Apologies for my previous indecipherable post. 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). The CMT tests for somatic cells in milk
(leucocytes, macrophage and epithelial cells from the secretory
tissue) in cows which 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