Dynamics of Helicobacter pylori detection in stools during the first 5 years of life in Chile, a rapidly developing country.

Pediatr Infect Dis J. 2013 Feb;32(2):99-103.

O’Ryan ML, Rabello M, Cortés H, Lucero Y, Peña A, Torres JP.

Microbiology and Mycology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile. moryan@med.uchile.cl


BACKGROUND: : Helicobacter pylori colonization/infection can be transitory or persistent, conditions that have not been thoroughly evaluated in young children. We aimed to characterize the dynamics of H. pylori stool detection and to determine host and environmental factors and symptoms associated with persistence.

METHOD: : In a 5-year cohort study, we followed-up infants from birth with clinic visits every 3 months. Symptoms and environmental risk factor survey and a stool sample for H. pylori antigen detection were requested in every visit. Secretor/ABH histo-blood group phenotype was determined in saliva.

RESULTS: : Overall, 218 of 1456 (15%) stool samples were positive for H. pylori and 39 of 96 (41%) children had at least 1 positive sample. Stool detection was transitory in 16 of 39 (41%), persistent in 19 (49%) and undetermined in 4 (10%) children. Persistence was acquired largely during the first 24 months (17/19 cases) and was associated with nonsecretor phenotype (32% versus 0% for transitory infection; P = 0.02) and daycare attendance (67% versus 26% for never infected; P = 0.019). Symptoms possibly associated with persistence were referred in only 1 child.

CONCLUSIONS: : Nearly 20% of this Chilean cohort had persistent H. pylori stool sample detections during the first 5 years of life, acquired mostly during the first 24 months. Persistence was significantly associated with nonsecretor phenotype and daycare attendance, and possibly associated gastrointestinal symptoms were rare. This relatively common group of young children with persistent H. pylori colonization/infection will require further study.

PMID: 23076385



Our overall aim is to characterize the “natural history” of helicobacter pylori colonization/infection in children in Chile, a rapidly developing country with a high incidence of gastric cancer in adults. Our main focus is to determine the colonization/infection patterns during childhood and the significance that early colonization/infection may have in the short and intermediate term. If persistent colonization/infection begins early in life and proves to be relevant for future pathology, this information becomes critical for eventual prevention through vaccination. The uniqueness of this pilot study is that it follows a birth cohort of “healthy” children living in a semirural area for several years taking advantage of the high sensitivity and specificity of stool antigen detection of H pylori as a proxy for intestinal colonization/infection. Stool samples were tested every 3 months from birth up to 42 months of age. We identified 3 distinct patterns of colonization/infection: 60% of children that never presented a positive stool detection for H pylori during the first 42 months of life, 17% that had a transitory detection of only one or two positive samples (T1 to T16 in the figure), and 20% that had a persistent colonization/infection characterized by stool positivity throughout the study period (P1 to P19 in the figure). Interestingly, stool detection occurred at earlier ages and more commonly in children with a “non-secretor” status (contrary than expected as Lewis b and H antigens are considered receptors for H pylori) when compared to children with transitory detections. These results were pivotal for the design of a more recent cohort study including over 200 children from 1 to 4 years of age and a case-control study of persistent vs. non-infected children between 5 and 10 years of age aimed to determine microbial factors and host factors associated with persistence, the host response to this “asymptomatic” colonization/infection and its potential clinical impact.

Miguel O'Ryan-1




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