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Prospective study of Campylobacter jejuni infection in Chilean infants evaluated by culture and serology
G Figueroa1, H Galeno, M Troncoso
1Microbiology Unit, University of Chile, Santiago.
Insights
Campylobacter jejuni infection is common in Chilean infants, causing diarrhea and asymptomatic infections. Antibody levels rise significantly, indicating widespread exposure and immune response in this vulnerable population.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Campylobacter jejuni is a leading cause of bacterial gastroenteritis globally.
- Infant populations in developing regions are particularly susceptible to enteric infections.
- Understanding C. jejuni epidemiology in infants is crucial for public health interventions.
Purpose of the Study:
- To investigate the incidence and seroprevalence of Campylobacter jejuni infection in Chilean infants.
- To determine the association between C. jejuni infection and age, and symptomatic vs. asymptomatic illness.
- To assess the development of specific antibodies in response to C. jejuni exposure.
Main Methods:
- Prospective cohort study of 198 Chilean infants over 6 months.
- Biweekly home visits for surveillance and stool sample collection.
- Stool culture for C. jejuni isolation and enzyme-linked immunosorbent assay (ELISA) for antibody detection.
Main Results:
- C. jejuni was isolated from 10% of diarrheal episodes and 6% of asymptomatic samples.
- Higher illness/infection ratios were observed in infants < 9 months old.
- Seroprevalence increased from 8% to 50% during the study, with antibody rise indicating asymptomatic infections in some cases.
Conclusions:
- Campylobacter jejuni infection poses a significant burden on Chilean infants, with both symptomatic and asymptomatic cases.
- Asymptomatic C. jejuni infections are frequent and effectively elicit specific antibody responses.
- Age is a critical factor in C. jejuni infection severity and prevalence in infants.
Abstract:
A prospective study of Campylobacter jejuni infection was performed during a 6-month period in a cohort of 198 Chilean infants. Surveillance was based on biweekly home visits by a team of trained nurses. C. jejuni colonization was studied by culturing stool samples from diarrheal episodes and paired asymptomatic controls and by performing an enzyme-linked immunosorbent assay developed to measure C. jejuni outer membrane protein polyvalent antibodies in a representative group of infants. C. jejuni was isolated from 30 of 299 diarrheal episodes (10%) and from 17 of 304 samples from asymptomatic infants (6%). Significantly higher (P less than 0.05) C. jejuni illness/infection ratios were found in infants less than 9 months old. Polyvalent antibodies to C. jejuni were found in 27 of 89 serum samples (30%). The lowest prevalence (4%) was observed among infants less than 9 months old, and the highest was found in patients older than 15 months (63%; P less than 0.01). Data obtained by analysis of paired serum samples revealed a significant increase in the number of seropositive individuals, from 8% on admission to 50% at the end of the protocol (P less than 0.001). The change in the immune status of these infants was associated with symptomatic infection in 9 of 18 cases. The antibody rise found in the remaining nine infants suggested the presence of asymptomatic C. jejuni infections. This inference was documented by the isolation of C. jejuni from stools of two of these infants when the infants were randomly studied while asymptomatic. This study points out the impact of C. jejuni-associated diarrheal episodes and the high frequency with which asymptomatic infections elicit specific antibodies in infants living in areas such as Chile.