Prevalence of pathogenic enteric bacteria in wild birds associated with agriculture in Humboldt County, California

Cloacal and fecal samples of 243 wild birds, including 65 house sparrows (Passer domesticus), 29 white-crowned sparrows (Zonotrichia leucophrys), 16 Brewer's blackbirds (Euphagus cyanocephalus), 43 red-winged blackbirds (Agelaius phoeniceus), 56 brown-headed cowbirds (Molothrus ater), and 34 European starlings (Sturnus vulgaris) were sampled for potentially pathogenic bacteria between July 2002 and February 2004, on five dairy farms in coastal Humboldt County, California (USA). Thirty-seven bacterial species in 14 genera were isolated from wild birds. Escherichia coli (93/243; 38%), Pantoea spp. (41/243; 17%), Enterobacter spp. (39/243; 16%), Yersinia spp. (29/243; 12%), and Citrobacter spp. (27/243; 11%) were the most prevalent bacterial groups recovered from wild birds. Bacterial species composition varied between bird species, farms, and seasons. Fecal samples from 100 dairy cattle on the five farms also were sampled for pathogenic enteric bacteria during November 2002 and April 2004. Twenty-four bacterial species in 13 genera were recovered from cattle. Escherichia coli (88/100; 88%), Citrobacter spp. (18/100; 18%), Aeromonas hydrophila (13/100; 13%), Proteus vulgaris (13/100; 13%), and Citrobacter braakii (11/100; 11%) were the most prevalent bacteria isolated from cattle. Nineteen bacterial species in 10 genera were recovered from both the 243 wild birds and 100 dairy cattle. Eleven of these 19 bacterial species had the same API 20E code represented in both birds and cattle. This suggests that there is a potential for bacterial transmission between birds and cattle.