Clonal dissemination of Vibrio parahaemolyticus displaying similar DNA fingerprint but belonging to two different serovars (O3:K6 and O4:K68) in Thailand and India.

Active surveillance of Vibrio parahaemolyticus infection among hospitalized patients in Calcutta, India, showed the appearance of the O4:K68 serovar for the first time in March 1998 alongside the continued predominant incidence of the O3:K6 serovar. Strains belonging to both these serovars have been reported to possess pandemic potential. The genomes of O3:K6 and O4:K68 strains and for comparison, non-O3:K6 and non-O4:K68 strains isolated from two different countries, India and Thailand, were examined by different molecular techniques to determine their relatedness. The O3:K6 and O4:K68 strains from Calcutta and Bangkok carried the tdh gene but not the trh gene. Characterization of representative strains of these two serovars by ribotyping and by arbitrarily primed-polymerase chain reaction (AP-PCR) showed that the isolates had identical ribotype and DNA fingerprint. Pulsed-field gel electrophoresis (PFGE) performed with the same set of strains yielded nearly similar restriction fragment length polymorphism (RFLP) patterns for the O3:K6 and O4:K68 isolates from Calcutta and Thailand. Phylogenetic analysis of the NotI RFLP showed that the O3:K6 and O4:K68 strains formed a cluster with 78-91% similarity thus indicating close genetic relationship between the two different serovars isolated during the same time-frame but from widely separated geographical regions. The non-O3:K6 and non-O4:K68, in contrast, showed different ribotype, AP-PCR and PFGE patterns.

Giardia lamblia in AIDS patients with diarrhea.

Giardia lamblia, a flagellate protozoan is a protozoa, frequently associated with diarrhea in AIDS patients (adults and children). Transmission occurs via the fecal-oral route by ingestion of infectious cysts in contaminated food or drinking water. Giardia lamblia can cause diarrhea and intestinal malabsorption in both AIDS and non-AIDS patients. The prevalence rate of diarrhea caused by Giardia lamblia in AIDS patients is higher than in those without AIDS, due to humoral immune defect in AIDS patients. The most common symptoms are abdominal distress, watery diarrhea and weight loss. The clinical symptoms in AIDS patients are similar to those in non-AIDS patients. Diagnosis may be made by identifying either cysts or trophozoites in a stool sample, duodenal biopsy and aspirate. Metronidazole is the common drug of choice. Relapse may be found in AIDS patients. At present there is no vaccine. Prevention requires proper handling, good hygiene and treatment of water used for AIDS patients.

Comparison of the efficacy of ceftibuten and norfloxacin in the treatment of acute gastrointestinal infection in children.

A prospective randomized study was conducted at an infectious disease hospital in Thailand. Ceftibuten was compared with norfloxacin, both given orally for five days for treatment of acute gastroenteritis in children. One hundred and seventy cases were included in the study. Eighty-eight cases were treated with ceftibuten and eighty-two cases with norfloxacin. The baseline characteristics of the patients in both treatment groups were similar. The results showed that mean durations of diarrhea in the ceftibuten and norfloxacin groups were 2.48 days and 2.29 days, respectively, but there was no statistically significant difference between the two groups (p > 0.05). There were Salmonella spp and Shigella spp isolated in both treatment groups and all were susceptible to both antibiotics. The mean durations of Salmonella diarrhea in the ceftibuten and norfloxacin groups were 2.7 and 2.2 days, respectively, while those of Shigella diarrhea were 2.3 days and 2.0 days, respectively. There were no statistically significant differences in either comparison (p > 0.05). Neither complications nor clinical relapses were observed after both antibiotics' treatment.

Rapid diagnosis of cholera caused by Vibrio cholerae O139.

