Bacterial infections of the gut don't always kill quickly and can cause wasting and a slow deterioration of the fish. There was a medication that is no longer available called Paragon 2 from Aquatronics (*Aquatronics Paragon 2; Kanamycin can be combined with Furan 2 & Metronidazole for an excellent parasitic, fungal, & bacterial infection treatment.) This is no longer avaiable but can be made using equal parts of the above medications dosed into the hospital tank, it is a way to attack on two fronts at once. A Methylene blue bath in conjunction to the above is also a good idea.
I will never put anything into my tanks that doesn't list the ingreediance.