>The authors grew Group B Strep from the mothers' milk and
>cautioned against breastfeeding if mastitis was bilateral.

Ginna,
Thank you for posting that reference!  Ruth Lawrence used to have a
caution in an earlier edition of her book to suspect Group B strep if the
mother has bilateral mastitis.  Another lactnetter and friend of mine
posted a couple of years ago about her own sister who developed bilateral
mastitis a week or so postpartum.  Baby got sick and died before they
figured out what was wrong. Group B was later cultured from the mom
(vaginally, I think), but my friend felt awful because she had read the
comments in Ruth's book but had not flagged the bilateral mastitis until
it was too late.

I don't know why Ruth pulled that section from the current editions;
maybe there just was not enough validating information. However, your
story, my LC friend's story and now your reference tell me that maybe
we'd better not forget this uncommon but distinct possible connection.
If I see a bilateral mastitis, I will most likely tell mom to take baby
to the pediatrician ASAP for a nose and throat culture, rather than wait
and see what develops.

-Lisa Marasco, BA, IBCLC