Reduction in broad-spectrum antimicrobial use associated with no improvement in hospital antibiogram.

Objective: To evaluate the effect of an antimicrobial management programme on broad-spectrum antimicrobial use and antimicrobial susceptibilities of common nosocomial pathogens at a tertiary-care teaching hospital.
Methods: Review of hospital charts of patients who had been prescribed broad-spectrum antimicrobials 48 h earlier. Recommendations to streamline or discontinue antimicrobials were made based on results of available microbiology data, radiography studies, as well as the working diagnosis at the time of review. The charts were reviewed again on the following day to assess acceptance or rejection of the recommendations. Antimicrobial use, measured as defined daily dose per 1000 patient days (DDD/1000 PD), was determined before and after the antimicrobial management programme was started and was assessed as the mean quarterly use in the six quarters preceding implementation of the programme compared to the most recent six quarters that the programme has been in existence. Antibiotic susceptibilities were obtained from the clinical microbiology laboratory.
Results: Compared to the six quarters before the programme, broad-spectrum antibiotic use decreased by 28% (693 DDD/1000 PD to 502 DDD/1000 PD, P = 0.003). Total antifungal agent use decreased by a similar amount, i.e. 28% (144 DDD/1000 PD to 103 DDD/1000 PD, P = 0.02). Total antimicrobial use decreased by 27% (1461 DDD/1000 PD to 1069 DDD/1000 PD, P = 0.0007). Susceptibilities of common nosocomial Gram-negative organisms to commonly prescribed antibiotics did not change significantly over the 3 years of the programme. The rate of methicillin-resistant Staphylococcus aureus increased significantly in the non-intensive care areas of the hospital (P = 0.02) and decreased significantly in the intensive care areas of the hospital (P = 0.009) over the 4 year period from 2000 to 2003.
Conclusion: Implementation of an antibiotic management programme resulted in substantial reductions in both broad-spectrum and total antimicrobial consumption without having a significant impact on antibiotic susceptibilities of common Gram-negative microorganisms within the institution. The changes in MRSA rate in the non-ICU and ICU settings may reflect infection control measures that were in place during the study period.