Mutations in the 23S rRNA gene are associated with clarithromycin resistance in Helicobacter pylori isolates in Brazil

Ribeiro, Marcelo Lima; Vitiello, L; Miranda, Maíra C. B.; Benvengo, Yune Helena Borges; Godoy, Anita Paula Ortiz de; Mendonça, Sérgio; Pedrazzoli, José

doi:10.1186/1476-0711-2-11

Cited by 34 publications

(25 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, four previously reported nucleotide substitutions were identified in 9 other isolates with MICs ranging from 4 to 32 µg/mL, 2116A>G (n = 3/10 CLR-resistant isolates), 2142A>G (n = 1), 2143A>G (n = 3), and 2182T>C (n = 2) [6,7,31]. Variation at position 2116A>G was associated high MICs to CLR (16 and 32 µg/mL) as compared to other observed nucleotide substitutions in the 23S rRNA gene.…”

Section: Resultsmentioning

confidence: 99%

“…Following 3-day incubation at 37 °C under microaerophilic conditions, Etest ® strips were read and resistance to an antibiotic determined using breakpoint concentrations as follows: MTZ (>8 µg/mL), CLR (>1 µg/mL), AML (>1 µg/mL), TET (>1 µg/mL), and CIP (>1 µg/mL). Breakpoint concentrations were defined on the basis of previously approved clinical laboratory standards [6,25–27]. Helicobacter pylori strain 26695 was included as an antibiotic susceptibility testing quality control.…”

Section: Methodsmentioning

confidence: 99%

“…Amino acid substitutions in the sequences of oxygen-independent NADPH nitroreductase (RdxA) and NADH flavin oxidoreductase (FrxA) have been reported to be associated with metronidazole (MTZ) resistance [4,5]. Point mutations in 23S ribosomal RNA (23S rRNA ) and amino acid changes in penicillin binding protein 1 (Pbp1) have been shown to cause clarithromycin (CLR) and amoxicillin (AML) resistance, respectively [6–9]. …”

mentioning

confidence: 99%

See 2 more Smart Citations

Analysis of Clinical Isolates of Helicobacter pylori in Pakistan Reveals High Degrees of Pathogenicity and High Frequencies of Antibiotic Resistance

et al. 2014

View full text Add to dashboard Cite

Background Antibiotic resistance in Helicobacter pylori contributes to failure in eradicating the infection and is most often due to point and missense mutations in a few key genes. Methods The antibiotic susceptibility profiles of H. pylori isolates from 46 Pakistani patients were determined by Etest. Resistance and pathogenicity genes were amplified, and sequences were analyzed to determine the presence of mutations. Results A high percentage of isolates (73.9%) were resistant to metronidazole (MTZ), with considerable resistance to clarithromycin (CLR; 47.8%) and amoxicillin (AML; 54.3%) also observed. Relatively few isolates were resistant to tetracycline (TET; 4.3%) or to ciprofloxacin (CIP; 13%). However, most isolates (n = 43) exhibited resistance to one or more antibiotics. MTZ-resistant isolates contained missense mutations in oxygen-independent NADPH nitroreductase (RdxA; 8 mutations found) and NADH flavin oxidoreductase (FrxA; 4 mutations found). In the 23S rRNA gene, responsible for CLR resistance, a new point mutation (A2181G) and 4 previously reported mutations were identified. Pathogenicity genes cagA, dupA, and vacA s1a/m1 were detected frequently in isolates which were also found to be resistant to MTZ, CLR, and AML. A high percentage of CagA and VacA seropositivity was also observed in these patients. Phylogenetic analysis of partial sequences showed uniform distribution of the 3′ region of cagA throughout the tree. Conclusions We have identified H. pylori isolates in Pakistan which harbor pathogenicity genes and worrying antibiotic resistance profiles as a result of having acquired multiple point and missense mutations. H. pylori eradication regimens should therefore be reevaluated in this setting.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Analysis of Clinical Isolates of Helicobacter pylori in Pakistan Reveals High Degrees of Pathogenicity and High Frequencies of Antibiotic Resistance

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Mutation G3A in rdxA was successfully transformed into metronidazolesusceptible strain 26695-1, which had a low metronidazole MIC (16 mg/liter). Although the methodology has been established and used not only for experiments on metronidazole resistance (38,(45)(46)(47)(48) but also for clarithromycin (32), tetracycline (49), fluoroquinolones (50,51), and amoxicillin (52,53), spontaneous mutations may have occurred under the metronidazole selection introduced during our experiment. However, no transformants were obtained with the plates containing 2.0 mg/liter metronidazole when the metronidazole-susceptible strain 26695-1 was transformed with PCR products without any mutations, which suggests that spontaneous mutations are unlikely to account for the resistant phenotype observed.…”

Section: Discussionmentioning

confidence: 99%

Search for Novel Candidate Mutations for Metronidazole Resistance in Helicobacter pylori Using Next-Generation Sequencing

