Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii Circulation in a Dairy Farm and Sources of Milk Contamination

Abstract

ABSTRACTEven though dairy cows are known carriers ofArcobacterspecies and raw or minimally processed foods are recognized as the main sources of humanArcobacterinfections in industrialized countries, data onArcobacterexcretion patterns in cows and in milk are scant. This study aimed to identify potentially pathogenicArcobacterspecies in a dairy herd and to investigate the routes ofArcobactertransmission among animals and the potential sources of cattle infection and milk contamination. A strategy of sampling the same 50 dairy animals, feed, water, and milk every month for a 10-month period, as well as the sampling of quarter milk, animal teats, the milking environment, and animals living on the farm (pigeons and cats), was used to evaluate, by pulsed-field gel electrophoresis (PFGE), the characteristic patterns in animals, their living environment, and the raw milk they produced. Of the 463 samples collected, 105 (22.6%) were positive forArcobacterspp. by culture examination. All the matrices except quarter milk and pigeon gut samples were positive, with prevalences ranging from 15 to 83% depending on the sample. Only threeArcobacterspecies,Arcobactercryaerophilus(54.2%),A. butzleri(34.2%), andA. skirrowii(32.3%), were detected. PFGE analysis of 370 isolates from positive samples provided strong evidence ofArcobactercirculation in the herd: cattle likely acquire the microorganisms by orofecal transmission, either by direct contact or from the environment, or both. Water appears to be a major source of animal infection. Raw milk produced by the farm and collected from a bulk tank was frequently contaminated (80%) byA. butzleri; our PFGE findings excluded primary contamination of milk, whereas teats and milking machine surfaces could be sources ofArcobactermilk contamination.