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Published on: December 23, 2022
[Microbiological and epidemiological characteristics of vancomycin-dependent enterococci]
Keumrock Hwang1, Heungsup Sung, Seung Namgoong
1Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
The Korean Journal of Laboratory Medicine
|September 4, 2009
Summary
Vancomycin-dependent enterococci (VDE) are not rare and can emerge independently from vancomycin-resistant enterococci (VRE) with prolonged vancomycin use. Vancomycin dependence is often reversible within several passages.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Science
Background:
- Vancomycin-dependent enterococci (VDE) present similar clinical challenges to vancomycin-resistant enterococci (VRE) but are harder to detect.
- This study aimed to microbiologically and epidemiologically characterize VDE isolates.
Observation:
- VDE were identified in 6 (2.2%) of 272 patients colonized or infected with VRE between April 2007 and March 2008.
- Patients with VDE had prolonged vancomycin treatment (13-107 days) and VDE were isolated from various clinical samples including pleural fluid, urine, and stool.
- All VDE isolates harbored the vanA gene, exhibiting high-level vancomycin resistance (MICs >256 µg/mL), with some showing intermediate susceptibility to teicoplanin.
Findings:
- VDE isolates demonstrated reversion to non-dependent VRE (NDVRE) within a few passages, indicating a dynamic vancomycin dependence.
- Pulsed field gel electrophoresis (PFGE) analysis revealed that VDE isolates did not represent a single clone, and 75% of VDE isolates were clonally related to the initial VRE isolates.
- Vancomycin dependence was measurable in only two isolates, with reversion occurring after 5 and 7 passages.
Implications:
- VDE may emerge independently and are not as rare as previously thought, particularly following extended vancomycin therapy.
- The reversibility of vancomycin dependence suggests potential therapeutic strategies or monitoring considerations.
- Understanding the emergence and characteristics of VDE is crucial for accurate clinical detection and management of enterococcal infections.
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