Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 2/20/2008
Publication Date: 6/1/2008
Citation: Karns, J.S., Son, I., Van Kessel, J.S. 2008. Comparison of Escherichia coli from Milk and Milk Filters with E. coli from Feces and Environmental Samples on a Dairy Farm. The American Society for Microbiology 108th General Meeting, Boston, Massachusetts. June 1-5, 2008. Interpretive Summary:
Technical Abstract: On a modern US dairy farm, as the cows are milked the milk is pumped into a holding tank through an in-line milk filter and subsequently cooled. The milk filter is designed to prevent large particulate matter such as bedding and fecal matter accidently introduced during the milking process from entering the bulk tank. It appears that bacteria are trapped along with the particulate matter, and milk filters have been used to detect the presence of bacterial pathogens. E. coli is commonly used as an indicator of fecal contamination but it’s presence in the milk can also be due to mammary gland infections. This study was conducted to examine the relationship between E. coli isolated from the milk and milk filter and from the dairy environment. Milk and milk filters were collected along with fecal and environmental samples on Dec., 2005 and Dec., 2006 from a 100 cow dairy farm in PA. Pulsed field gel electrophoresis (PFGE) was used to compare multiple E. coli isolates from each sample. Restriction digestion pattern (RDP) comparisons were based upon cluster analysis using 95% Dice similarity in conjunction with unweighted pair group method with arithmetic mean. Diversity within milk samples was limited with just three distinct RDPs identified in the 2005 sample and only one RDP identified in the sample from 2006. Diversity was greater in the milk filter samples with 8 distinct RDPs identified in 2005 and 3 distinct patterns identified in the 2006 sample. No common RDPs were identified between the milk and milk filter isolates. Several of the isolates from the milk filters had RDP patterns indistinguishable from environmental isolates. In the samples collected in 2005, there were no common RDP patterns between the milk isolates and those from the environment. Fecal isolates were identified in both the milk and the milk filter in the 2006 samples. These data show that both environmental and fecal contamination are significant sources of E. coli in bulk tank milk.