What do the different spectrums tell you about cephalosporins?

The narrow spectrum cephalosporins are the antibiotics that were first found and that are not that effective to a lot of bacteria. the more you move up in spectrum (expanded, broad, extended) the more active the antibiotics are to other bacteria. the antibiotics in the broad spectrum can pass the blood-brain barrier and the ones in the extended spectrum can pass the outer membrane more easily.