Piperacillin is a broad spectrum antibacterial antibiotic encompassing most Gram-positive and Gram-negative aerobic bacteria and anaerobic bacteria in humans. It works on respiratory infections in humans as well. I would think it should be good for chameleons too…but I’m not a vet and it’s never been used in any chamekeons I have had for respiratory infections…so I can’t speak from experience.
(I’m still looking for information on use of piperacillan because in the back of my mind I remember an article about it…but, of course, I can’t find it right now.)
I’ve been told by my vet many years ago though, that a chameleon can not produce a fever so to create the “effect” of the fever and maybe help the chameleon fight the infection, it’s useful to make sure it stays warm enough to be like it has a fever….but you don’t want to cook the chameleon…of course. This might help the immune system. With the temperature on the warm side, it should help the digestion, too, and it should poop more often.
I asked about the blood tests because I’m not sure it’s a respiratory infection…just a feeling. So I hoped the blood tests would give other clues as to what’s going on.
I don’t have a solution to what to do to fix your chameleon…I'm not a vet…so I can only give you information from what I’ve learned over the years.
I hope you can figure it out and get your chameleon back on track.