Intragastric Acidity, Bacteria, Nitrite, and N-Nitroso Compounds Before, During, and After Cimetidine Treatment

Milton-Thompson, G J; Ahmet, Z.; Lightfoot, N. F.; Hunt, R H; Barnard, J.; Brimblecombe, R. W.; Moore, P. J.; Bavin, P. M. G.; Darkin, D.; Viney, Nicholas J.

doi:10.1016/s0140-6736(82)92277-2

Cited by 100 publications

(33 citation statements)

References 19 publications

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“…For the 24 patients with fasting gastric pH !4, the mean was pH 1.87, which fits in well with the average intragastric pH 1.98 observed during 24-hour recordings in healthy individuals eating four meals [33]. The mean + 2 SD was pH 2.95 [32], corresponding to the recommended upper limit of pH 3 for normal pH of fasting gastric aspirates [1,14,34,35].…”

Section: Testing the Gastric Acid Barriersupporting

confidence: 79%

The Pathogenesis of Gastrointestinal Bacterial Overgrowth

Husebye

2005

Chemotherapy

137

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The normal indigenous intestinal microflora consists of about 10¹⁵ bacteria that under physiological conditions reside mainly in the lower gastrointestinal tract. Bacterial overgrowth implies abnormal bacterial colonization of the upper gut, resulting from failure of specific defense mechanisms restricting colonization under physiological conditions. At present two types of bacterial overgrowth with defined pathogenesis can be distinguished: (1) gastric overgrowth with upper respiratory tract microflora resulting from selective failure of the gastric acid barrier, and (2) gastrointestinal overgrowth with Gram-negative bacilli (enteric bacteria) resulting from failure of intestinal clearance. Helicobacter pylori-induced gastritis of the oxyntic mucosa is the main cause of acquired failure of the gastric acid barrier, which is common among the healthy elderly. Intestinal clearance may fail as the result of impaired intestinal peristalsis or anatomical abnormalities that alter luminal flow. Impaired peristalsis is associated with conditions interfering with intestinal neuromuscular function including myopathic, neuropathic, autoimmune, infectious, inflammatory, metabolic, endocrine, and neoplastic diseases. Anatomical abnormalities are mainly the result of gastrointestinal surgery, intestinal diverticula or fistula. Combined failure of intestinal clearance and the gastric acid barrier results in more severe colonization with Gram-negative bacilli. Gram-negative bacilli are uncommon in the upper gut of otherwise healthy individuals with gastric hypochlorhydria, being acquired (H. pylori) or drug-induced. Significant bacterial overgrowth with Gram-negative bacilli is a rational in the search for an explanation to optimize clinical management. The clinical significance of colonization with upper respiratory tract microflora remains unclear. Translocation of live bacteria, their metabolic products, or antigens from a small bowel colonized by Gram-negative bacilli play a role in the pathogenesis of spontaneous bacterial peritonitis in hepatic disease and in certain types of sepsis, indicating that further studies can point to new patient populations with potential benefit from medical treatment.

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Section: Testing the Gastric Acid Barriersupporting

confidence: 79%

The Pathogenesis of Gastrointestinal Bacterial Overgrowth

Husebye

2005

Chemotherapy

137

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“…The high acid tolerance of V . alcalescens observed here might also account for the relatively large numbers of this species found in the stomach of patients with, for example, dyspepsia (Borriello et al, 1985) or when the pH is raised to around pH 4.0 after drug treatment (Milton-Thompson et al, 1982).…”

Section: Glucosementioning

confidence: 56%

The Effect of Lowering the pH on the Composition and Metabolism of a Community of Nine Oral Bacteria Grown in a Chemostat

McDermid¹,

McKee²,

Ellwood³

et al. 1986

Microbiology

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Nine oral bacteria, associated with both healthy and diseased sites in the mouth, were grown at D = 0.05 h-' (mean generation time 13.9 h) in a glucose-limited chemostat. After an initial period of steady-state growth at pH 7.0, pH control was discontinued. The pH then decreased until it stabilized at pH 4-1 after 9 d (16 generations), while the Eh rose from -165 mV to + 160 mV. The lowering in pH resulted in the composition and metabolism of the flora being altered and in increased bacterial aggregation. At pH 7.0, 'Streptococcus mitior', Veillonella alcalescens and S. sanguis were most numerous while at pH 4.1 the counts of all bacteria fell except for Lactobacilius casei, which became predominant. The proportions of S . mutans within the community also increased while S. sanguis was recovered only occasionally and Bacteroides intermedius was not detected below pH 4.6. The survival at pH 4.1 of several other species would not have been predicted from earlier pure culture studies. Relative to pH 7.0, the community growing at pH 4.1 produced more lactic acid, washed cells had a greater glycolytic activity over a wider pH range but amino acid metabolism decreased. In general, when pH control was restored, so were the original patterns of metabolism and bacterial counts, except for B. intermedius, which was still not detected. The inverse relationship between S. sanguis and S. mutans, and the increase in proportions of L. casei and S . mutans during growth in a low pH environment parallel observations made in vivo and suggest that the chemostat can be used as a model for microbial behaviour in dental plaque.

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“…Nitrite concentrations were roughly 10 times higher in the subjects with hypochlorhydria than in the controls. The mean total N-nitroso compound concentration was 1-82 (SEM 0-17) nmol/l (83-7 (7-8) ng/100 ml) in the subjects with hypochlorhydria, which was not appreciably different from the concentration of 177 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) nmol/l (814 (53-8) ng/100 ml) in the controls. The mean stable N-nitroso compound concentration, however, was 0 37 (0-08) nmol/l (17-0 (3 7) ng/100 ml) in the subjects with hypochlorhydria, which was lower than but not appreciably different from the concentration of 0-66 (0 08) nmol/l (30 3 (3 7) ng/100 ml) in the controls.…”

Section: Methodsmentioning

confidence: 79%