Analysis of drug resistance and virulence‐factor genotype of Irish <i>Helicobacter pylori</i> strains: is there any relationship between resistance to metronidazole and <i>cagA</i> status?

Taneike, Ikue; Nami, Abdurrazag; OʼConnor, Anthony; Fitzgerald, Niamh; Murphy, Philip G.; Qasim, Asghar; O'Connor, H.J.; O’Moráin, Colm

doi:10.1111/j.1365-2036.2009.04095.x

Cited by 41 publications

(39 citation statements)

References 46 publications

(70 reference statements)

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“…The prevalence of cagA-positive H. pylori strains varies from one geographic region to another (29). In this research such as the study from Isfahan-Iran (30), the prevalence of cagA-positive H. pylori strains was 68.3% which is more similar to the findings reported from Western countries (18,27) and Brazil (31) than those reported from East or Southeast Asia (14,28,32). The presence of the cagA gene is thought to be associated with a further severe clinical outcome of the disease (3,27,(33)(34)(35).…”

Section: Discussionsupporting

confidence: 80%

“…Similarly, some studies also failed to find any general association between virulence markers and antibiotic resistance (18,22,37). This result is inconsistent with other studies that suggesting the statistically relation between drug resistance and cagA-positive strains (27,31,38,39). There is little information about the relation between the variability of the strain and any outcome on the drug resistance rates of H. pylori.…”

Section: Discussionmentioning

confidence: 89%

“…There are new facts about the existence of various strains of H. pylori with different levels of virulence (1,3,8,(25)(26)(27). The cagA gene is located at one end of a 40-kilobase DNA section called cag pathogenicity island (cag PAI) (28,29).…”

Section: Discussionmentioning

confidence: 99%

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Relationship Between Drug Resistance and cagA Gene in Helicobacter pylori

Ghotaslou

Milani

Akhi

et al. 2013

Jundishapur J Microbiol

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Background: Currently, there are evidences for the existence of diverse strains of Helicobacter pylori with different levels of virulence. In other way, the most important reason of therapeutic failure is resistance to the antibiotics. Objectives: The aim of this study was to evaluate the relationship between H. pylori drug resistance and the presence of cagA gene. Patients and Methods: Gastric biopsy specimens were cultured for H. pylori isolation. Resistance to antimicrobial agents, including clarithromycin, metronidazole, and amoxicillin were detected by modified disk agar diffusion tests. The cagA gene was detected using PCR, and the results were analyzed by χ2 and Fishers exact tests using SPSS software version 16. Results: A total of 123 H. pylori-positive patients (68 males, 55 females, mean age 35 ± 18 years old) were studied. The rate of resistance to clarithromycin, metronidazole and amoxicillin were 17.07, 78.86 and 27.64%, respectively. In this study, the cagA was detected in 84 of 123 strains (68.3%). The frequency of resistance to clarithromycin, metronidazole and amoxicillin in cagA positive confirmed microorganisms were, 16 (13.01%), 67 (54.47%) and 24 (19.51%), respectively. While the results for cagA negative ones were 5 (4.06%), 30 (24.39%) and 10 (8.13%), respectively. Conclusions: Our results indicated that the overall antibiotic resistance of H. pylori was high, and the relationship between drug resistance and cagA status was not statistically significant. Therefore, different treatment regimens are not recommended for patients with H. pyloricagA positive infections.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 89%

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Relationship Between Drug Resistance and cagA Gene in Helicobacter pylori

Ghotaslou

Milani

Akhi

et al. 2013

Jundishapur J Microbiol

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“…cagA is located in the cag pathogenicity island (PAI), which encodes a type IV secretion system, and the presence of cagA is closely associated with more severe gastric diseases (2,15,34). The VacA toxin induces vacuole formation in the host cells.…”

mentioning

confidence: 99%

High Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains and Risk Factors Associated with Resistance in Madrid, Spain

