Increasing consumption of MRSA-active drugs without increasing MRSA in German ICUs.

Purpose: The aim of our study was to analyze changes in the consumption of MRSA-active antibiotics and in the burden of methicillin-resistant S. aureus (MRSA) over a period of 9 years in a network of German intensive care units (ICU).

Methods: Data from 55 ICUs in Germany were analyzed from 2001 through 2009. The term "old MRSA-active antibiotics" included vancomycin, teicoplanin and fosfomycin, whereas the term "new MRSA-active antibiotics" included quinupristin/dalfopristin, linezolid and daptomycin. The burden of MRSA was defined as MRSA per 1,000 patient-days.

Results: A total of 1,584,995 patient-days and 32,450 S. aureus isolates were analyzed. The burden of MRSA was 4.4, and the pooled mean MRSA resistance proportion was 21.8%. Both parameters did not change significantly over time. In contrast, MRSA-active antibiotics more than doubled from 44 defined daily doses per 1,000 patient-days in 2001 to 92 in 2009. This was due to the significant increase of new MRSA-active antibiotics (from 1 to 40), whereas old MRSA antibiotics stayed stable (43 in 2001 and 52 in 2009).

Conclusion: New MRSA-active antibiotics did not replace old ones, but were added on top. The use of new MRSA-active antibiotics-mainly linezolid-steadily increased over a period of 9 years, although the burden of MRSA stayed stable, as did the proportion of MRSA (%).