Survival of Escherichia coli O157:H7 in farm water: its role as a vector in the transmission of the organism within herds.
OBJECTIVE
The study aimed to investigate the survival characteristics of Escherichia coli O157:H7 in farm water (FW), and in sterile distilled municipal water (SDW), stored outdoors under field conditions, with or without the addition of faeces (1% w/v), in a farmyard shed and the laboratory at 15 degrees C.


RESULTS
Water samples were inoculated with E. coli O157:H7 at 10(3) and 10(6) ml(-1), and sampled over a 31-day period. In FW stored outdoors in a field, E. coli O157:H7 survived for 14 days at temperatures <15 degrees C, at both inoculation levels, while in the laboratory at 15 degrees C, the organism was still detectable at low levels (<1 log10 cfu ml(-1)) after 31 days. The addition of bovine faeces to water outdoors (1% w/v) resulted in survival for 24 days. In SDW inoculated at 10(6) ml(-1) and stored in the laboratory (15 degrees C), only a 2.5 log reduction was observed after 31 days, while the organism could not be detected after 17 days in the field. Preliminary screening of water samples stored outdoors isolated a bacterium which exhibited antimicrobial activity towards E. coli O157:H7.


CONCLUSIONS
The survival of E. coli O157:H7 observed in this study illustrates the potential of farm water to act as a vehicle in the transfer of the organism across a herd.


CONCLUSIONS
The difficulty in extrapolating results from controlled laboratory situations to on-farm conditions is also highlighted in this study.
McGee
P
P
Teagasc, The National Food Centre, Dublin, Ireland. pmcgee@nfc.teagasc.ie
Bolton
D J
DJ
Sheridan
J J
JJ
Earley
B
B
Kelly
G
G
Leonard
N
N
D000383:Agriculture; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000302:isolation & purification / Q000378:metabolism; D002417:Cattle; D015169:Colony Count, Microbial; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D005243:Feces / Q000382:microbiology; D005618:Fresh Water / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D014881:Water Supply
D000900:Anti-Bacterial Agents