Polymicrobial enteric infections in African infants with diarrhoea—results from a longitudinal prospective case–control study

Objectives: This longitudinal case–control study aimed to determine the frequency of polymicrobial enteric detections in Ghanaian infants with and without diarrhoea. Methods: Infants aged 1–12 months with and without diarrhoea attending the outpatient department of a peri-urban Ghanaian hospital were prospectively assessed and stool samples were collected on days 0, 6 and 28 and analysed for 18 enteric pathogens with PCR. Results: At least one enteric pathogen was detected in 100 of 107 cases with diarrhoea (93%) and in 82 of 97 controls (85%). The number of pathogens was higher in cases than in controls (median three versus two pathogens, p 0.001). The adjusted attributable fraction (AF) for diarrhoea was highest for enterotoxigenic Escherichia coli (7.2%, 95% CI –2.0% to 16.3%), rotavirus (4.1%, 95% CI 0.6%–7.5%), Giardia lamblia (2.3%, 95% CI –0.7 to 5.3%) and astrovirus (2.3%, 95% CI –2.9 to 7.5%). In cases, a higher pathogen number was significantly associated with watery stool consistency (median 3, interquartile range (IQR) 2–5 versus median 2.5, IQR 1–4, p 0.014), stool frequency five or more per day (median 4, IQR 3–5 versus median 3, IQR 2–4, p 0.048) and vomiting (median 4, IQR 3–5 versus median 3, IQR 2–4, p 0.025). During follow-up, 94% (78/83) of cases and 85% (67/79) of controls had acquired at least one new pathogen without developing a new episode of diarrhoea. Conclusion: Enteric pathogens could be identified in the stool of the vast majority of Ghanaian infants, whereby pathogens were very frequently acquired without resulting in new episodes of diarrhoea during follow-up. A higher number of co-occurring pathogens may increase the risk of diarrhoea and disease severity.