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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #314996

Title: Dynamics of E.coli virulence factors in dairy cow herds

item LAMBERTINI, ELISABETTA - University Of Maryland
item Karns, Jeffrey
item Van Kessel, Jo Ann
item CAO, HUILIN - University Of Maryland
item PRADHAM, ABANI - University Of Maryland

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2015
Publication Date: 7/1/2015
Citation: Lambertini, E., Karns, J.S., Van Kessel, J.S., Cao, H., Pradham, A. 2015. Dynamics of E.coli virulence factors in dairy cow herds. Meeting Abstract. American Society for Microbiology, New Orleans, LA. May 30-June 2, 2015.

Interpretive Summary: .

Technical Abstract: Background. Dairy farms are known reservoirs of entero-pathogenic E. coli (EPEC). EPEC, or the virulence factors associated with pathogenicity, have been detected in manure, milk, and the farm environment. However, it is unclear which farm compartments are reservoirs contributing to EPEC persistence or spikes, and what EPEC long-term dynamics are. Methods. This study investigated the occurrence and dynamics of four major E. coli virulence factors (eaeA, stx1, stx2, and '-tir) in three U.S. dairy farms. Virulence factors were measured by post-enrichment quantitative PCR. Fecal, manure, water, feed, milk, and milk filter samples were collected from 2004 to 2012. Results. All virulence factors were detected in most compartments in all three farms. Fecal and manure samples showed the highest prevalence, up to 53% for stx and 21% for '-tir in fecal samples, and up to 84% and 44% in manure. 10 to 18% of the lactating cows were potential shedders of E. coli O157 at least once during their time in the herds. Prevalence was low in milk (up to 1.9% for stx, 0.7% for '-tir). However, milk filters showed prevalence up to 35% for stx and 20% for '-tir. All factors were also detected in feed and water. Prevalence and levels of the factors, expressed as qPCR cycle threshold categories, fluctuated significantly over time, with no clear seasonal signal distinct from year-to-year variability. Levels were correlated between fecal and manure samples, and in some cases autocorrelated, while no correlation was detected between manure and milk filters. Conclusions. Based on these observations, no single farm compartment can be considered as the major reservoir that contributes to the persistence or transmission of E. coli virulence factors.