Use of penicillin-based drugs was 49% (45/92) after PST and cephalosporin use increased from 4.4% (4/92 (all third generation cephalosporins)) to 47.8% (44/92( second and third generation cephalosporins)). i.e., 97% of patients with a negative PST received a penicillin or a cephalosporin.