ARS | Publication request: Prevalence, distribution and diversity of salmonella enterica in a major produce region of California

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2011
Publication Date: April 15, 2011
Citation: Gorski, L.A., Parker, C., Liang, A.S., Cooley, M.B., Jay-Russell, M., Gordus, A., Atwill, R.E., Mandrell, R.E. 2011. Prevalence, distribution and diversity of salmonella enterica in a major produce region of California. Applied and Environmental Microbiology. 77:2734-2748.

Interpretive Summary: A survey was initiated to determine the incidence of Salmonella enterica in the environment of Monterey County, California, a major agriculture region of the United States. Trypticase soy broth enrichment cultures of samples of soil, water, wildlife feces, cattle feces, and pre-harvest lettuce and spinach tested originally for the presence of pathogenic Escherichia coli were kept in frozen storage, and later used to test for the presence of Salmonella enterica. A multi-pathogen oligonucleotide microarray was used to identify a subset of samples that might contain Salmonella in order to test various culture methods for a larger survey of samples. Of 2400 samples screened, 55 yielded Salmonella isolates representing samples obtained from 21 different locations in Monterey County. Sixteen different serotypes were identified among the isolates, including S. Give, S. Typhimurium, S. Montevideo, and S. Infantis; the remainder of strains were monophasic, rough, or other types. Fifty-four strains were sensitive to the 12 antibiotics tested; one strain of S. Montevideo was resistant to streptomycin and gentamycin. Pulse Field Gel Electrophoresis (PFGE) analysis of the isolates revealed over 40 different pulsotypes. Several strains were isolated from water, wildlife, or soil spanning several months suggesting they were persistent in this environment. The highest percentage of the isolates (7.1%) were from water samples, whereas the highest number of positive samples (20 out of 55) came from wildlife, including birds, coyotes, deer, elk, cattle, feral pig, and skunk.

Technical Abstract: A survey was initiated to determine the incidence of Salmonella enterica in the environment of Monterey County, California, a major agriculture region of the United States. Of 2400 samples screened, 55 yielded Salmonella isolates representing samples obtained from 21 different locations in Monterey County. Sixteen different serotypes were identified among the isolates, including S. Give, S. Typhimurium, S. Montevideo, and S. Infantis. Pulse Field Gel Electrophoresis (PFGE) analysis of the isolates revealed over 40 different pulsotypes. Several strains were isolated from water, wildlife, or soil spanning several months suggesting they were persistent in this environment. The highest percentage of the isolates (7.1%) were from water samples, whereas the highest number of positive samples (20 out of 55) came from wildlife, including birds, coyotes, deer, elk, cattle, feral pig, and skunk.