et al. 2010

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Clarithromycin is one of the antibiotics used for the treatment of Helicobacter pylori infections, and clarithromycin resistance is the most important factor when it comes to predicting eradication failure. The present study analyzed H. pylori isolates for the presence of 23S rRNA gene mutations and determined the risk factors associated with resistance among H. pylori isolates collected in Madrid, Spain, in 2008. We studied 118 H. pylori strains isolated from the same number of patients. A total of 76.3% of the patients were born in Spain, 52.7% were children, 20.3% had previously been treated, and 66.1% were female. Clarithromycin resistance was determined by Etest. H. pylori strains were considered resistant if the MIC was >1 mg/liter. DNA extraction was carried out by use of the NucliSens easyMAG platform with NucliSens magnetic extraction reagents (bioMérieux). The DNA sequences of the 23S rRNA genes of clarithromycin-resistant and -sensitive strains were determined to identify specific point mutations. The vacA genotype and cagA status were determined by PCR. We found that 42 (35.6%) strains were resistant to clarithromycin by Etest. Etest results were confirmed by detection of the presence of point mutations in 34 (88.1%) of these strains. Eight H. pylori strains were resistant to clarithromycin by Etest but did not have a point mutation in the 23S rRNA gene. Mutation at A2143G was found in 85.3% of the strains, mutation at A2142G in 8.8%, and mutation at T2182C in 5.9%. Dual mutations were found in 8.8% of the strains. H. pylori clarithromycin-resistant strains were strongly associated with pediatric patients, with patients born in Spain, and with patients who had previously been treated (P < 0.02). In addition, H. pylori strains resistant to clarithromycin more frequently presented the vacA s2/m2 genotype and were more likely to be cagA negative than susceptible strains (39.1% and 11.2%, respectively; P value < 0.001). We concluded that, in the present study, H. pylori clarithromycin-resistant strains are more frequently found in children, in patients mostly born in Spain, and in individuals who were previously treated for H. pylori infection and that these individuals are more likely colonized with a less virulent H. pylori strain.

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“…Upon H. pylori infection, CagA is translocated into gastric epithelial cells where it deregulates intracellular signalling pathways and thereby promotes lymphomagenesis [10]. H. pylori strains that do not encode cagA were associated with resistance to metronidazole, but not to clarithromycin [25][26][27]. CagA-specific antibodies are found in 89-96 % of sera from patients with gastric MALT lymphoma [18,19].…”

Section: Discussionmentioning

confidence: 99%

Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains in Gastric Mucosa-Associated Lymphoid Tissue Lymphoma Patients

et al. 2016

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Gastric MALT lymphoma is closely associated with Helicobacter pylori infection. Bacterial eradication therapy comprising clarithromycin is the first-line treatment in gastric MALT lymphoma patients. However, antimicrobial resistance to clarithromycin has been increasing in Europe, and thus far, it has not been examined in gastric MALT lymphoma patients. Based upon histopathological investigation, 17 adult gastric MALT lymphoma patients were identified to be related with H. pylori infection between 1997 and 2014. Detection of H. pylori infection in these patients and clarithromycin susceptibility testing were performed by 23S rRNA gene real-time PCR. Twelve of the patients were confirmed with H. pylori infection by real-time PCR. Among these patients, only two were found to be infected with clarithromycin-resistant H. pylori strain. In one of them, both the clarithromycin-resistant and sensitive genotype were detected. The rate of clarithromycin resistance was 15.4 %. Clarithromycin resistance pattern in gastric MALT lymphoma patients is under the predictions since a previous study performed in Central Europe revealed a rate of 36.6 % in Austria.Considering the low antimicrobial resistance rate, clarithromycin is still an option in gastric MALT lymphoma management.

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Analysis of drug resistance and virulence‐factor genotype of Irish Helicobacter pylori strains: is there any relationship between resistance to metronidazole and cagA status?

Abstract: SUMMARY BackgroundHelicobacter pylori infection is eradicated with antimicrobial agents and drug-resistant strains make successful treatment difficult. Geographical variations in virulence-factor genotype also exist.

Cited by 41 publications

References 46 publications

Relationship Between Drug Resistance and cagA Gene in Helicobacter pylori

Relationship Between Drug Resistance and cagA Gene in Helicobacter pylori

High Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains and Risk Factors Associated with Resistance in Madrid, Spain

Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains in Gastric Mucosa-Associated Lymphoid Tissue Lymphoma Patients

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