LONG-TERM COLONIZATION WITH SINGLE AND MULTIPLE STRAINS OF HELICOBACTER-PYLORI ASSESSED BY DNA-FINGERPRINTING

The gastric pathogen Helicobacter pylori establishes long-term chronic infections that can lead to gastritis, peptic ulcers, and cancer. The species is so diverse that distinctly different strains are generally recovered from each patient. To better understand the dynamics of lon g-term carriage, we characterized H. pylori isolates from initial and follow-up biopsy specimens from a patient population at high risk of H . pylori infection and gastric cancer. Eighty-five isolates were obtai ned from 23 patients and were analyzed by genomic restriction enzyme a nalysis, arbitrarily primed PCR fingerprinting, (random amplified poly morphic DNA analysis), and/or restriction of specific PCR-amplified ge nes (restriction fragment length polymorphism analysis). A single stra in was found in sequential biopsy specimens from 12 of 15 patients (80 %) receiving sucralfate. In the remaining three patients treated with sucralfate, two strains were identified in two patients and three stra ins were identified in the third patient. In contrast, a single strain was found in sequential biopsy specimens from only three of eight pat ients (37%) receiving bismuth, metronidazole, and nitrofurantoin. Two strains were identified in five other patients receiving bismuth-antib iotic (63%). Immunoglobulin G antibodies to H. pylori were present in the sera of all patients. Thus, H. pylori colonization can persist for long periods (up to at least 4 years), despite high titers of immunog lobulin G antibodies in serum. Resistance to metronidazole was noted i n some strains before and/or after treatment, but all strains remained susceptible to amoxicillin, tetracycline, and nitrofurantoin. We conc lude that H. pylori genotypes, as measured by several sensitive DNA fi ngerprinting methods, can remain stable for years in vivo, despite the acquisition or loss of drug resistance, circulating antibody, or expo sure to antibiotics or sucralfate.