No abstract

Vibrio vulnificus was enumerated in seawater and shellfish from two Florida estuaries at selected seasonal intervals. There were significant fluctuations in the presence and numbers of V. vulnificus. Relatively high seawater temperature and salinity favored the presence of V. vulnificus in both seawater and shellfish samples. Vibrio vulnificus is a lactose-fermenting, halophilic, gram-negative, and potentially pathogenic marine vibrio. Reports of its occurrence in seawater and association in human infections are increasing (2, 3, 5). It has been suggested that some Vibrio spp. may be indigenous to estuarine microflora (4). Kaneko and Colwell (4) have reported high levels of Vibrio parahaemolyticus in seawater during the warm months and low levels in cold months, appearing mostly in sediments. This study reports the seasonal occurrence of V. vulnificus in both seawater and shellfish from two Florida estuaries which are closely associated with both shellfish harvesting and recreational activities. Seawater, oyster, and clam samples were collected from three Tampa Bay and eight Apalachicola Bay stations (Fig. 1-3).

The Suwannee River spans the Florida/Georgia border to the Gulf of Mexico, and contributes to regional irrigation and recreational activities. Association of Salmonella enterica with these resources may result in the contamination of produce and disease outbreaks. Therefore, surface water was examined for the distribution of S. enterica at multiple time points from 4 sites on the upper Suwannee River. Isolates were confirmed by detection of the invA gene, and 96% of all samples were positive for the bacterium. Most probable number enumeration ranged from <18 to 5400 MPN/100 mL. Genetic diversity of these isolates (n=110) was compared to other environmental (n=47) or clinical (n=28) strains and to an online library (n=314) using DiversiLab rep-PCR. All strains showed >60% similarity and distributed into 16 rep-PCR genogroups. Most (74%) of the Suwannee River isolates were clustered into two genogroups that were comprised almost exclusively (97%) of just these isolates. Conversely, 85% of the clinical reference strains clustered into other genogroups. However, some Suwannee River isolates (12%) were clustered with these primarily clinically-associated genogroups, supporting the hypothesis that river water can serve as a disease reservoir and that pathogenic strains may persist or possibly originate from environmental sources.