Bacterial enteropathogens and factors associated with seasonal episodes of gastroenteritis in Nsukka, Nigeria

Abstract

Each year, between April and October, many children of school age and some young adults in Nsukka, Nigeria suffer from gastroenteritis. The period covers the rainy season in this part of Africa, when manured farmland occasionally is flooded. In view of the number of people suffering diarrhoea and occasionally low-grade fever, it became necessary to investigate the nature of the bacterial agents responsible. Between April and October (1996-1998), 500 loose or watery stools were collected from patients, the ages of which ranged from one month to 31 years. Stools that contained parasites were excluded from the study. Samples were cultured on 5% blood agar and 1% egg-yolk agar (both containing 10 μg/mL ampicillin), MacConkey agar, Shigella Salmonella agar and in alkaline peptone water. Bacterial growths were identified using standard bacteriological procedures. Drinking water and some fruit and vegetables prevalent during this period of the year also were cultured. Of the 500 stool samples tested, 138 (27.6%) grew a range of organisms including Aeromonas hydrophila (65 [13%]), Salmonella spp. (55 [11%]), Shigella spp. (9 [1.8%]) and enteropathogenic Escherichia coli (9 [1.8%]). Drinking water and some vegetables grew Pseudomonas aeruginosa and Enterococcus faecalis, respectively. The highest isolation rate occurred during June and July, corresponding to the period of greatest flooding of arable land. Although no enteropathogens were isolated from the fruit and vegetables examined, they contained E. faecalis – an organism found in faeces. Our findings failed to explain why 72% of the samples grew no bacterial enteropathogens.