Background: Human listeriosis is an uncommon infection caused by the Gram-positive organism Listeria monocytogenes.
Objective: To investigate the effects of therapeutic gastric acid suppression on faecal isolation of L. monocytogenes and the incidence of human listeriosis.
Methods: Five stool specimens from each of 20 patients on continuous H2-antagonist therapy and two faecal samples from each of 47 healthy controls were investigated for the presence of Listeria spp.
Results: A higher faecal isolation rate of L. monocytogenes was detected amongst the patients (20%) compared with the controls (2.1%) (P < 0.025). All subjects with stools positive for Listeria spp. were female, this sex difference being significant in the patient group (P < 0.0036) compared with controls. No patient, however, developed listeriosis.
Conclusion: Patients on long-term gastric acid suppressive therapy may be at increased risk of faecal carriage of L. monocytogenes.