New issues in infectious diarrhea.

Infectious diarrhea remains a leading cause of both mortality and morbidity worldwide. Novel organisms recently have been described as causes of previously undiagnosed diarrhea. In addition, changes in epidemiologic trends of known pathogens, such as Clostridium difficile, are occurring, including multiple outbreaks of a newly recognized epidemic strain associated with increased severity of cases and poor response to current antibiotics. Given rising resistance rates, new antimicrobial agents are being studied. Rifaximin is a nonabsorbable, gut-selective antibiotic recently approved by the US Food and Drug Administration for the treatment of travelers' diarrhea caused by noninvasive Escherichia coli. This novel antibiotic has also shown promise in the prevention of travelers' diarrhea, as well as a host of other gastrointestinal disorders. Development of a vaccine against diarrheagenic organisms is of high global importance but has been a challenge, owing to the multiple causative serotypes of E. coli and other organisms.