BackgroundThe epidemiology of diarrheal disease in Botswana, an HIV endemic region, is largely unknown. Our primary objective was to characterize the prevalent bacterial and parasitic enteropathogens in Gaborone, Botswana. Secondary objectives included determining corresponding antimicrobial resistance patterns and the value of stool white and red blood cells for predicting bacterial and parasitic enteropathogens.Methodology/Principal FindingsA retrospective cross-sectional study examined laboratory records of stool specimens analyzed by the Botswana National Health Laboratory in Gaborone, Botswana from February 2003 through July 2008. In 4485 specimens the median subject age was 23 [interquartile range 1.6–34] years. Overall, 14.4% (644 of 4485) of samples yielded a pathogen. Bacteria alone were isolated in 8.2% (367 of 4485), parasites alone in 5.6% (253 of 4485) and both in 0.5% (24 of 4485) of samples. The most common bacterial pathogens were Shigella spp. and Salmonella spp., isolated from 4.0% (180 of 4485) and 3.9% (175 of 4485) of specimens, respectively. Escherichia coli (22 of 4485) and Campylobacter spp. (22 of 4485) each accounted for 0.5% of pathogens. Comparing antimicrobial resistance among Shigella spp. and Salmonella spp. between two periods, February 2003 to February 2004 and July 2006 to July 2008, revealed an increase in ampicillin resistance among Shigella spp. from 43% to 83% (p<0.001). Among Salmonella spp., resistance to chloramphenicol decreased from 56% to 6% (p<0.001). The absence of stool white and red blood cells correlated with a high specificity and negative predictive value.Conclusions/SignificanceMost gastroenteritis stools were culture and microscopy negative suggesting that viral pathogens were the majority etiologic agents in this Botswana cohort. Shigella spp. and Salmonella spp. were the most common bacteria; Isospora spp. and Cryptosporidium spp. were the most common parasites. Resistance to commonly used antimicrobials is high and should be closely monitored.