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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR MICROBIOLOGY AND CONTROL OF ENTERIC PATHOGENS THAT CONTAMINATE FRESH PRODUCE Title: A Survey for the Prevalence of Salmonella in the California Agricultural and Wildlife Environments

Authors
item Gorski, Lisa
item Liang, Anita
item Jay-Russell, Michele -
item Atwill, E -
item Chandler, S -
item Orthmeyer, D -
item Mandrell, Robert

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 2010
Publication Date: N/A

Interpretive Summary: A survey for the prevalence of Salmonella enterica was done as part of an ongoing study to assess the prevalence of enteric foodborne pathogens in California agricultural and wildlife environments. A total of 2431 enrichment cultures derived from samples of soil, sediment, water, growing leafy produce, and fecal material from cattle, feral pigs, coyotes, skunks, rabbits, and birds were tested for the presence of Salmonella. To date 52 isolates have been confirmed as Salmonella, giving a percentage positive of 2.1%. More isolates are being tested for confirmation.

Technical Abstract: A survey for the prevalence of Salmonella enterica was done as part of an ongoing study to assess the prevalence of enteric foodborne pathogens in California agricultural and wildlife environments. A total of 2431 enrichment cultures derived from samples of soil, sediment, water, growing leafy produce, and fecal material from cattle, feral pigs, coyotes, skunks, rabbits, and birds were tested for the presence of Salmonella. Enrichment cultures in Tryptic Soy Broth were spotted onto Modified Semi-Solid Rappaport-Vassiliadis medium (MSRV), and portions of spreading colonies from MSRV were streaked onto Xylose-lysine desoxycholate agar (XLD), as part of the Salmonella enrichment protocol used by the U.S. Environmental Protection Agency. Colonies that were black on XLD were tested by PCR for the presence of the invA gene of Salmonella. PCR-positive colonies were confirmed as Salmonella by sequencing of 16S rDNA. To date 52 isolates have been confirmed as Salmonella, giving a percentage positive of 2.1%. More isolates are being tested for confirmation. Most of the Salmonella have been isolated from water, soil/sediment, and wildlife fecal samples. Isolates are being analyzed for antibiotic resistance, serotype, and by pulsed-field gel electrophoresis for submission to PulseNet. At least 15 distinguishable patterns are evident from a subset of 20 strains. A subset of strains have been analyzed; most are sensitive to the antibiotics tested (including ampicillin, amoxicillin, chloramphenicaol, ciprofloxacin, gentamycin, kanamycin, streptomycin, sulfamethoxazole, and tetracycline), with one bird fecal isolate showing resistance to amoxicillin, cephalothin, and ampicillin. Serovar information for 10 isolates shows a mixture of types relevant to human disease including Typhimurium, Infantis, and Give.

Last Modified: 10/22/2014
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