They likely ment myco.
All pet rats are assumed to have myco and rats experience myco flareups of symptoms from time to time ... some more then others.
Rats are not separated for myco.
Actually it is extremely rare to need to separate rats for any medical reason.
Please put Ellie back in with the others right now.
If she had anything contagious, they would already have it.
Being separated will stress her, causing her to become more ill .... not to mention lonely, etc.
I measure out the amount each rat gets and add a drop of strawberry quik, a drop or 2 of olive oil, a couple of drops of water and mix it up with a bit of baby cereal to thicken it. My rats think it is a great treat.
Baytril, an antibiotic, is good for treating myco and is often used in combo with other antibiotics.
Cat or kitten revolution is used to treat mites and it is put on the back of their necks. The amount used is based on the weight of the rat.
It lasts for a month. Mites can not be seen and skin scraping are painful and often give false results so do not get skin scrapings done to test for mites.
You can get revolution from a vet.
Edit: Here is a thread on masking meds so that rats will eat them
viewtopic.php?f=21&t=4656&p=232782&hilit=masking+meds#p232782