Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 2008
Publication Date: April 18, 2009
Citation: Looper, M.L., Edrington, T.S., Callaway, T.R., Rosenkrans, C.F. 2009. Fate of Escherichia coli O157:H7 and Salmonella from contaminated manure slurry applied to soil surrounding tall fescue. Letters in Applied Microbiology. 48:513-516. Interpretive Summary: Animal manure can contain numerous pathogenic bacteria including E. coli O157:H7 and Salmonella. Possible internalization of pathogenic bacteria has resulted recently in numerous cases of contaminated vegetables with subsequent foodborne illnesses in humans. Research regarding transfer of pathogenic bacteria into forages consumed by grazing ruminants is nonexistent. ARS scientists from Booneville, AR, and College Station, TX, and personnel from the University of Arkansas conducted a study to determine if E. coli O157:H7 and Salmonella could be transferred from contaminated manure slurry to tall fescue plants. Both pathogens persisted in the soil for 2 week indicating E. coli O157:H7 and (or) Salmonella shed in the manure of grazing cattle could potentially infect additional animals. Escherichia coli O157:H7 was transferred to tall fescue plant tissue and appeared to be internalized within 4 days of exposure to an E. coli O157:H7-contaminated manure slurry; however, Salmonella was not detected in fescue plant tissue samples. This information is of interest to livestock producers, extension personnel, and agricultural professionals who advise producers on livestock management practices.
Technical Abstract: Objective of this study was to investigate the potential transfer of E. coli O157:H7 and Salmonella from soil fertilized with contaminated manure slurry into the tissue of tall fescue plants. Tall fescue plants (n = 50) were fertilized with a manure slurry inoculated with E. coli O157:H7 and Salmonella. Soil was collected and tall fescue plants (n = 10/d) harvested on d 1, 2, 4, 8, and 14 after manure slurry fertilization. Soil samples were positive for E. coli O157:H7 on all days, while soil samples were positive for Salmonella on d 1, 2, 8, and 14. None of the plant tissue samples were positive for E. coli O157:H7 on d 1 or 2; however, 20, 30 and 40% of plant tissue samples were positive for E. coli O157:H7 on d 4, 8, and 14, respectively. No plant tissue samples were positive for Salmonella on any day. Both pathogens persisted in the soil for the duration of the 2 wk experiment. It may be possible that E. coli O157:H7 can become transmitted and internalized into tall fescue plant tissue within 4 d after exposure to an E. coli O157:H7-contaminated manure slurry. Salmonella does not appear to be transferred to plant tissue at the same rate as E. coli O157:H7. Feces contaminated with E. coli O157:H7 may be one means of how grazing ruminants spread bacterial pathogens to additional animals. Increased knowledge of factors affecting on-farm pathogen transmission is necessary to identify management schemes effective at alleviating reservoirs of pathogenic bacteria.