Appropriate use of restricted antimicrobial agents in hospitals: the importance of empirical therapy and assisted re-evaluation

We evaluated the appropriateness of use of restricted antimicrobial agents in the context of a newly implemented order form and delivery system for restricted antimicrobial agents, using sequential prospective audits of prescriptions. Four antimicrobial agents were selected: glycopeptides (61 prescriptions), ciprofloxacin (42), piperacillin-tazobactam (42) and imipenem- cilastatin (47). The justification and adequacy of the antibiotic or combination used, reassessment of therapy and duration of treatment were appraised with reference to the clinical situation and hospital's guidelines. Of the 192 prescriptions, 30 (16%) were empirical therapy, 95 (49%) empirical and secondarily documented and 67 (35%) initially documented therapy. Overall, 73% of prescriptions conformed to guidelines, but the adequacy varied from 93% for vancomycin to only 38% for ciprofloxacin. Of 83/157 initially inadequate prescriptions, 42 (51%) were switched according to guidelines, but only 14% of ciprofloxacin prescriptions were adapted later. An intervention audit with counselling on ciprofloxacin usage increased this rate to 75%. Although implementation of the guidelines resulted in a marked reduction in overall antimicrobial costs, inappropriate antibiotic usage may persist for some drugs despite restricted access. These results emphasize the need for combined interventions using education and expert counselling, targeted to classes of antibiotic for which inappropriate usage is most common.