Studies on natural gastric flora: survival of bacteria in fasting human subjects.

The present report deals with the survival of micro-organisms in the gastric lumen of fasting human subjects. Studies were carried out on hospitalized adult patients during the day, at night and over a 24-hour period.It is concluded that the survival of bacteria in the gastric lumen depends on the pH of the gastric juice. The duration of survival of the organisms at the pH <3.0 varied; however, at pH> 4.0, when a subsequent rapid drop in pH occurred, the clearing of viable organisms occurred within the hour sampling period in most cases. It is possible that medications which decrease gastric acidity favour an increase in the growth of gastric bacteria, while substances with a low pH may decrease bacterial growth.