A Nordic study of antibiotic susceptibility of enterococci at different ward levels

Abstract number: 1134_01_353

Claesson C., Nilsson M., Hällgren A., Hanberger H., Nilsson L.E., on behalf of the SCOPE Study Group 

Objectives:  

To study the antibiotic susceptibility of enterococci at different ward levels.

Methods:  

Initial isolates of enterococci from patients at primary care centres (PCC) (N = 220), general hospital wards (GHW) (N = 215) and intensive care units (ICU) (N = 176) at 16 hospitals and counties, in Denmark, Finland, Norway and Sweden, were collected during 1999–2000. Minimal Inhibitory Concentrations (MICs) were determined using Etest (AB Biodisk). Species related MIC breakpoints of the Swedish Reference Group for Antibiotics were used for all antibiotics except for moxifloxacin and levofloxacin. For these two antibiotics the European Committee on Antimicrobial Susceptibility testing nonspecies related clinical breakpoints were used.

Results:  

There were significant differences in the frequency of E. faecium among the enterococci at the PCC (7.3%), GHW (13%) and the ICUs (28%) (p < 0.05). A total of 0.8% of the E. faecalis isolates and 2.7% of the E. faecium isolates were low level (MIC 8–16 mg/l) vancomycin resistant (VRE) but teicoplanin susceptible. High level gentamicin resistance (HLGR) was seen among a total of 13% and 17% of the E. faecalis and the E. faecium isolates, respectively. There were significant higher frequency of HLGR among the E. faecalis isolates at both the GHW (20/%) and the ICUs (17%) compared to the PCCs (5.9%) (p < 0.05). The E. faecalis isolates showed a significant difference in susceptibility to imipenem, moxifloxacin, and vancomycin at the ICUs compared to the PCCs (p < 0.05). A significant difference in susceptibility between the GHW and PCC was only seen for moxifloxacin. The E. faecium isolates showed no difference in susceptibility between the ward levels.

Conclusion:  

There were significant differences in the frequency of E. faecium at the different ward levels, E. faecalis showed a high susceptibility against all the tested antibiotics except for imipenem, the quinolones and gentamicin (HLGR). These antibiotics showed a significant difference in susceptibility between the ward levels. Vancomycin and teicoplanin were the only antibiotics that showed high susceptibility against most E. faecium at all ward levels.