight Marker (50 bp O'Gene Ruler, Thermo Scientific, USA). 2014 K. Klesiewicz and others graud, 2004; Raymond et al., 2007; Agudo et al., 2011 "
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    ABSTRACT: Background: The occurrence of clarithromycin resistance among Helicobacter pylori strains is a major cause of the treatment failure. Resistance to this drug is conferred by point mutations in 23S rRNA gene and the most prevalent mutations are A2143G and A2142G. The aim of the study was to evaluate the occurrence of A2143G and A2142G mutations in a group of H. pylori strains resistant to clarithromycin. Materials and methods: The study included 21 clarithromycin-resistant H. pylori strains collected between 2006 and 2009 in southern Poland. Resistance to clarithromycin was quantitatively tested with the E-test to determine the minimal inhibitory concentration (MIC value). The point mutations of H. pylori isolates were detected by PCR followed by RFLP analysis. Results: The MIC values for clarithromycin for the analyzed strains ranged from 1.5 mg/L to 64 mg/L. Nine H. pylori strains exhibited A2143G mutation and A2142G mutation was found in 9 isolates as well. The results of RFLP analysis of 3 clarithromycin-resistant strains were negative for both mutations. The average MIC values for A2143G and A2142G mutants were 6 and 30 mg/L, respectively. Conclusions: Frequencies of A2143G and A2142G mutations were the same in all isolates tested. Strains with A2143G mutation exhibited lower MIC values than A2142G mutants. Application of PCR-RFLP method for detection of clarithromycin resistance allows for better and more efficient management of H. pylori infections.
    Full-text · Article · Jun 2014 · Acta biochimica Polonica
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    • "Besides the resistance loci A2142G and A2143G, several other less frequent resistance loci have been described, such as 23S rRNA mutations at positions 2058 and 2059, which are found in various geographic locations (including Japan) but have not yet been detected in European H. pylori isolates [10]. Mutation at T2182C was found in 5.9% of isolates in Spain [9]. It is also known that in addition to mutations in the 23S rRNA gene, other mechanisms are important in CLR resistance in vivo, in particular an active multidrug efflux mechanism of H. pylori[11]. "
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    ABSTRACT: Background: Clarithromycin (CLR) is the most commonly recommended antibiotic in Helicobacter pylori eradication regimens, but the prevalence of CLR-resistant H. pylori is increasing. CLR resistance is associated with mutations in the 23S rRNA gene. However, H. pylori eradication can still be achieved with triple therapy, and an additive effect may occur with multiple antibiotics. Methods: Twenty-six CLR-resistant strains were examined. The MIC of clarithromycin was determined by agar-dilution-testing on Columbia agar, as described elsewhere. The conserved region of the H. pylori 23S rRNA gene between nucleotide positions 1445 and 2846 [GenBank: U27270] was amplified. RFLP and sequence analysis were performed with the 1402-bp PCR product. Synergy between clarithromycin and amoxicillin was assessed using the agar dilution checkerboard technique. To confirm the correlation between mutation and synergistic effect with subinhibitory concentrations of AMX, site-directed mutagenesis was performed in four CLR-susceptible H. pylori isolates. Results: Twenty-six clarithromycin-resistant strains were examined. The conserved region of the H. pylori 23S rRNA gene was amplified, and the purified PCR product was checked for mutations by restriction fragment length polymorphism (RFLP) analysis and sequencing. A synergistic effect was found in only three of the 12 H. pylori strains (25%) with the A2142G mutation and five of the 10 H. pylori strains (50%) with the A2143G mutation (fractional inhibitory concentration: FIC < 0.5, minimal inhibitory concentration: MIC<2 mg/L) was found. Site-directed mutagenesis was performed in four CLR-susceptible H. pylori isolates.Three of these isolates harboring a mutation in position A2143G grew under selection with CLR (MIC >16 mg/L), and all three strains showed the synergistic effect (FIC<0.5). In contrast, three of the same four strains transformed with DNA fragments with a mutation in position A2142G were resistant to CLR (MIC>16 mg/L) and showed no synergism with amoxicillin (FIC>2). Conclusions: Here we demonstrate that in 100% of the in vitro transformed strains, a mutation at position A2143G leads to a synergistic effect between clarithromycin and amoxicillin, whereas a mutation at position at A2142G had no discernible effect.
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