Antibiotic costs and prescribing patterns in a recently commissioned Liverpool teaching hospital. Part II: Antimicrobial chemoprophylaxis.

All antibiotics prescribed for prophylaxis in a major teaching hospital were prospectively surveyed during 31 consecutive days. Of 2350 patients admitted during that period, 238 (10.1%) received antibiotics for prophylaxis. A total of 1238 operations were performed during the period of study, of which 201 (16.2%) were covered with antibiotics, at a cost of 3472 pounds. The use of prophylaxis increased according to the risk of peri-operative wound contamination, from 15.8% in Class I to 52.4% in Class III operations. The average cost of chemoprophylaxis also increased correspondingly. A further 40 regimens were issued for non-surgical prophylaxis at a cost of 258 pounds. Twenty antibiotics were prescribed either alone or in 37 different combinations for surgical prophylaxis, the most frequent being cephradine (22%), metronidazole (17%), penicillin (12%), and tobramycin (11%). The mean duration of antibiotic administration for all surgical procedures was 6.1 days.