1232
EFFECTS OF UREA AND UREASE INHIBITOR ON SURVIVAL OF H PYLORI/ IN ACID
Serial
MIFso during evolution of respiratory symptoms.
with a diagnosis of active vasculitis; false positives are rare and even some of these may indicate early or limited disease, as in our patient with subglottic stenosis.9,lO However, clinicians will continue to be forced into controversial decisions until the pathogenesis of systemic vasculitis is understood and the diagnosis can be established unambiguously even in cases with limited disease.
Hammersmith
Hospital.
London W12 0HS, UK
C. N. Ross F. W. K. TAM R. J. D. WINTER C. D. PUSEY A. J. REES
Hoare TJ, Rhys Evans PH. Anti-neutrophil cytoplasmic antibody assay in diagnosis of recurrent subglottic stenosis. Lancet 1988; ii: 1360. 2. Michaels L. Anti-neutrophil cytoplasmic antibody and subglottic stenosis. Lancet 1989; i: 53. 3. Fauci AS, Haynes BF, Katz P, Wolff SM. Wegener’s granulomatosis: prospective clinical and therapeutic experience with 85 patients for 21 years. Ann Intern Med 1983; 98: 76-85. 4. Stem MG, Gamsu G, Webb WR, Stulbarg MS. Computed tomography of diffuse tracheal stenosis in Wegener granulomatosis. J Comput Assist Tomogr 1986; 10: 1.
868-70. 5. Cohen MI, Gore RM, August CZ, Ossof RH. Tracheal and bronchial stenosis associated with mediastinal adenopathy in Wegener granulomatosis: CT findings. J Comput Assist Tomogr 1984; 8: 327-29. 6. Gohel VK, Dalinka MK, Israel HL, Libshitz HI. The radiological manifestations of Wegener’s granulomatosis. Br J Radiol 1973; 46: 427-32. 7. Lampman JH, Querubin R, Kondapalli P. Subglottic stenosis in Wegener’s granulomatosis. Chest 1981; 79: 230-34. 8. Scully RE, Mark EJ, McNeely BU. Case records of the Massachusetts General Hospital. N Engl J Med 1986; 315: 378-87. 9. van der Woude FJ, Lobatto S, Petmin H, et al. Autoantibodies against neutrophils and monocytes: tool for diagnosis and marker of disease activity in Wegener’s granulomatosis. Lancet 1985; i: 425-29. 10. Savage COS, Winearls CG, Jones S, Marshall PD, Lockwood CM. Prospective study of a radioimmunoassay for antibodies against neutrophil cytoplasm in diagnosis of systemic vasculitis. Lancet 1987; i: 1389-93.
*Three experiments
tColony-formmg NG = no growth
(1-3)
x units
10-6/ml.
In some patients with urinary tract infections struvite form in urine rendered alkaline by ammonia that is produced by urease-containing organisms. Urease inhibitors such as acetohydroxamic acid are used clinically to prevent stone formation. We grew H pylori for 3 days on sheep blood agar plates in a microaerobic environment at 35°C, suspended in normal saline. 250 ltl samples, some mixed 5 min beforehand with 100 µl of 25 mg acetohydroxamic acid per ml, were added to 4-75 ml 0.1mol/1 HCI + 0-05 mol/I saline (pH 1-0), 0-3 mol/1 citrate (pH 2-0), or phosphate-buffered normal saline (PBS, pH 7-2) at 37’C, +14 mmol/1 urea. After 30 min at 37°C, samples were diluted in PBS, plated in duplicate, grown as above, and colonies counted. Post-30 min incubation pH values were always within 0of the initial value. At pH 1 and 2 acetohydroxamic acid abolished the urea/ureasedependent acid resistance of H pylori (table). Existing treatments for the eradication of H pylori are not always successful. A trial of urease inhibitors might show that they are efficacious alone or in combination with current treatments. Combination with other drugs is likely to be more successful in view of the synergism observed between antibiotics and urease inhibitors in urinary tract infections. Acetohydroxamic acid itself, although possibly mutagenic, may be especially effective because it also prevents the growth of H pylori in vitro, both alone and synergistically with antimicrobial agents.9 In the absence of animal model data, the results of such a trial would elucidate the importance of urease in the pathogenesis of H pylori infection. Even if acid resistance is not a central feature, ammonia affects the gastric mucosal barrier, 10 and it can inhibit bacterial killing by host phagocytes.ll Thus, urease inhibitors may reduce mucosal damage and enhance the ability of the host defences to clear the infection.
