Heterogeneity of Strains Isolated from Patients with Gastric Disorders in Guiyang, China.

PURPOSE

Chronic infection causes peptic ulcers in a subpopulation of individuals and is a risk factor for the development of gastric cancer. Multiple infections and heteroresistant contribute to poor treatment efficacy. Here, we investigated the extent of genetic diversity among strains within a given host and its influence on the results of antibiotic (metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline) susceptibility testing.

MATERIALS AND METHODS

Gastric mucosa biopsy samples were obtained from patients with gastric disorders, including 48 positive patients, who were never previously treated for infection. Five potential colonies isolated from each sample were subcultured for enrichment. Enriched colonies were identified through Gram staining and assays for urease, oxidase, and catalase. For each monoclonal colony, the antibiotic susceptibility was assessed, genomic DNA was sequenced, and the () genotype was verified. Co-infection with multiple strains was determined using random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR).

RESULTS

Thirteen gastric mucosa biopsy samples were positive for . Five monoclonal strains isolated from each of these 13 patients were identified as . RAPD-PCR indicated that intra-patient monoclonal strains of in 10 of the 13 samples exhibited heterogeneity. Among the 13 patients, intra-patient monoclonal strains isolated from 4 patients had identical genotype, whereas intra-patient monoclonal strains isolated from the other 9 patients harbored more than one genotype. The antibiotic susceptibility of five intra-patient monoclonal strains from seven patients was inconsistent.

CONCLUSION

The existence of heterogeneous strains with resistance to different drugs and virulence were common within the gastric mucosa of an individual patient.