A study of antimicrobial misuse in a university hospital.

We undertook a prospective study to determine patterns and sequelae of antimicrobial misuse and factors associated with inappropriate antimicrobial therapy in a teaching hospital. Over an eight-week period, 144 (26.2%) of 549 hospitalized medical and surgical patients received one or more courses of antimicrobial therapy. An average course comprised 1.4 drugs. Presumptive infection was the reason for 70% of courses and prophylaxis, 30%. Therapy was judged appropriate in 59% of courses overall. Unnecessary therapy, poor drug choice (bacteriologically, pharmacologically, or both), or misguided prophylaxis most frequently underlay inappropriate therapy. Adverse reactions (17% overall) were twice as frequent and the cost of therapy was 55% greater in inappropriate courses. Performance of pretherapy cultures (p less than 0.05), obtaining gram-stained smears of sputum in presumed respiratory tract infections (p 0.001), and notation in the record that antimicrobial therapy had been instituted (p less than 0.001) were strongly associated with appropriate therapy. This study underscores the need for more effective programs of postgraduate education which stress basic principals of infectious disease and antimicrobial pharmacology and guidelines for prophylaxis. Antimicrobial utilization review should figure heavily in hospital programs of medical self-evaluation. Additional measures to upgrade the use of antibiotics are discussed.