RESEARCH Aeromonas spp. and Traveler’s Diar rhea: Clinical Features and Antimicrobial Resistance Jordi Vila,* Joaquin Ruiz,* Francisco Gallardo,* Martha Vargas,* Lara Soler†, Maria José Figueras,† and Joaquin Gascon‡ Traveler’s diarrhea is the most common health prob- improved (7). The main objective of this study was to lem of international travelers. We determined the preva- determine the prevalence of Aeromonas spp. as a cause of lence of Aeromonas spp. associated with traveler’s diar- traveler’s diarrhea and to analyze the species’ geographic rhea and analyzed the geographic distribution, clinical fea- distribution, clinical features, and susceptibility to antimi- tures, and antimicrobial susceptibility. Aeromonas spp. crobial agents. were isolated as a cause of traveler’s diarrhea in 18 (2%) of 863 patients. A. veronii biotype sobria was isolated in nine patients, A. caviae in seven patients, and A. jandaei Methods and A. hydrophila in one patient each. Aeromonas spp. were isolated with a similar prevalence in Africa, Latin America, and Asia. Watery and persistent diarrhea, fever, and abdominal cramps were common complaints. All strains were resistant to ampicillin; showed variable resist- ance to chloramphenicol, tetracycline, and cotrimoxazole; and were susceptible to cefotaxime, ciprofloxacin, and nalidixic acid. The persistence of symptoms made antimi- crobial treatment necessary. Patients A total of 863 patients with traveler’s diarrhea were recruited from the Tropical Medicine Unit of the Hospital Clinic of Barcelona, Spain, during the period January 1999–December 2001. All patients completed an epidemi- ologic questionnaire; their clinical history was taken, and a physical examination was performed. Traveler’s diarrhea was defined as the occurrence of three or more episodes of watery stool within a 24-hour period, with or without other symptoms, or the occurrence of unformed stools accompa- nied by one of the following: vomiting, nausea, abdominal cramps, fever, chills, prostration, or tenesmus. Persistent diarrhea was defined as that of >14 days’ duration. Ted in persons traveling abroad. Among the microor- raveler’s diarrhea is the main infectious disease report- ganisms responsible, bacteria represent approximately 61% (1). Enterotoxigenic Escherichia coli, enteroaggrega- tive E. coli, and Shigella spp. are the most common bacte- ria involved (1,2). Other bacteria that cause diarrhea, such as Salmonella, Campylobacter, Yersinia, Aeromonas, and Plesiomonas spp., are isolated less often (1). The genus Aeromonas has high diversity: at least 16 DNA hybridization groups are recognized (3). Among these genospecies, A. hydrophila, A. caviae, and A. veronii biotype sobria are considered of clinical significance (4,5). The spectrum of infectious diseases caused by Aeromonas species includes gastrointestinal infections as well as extraintestinal infections such as cellulitis, wound infec- tions, septicemia, urinary tract infections, and hepatobil- iary and ear infections, among others (6). Although healthy carriers of Aeromonas spp. have been described, several case-control studies have shown that these bacteria cause diarrhea (6). With the incorporation of genotypic tech- niques, identification of Aeromonas to species level has *Hospital Clinic, Barcelona, Spain; †Universitat Rovira i Virgili, Reus, Spain; and ‡Universitat de Barcelona, Barcelona, Spain 552 Emerging Infectious Diseases • Vol. 9, No. 5, May 2003 Microbiologic Tests A stool sample was collected, sent to the Laboratory of Clinical Microbiology, and processed for bacterial, viral, and parasitologic studies. To isolate Aeromonas spp., blood agar supplemented with ampicillin and a selective media, CIN (cefsulodin-irgasan-novobiocin) agar, were used. After incubation at 37°C for 24–48 hours, an oxidase test was performed on the colonies compatible with bacil- li. Biochemical criteria were used to identify Aeromonas. Identification of the species was performed by 16S rDNA–restriction fragment length polymorphism as previ- ously described (7,8). The biotype of A. veronii strains was identified on the basis of a positive reaction to arginine dihydrolase and negative response to bilis-esculin hydrol- ysis and production of ornithine decarboxylase (9). Susceptibility Testing Antimicrobial susceptibility tests were performed by using an agar disk diffusion method advocated by the