Isolation and Characterization of Tetracycline-Resistant Clinical Isolates of
            <i>Helicobacter pylori</i>

Kwon, Dong H.; Kim, J. J.; Lee, M.; Yamaoka, Yoshio; Kato, Mototsugu; Osato, Michael S.; El-Zaatari, F. A. K.; Graham, David Y.

doi:10.1128/aac.44.11.3203-3205.2000

Cited by 45 publications

(46 citation statements)

References 14 publications

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“…All isolates tested in the present study were frozen at least once, and the low prevalence of the resistance phenotype may be due to loss during storage. Primary resistance to tetracycline ranges between 5 and 59% in Asian countries (14,24,27). Around 15% of the isolates in the present study were tetracycline …”

Section: Eradication Ofmentioning

confidence: 94%

Antimicrobial Susceptibility of Helicobacter pylori Strains Isolated in Bangladesh

et al. 2004

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Antimicrobial susceptibility of 120 Helicobacter pylori isolates to metronidazole, tetracycline, clarithromycin, and amoxicillin was determined, and 77.5, 15, 10, and 6.6% of the isolates, respectively, were resistant. Only rdxA inactivation and both rdxA and frxA inactivation were responsible for metronidazole resistance in 66% (8 of 12) and 33% (4 of 12) of the isolates, respectively. Eradication ofHelicobacter pylori infection by treatment with two antimicrobial agents (clarithromycin and amoxicillin or metronidazole) and a proton pump inhibitor is recommended by various consensus groups (10,16,20). Antimicrobial resistance in H. pylori is a growing problem as it is the most important factor in determining treatment outcome. The prevalence of antimicrobial resistance varies with geographical regions (3, 25). Metronidazole resistance in H. pylori has been shown to be due to mutation in rdxA; mutation in frxA has also been shown to be associated with metronidazole resistance (11,12,23). In Bangladesh, the prevalences of H. pylori infection among infants, children, and adults are 61, 84, and 92%, respectively (1, 21, 22); however, information on antimicrobial susceptibility to commonly used drugs in H. pylori treatment is lacking. This study was conducted to evaluate (i) the prevalence of primary antibiotic resistance to commonly used antimicrobial agents and (ii) the genetic basis for metronidazole resistance in H. pylori isolates from Bangladesh.Consecutive patients attending the Gastroenterology Department of Dhaka Medical College Hospital for upper gastrointestinal endoscopy were enrolled during 1999 to 2001. Diagnosis of peptic ulcer (PU) and non-ulcer dyspepsia (NUD) or gastritis was based on endoscopic examination of the stomach and duodenum. Biopsy samples were taken from each patient for culture.Bacteria were grown in brain heart infusion agar with 7% sheep blood and incubated at 37°C in 5% O 2 , 10% CO 2 , and 85% N 2 for 3 to 6 days. The MICs of amoxicillin, clarithromycin, metronidazole, and tetracycline for the isolates were determined by the agar dilution method as described elsewhere (18,19). All tests were repeated twice, and H. pylori 26695 was used as a control. ␤-Lactamase production was tested by the chromogenic cephalosporin method (6). The molecular mechanism of susceptibility and resistance to metronidazole was studied in 12 isolates. Metronidazole-susceptible (Mtz s ) isolates were further studied (by inactivation of rdxA alone or rdxA and frxA for conversion into an Mtz r phenotype) by transformation of Mtz s isolates with plasmids pBS-rdxA-cam (rdxA::cat) and pBS-frxA-kan (frxA::kan) as described earlier (11,12).A total of 278 consecutive patients between 15 and 78 years of age were enrolled, and among them, 72.7% (202 patients) were male and 27.3% (76 patients) were female. Among the patients, 162 had PU and 116 had NUD and 62.6% (174 of 278) were culture positive for H. pylori. Among the culturepositive patients, 121 (69.5%) were male and 53 (30.4%) were female and 112 (64.3%) had PU ...

