Efficacy and efficiency of a restrictive antibiotic policy on MRSA in the intensive care unit

Abstract number: O89

Vernaz N., Aschbacher R., Moser B., Harbarth S., Mian P., Bonnabry P., Pagani L.

Objectives: To determine the efficacy and the efficiency of a restrictive antibiotic policy on the incidence of methicillin-resistant Staphylococcus aureus (MRSA) in the 18-bed general Intensive Care Unit (ICU) of an 850-bed tertiary care hospital in Italy.

Methods: Based on updated microbiological reports and clinical pharmacology parameters, the dedicated Antimicrobial Management Team pursued a more appropriate approach to antimicrobial prophylaxis and empirical therapy in ICU, either withdrawing ampicillin/sulbactam (AS) prophylaxis, or targeting vancomycin (VAN) therapy whenever indicated. Using an intervention time-series analysis, we first evaluated the efficacy of AS and VAN restrictions on their consumption, then combined this model with a transfer function model on use of other antibiotics and finally assessed the efficiency on the incidence of clinical isolates of MRSA from April 2004 to December 2007. The WHO ATC/DDD classification was used as reference normalized per 100 patient-days (PD).

Results: The intervention model demonstrated that the restrictive antibiotic policy yielded a statistical significant decrease of AS from 303 to 134 DDD/100 PD, and R2 was 64% in November 2003; six months later, VAN decreased from 36 to 11 DDD/100 PD (R2 of 46%). Five months after AS restriction, the MRSA incidence significantly decreased from 3.4 to 1.4 cases. The final model explained 42% of the incidence of MRSA over time, showing, conversely, that an increase of 1 DDD/100 PD of antibiotics increased the incidence of MRSA isolates from current level, i.e. 0.043 for ceftriaxone (significant impact at lag 2 and 3), and 0.012 for levofloxacin, at the same time.

Conclusion: This study shows that modelling antibiotic use can either drive a more appropriate empirical and targeted antimicrobial therapy, or inform policy makers about negative adverse effects of certain antibiotic agents on selection of MRSA, and may ultimately control and prevent the misuse of antimicrobials. Restriction of several broad-spectrum antimicrobials might positively impact on MRSA, even if case-mix and the huge inhomogeneity of patients in general ICU may negatively affect the overall fitness of the model.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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