Antibiotic resistance among Helicobacter pylori clinical isolates in Lima, Peru

Abstract

Objectives

Gastric carcinoma is the most common cancer and cause of cancer mortality in Peru. Helicobacter pylori, a bacterium that colonizes the human stomach, is a Group 1 carcinogen due to its causal relationship to gastric carcinoma. While eradication of H. pylori can help prevent gastric cancer, characterizing regional antibiotic resistance patterns is necessary to determine targeted treatment for each region. Thus, we examined primary antibiotic resistance in clinical isolates of H. pylori in Lima, Peru.

Materials and methods

H. pylori strains were isolated from gastric biopsies of patients with histologically proven H. pylori infection. Primary antibiotic resistance among isolates was examined using E-test strips. Isolates were examined for the presence of the cagA pathogenicity island and the vacA m1/m2 alleles via polymerase chain reaction.

Results

Seventy-six isolates were recovered from gastric biopsies. Clinical isolates showed evidence of antibiotic resistance to 1 (27.6%, n=21/76), 2 (28.9%, n=22/76), or ≥3 antibiotics (40.8%). Of 76 isolates, eight (10.5%) were resistant to amoxicillin and clarithromycin, which are part of the standard triple therapy for H. pylori infection. No trends were seen between the presence of cagA, vacA m1, or vacA m2 and antibiotic resistance.

Conclusion

The rate of antibiotic resistance among H. pylori isolates in Lima, Peru, is higher than expected and presents cause for concern. To develop more targeted eradication therapies for H. pylori in Peru, more research is needed to better characterize antibiotic resistance among a larger number of clinical isolates prospectively.

Keywords:

• H. pylori
• antibiotic resistance
• Peru
• amoxicillin

Acknowledgments

The authors wish to thank Dr. Jorge Huerta Mercado, Jefe del Servicio de Gastroenterologia del Hospital Cayetano Heredia, Lima, Peru, and all members of his GI team; Licenciada en Enfermeria Claudia Meza, del Servicio de Gastroenterologia del Hospital Cayetano Heredia, Lima, Peru; Alfredo A. Rodríguez, Consultant, Civil and Sanitation Engineer; Biologo Jorge Mucha and Engineer Leopoldo Goetendia, both from the Dirección de Saneamiento Basico, Dirección General de Salud Ambiental, Ministry of Health, Lima, Peru; Laboratorios Farmindustria, Lima, Peru, for their generous donation of anti H. pylori triple antibiotic therapy for indigent participants on this study; and Dr. Gary Goodman, MD, for his input on this study.

This work was supported, in part, by The Hope Foundation, Ann Arbor, MI, USA; The Graham Sustainability Institute, University of Michigan; The Center for Global Health, University of Michigan; and the National Cancer Institute, Division of Cancer Prevention, NCI Community Oncology Research Program (NCORP) Research Base grant to SWOG (1UG1CA189974-01). The sponsors of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

Author contributions

All authors participated in the design and conduct of the study. MV, AB, and INR directed the clinical trial. CX, KFB, KCT, and SO conducted the laboratory studies. RS performed the statistical analyses. All authors reviewed, critically revised, and approved the final manuscript.

Disclosure

LHB receives personal fees from Teva Pharmaceutical Industries Ltd. and Morphotek, Inc., for consulting/advisory role and is outside of the submitted work. All other authors report no conflicts of interest in this work.