My friend's DD has a chest infection and I was meant to be babysitting her tonight. I said I wasn't sure as DS is prone to chest infections but she says bronchitis, sinusitis, chest infections, bacterial tonsillitis and bacterial throat infections are no longer contagious after 24 hours on antibiotics.
I have found a few things by googling that seem to back this up. Just thought I'd share this because I always presumed you were contagious until the symptoms had disappeared.
bronchitis and sinusitis
bacterial throat infection
bacterial tonsillitis
Also found out bacterial pneumonia isn't contagious.