Purpose: This work identifies Salmonella serotypes associated with Central Florida surface waters over a twelve-month period.
Methods: Water samples (10 l) were taken monthly, for 12 months, from 18 locations (202 samples). Salmonella was enumerated by MPN using a modified FDA-BAM Salmonella method using 33.3 ml of the water sample. Up to 36 isolates from each water sample were determined to be either different, or likely the same, using multiplex PCR patterns and serogrouping. All Salmonella isolates from each water sample determined to be different using multiplex PCR patterns and serogrouping, were serotyped and analyzed with PFGE.
Results: Salmonella isolates (223) were cultured from 81.7 % (165/202) of water samples. Of the serotypes identified (32), the most frequently isolated included Muenchen (11.5%), Rubislaw (9.5%), Anatum (8.8%), Gaminara (8.8%), and IV_50:z4,z23:- (6.8%). Each Salmonella-positive water sample yielded at least two, and at most 11, different serotypes; the average number of serotypes from a Salmonella-positive water sample was six. Serotypes most frequently isolated during each monthly sampling period included Anatum (8/12), Muenchen (7/12), and Rubislaw (6/12). No single serotype was isolated during every monthly sampling period from any of the sampling locations and no temporal patterns were observed. The majority (143) of isolates, including some from all sampling locations, clustered into one genotypic group (>80% similar) by PFGE analysis; this group included 23 of the 32 serotypes.
Significance: Salmonella in Central Florida surface waters are serotypically diverse and include clinically common serotypes. The use of untreated surface water for agricultural purposes that contacts the harvested portion of edible horticultural crops close to time of harvest should be considered a food safety risk.