Etiology of Acute Diarrhea in Adults in Southwestern Nigeria

Abstract

Stool specimens from 113 adult outpatients with diarrhea in southwestern Nigeria and 63 controls were examined for bacterial and parasitic enteric pathogens. Enterohemorrhagic Escherichia coli (EHEC) (P < 0.02), enteroaggregative E. coli (EAEC) (P < 0.02), and Entamoeba histolytica (P < 0.0002) were significantly associated with diarrhea. Salmonella, Shigella, nontoxigenic Vibrio cholerae, other categories of diarrheagenic E. coli, as well as a variety of helminths were recovered more frequently from the stools of patients than from the stools of controls but did not show a significant association with disease. Multiple pathogens were recovered from 36.3% of specimens, and bloody diarrhea was commonly associated with E. histolytica and diarrheagenic E. coli infections. The majority of EHEC isolates were non-O157 strains that carried the stx 2 gene. Of the 23 EHEC-infected patients, 12 (52.2%) presented during the 10th week of the study. EHEC strains isolated within this cluster were more likely to hybridize with the enterohemolysin gene probe, to be nonmotile and sorbitol positive, and to fail to agglutinate O157 antisera. Pulsed-field gel electrophoresis demonstrated that the only strains with XbaI profiles that occurred more than once were isolated during the 10th and 11th weeks of the study, suggesting an outbreak. The study has demonstrated that E. histolytica, EHEC, and EAEC are important diarrheal pathogens within the study area and that sporadic and epidemic EHEC infections occur in developing as well as developed countries. Routine surveillance for diarrheagenic E. coli, even only at the tertiary-care level, would be useful in identifying outbreaks and assist in identifying environmental reservoirs and transmission routes.Diarrhea is an important cause of disease and death among children in developing countries (20). Adult visitors to tropical developing countries frequently experience traveler's diarrhea, caused by agents that are endemic in those countries but to which visitors have not had the opportunity to develop protective immunity (36). Adult residents of developing countries are less likely to have sporadic diarrhea, and when it occurs, it is unlikely to be life threatening. Therefore, diarrheal pathogens in adults residing in developing countries have been the subject of few investigations, and very little is known about the etiologic epidemiology of pathogens other than epidemic Vibrio cholerae and Shigella. Sporadic endemic diarrhea in adults, however, contributes to the loss of productivity in developing countries and increases the risk that pathogens will be passed to susceptible children or visitors. When such infections do occur, they are often treated empirically, even though very little is known about the etiologic agents in this population; and in many cases, they prompt self-medication with antibiotics, which are often available without prescription (33). We conducted a case-control study over an 11-week period to determine the causes of diarrhea among adults visiting the outpatient c...

Diarrheagenic Escherichia coli in sub-Saharan Africa: Status, Uncertainties and Necessities

“…[14]. EHEC was significantly associated with diarrhea in that study (even with outbreak cases removed) and was the most common bacterial pathogen recovered from bloody diarrhea specimens in which only one pathogen was identified [14].…”

“…Over the last decade, EIEC were sought but not found in one Gabonese study and studies from Kenya, Mozambique, Ghana and Nigeria also identified a small number of EIEC isolates but saw no significant association with disease [14,15,20,[134][135][136]. In Senegal, ipaH-positive E. coli (ipaH is a marker for Shigella and EIEC) were recovered from 16 of 279 people with diarrhea and 8 of 276 controls (P < .000001) [137].…”

“…Other studies have invariably found proportionately more EIEC in cases than controls and the failure to detect disease association appears to be linked to overall low prevalence of these pathogens and the small sample size of these studies. EIEC may be at least as prevalent as Shigella in some areas but studies specifically designed to study EIEC may be needed to verify this [14,65].…”

“…Available data suggests that pathogens that typically cause persistent or invasive infections in children are often isolated from adults [13][14][15]. It is not clear whether this arises from bias since adults in endemic areas are least likely to seek care for diarrheal disease and, in Africa, these studies have always been performed at health institutions.…”

Acute Gastroenteritis Agents Among 0–5 Years-Old Turkish Children

“…and Shigella spp. are the bacterial agents which are mostly isolated from stool samples of diarrheal patients, especially in rural areas from developing countries 6,7 . Additionally, Clostridium difficile, another bacterial diarrheal agent, is a big threat for children in both community and hospitals 8,9 .…”