Related Experiment Video
Updated: Jun 20, 2026
A 1.5 Hour Procedure for Identification of Enterococcus Species Directly from Blood Cultures
Published on: February 10, 2011
Comparison of Five Different Selective Agar for the Detection of Vancomycin-Resistant Enterococcus faecium
Alessa L Boschert1, Franca Arndt1,2, Axel Hamprecht1,3,4
1Institute for Medical Microbiology, Immunology and Hygiene, University Hospital of Cologne, 50935 Cologne, Germany.
Abstract:
Five commercially available selective agar were evaluated regarding sensitivity and specificity to detect vancomycin-resistant Enterococcus (E.) faecium. Altogether 187 E. faecium strains were included, comprising 119 van-carrying strains (phenotypically vancomycin-resistant n = 105; phenotypically vancomycin-susceptible VVE-B n = 14) and 68 vancomycin-susceptible isolates. Limit of detection was calculated for each selective agar for pure cultures, stool suspensions and artificial rectal swabs. After 24-h incubation sensitivity ranged between 91.6% and 95.0%. It increased in 2 out of 5 agar after 48-h incubation. Specificity ranged between 94.1% and 100% and was highest after 24 h in 4 out of the 5 agar. Sensitivity of van-carrying phenotypically vancomycin-resistant strains was higher after 24 h (97.1-100%) and 48 h (99.1-100%) when compared to van-carrying strains that tested vancomycin-susceptible (50.0-57.1% after both incubation periods). Overall, chromID VRE, CHROMagar VRE and Brilliance VRE demonstrated the highest detection rates after 24 h. Detection rates of Chromatic VRE and VRESelect improved after 48 h. Adjustment of incubation time depending on the applied media may be advised. As detection of VVE-B was impeded with all selective agar, screening for vancomycin-resistant enterococci relying solely on selective media would not be recommended for critical clinical samples, but rather in combination with molecular methods to improve detection of these strains. Furthermore, stool samples were demonstrated to be superior to rectal swabs and should be favoured, if possible, in screening strategies.
Insights
Evaluating selective agar for detecting vancomycin-resistant Enterococcus faecium (VRE) showed varying sensitivity and specificity. Stool samples and molecular methods combined with selective media improve VRE detection, especially for challenging strains.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Diagnostic Microbiology
Background:
- Vancomycin-resistant Enterococcus faecium (VRE) is a significant nosocomial pathogen.
- Accurate and rapid detection of VRE is crucial for infection control and patient management.
- Selective agar media are commonly used for VRE screening.
Purpose of the Study:
- To evaluate the sensitivity and specificity of five commercially available selective agar media for detecting VRE.
- To compare the performance of these media using different sample types (pure cultures, stool suspensions, rectal swabs) and incubation times.
- To assess the optimal conditions for VRE detection and provide recommendations for clinical practice.
Main Methods:
- Evaluation of five selective agar media against 187 Enterococcus faecium strains (119 van-carrying, 68 vancomycin-susceptible).
- Determination of the limit of detection for each agar using pure cultures, stool suspensions, and artificial rectal swabs.
- Assessment of sensitivity and specificity after 24-h and 48-h incubation periods.
Main Results:
- Sensitivity ranged from 91.6% to 95.0% after 24 h, increasing for some media after 48 h.
- Specificity ranged from 94.1% to 100%, generally higher after 24 h.
- chromID VRE, CHROMagar VRE, and Brilliance VRE showed the highest detection rates at 24 h; Chromatic VRE and VRESelect improved at 48 h.
- Detection of vancomycin-susceptible VRE strains was impeded across all media.
- Stool samples were superior to rectal swabs for VRE detection.
Conclusions:
- Selective agar performance varies, with some media showing higher detection rates at 24 h and others improving after 48 h.
- Relying solely on selective media for VRE screening is not recommended due to limitations, especially for VVE-B strains.
- Combining selective media with molecular methods and prioritizing stool samples can enhance VRE detection strategies.
More Related Videos
08:30One-day Workflow Scheme for Bacterial Pathogen Detection and Antimicrobial Resistance Testing from Blood Cultures
Published on: July 9, 2012
09:34Development of a More Sensitive and Specific Chromogenic Agar Medium for the Detection of Vibrio parahaemolyticus and Other Vibrio Species
Published on: November 8, 2016