Binh

Suzuki

Trang

et al. 2015

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Metronidazole resistance is a key factor associated with Helicobacter pylori treatment failure. Although this resistance is mainly associated with mutations in the rdxA and frxA genes, the question of whether metronidazole resistance is caused by the inactivation of frxA alone is still debated. Furthermore, it is unclear whether there are other mutations involved in addition to the two genes that are associated with resistance. A metronidazole-resistant strain was cultured from the metronidazole-susceptible H. pylori strain 26695-1 by exposure to low concentrations of metronidazole. The genome sequences of both susceptible and resistant H. pylori strains were determined by Illumina next-generation sequencing, from which putative candidate resistance mutations were identified. Natural transformation was used to introduce PCR products containing candidate mutations into the susceptible parent strain 26695-1, and the metronidazole MIC was determined for each strain. Mutations in frxA (hp0642), rdxA (hp0954), and rpsU (hp0562) were confirmed by the Sanger method. The mutated sequence in rdxA was successfully transformed into strain 26695-1, and the transformants showed resistance to metronidazole. The transformants containing a single mutation in rdxA showed a low MIC (16 mg/liter), while those containing mutations in both rdxA and frxA showed a higher MIC (48 mg/ liter). No transformants containing a single mutation in frxA or rpsU were obtained. Next-generation sequencing was used to identify mutations related to drug resistance. We confirmed that the mutations in rdxA are mainly associated with metronidazole resistance, and mutations in frxA are able to enhance H. pylori resistance only in the presence of rdxA mutations. Moreover, mutations in rpsU may play a role in metronidazole resistance. Helicobacter pylori is a spiral-shaped Gram-negative bacterium that infects more than half of the world's population and is a major cause of chronic gastritis, peptic ulcer diseases, gastric cancer, and mucosa-associated lymphoid tissue lymphoma (1, 2). The eradication of H. pylori not only improves peptic ulcer healing but also prevents its recurrence and reduces the risk of developing gastric cancer (3-5). Furthermore, other H. pylori-related disorders, such as mucosa-associated lymphoid tissue lymphoma, atrophic gastritis, and intestinal metaplasia, have been shown to regress after antimicrobial therapy (6-8). Metronidazole has been used widely in combination therapies, such as metronidazolebased triple therapy, concomitant therapy, and bismuth-containing quadruple therapy, to eradicate this bacterium (5, 9, 10). Although treatment success depends on several factors, such as smoking status and patient compliance, antibiotic resistance is the major cause of treatment failure (11-13). However, along with clarithromycin resistance, resistance to metronidazole has arisen independently and is becoming increasingly common (14, 15).Resistance to metronidazole was described previously and is predominantly associated with mutation...

show abstract

“…This explains why not all strains are associated with clinical symptoms [10]. Strains of H. pylori with cagA positive are more virulent than others.…”

Section: Introductionmentioning

confidence: 99%

Helicobacter pylori Pathogenicity Associated cagA and vacA Genotypes Among Nigerian Dyspeptic Patients

E¹,

Emmanuel²,

Eu³

2017

J Mol Biomark Diagn

View full text Add to dashboard Cite

Objective: Although Helicobacter pylori infection is endemic in Nigeria, the specific genotypes that influence treatment responses are scarcely known. We aimed to determine the specific genotypes of H. pylori virulence genes, vacA and cagA in dyspeptic patients. Subjects and methods:Gastric biopsy samples were obtained from 80 dyspeptic patients referred for endoscopy. Genomic DNA was extracted from biopsies using the ReliaPrep DNA kit. H. pylori DNA was detected by a singleplex PCR based on the genus specific 16s rRNA gene. The vacA subtypes for the s1 and s2 regions and the m1 and m2 alleles were detected by allele specific multiplex PCR. The cagA gene was amplified by a singleplex PCR. Results:Of the 80 samples, 30 (37.5%) had abnormal mucosa which were chronic gastritis. The rest (62.5%) had normal mucosa lining. Of the 30 chronic gastritis cases, 22 (73%) had H. pylori infection as detected by 16s rRNA PCR. Only 2 (4%) of the normal mucosa cases had H. pylori infection. For the vacA genotypes, 79% of the H. pylori infections were s1c/m2 genotype, followed by 8% s1b/m2 genotype. Three different genotypes: s1c/m1/m2, s1c/s2/m2 and s1c/m1 occurred at 4% each. The most virulent vacA genotype, s1/m1 was only 8% while the least virulent vacA genotype s2/m2 was 4%. The moderate virulent vacA genotype, s1/m2 was the most prevalent (83%) in the Nigerian patients. The most prevalent subtype was the s1c/m2. Only 7 cases (29%) were cagA positive. Conclusion:The pathogenicity-associated virulence genes present in Nigerian dyspeptic patients were moderate types. The endemicity of the disease may not necessarily lead to high rate of fatal outcomes or treatment failures as reported in other parts of the world.

show abstract

Mutations in the 23S rRNA gene are associated with clarithromycin resistance in Helicobacter pylori isolates in Brazil

Cited by 34 publications

References 24 publications

Analysis of Clinical Isolates of Helicobacter pylori in Pakistan Reveals High Degrees of Pathogenicity and High Frequencies of Antibiotic Resistance

Analysis of Clinical Isolates of Helicobacter pylori in Pakistan Reveals High Degrees of Pathogenicity and High Frequencies of Antibiotic Resistance

Search for Novel Candidate Mutations for Metronidazole Resistance in Helicobacter pylori Using Next-Generation Sequencing

Helicobacter pylori Pathogenicity Associated cagA and vacA Genotypes Among Nigerian Dyspeptic Patients

Contact Info

Product

Resources

About