Short communication: methicillin-resistant Staphylococcus aureus detection in US bulk tank milk.
J Dairy Sci. 2009 Oct
Virgin JE, Van Slyke TM, Lombard JE, Zadoks RN.
USDA, APHIS, VS, Centers for Epidemiology and Animal Health, Fort Collins, CO 80526-8117, USA.
* USDA:APHIS:VS, Centers for Epidemiology and Animal Health, 2150 Centre Ave., Bldg B, Fort Collins, CO 80526-8117 Quality Milk Production Services, College of Veterinary Medicine, Cornell University, Ithaca, NY14850-1263
1 Corresponding author: jason.e.lombard@aphis.usda.gov
Staphylococcus aureus is a major cause of mastitis in dairy cattle. This study estimated the herd prevalence of methicillin-resistant Staph. aureus (MRSA) among US dairy herds by testing bulk tank milk (BTM) samples using genotypic and phenotypic methods. A nationally representative sample of 542 operations had BTM cultured for Staph. aureus, and 218 BTM samples were positive upon initial culture. After 4 wk to 4 mo of frozen storage, 87% of 218 samples (n = 190) were still culture positive for Staph. aureus on blood agar, but none were positive for MRSA on the selective indicator medium CHROMagar MRSA. A duplex PCR was used to detect the Staph. aureus-specific nuc gene and the methicillin resistance gene, mecA, in mixed staphylococcal isolates from the 190 BTM samples that were positive for Staph. aureus after storage. Seven samples tested positive for nuc and mecA, and 2 samples tested positive for mecA only. MecA-positive Staphylococcus spp., but not MRSA, were subsequently isolated from 5 samples, whereas neither mecA-positive Staphylococcus spp. nor MRSA was isolated from the remaining 4 samples. Presence of methicillin-resistant, coagulase-negative Staphylococcus spp. may complicate the detection of MRSA by means of PCR on BTM. Bulk tank milk in the United States is not a common source of MRSA.
Journal of Dairy Science
About Me
- Pat O'Connor
- Am old enough to understand the difference between the Bay of Pigs - and roasting a pig at a epicurian feast. Been thru the hippy, yippie and yuppie years - always remaining who I am. Very much believe in "Sing your own song - weave your own tapestry" Am young enough to still know the thrill of new discoveries, the beauty of the evening, to celebrate the joy of another tommorow. Survived these many decades with a severe medical problems. Sorting out the maze of now having two lymphomas and all their nasty little companions, but I continue. Besides, being a simple iconoclastic eclectic, have been called many things. An incurable romanticist - with a strong touch of reality. Thinker, intellectual (God, how I hate that term) - been told I am a lion with the heart of the poet. Know how to wage war and conquer my foes - but would rather be known as one who brings hope and life. To bring hope into anothers life is the ultimate of joys. Life should be about bringing hope, peace, vision... a sense of purpose beyond yourself.
