I went through exactly that with my Dad 20+ years ago. Rushed to the hospital, terrible bacterial infection focused on his lungs. Doctors said they had to "take a guess" at what drug would match the bug, because they didn't have time to culture anything. Apparently, they guessed correctly, and I took him home literally less than 48 hours after admission.
Here's to hoping your Dad's Doctors guess as well, or at least guess well enough to get a culture and get the right drug in him!
