Vibrio cholerae 638 (El Tor, Ogawa), a new CTXΦ-negative hemagglutinin/protease-defective strain that is a cholera vaccine candidate, was examined for safety and immunogenicity in healthy adult volunteers. In a double-blind placebo-controlled study, no significant adverse reactions were observed in volunteers ingesting strain 638. Four volunteers of 42 who ingested strain 638 and 1 of 14 who received placebo experienced loose stools. The strain strongly colonized the human small bowel, as evidenced by its isolation from the stools of 37 of 42 volunteers. V. cholerae 638, at doses ranging from 4 × 107 to 2 × 109 vibrios, elicited significant serum vibriocidal antibody and anti-Ogawa immunoglobulin A antibody secreting cell responses.
Twenty-five strains of Plesiomonas shigelloides isolated from aquatic environment, 10 strains from human cases of diarrhoea and five strains from animals were identified by the polymerase chain reaction technique based on 23S rRNA gene. For this purpose, two primers targeted against part of the 5P half of the 23S rRNA gene of P. shigelloides (Escherichia coli number C-912, G-1195; Plesiomonas number C-906, G-1189) were designed. Results from our study indicated that this method might serve as a tool for a rapid and sensitive identification of P. shigelloides from different environmental and clinical sources. ß
DNA molecules of Vibrio cholerae and Aeromonas species were prepared by incubating immobilized cells for 4 and 2 h, respectively, with a nonenzymatic solution that contains chemical reagents only (NDSUPlus). This method gave results as reproducible as the enzymatic one that uses proteinase K, and rendered DNA molecules suitable for fingerprinting by mini-CHEF electrophoresis. As rapid DNA separations at high electric field are achieved in mini-CHEF chamber with low heat evolution, DNA restriction fragments were separated in 5 h at 10 V/cm in a single resolution window. Then, fragment separations in three resolution windows were done in 15 h. This time is shorter than the one needed by the large CHEF chamber for resolving fragments in a single resolution window. Three windows permitted to include larger numbers of restriction fragments in the calculation of isolate similarities. Both sample preparation and mini-CHEF electrophoresis may represent an alternative for performing massive epidemiological studies of V. cholerae and Aeromonas species.
In this preliminary report the results of PCR for detection of DNA sequences (65 KDa antigen) of Mycobacterium tuberculosis in CSF samples from 20 patients are registered. In 10 patients there were clinical and laboratory findings suggesting the diagnosis of tuberculous meningitis (test group). In the other 10 patients, clinical and laboratory findings suggested meningitis or meningo-encephalitis from other etiologies (control group). In 7 patients from the test group antigenic DNA sequences of Mycobacterium tuberculosis were found in CSF by PCR; positive results were not registered in the control group.
The molecular epidemiology, antimicrobial susceptibility, and mechanisms of resistance of 34 Salmonella spp. strains causing acute gastroenteritis, isolated from different provinces in Cuba, were determined. Sixty-four percent of the strains showed multiresistance. Salmonella typhimurium was the most frequent with 15 strains (44%), 13 of which belonged to phagotype 104 and presented similar genetic profiles of pulsed field gel electrophoresis. High levels of resistance to tetracycline (53%), spectinomycin (50%), ampicillin (44%), and chloramphenicol (41%) were found. Resistance to tetracycline was associated with the tet G and tet A genes. Resistance to ampicillin was caused by the presence of beta-lactamases, mainly the CARB type. The floR gene was the main mechanism of resistance to chloramphenicol. Our results showed an antimicrobial susceptible clone of Salmonella enterica serotype Agona in two separate regions. This is the first report of the widespread dissemination of a multiresistant clone of S. enterica serotype Typhimurium definitive phage type 104 in Cuba.
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