Hybridomas secreting specific monoclonal antibodies (MAbs) to Vibrio cholerae serogroup O139 were produced. Six monoclones (hybridomas) secreting MAbs specific only to lipopolysaccharide of V. cholerae O139 strains and which did not cross-react to 137 strains of other enteric microorganisms were obtained. These clones were designated 12F5-G11, 12F5-G2, 15F5-H5, 5B9-F8, 14C9-D2, and 6D2-D8. The immunoglobulin (Ig) heavy chain isotypes secreted by these clones were IgG2b, IgG2b, IgG2b, IgM, IgG2b, and IgG3, respectively. Clone 12F5-G11 was selected for mass production of MAb, which was used as a detection reagent in the antigen detection assay for diagnosis of cholera caused by V. cholerae O139, and this assay was compared to the conventional bacterial isolation method. Five batches of rectal swab cultures in alkaline-peptone water were collected from 6,497 patients with watery diarrhea. These were 6,310 patients admitted to Bamrasnaradura Infectious Diseases Hospital, 16 patients from Krung Thon Hospital, 78 patients from Bangkok Children's Hospital, 19 patients from Karen refugee camps, and 74 Indian patients from the National Institute of Cholera and Enteric Diseases, Calcutta, India. The V. cholerae O139 isolations from the rectal swab cultures and the antigen detection assays (i.e., the MAb-based dot-blot ELISA) were performed by different persons of different laboratories, and the results were revealed after all specimens had been tested. Of the 6,497 samples tested, the dot-blot ELISA correctly identified 42 of 42 V. cholerae O139-positive samples and gave a result of positive for three samples which were culture negative for V. cholerae O139. The diagnostic sensitivity, specificity, and efficacy of the dot-blot ELISA were 100, 99.95, and 99.26%, respectively. The ELISA is easy to perform and relatively inexpensive. It can test multiple samples at a single time, does not require special equipment, and does not produce great quantities of contaminated waste. Most of all, it reduces the diagnostic time from at least 2 days for the bacterial isolation to less than 90 min. The assay is recommended as a rapid screening test of cholera cases caused by V. cholerae O139.

Comparison of the efficacy of tetracycline and norfloxacin in the treatment of acute severe watery diarrhea.

Antibiotic treatment appears to shorten the duration of diarrhea and eradicate Vibrio cholerae. The objective of this study was to compare the efficacy of tetracycline with norfloxacin therapy in patients (adults and children) with acute severe watery diarrhea caused by VC 01 and VC 0139. Patients (adults and children) with acute severe watery diarrhea admitted to Bamrasnaradura Infectious Disease Hospital, Thailand were randomized to receive either tetracycline (500 mg qid in adults and 12.5 mg/kg qid in children) or norfloxacin (400 mg bid in adults and 7.5 mg/kg bid in children) for 3 days each. The duration of diarrhea and the fecal shedding were comparable between two groups. Thirteen cases were treated with tetracycline and twelve cases with norfloxacin. The results showed the mean duration of diarrhea in tetracycline-treated and norfloxacin-treated groups were 1.31 and 1.25 days, respectively. The mean fecal shedding in tetracycline-treated and norfloxacin-treated group were 1.38 and 1.33 days, respectively. However, there were no statistically significant differences between two groups of both comparisons (p > 0.05). All isolates (VC 01 and VC 0139) in this study were susceptible to both antibiotics. Tetracycline therapy is as good as norfloxacin therapy for quick recovery and time for bacterial eradication in patients with acute severe watery diarrhea caused by Vibrio cholerae. Children aged less than 8 years should not use tetracycline therapy because of its toxic effects.

Nontyphoidal Salmonella diarrhea in Thai children: a study at Bamrasnaradura Hospital, Nonthaburi, Thailand.

From July 1, 1994 to June 30, 1996, 394 children with Nontyphoidal Salmonella diarrhea were studied at Bamrasnaradura Infectious Disease Hospital in Thailand. The ages ranged from 1 month to 12 years (mean, 1.4 years). Eighty-seven per cent of patients were in the first 2 years of life. Diarrhea, mostly acute with watery stool and fever were the most common presenting symptoms. The duration of diarrhea ranged from 1 to 20 days (mean, 5.2 days). Salmonella group B was the most common serogroup (56.1%). Most isolates were multiresistant strains, however, they were all sensitive to norfloxacin. Four (1%) patients were HIV-infected. Pneumonia found in 2 patients (0.5%) and septicemia in 1 patient (0.3%). None of the patients died. We conclude that nontyphoidal Salmonella diarrhea in children is still endemic in Thailand, especially among infants and high multidrug resistance occurs.

Cryptosporidiosis in HIV infected patients in Thailand.

Diarrhea, mostly chronic diarrhea and weight loss are common in patients with AIDS. Cryptosporidium had been identified as responsible for chronic, debilitating secretory diarrhea in HIV infected patients. We performed a retrospective study of the prevalence, clinical features and laboratory findings of cryptosporidiosis in HIV infected patients (adults and children), in the period of 6 years from January 1988 to December 1993 at Bamrasnaradura Hospital in Nonthaburi, Thailand. In this study, Cryptosporidium was found in 22 (8.8%) by detection in stool specimens of 250 HIV infected patients with diarrhea and was found throughout the year. The prevalence rates of cryptosporidiosis in this study among children and adults were 19% and 7.9%, respectively. The common features were chronic diarrhea (84.6%), mostly watery diarrhea and weight loss/malnutrition (100%). A few fecal leukocytes were found in 15.4%.