Cephalosporins have all of the following interactions & uses, except:
Show cross sensitivity with penicillins
Are penicillinase resistant
Have a broad spectrum but are inactive against anaerobes
Are used in upper respiratory tract infections
CEPHALOSPORINS 

These are a group of semisynthetic antibiotics derived from 'cephalosporin-C obtained from a fungus Cephalosporium. They are chemically related to penicillins; the nucleus consists of a beta-lactam ring fused to a dihydrothiazine ring, (7-aminocepha losporanic acid). By addition of different side chains at position 7 of beta-lactam ring (altering spectrum of activity) and at position 3 of dihydrothiazine ring (affecting pharmacokinetics), a large number of semisynthetic compounds have been produced. 

Some salient features are:

These are not penicillinase resistance (just like penicillins).
Attributed to the similar chemical structure to penicillins they show cross sensitivity with penicillins.
These are broadspectrum antibiotics but are inactive against anaerobes.
These can be used effectively in upper respiratory tract infection.

Reference: Essentials of Medical Pharmacology Eighth Edition KD TRIPATHI page no 775,776