UREASE-MEDIATED DESTRUCTION OF BACTERIA IS SPECIFIC FOR HELICOBACTER UREASE AND RESULTS IN TOTAL CELLULAR DISRUPTION

The survival of Helicobacter mustelae, Proteus mirabilis, Escherichia coli and Campylobacter jejuni in the presence of urea and citrate at p H 6.0 was examined. H. mustelae, which has urease activity similar to H. pylori, had a markedly reduced survival, median 2.5% (0-78%) (P < 0 .001) when incubated under these conditions. Only 7% of the ammonia pr oduced by H. mustelae urease activity was recovered from the buffer, a similar percentage to that previously reported with H. pylori. None o f the other organisms, all of which had lower urease activity, had imp aired survival under these conditions. Electron microscopical studies demonstrated extensive structural damage to H. pylori following exposu re to urea and citrate at pH 6.0. This structural damage to the organi sms makes it unlikely that the low recovery of ammonia was due to rete ntion of ammonia within the bacteria and suggests that the ammonia may have been incorporated into glutamate or other amino acids. Incorpora tion of ammonia into these compounds would deplete the cell of the key metabolic intermediate cr-ketoglutarate and could thus explain the me chanism of the urease-dependent destruction of the organism.