C. Williams et al., UREASE-MEDIATED DESTRUCTION OF BACTERIA IS SPECIFIC FOR HELICOBACTER UREASE AND RESULTS IN TOTAL CELLULAR DISRUPTION, FEMS immunology and medical microbiology, 9(4), 1994, pp. 273-280
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.