Drug-induced hypochlorhydria causes high duodenal bacterial counts in the elderly.

BACKGROUND: Small bowel bacterial overgrowth secondary to drug-induced hypochlorhydria may be of particular importance in the elderly, in whom anti-ulcer drugs are commonly prescribed and the consequences of malabsorption may be severe.

METHODS: Duodenal aspirates were obtained from elderly individuals before (n = 24) and during a 2-month treatment course with either omeprazole (20 mg daily; n = 8) or ranitidine (300 mg b.d.; n = 6), and from six patients with small bowel bacterial overgrowth who had diarrhoea and malabsorption.

RESULTS: Before treatment, duodenal bacterial counts were normal (< 10(4) colony forming units/mL) in 23 elderly subjects (96%). However, six of 14 patients (43%) treated with omeprazole (5 of 8) or ranitidine (1 of 6) developed bacterial counts > 10(5) cfu/mL. All remained asymptomatic and had normal lactulose breath H2 profiles during treatment.

CONCLUSION: Drug-induced hypochlorhydria causes high duodenal bacterial counts in the elderly but, in the short term, this bacterial overgrowth is not associated with malabsorption.