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Title: EFFECTS OF ESCHERICHIA COLI LIPOPOLYSCCHARIDE (LPS) INFUSION ON THE GROWTH OF STAPHYLOCOCCUS AUREUS IN THE BOVINE MAMMARY GLAND

Author
item Kauf, Adam
item Bannerman, Douglas

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2005
Publication Date: 5/21/2005
Citation: Kauf, A.C., Bannerman, D.D. 2005. Effects of escherichia coli lipopolysccharide (lps) infusion on the growth of staphylococcus aureus in the bovine mammary gland [abstract]. BARC Poster Day.

Interpretive Summary:

Technical Abstract: Mastitis is a common and expensive problem in dairy production, resulting in up to $2 billion in annual economic losses in the United States. Staphylococcus aureus is among the most common causes of bovine mastitis, and often results in a persistent, chronic infection of the mammary gland. Infection of the bovine mammary gland by either Escherichia coli or Staphylococcus aureus results in transient increases in milk somatic cell counts (SCC) and milk blood serum albumin (BSA). Infection with Escherichia coli is usually more acute in nature and cleared sooner than that from Staphylococcus aureus, and this may be related to a more rapid and intense immune response elicited by Gram negative bacteria. The researchers hypothesized that invoking the cytokine response characteristic of Gram negative infection, as those evoked by LPS from Escherichia coli, during Staphylococcus aureus infection, this may result in a more rapid and/or complete elimination of bacteria from the gland. To test this, 16 first-lactation Holstein cows were infected with approximately 75 colony-forming units (CFU) of Staphylococcus aureus in phosphate buffered saline (PBS) in one quarter. Twenty-four hours later, 8 of the cows were infused with 100 ug of LPS from Escherichia coli O111:B4 in PBS and 8 cows were infused with PBS alone. LPS-infused cows had higher rectal temperatures (P < 0.01) at 32 h post-infusion of Staphylococcus aureus (8 h post-LPS), higher milk SCC (P < 0.05) from 48-96 h post-infusion of Staphylococcus aureus (24-72 h post-LPS), and higher milk BSA from 28-60 h post-infusion of Staphylococcus aureus (4-46 h post-LPS). In contrast to the hypothesis, Staphylococcus aureus concentration in milk (milk CFU/ml) was no different or slightly, though not significantly, higher in LPS-infused cows post-LPS infusion. This may have been the result of influx of serum components and/or LPS-induced cytokine release into the milk space providing a more hospitable growth environment for Staphylococcus aureus, a conclusion supported by in vitro results. The 24 h growth of Staphylococcus aureus in milk collected from LPS-infused mammary glands at 72-h post-infusion was greater (P < 0.01) than that in milk collected from PBS-infused glands. Supported by USDA ARS CRIS Project No. 1265-32000-065.