MOLECULAR BIOLOGY OF HUMAN PATHOGENS ASSOCIATED WITH FOOD
Location: Produce Safety and Microbiology Research
Title: Isolation of Campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California
Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 19, 2012
Publication Date: March 14, 2012
Citation: Jay-Russell, M.J., Bates, A.H., Harden, L.A., Miller, W.G., Mandrell, R.E. 2012. Isolation of Campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California. Zoonoses and Public Health. 10.1111/j.1863-2378.2012.01465.x.
Interpretive Summary: In this study, we document that feral swine in a major produce production region may harbor zoonotic Campylobacter species in their gastrointestinal tract and oral cavity. The results underscore the importance of protecting raw food crops from fecal contamination by feral or wild animals, and reinforce recommendations for safe handling of feral swine meat by hunters. The continued expansion of feral swine in agricultural regions throughout the U.S. represents a potential public health threat and challenge in wildlife management.
We report the isolation of Campylobacter species from the same population of feral swine that was investigated in San Benito County, California during the 2006 spinach-related Escherichia coli O157:H7 outbreak. This is the first survey of Campylobacter in a free-ranging feral swine population in the U.S. Campylobacter species were cultured from buccal and rectalanal swabs, colonic feces, and tonsils, using a combination of selective enrichment and
antibiotic-free membrane filtration methods. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) was used to identify species followed by confirmatory multiplex PCR or 16S rRNA sequencing. Genetic relatedness of C. jejuni and C. coli strains was determined by multilocus sequence typing (MLST) and porA allele sequencing.
Altogether, 12 (40%) of 30 feral swine gastrointestinal and oral cavity specimens were positive and 6 species were isolated: C. coli, C. fetus, C. hyointestinalsis, C. jejuni, C. lanienae, and C.sputorum. Campylobacter jejuni subtypes were closely related to MLST sequence type 21 (ST-21) and had identical porA sequences. Campylobacter coli subtypes were unrelated to isolates in the pubMLST/porA database. This feral swine population lived in close association with a “grassfed” beef cattle herd adjacent to spinach and other leafy green row crop fields. The findings underscore the importance of protecting raw vegetable crops from fecal contamination by wild or feral animals. The study also illustrates a potential risk of Campylobacter exposure for hunters during handling and processing of wild swine meat.