suggested.8 stones
Helicobacter pylori acid resistance SIR,-Surprisingly little attention is given to the resistance of Helicobacter pylori to acid, despite the fact that the human stomach and duodenum are the usual site of colonisation. One possible way for this organism to survive in the stomach is that it may occupy regions of higher pH in the mucus layer.1 Several workers have suggested that a period of hypochlorhydria is necessary for successful colonisation.1-3 Barrett and colleagues’ results4 indicate that H pylori can survive for 30 min at pH 1 5, in the presence of 5 mmol/1 urea. We have also shown substantial resistance to acid, even at pH 1 0, and at the more physiological gastric juice urea concentration of 1 4 mmol/1 (table).5 In strong acid H pylori urease and urea seem to provide a physiological pH in the immediate vicinity of the H pylori cell, without much altering the pH of the medium as a whole. Thus, exposure to acidic gastric juice need not prevent successful H pylori challenge. This resistance to acid may also be important in the maintenance of a continuing infection, by allowing the H pylori organism to escape from host phagocytic cells. Phagocytes can enter the gastric mucus layer,but do not function effectively at low pH.7 If urea/urease-dependent resistance to acid is important for H pylori survival, a different approach to eradication of the organism is
C. MOONEY Department of Surgery. Christchurch School of Medicine, Christchurch, New Zealand
D. J. MUNSTER P. F. BAGSHAW R. A. ALLARDYCE
1. Warren JR. Unidentified curved bacilli on gastnc epithelium in active chronic gastritis Lancet 1983; i: 1273. 2. Marshall BJ, Armstrong JA, McGechie DB, Glancy RJ. Attempt to fulfil Koch’s postulates for pyloric campylobacter. Med JAust 1985; 142: 436-39. 3. Morris A, Nicholson G. Ingestion of C pyloridis causes gastritis and raised fasting
gastric pH. Am J Gastroenterol 1987; 82: 192-99. 4. Barrett LJ, Marshall BJ, Prakash C, Guerrant RL. Protection of Campylobacter pylori but not Campylobacter jejum against acid susceptibility by urea. In. de Wal J, ed. Campylobacter pylon. Bibliography, Gist-Brocades, 1988. 261 5. Lieber CS, Lefevre A. Ammonia as a source of gastric hypoacidity in patients with uremia. J Clin Invest 1959; 38: 1271-77. 6. Shousha S, Bull TB, Parkins RA. Gastric spiral bacteria. Lancet 1984; ii. 101 7. Gabig TG, Bearman SI, Babior BM. Effects of oxygen tension and pH on the respiratory burst of human neutrophils. Blood 1979; 53: 1133-39. 8. Mobley HLT, Cortesia MJ, Rosenthal LE, Jones BD. Characterization of urease from Campylobacter pylori. J Clin Microbiol 1988; 26: 831-36. 9. McNulty CAM. Bacteriological and pharmacological basis for the treatment of Campylobacter pylori infection. In: Rathbone BJ, Heatley RV, eds. Campylobacter pylori and gastroduodenal disease. Oxford: Blackwell Scientific, 1989 209-16. 10. Sidebotham RL, Baron JH Hypothesis: Helicobacter pylon, urease, mucus, and gastric ulcer. Lancet 1990; 335: 193-95. 11. Gordon AH, D’Arcy Hart P, Young MR Ammonia inhibits phagosome-lysosome fusion in macrophages. Nature 1980; 286: 79-80.
