Identification of Campylobacter pyloridis isolates by restriction endonuclease DNA analysis.

Campylobacter pyloridis isolates recovered from gastric biopsy specimens of 16 patients were examined by restriction endonuclease DNA analysis with HindIII. For 8 of these 16 patients two different isolates were compared to study the persistence of the colonizing strains and the stability of their DNA digest patterns during a period of 2 years (two patients), the identity or nonidentity of different colony types within one culture (two patients), and the nature of the relapses after apparently successful antibacterial therapy (four patients). The isolates from the 16 patients all produced different DNA digest patterns. Comparison of the two different isolates recovered from the same patients showed that these isolates were identical in all eight cases. Laboratory subculturing of a C. pyloridis strain (10 times) did not change its DNA digest pattern. These results indicate the stability of the DNA digest patterns and a marked variability of these patterns among isolates from different patients. Using restriction endonuclease DNA analysis, we found the persistence in the stomach of the same C. pyloridis strain during a period of 2 years and the identity of different colony types within one culture. The relapses after apparently successful antibacterial treatment could be attributed to recrudescence rather than reinfection. Restriction endonuclease DNA analysis is a sensitive and useful method for identifying C. pyloridis isolates.