Our data suggest that ciprofloxacin and ceftriaxone are appropriate empirical therapy for suspected typhoid fever; however, resistance may be anticipated. Continued monitoring of antimicrobial resistance among Salmonella Typhi strains will help determine vaccination and treatment policies. JAMA. 2000;283:2668-2673.

Vibrio, a diverse genus of aquatic bacteria, currently includes 72 species, 12 of which occur in human clinical samples. Of these 12, three species-Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus-account for the majority of Vibrio infections in humans. Rapid and accurate identification of Vibrio species has been problematic because phenotypic characteristics are variable within species and biochemical identification requires 2 or more days to complete. To facilitate the identification of human-pathogenic species, we developed a multiplex PCR that uses species-specific primers to amplify gene regions in four species (V. cholerae, V. parahaemolyticus, V. vulnificus, and V. mimicus). The assay was tested on a sample of 309 Vibrio isolates representing 26 named species (including 12 human pathogens) that had been characterized by biochemical methods. A total of 190 isolates that had been identified as one of the four target species all yielded results consistent with the previous classification. The assay identified an additional four V. parahaemolyticus isolates among the other 119 isolates. Sequence analysis based on rpoB was used to validate the multiplex results for these four isolates, and all clustered with other V. parahaemolyticus sequences. The rpoB sequences for 12 of 15 previously unidentified isolates clustered with other Vibrio species in a phylogenetic analysis, and three isolates appeared to represent unnamed Vibrio species. The PCR assay provides a simple, rapid, and reliable tool for identification of the major Vibrio pathogens in clinical samples, and rpoB sequencing provides an additional identification tool for other species in the genus Vibrio.The genus Vibrio is a highly diverse group of gram-negative bacteria that contains approximately 72 species (www.bacterio .net). The group includes symbionts and commensals that are found in or on marine animals, as well as many species that are pathogenic to animals (21). There are 12 species that are routinely isolated from human clinical samples, and the diseases in which they are implicated include diarrheal disease, septicemia, and wound infections (6).Three species account for the majority of human Vibrio infections. Toxigenic Vibrio cholerae is the causative agent of the disease cholera and is acquired through ingestion of contaminated food or water. Infection may lead to a profuse, watery diarrhea that can lead to severe dehydration and death if left untreated. Worldwide, large outbreaks are caused by toxigenic strains of serogroups O1 and O139 that produce the cholera toxin, but in the United States, nontoxigenic strains predominate among the cases reported to the Centers for Disease Control and Prevention (CDC) (4). A total of 48 cases of cholera occurred in the United States in 2004 and were reported to the CDC (4), including eight cases infected with toxigenic V. cholerae, four of which were associated with travel, and 40 cases infected with nontoxigenic cholera. Vibrio cholerae accounted for 9.8% of all Vibrio isolates reported...

Potential virulence attributes, serotypes, and ribotypes were determined for 178 pathogenic Vibrio parahaemolyticus isolates from clinical, environmental, and food sources on the Pacific, Atlantic, and Gulf Coasts of the United States and from clinical sources in Asia. The food and environmental isolates were generally from oysters, and they were defined as being pathogenic by using DNA probes to detect the presence of the thermostable direct hemolysin (tdh) gene. The clinical isolates from the United States were generally associated with oyster consumption, and most were obtained from outbreaks in Washington, Texas, and New York. Multiplex PCR was used to confirm the species identification and the presence of tdh and to test for the tdh-related hemolysin trh. Most of the environmental, food, and clinical isolates from the United States were positive for tdh, trh, and urease production. Outbreak-associated isolates from Texas, New York, and Asia were predominantly serotype O3:K6 and possessed only tdh. A total of 27 serotypes and 28 ribogroups were identified among the isolates, but the patterns of strain distribution differed between the serotypes and ribogroups. All but one of the O3:K6 isolates from Texas were in a different ribogroup from the O3:K6 isolates from New York or Asia. The O3:K6 serotype was not detected in any of the environmental and food isolates from the United States, and none of the food or environmental isolates belonged to any of the three ribogroups that contained all of the O3:K6 and related clinical isolates. The combination of serotyping and ribotyping showed that the Pacific Coast V. parahaemolyticus population appeared to be distinct from that of either the Atlantic Coast or Gulf Coast. The fact that certain serotypes and ribotypes contained both clinical and environmental isolates while many others contained only environmental isolates implies that certain serotypes or ribotypes are more relevant for human disease.Vibrio parahaemolyticus is the leading cause of seafood-associated bacterial gastroenteritis in the United States (29) and is a major cause of food-borne illness in the world (21, 41). However, the relationship between strains isolated from estuarine environments, those isolated from seafood, and human clinical isolates is poorly understood. The presence of thermostable direct hemolysin (TDH) is a proven virulence factor (31), and TDH occurs in over 90% of clinical

In September and October 1978, after a case of cholera had been discovered in southwestern Louisiana, 10 more Vibrio cholerae O-Group 1 infections were detected in four additional clusters. All 11 infected persons had recently eaten cooked crabs from five widely separated sites in the coastal marsh, and a matched-triplet case-control study showed a significant relation between cholera and eating such crabs (P = 0.007). V. cholerae O1 was isolated from estuarine water, from fresh shrimp, from a leftover cooked crab from a patient's refrigerator, and from sewage in six towns, including three without identified cases. All isolates in Louisiana and an isolate from a single unexplained case in Texas in 1973 were biotype El Tor and serotype inaba; they were hemolytic and of a phage type unique to the United States--suggesting that the organism persisted undetected along the Gulf Coast for at least five years.