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Section: Eradication Ofmentioning

confidence: 94%

Antimicrobial Susceptibility of Helicobacter pylori Strains Isolated in Bangladesh

et al. 2004

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“…They were also resistant to metronidazole (E-test MIC, Ն32 g/ml). This crossresistance to tetracycline and metronidazole was also identified in a study of tetracycline-resistant H. pylori isolates from Korea and Japan (14). Furthermore, the resistance to both tetracycline and metronidazole was transferred to susceptible strains by transformation with the genomic DNA of the resistant organisms.…”

mentioning

confidence: 88%

“…However, with the use of tetracycline in therapy, tetracycline-resistant isolates have started to emerge at low levels, on average 5 to 7% of isolates (12,14). In one recent study of clinical isolates from Shanghai, China, the level of tetracycline resistance was an astonishing 59% (39).…”

mentioning

confidence: 99%

Mutations in the 16S rRNA Genes ofHelicobacter pyloriMediate Resistance to Tetracycline

Trieber¹,

2002

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Low-cost and rescue treatments for Helicobacter pylori infections involve combinations of several drugs including tetracycline. Resistance to tetracycline has recently emerged in H. pylori. The 16S rRNA gene sequences of two tetracycline-resistant clinical isolates (MIC ‫؍‬ 64 g/ml) were determined and compared to the consensus H. pylori 16S rRNA sequence. One isolate had four nucleotide substitutions, and the other had four substitutions and two deletions. Natural transformation with the 16S rRNA genes from the resistant organisms conferred tetracycline resistance on susceptible strains. 16S rRNA genes containing the individual mutations were constructed and tested for the ability to confer resistance. Only the 16S rRNA gene containing the triple mutation, AGA965-967TTC, was able to confer tetracycline resistance on H. pylori 26695. The MICs of tetracycline for the transformed strains were equivalent to those for the original clinical isolates. The two original isolates were also metronidazole resistant, but this trait was not linked to the tetracycline resistance phenotype. Serial passage of several H. pylori strains on increasing concentrations of tetracycline yielded mutants with only a very modest increase in tetracycline resistance to a MIC of 4 to 8 g/ml. These mutants all had a deletion of G942 in the 16S rRNA genes. The mutations in the 16S rRNA are clearly responsible for tetracycline resistance in H. pylori.

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“…Resistance to amoxicillin, tetracycline and furazolidone has been already reported in different countries, including Brazil (7,10,20,24) , with a potential negative impact in treatment outcome. We were not able to detected resistant strains to these antimicrobials among our clinical isolates (Table 1).…”

Section: Antimicrobialsmentioning

confidence: 99%

Helicobacter pylori antibiotic resistance in Brazil: clarithromycin is still a good option

Eisig

Silva

Barbuti

et al. 2011

Arq. Gastroenterol.

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-Context -The antibiotic susceptibility is the cornerstone for the eradication therapies of Helicobacter pylori. Objectives -To evaluate the prevalence of primary resistance of H. pylori was evaluated in an urban Brazilian population. Methods -H. pylori isolates were obtained from patients submitted to an upper gastrointestinal endoscopy for the evaluation of dyspeptic symptoms.Biopsies from antrum, corpus and fundus were taken to determine the antibiotic susceptibility of H. pylori isolates. The minimal inhibitory concentration of furazolidone and bismuth were routinely determined by agar dilution method and the minimal inhibitory for amoxicillin, clarithromycin, tetracycline, levofloxacin, and metronidazole were routinely determined with the E-test. ResultsFifty-four patients were included. In vitro antimicrobial susceptibility of H. pylori strains were obtained from 39 patients. Resistance to metronidazole was detected in 20 patients (51%), to clarithromycin in 3 patients (8%), to levofloxacin in 9 patients (23%) and to bismuth in 2 patients (5%). There was no observed resistance to amoxicillin, tetracycline or furazolidone. Conclusion -Due to the low amoxicillin and clarithromycin resistance observed in this study, therapies using these antimicrobials remain appropriated first-line H. pylori therapy.

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Isolation and Characterization of Tetracycline-Resistant Clinical Isolates of Helicobacter pylori

Cited by 45 publications

References 14 publications

Antimicrobial Susceptibility of Helicobacter pylori Strains Isolated in Bangladesh

Antimicrobial Susceptibility of Helicobacter pylori Strains Isolated in Bangladesh

Mutations in the 16S rRNA Genes ofHelicobacter pyloriMediate Resistance to Tetracycline

Helicobacter pylori antibiotic resistance in Brazil: clarithromycin is still a good option

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