How do modern day doctors use penicillin?

Question

-specific treatments?
-how does it work in those treatments?

Answer 1

penicillin is a beta lactam, it inhibits growth of cell walls in some organisms. Many organisms are resistant to it, for many reasons, but that's not the point of the question. Bacteria without a cell wall are naturally immune to its function, and organisms which possess beta-lactamase enzymes are resistant to it (staph infections for example).

Penicillin is still used to treat a number of organisms, the big one i think of off hand are Pnuemococcal organisms (strept. pnuemoniae for example).

Answer 2

Penicillin is an antibiotic, which means it kills bacteria. It's a broad-spectrum antibiotic, so it kills lots of different kinds of bacteria.

Look up penicillin at wikipedia.org