Influence of Gastric Acidity on Bacterial and Parasitic Enteric Infections: A Perspective

Abstract

In the early twentieth century various investigators believed that patients with reduced gastric acid secretion were especially susceptible to bacterial enteric infections. Since many bacteria are promptly killed in an acidic environment, gastric acidity was thought to act as a "barrier" to ingested microorganisms. Despite a century of study, the concept of a "gastric barrier" to ingested microorganisms is still insufficiently understood. In this paper we update the older observations and discuss the interaction between bacteria and gastric acid, and other variables that may influence the survival of ingested bacteria in the stomach. In addition to recent data dealing with nontyphoidal salmonellosis, cholera, and shigellosis, we present information pertinent to other bacterial and parasitic enteric diseases. We believe that the available data, although incomplete, support the concept that gastric hypochlorhydria or achlorhydria increases both susceptibility to and severity of bacterial and perhaps also of certain parasitic enteric infections.