Well this sounds miserable.
If your Xray showed infection and you have fevers, this may be pneumonia
rather than bronchitis
One class of antibiotics that your doctor(s) haven't tried are the macrolides such as Azithromycin
. These are particularly effective for pneumonia and other bacterial respiratory infections.
The sputum sample will be helpful. In addition to culturing the sputum, I assume the doctor also ordered a "sensitivity" test which shows what antibiotics the bacteria that is causing the infection (if it is caused by bacteria) is sensitive to.
If you are on multiple antibiotics, if possible, take a probiotic
too to keep your gut healthy. Best to take it at least 2 hr. after the antibiotic so the antibiotic doesn't just kill it.
If you smoke cigarettes it would be imperative to quit now so that your immune system can respond adequately.
I know the idea of superbugs are frightening (that's what we call them in the US) but there are other classes of antibiotics that your doctor hasn't tried yet.
I hope this information helps. Please let me know if I can provide further information.