Antibiotic use in an Italian university hospital.

The aim of this retrospective observational study was to investigate: a) expenditure for antibiotics with respect to the total pharmacy drug budget and to costs of other medical devices; b) the most frequently used antimicrobial classes and molecules; c) the clinical units that most frequently use antimicrobial therapy; d) the preferred route of administration; e) consumption patterns of antibiotics over two periods (January-September 1999 and January-September 2000). The consumption of a single antimicrobial agent was expressed as daily defined doses (DDD) per 100 bed days. In 1999 drugs accounted for 56\% of the total costs but decreased to 46\% in 2000. Antibiotics accounted for 15\% of the pharmacy's overall acquisition costs in 1999 and dropped to 13\% in 2000. In both 1999 and 2000, penicillins were used most, followed by cephalosporins and aminoglycosides. In 1999, the most frequently used antibiotic was amoxicillin (4.02 DDD per 100 bed days) followed by ceftazidime, ampicillin, ceftriaxone, and co-amoxiclav. In 2000 ceftriaxone was the most commonly used antibiotic (4.35 DDD per 100 bed days) followed by co-amoxiclav, amoxicillin, ceftazidime. The general surgery, medical therapy and infectious diseases units accounted for the majority of penicillin consumption, while cephalosporins were most widely used in general surgery, orthopedics and neurosurgery units. Parenteral administration was the most widely used route in both years.