Institute of Environmental Medicine and Hospital Epidemiology
Freiburg University Hospital
Antimicrobial use is the key to resistance, with resistance being caused either by selection of a resistant mutant or by allowing the emergence of a resistant pathogen in a colonisation flora. The intensive care setting is of particular interest because of the frequent and extended use of antimicrobials and invasive devices, the acute or chronic suppression of the immune system in intensive care unit (ICU) patients and the increased likelihood of cross- transmission of resistant pathogens. It seems reasonable to promote prudent antibiotic use, as it is an important measure to stop resistance from increasing. The SARI (surveillance on antibiotic use and bacterial resistance in ICUs) project is supported by the German Ministry of Science and Education (BMBF).(1)
SARI started in February 2000; by June 2004, it included 40 ICUs reporting monthly on antibiotic use data. The participating ICUs are stratified by type (interdisciplinary, surgical and medical). All antimicrobial usage data are obtained from computerised hospital databases. Consumption is expressed as daily defined doses (DDD) and normalised per 1,000 patient-days (antimicrobial usage density [AD]), one DDD being the standard adult daily dose of antimicrobial agent for one day of treatment, as defined by the WHO : AD=(antibiotic use/DDD) x (1000/patient-days)
Statistical data on antimicrobial use is fed back on a half-yearly basis to SARI ICUs. Median total antibiotic use was 1190.4 in all SARI ICUs combined, indicating that, on average, each ICU patient was given 1.2 DDD of an antibiotic per ICU day. Figure 1 shows the median antimicrobial ADs, stratified according to the type of ICU. Although in all ICU types the preferred antimicrobial groups were penicillins with lactamase inhibitor, followed by quinolones, some differences could be found among the different ICU types. Carbapenems and glycopeptides were used almost twice more in surgical ICUs than in interdisciplinary ICUs, whereas medical ICUs had an at least threefold higher AD for macrolides than surgical ICUs.(2)
Table 1 gives an example (quinolones) of feedback from the participating ICUs and provides data on the number of DDDs, the mean antimicrobial ADs and key percentages (25%, median and 75%). Mean quinolone use for all surgical ICUs was 157.0, and 75% of all surgical ICUs had a lower quinolone use than 219.1. Our sample ICU had an AD of 53.5 and, compared with other surgical ICUs, had very low quinolone consumption (below 25%). Table 2 provides an analysis of changes over time with regard to use of third-generation cephalosporins in a sample ICU. From February 2000 to June 2004, the ICU successively decreased the use of third-generation cephalosporins from 118.3 to 51.3. The reference data for all antibiotic groups and antibiotics are available on the internet (see Resources). With respect to the growing problem of MRSA, we found that ICUs that increased their use of narrow- spectrum antimicrobials (beta-lactamase-sensitive penicillins) over three years (2001–2003) had a significant decrease in their MRSA rate, whereas increased use of third-generation cephalosporins, glycopeptides and aminoglycosides was significantly correlated with an increase in MRSA rates. Thus, it can be postulated that increase in the use of glycopeptides is a result of increasing MRSA rates, whereas increase in the use of third-generation cephalosporins precedes the emergence of MRSA, because of the ecological advantage of MRSA over other pathogens that are eliminated by these broad-spectrum antibiotics.(3)
One of the objectives of the SARI project is to provide feedback to all individual ICUs enrolled. To achieve this, we developed comparative benchmarks, by aggregating antibiotic resistance data and antibiotic use data from all participating ICUs. Together, they form a basis for improved antibiotic and infection control management in ICUs.
- Meyer E, Jonas D, Schwab F, et al. Design of a surveillance system of antibiotic use and bacterial resistance in German intensive care units (SARI). Infection 2003;31:208-15.
- Meyer E, Schwab F, Jonas D, et al. Surveillance of antimicrobial use and antimicrobial resistance in intensive care units (SARI): 1. Antimicrobial use in German intensive care units. Intensive Care Med 2004;30:1089-96.
- Meyer E, Jonas D, Schwab F, et al. MRSA und Antibiotikaverbrauch auf Intensivstationen in Deutschland, DGHM 2004, Münster, AHV 005.
WHO DDD: Antibiotic Consumption Calculator version 2.0 (2004)