EFFECTS OF UREA AND UREASE INHIBITOR ON SURVIVAL OF H PYLORI/ IN ACID
Serial
MIFso during evolution of respiratory symptoms.
with a diagnosis of active vasculitis; false positives are rare and even some of these may indicate early or limited disease, as in our patient with subglottic stenosis.9,lO However, clinicians will continue to be forced into controversial decisions until the pathogenesis of systemic vasculitis is understood and the diagnosis can be established unambiguously even in cases with limited disease.
Hammersmith
Hospital.
London W12 0HS, UK
C. N. Ross F. W. K. TAM R. J. D. WINTER C. D. PUSEY A. J. REES
Hoare TJ, Rhys Evans PH. Anti-neutrophil cytoplasmic antibody assay in diagnosis of recurrent subglottic stenosis. Lancet 1988; ii: 1360. 2. Michaels L. Anti-neutrophil cytoplasmic antibody and subglottic stenosis. Lancet 1989; i: 53. 3. Fauci AS, Haynes BF, Katz P, Wolff SM. Wegener’s granulomatosis: prospective clinical and therapeutic experience with 85 patients for 21 years. Ann Intern Med 1983; 98: 76-85. 4. Stem MG, Gamsu G, Webb WR, Stulbarg MS. Computed tomography of diffuse tracheal stenosis in Wegener granulomatosis. J Comput Assist Tomogr 1986; 10: 1.
868-70. 5. Cohen MI, Gore RM, August CZ, Ossof RH. Tracheal and bronchial stenosis associated with mediastinal adenopathy in Wegener granulomatosis: CT findings. J Comput Assist Tomogr 1984; 8: 327-29. 6. Gohel VK, Dalinka MK, Israel HL, Libshitz HI. The radiological manifestations of Wegener’s granulomatosis. Br J Radiol 1973; 46: 427-32. 7. Lampman JH, Querubin R, Kondapalli P. Subglottic stenosis in Wegener’s granulomatosis. Chest 1981; 79: 230-34. 8. Scully RE, Mark EJ, McNeely BU. Case records of the Massachusetts General Hospital. N Engl J Med 1986; 315: 378-87. 9. van der Woude FJ, Lobatto S, Petmin H, et al. Autoantibodies against neutrophils and monocytes: tool for diagnosis and marker of disease activity in Wegener’s granulomatosis. Lancet 1985; i: 425-29. 10. Savage COS, Winearls CG, Jones S, Marshall PD, Lockwood CM. Prospective study of a radioimmunoassay for antibodies against neutrophil cytoplasm in diagnosis of systemic vasculitis. Lancet 1987; i: 1389-93.
*Three experiments
tColony-formmg NG = no growth
(1-3)
x units
10-6/ml.
In some patients with urinary tract infections struvite form in urine rendered alkaline by ammonia that is produced by urease-containing organisms. Urease inhibitors such as acetohydroxamic acid are used clinically to prevent stone formation. We grew H pylori for 3 days on sheep blood agar plates in a microaerobic environment at 35°C, suspended in normal saline. 250 ltl samples, some mixed 5 min beforehand with 100 µl of 25 mg acetohydroxamic acid per ml, were added to 4-75 ml 0.1mol/1 HCI + 0-05 mol/I saline (pH 1-0), 0-3 mol/1 citrate (pH 2-0), or phosphate-buffered normal saline (PBS, pH 7-2) at 37’C, +14 mmol/1 urea. After 30 min at 37°C, samples were diluted in PBS, plated in duplicate, grown as above, and colonies counted. Post-30 min incubation pH values were always within 0of the initial value. At pH 1 and 2 acetohydroxamic acid abolished the urea/ureasedependent acid resistance of H pylori (table). Existing treatments for the eradication of H pylori are not always successful. A trial of urease inhibitors might show that they are efficacious alone or in combination with current treatments. Combination with other drugs is likely to be more successful in view of the synergism observed between antibiotics and urease inhibitors in urinary tract infections. Acetohydroxamic acid itself, although possibly mutagenic, may be especially effective because it also prevents the growth of H pylori in vitro, both alone and synergistically with antimicrobial agents.9 In the absence of animal model data, the results of such a trial would elucidate the importance of urease in the pathogenesis of H pylori infection. Even if acid resistance is not a central feature, ammonia affects the gastric mucosal barrier, 10 and it can inhibit bacterial killing by host phagocytes.ll Thus, urease inhibitors may reduce mucosal damage and enhance the ability of the host defences to clear the infection.
