I'm not going to be of much help. Most bacterial conjunctivitis are treated with DROPS not oral antibiotics. Oral TCN is not commonly used for conjunctivitis. It isused for blepharitis.
We don't usually culture conjunctivis unless very severe was the cultures take so long to get back we don't find them helpful.
Since your therapy is unusual you will need to ask your Eye MD why he/she made the choices.
JCH III MD