Its nice to back on Lactnet after such a long time and I couldn't
resist a reply to Rachel's comments on the CMT, Oh that mastitis
diagnosis in women was so easy  but it is true that there is a lot to
be learned from mastitis in the dairy industry which has spent many
years and a great deal of money investigating the problem of mastitis
(in cows that is)

The California Mastitis Test (CMT) has been around for about 50 years,
and is still widely used mainly as a test for subclinical mastitis (a
term we have unfortunately inappropriately applied to women with high
sodium concentrations in breastmilk). Somatic cells in milk
(leucocytes, macrophage and epithelial cells from the secretory
tissue) in cows are associated with clinical, subclinical mastitis and
reduced milk production. It uses a four compartment paddle and blue
reagent to test a sample of milk from each quarter (of the udder) for
somatic cells  and can help producers to easily identify cows that
probably have mastitis infections, and also provides an estimate of
the severity of those probable infections.  In general, as CMT
reactions increase, the likelihood of recovering pathogenic bacteria
increases. The CMT is good at detecting infections in quarters that
have Somatic Cell Counts (SCC) > 500,000 cells/ml but studies have
shown that infected quarters may be missed when the cell count is
lower. The rate of false negatives ranges from 8 to 43% depending on
the score used as a threshold for infection.   It does have its
limitations. More sophisticated equipment that actually counts the
number of leukocytes in a sample of milk do exist now.

Although the CMT doesn't actually measure bacteria  there is an
association between high SSC and infections, eg: a recent (2006)
study published in the Journal of Dairy Science concluded that CMT
score of ≥2 corresponding to ≥800,000 somatic cells is the best
cut-off to correctly identify S. aureus intramammary infections in low
yielding dairy cows in Tanzania.

Thomsen's work (in women)  in 1983/84 tried to use this premise of
relating leukocyte counts to bacteria counts in milk to differentiate
between infective inflammation, non infective inflammation and milk
stasis but it wasn't quite as straightforward as it theoretically
should have been and 20 years on we are still not much further
ahead...........

regards
Cathy Fetherston RM PhD IBCLC
Perth Western Australia

>
> Date:    Wed, 13 Jun 2007 21:06:08 +0200
> From:    Rachel Myr <[log in to unmask]>
> Subject: California Mastitis Test
>
> Since I mostly work with people I only recently became aware of a test kit
> by this name available in farm supply stores, for checking the number of
> white blood cells in cow's milk.  It involves taking a small amount of fresh
> milk and mixing it with a reagent which causes color change.  The color
> varies with the concentration of white cells.  For farmers it means they can
> check quickly whether a cow's production passes the test to go to the dairy.
>
> If this test or something like it could be used in humans, imagine how much
> simpler it would be to make the differential diagnosis between engorgement
> and mastitis.  Does anyone out there know anything about it?
> I have also heard unconfirmed rumors that there are tests to determine which
> bacterium is to blame, but since the ones in the test are the common
> pathogens for bovine mastitis, it wouldn't work for women unless they were
> cross-infected from a cow.
>
> Rachel Myr
> Kristiansand, Norway, and walking distance from the feed supply store where
> I can get these kits quite reasonably :-)
>
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