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.