Association between enteropathogens and malnutrition in children aged 6-23 mo in Bangladesh: a case-control study

Abstract

Background: Early exposure to enteropathogens has been associated with malnutrition in children in low-resource settings. However, the contribution of individual enteropathogens remains poorly defined. Molecular diagnostics offer an increase in sensitivity for detecting enteropathogens but have not been comprehensively applied to studies of malnutrition.Objective: We sought to identify enteropathogens associated with malnutrition in Bangladesh.Design: Malnourished children [weight-for-age z score (WAZ) <-2] aged 6-23 mo in Dhaka, Bangladesh, and identified by active community surveillance were enrolled as cases, and normal-weight children (WAZ >-1) of the same age and from the same community were enrolled as controls. Stools were collected at enrollment and, for cases, after a 5-mo nutritional intervention. Enrollment and follow-up stools were tested by quantitative polymerase chain reaction for 32 enteropathogens with the use of a custom-developed TaqMan Array Card.Results: Enteropathogen testing was performed on 486 cases and 442 controls upon enrollment and 365 cases at follow-up. At enrollment, the detection of enteroaggregative Escherichia coli (OR: 1.39; 95% CI: 1.05, 1.83), Campylobacter spp. (OR: 1.46; 95% CI: 1.11, 1.91), heat-labile enterotoxin-producing E. coli (OR: 1.55; 95% CI: 1.04, 2.33), Shigella/enteroinvasive E. coli (OR: 1.65; 95% CI: 1.10, 2.46), norovirus genogroup I (OR: 1.66; 95% CI: 1.23, 2.25), and Giardia (OR: 1.73; 95% CI: 1.20, 2.49) were associated with malnourished cases, and the total burden of these pathogens remained associated with malnutrition after adjusting for sociodemographic factors. The number of these pathogens at follow-up was negatively associated with the change in WAZ during the intervention (-0.10 change in WAZ per pathogen detected; 95% CI: -0.14, -0.06), whereas the number at enrollment was positively associated with the change in WAZ (0.05 change in WAZ per pathogen detected; 95% CI: 0.00, 0.10).Conclusions: A subset of enteropathogens was associated with malnutrition in this setting. Broad interventions designed to reduce the burden of infection with these pathogens are needed. This trial was registered at clinicaltrials.gov as NCT02441426.

Keywords: PCR; children; diarrhea; enteropathogens; low-resource settings; malnutrition.

FIGURE 1

Study flow diagram. qPCR, quantitative polymerase chain reaction; WAZ, weight-for-age z score.

FIGURE 2

Pathogen quantity when detected with the use of quantitative polymerase chain reaction in cases and controls. Box-and-whisker plots are shown with the use of Tukey’s method, in which the bottom and top of the box represent the first and third quartiles, respectively, the line within the box represents the median, the whiskers extend from the box to all values within 1.5 times the IQR, and points beyond the whiskers represent outliers. For all pathogens, there was no statistically significant difference in the quantity between cases and controls (Mann-Whitney test; P > 0.05). aEPEC, atypical enteropathogenic E. coli; EAEC, enteroaggregative E. coli; EIEC, enteroinvasive E. coli; GI, genogroup I; GII, genogroup II; LT-ETEC, heat-labile enterotoxin-producing E. coli; ST-ETEC, heat-stable enterotoxin-producing E. coli; tEPEC, typical enteropathogenic E. coli.

FIGURE 3

Association between pathogen detection at both enrollment and follow-up and change in weight during follow-up derived from a multivariable linear regression model for each pathogen, with the change in WAZ from enrollment until the end of the intervention as the outcome and the baseline WAZ, enrollment age, sex, diarrhea at enrollment, insufficient food in the home, income, location of primary water source, routine treatment of drinking water, and age of cessation of exclusive breastfeeding as well as the presence of the pathogen at both enrollment and follow-up as predictors. The x axis in panel A shows the difference in the change in WAZ from enrollment to the completion of a 5-mo nutritional intervention for cases in which each pathogen was detected compared with not being detected at enrollment (black) and after the completion of the intervention (gray); panel B shows the proportion of stools in which these pathogens were detected at enrollment (black) and follow-up (gray). EAEC, enteroaggregative E. coli; EIEC, enteroinvasive E. coli; GII, genogroup II; LT-ETEC, heat-labile enterotoxin-producing E. coli; WAZ, weight-for-age z score.