suggested.8 stones
Helicobacter pylori acid resistance SIR,-Surprisingly little attention is given to the resistance of Helicobacter pylori to acid, despite the fact that the human stomach and duodenum are the usual site of colonisation. One possible way for this organism to survive in the stomach is that it may occupy regions of higher pH in the mucus layer.1 Several workers have suggested that a period of hypochlorhydria is necessary for successful colonisation.1-3 Barrett and colleagues’ results4 indicate that H pylori can survive for 30 min at pH 1 5, in the presence of 5 mmol/1 urea. We have also shown substantial resistance to acid, even at pH 1 0, and at the more physiological gastric juice urea concentration of 1 4 mmol/1 (table).5 In strong acid H pylori urease and urea seem to provide a physiological pH in the immediate vicinity of the H pylori cell, without much altering the pH of the medium as a whole. Thus, exposure to acidic gastric juice need not prevent successful H pylori challenge. This resistance to acid may also be important in the maintenance of a continuing infection, by allowing the H pylori organism to escape from host phagocytic cells. Phagocytes can enter the gastric mucus layer,but do not function effectively at low pH.7 If urea/urease-dependent resistance to acid is important for H pylori survival, a different approach to eradication of the organism is
C. MOONEY Department of Surgery. Christchurch School of Medicine, Christchurch, New Zealand
D. J. MUNSTER P. F. BAGSHAW R. A. ALLARDYCE
1. Warren JR. Unidentified curved bacilli on gastnc epithelium in active chronic gastritis Lancet 1983; i: 1273. 2. Marshall BJ, Armstrong JA, McGechie DB, Glancy RJ. Attempt to fulfil Koch’s postulates for pyloric campylobacter. Med JAust 1985; 142: 436-39. 3. Morris A, Nicholson G. Ingestion of C pyloridis causes gastritis and raised fasting
gastric pH. Am J Gastroenterol 1987; 82: 192-99. 4. Barrett LJ, Marshall BJ, Prakash C, Guerrant RL. Protection of Campylobacter pylori but not Campylobacter jejum against acid susceptibility by urea. In. de Wal J, ed. Campylobacter pylon. Bibliography, Gist-Brocades, 1988. 261 5. Lieber CS, Lefevre A. Ammonia as a source of gastric hypoacidity in patients with uremia. J Clin Invest 1959; 38: 1271-77. 6. Shousha S, Bull TB, Parkins RA. Gastric spiral bacteria. Lancet 1984; ii. 101 7. Gabig TG, Bearman SI, Babior BM. Effects of oxygen tension and pH on the respiratory burst of human neutrophils. Blood 1979; 53: 1133-39. 8. Mobley HLT, Cortesia MJ, Rosenthal LE, Jones BD. Characterization of urease from Campylobacter pylori. J Clin Microbiol 1988; 26: 831-36. 9. McNulty CAM. Bacteriological and pharmacological basis for the treatment of Campylobacter pylori infection. In: Rathbone BJ, Heatley RV, eds. Campylobacter pylori and gastroduodenal disease. Oxford: Blackwell Scientific, 1989 209-16. 10. Sidebotham RL, Baron JH Hypothesis: Helicobacter pylon, urease, mucus, and gastric ulcer. Lancet 1990; 335: 193-95. 11. Gordon AH, D’Arcy Hart P, Young MR Ammonia inhibits phagosome-lysosome fusion in macrophages. Nature 1980; 286: 79-80.
