Same thing. I agree with Marty. Kanamycin is a broad spectrum gram-neg bactericidal and antibiotic and does well with Metronidazole in full doses. I've also safely used API Pimafix at half and full doses with both of these to control the onset of secondary fungal infections with great success.
Another Med that gives a synergistic effect with Kanamycin and Metro is added Nitrofurazone to the mix.
Try this site for further info on what you might be dealing with. Whatever you do, in between rounds of meds, make sure you that hit the tank with a fresh bag of carbon in a disinfected bag (or you could re-infect the tank) for a couple of days to give their liver and kidney's some rest. Toss the carbon as it will be basically completely exhausted only after a couple of days and could harbor what you're trying to eliminate.
http://www.americanaquariumproducts.com/Vibrio_Aeromonas.html Also, remember, that most onset of illness is because of tank conditions. No offense but things like regular siphoning of the substrate, cleaning of the filter media and rocks will all help to keep optimal immune systems in the fish and to keep bad bacteria (that exists in every tank even in the most minute amount).
last thing is that you might want to consider getting a UV Sterilizer and run that while using carbon. It will help to kill off bad bacteria while meds are being removed.