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

All antibiotics prescribed in a major teaching hospital were prospectively surveyed during 31 consecutive days. Of 2350 patients admitted during that period, 577 (24.6%) received antibiotics, 238 (10.1%) for prophylaxis and 417 (17.7%) for treatment. A total of 483 infections occurred in the treated patients, mainly in the chest (33.9%) and urinary tract (27.7%). Two hundred and forty-four infections (50.5%) were community-acquired and the remaining 239 hospital-acquired infections occurred in 8% of patients admitted. The cost of treating nosocomial sepsis was 4453 pounds (48% of the antibiotic expenditure for treatment). The average cost of treatment per patient varied considerably between hospital specialties; one-third of therapeutic antibiotic expenditure was consumed by haematological patients. Thirty-one antimicrobials alone or in 45 different combinations were issued; ampicillins were the most frequently prescribed antibiotics (31%), followed by co-trimoxazole (14%) and trimethoprim (8%). The patterns of antibiotic usage are discussed and inappropriate prescriptions examined.