Gastric bacterial overgrowth accompanies profound acid suppression

Suppression of gastric acid may lead to gastric colonization by aerobic and anaerobic bacteria, and consequent clinical manifestations. The risk is likely to be higher with poor environmental hygiene.

To study the effect of short-term acid suppression with omeprazole on gastric bacterial flora.

Twenty-five ambulatory patients with acid-peptic diseases underwent clinical assessment and gastric juice collection (for pH and culture) prior to start of therapy with 20 mg omeprazole daily, on days 7 and 14 of therapy, and 7 days after omission of therapy (day 21).

Eighteen patients completed the study. The median gastric pH was 1.8, 7.5, 7.5 and 3.4 on days 0, 7, 14 and 21 respectively. Positive gastric cultures were obtained in 13 of 25, 17 of 21, 18 of 18 and 14 of 18 patients on respective study days, with median colony counts of 1.5 x 10(4), 7.5 x 10(5), 8.7 x 10(7) and 7.3 x 10(4) cfu/mL respectively. Three patients developed self-limiting diarrhea during therapy and two more immediately after discontinuing therapy.

Gastric colonization is common with short-term profound acid-suppression, and may cause diarrhea. Acid suppressive therapy should be used with caution especially in patients with poor environmental hygiene.