Siderophore production and DNA hybridization groups of Aeromonas spp.

A correlation between the genospecies (DNA-DNA hybridization group) and the type of siderophore produced by 118 isolates of the genus Aeromonas was established. Organisms in hybridization groups 1 through 5 (including 5A, 5B, and 5AB) and group 12 predominantly produced the siderophore amonabactin, while an enterobactinlike siderophore was prevalent in groups 8/10 and 9. The siderophore produced by strains in group 6 may be an as-yet-unidentified nonphenolate, nonhydroxamate compound, and group 7 isolates synthesized no siderophores. Determination of the indigeneous siderophore (or the absence of one) produced by an isolate of the genus Aeromonas may assist in identification of the organism's genetic species and may suggest the presence of certain virulence properties.

Distribution of Vibrio cholerae in the Apalachicola (Florida) Bay Estuary.

Vibrio cholerae non-O1 was found throughout the Apalachicola, FL, estuary. V. cholerae O1 was isolated primarily at the City of Apalachicola sewage treatment plant, Scipio Creek and the north shore of St. George Island. Highest concentrations of both serogroups occurred in August and November. Concentrations were lowest in February and increased substantially in May. A cholera toxin-like toxin was not detected in any of the V. cholerae cultures by the Y-1 mouse adrenal cell assay or the enzyme-linked immunosorbent assay (ELISA). However, 35% of the V. cholerae O1 and 22% of the V. cholerae non-O1 cultures selected for testing caused diarrhea in infant rabbits. The proportion of V. cholerae O1 and non-O1 isolates pathogenic to infant rabbits increased as water temperature decreased. Fecal coliforms appeared to be more useful than total coliforms as indicators of the numbers of V. cholerae in water, but neither of those National Shellfish Sanitation Program indicator groups ensured against the presence of pathogenic V. cholerae in shellfish-growing areas.

Isolation of Vibrio cholerae serotype Ogawa from a Florida estuary.

Vibrio cholerae serotype Ogawa was recently isolated from the estuarine waters of Apalachicola Bay, Fla., in areas that are subject to consistent fecal contamination and in areas that are remote from any apparent source of contamination. The significance of these organisms in the environment has not been determined.

Non-O1 Vibrio cholerae in Shellfish, Sediment and Waters of the U.S. Gulf Coast.

In a study conducted throughout U.S. Gulf Coastal waters, Vibrio cholerae non-O1 was isolated more frequently from water samples than from shellfish or sediment samples. Frequency of V. cholerae recovery was directly related to water temperature and inversely related to salinity. The presence of V. cholerae was not adequately indicated by the fecal coliform standards for shellfish-growing waters and market shellfish as established by the National Shellfish Sanitation Program. Although all cultures tested by the Y-1 mouse adrenal cell assay or by radioimmunoassay for production of a cholera toxin-like toxin were negative, 4 of 13 isolates caused diarrhea in the infant rabbit.