|Year : 2013 | Volume
| Issue : 1 | Page : 91-92
Isolation and characterization of the first vancomycin-dependent Enterococcus from India
T Banerjee, S Anupurba
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
|Date of Submission||03-Aug-2012|
|Date of Acceptance||02-Dec-2012|
|Date of Web Publication||15-Mar-2013|
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Banerjee T, Anupurba S. Isolation and characterization of the first vancomycin-dependent Enterococcus from India. Indian J Med Microbiol 2013;31:91-2
|How to cite this URL:|
Banerjee T, Anupurba S. Isolation and characterization of the first vancomycin-dependent Enterococcus from India. Indian J Med Microbiol [serial online] 2013 [cited 2019 Dec 11];31:91-2. Available from: http://www.ijmm.org/text.asp?2013/31/1/91/108747
Besides glycopeptide resistance, enterococci show a peculiar phenomenon of glycopeptide dependence. We report the isolation and characterization of vancomycin-dependent Enterococcus faecium (VDE) van A type, from the stool of a patient on intravenous vancomycin therapy.
A 30-year-old female with multiple traumatic injuries was admitted in the intensive care unit (ICU), following explorative laparotomy and prolonged intake of third generation cephalosporin (18 days) and intravenous (iv) vancomycin (5 days). Her blood culture was sterile though her stool sample yielded vancomycin-resistant Enterococcus faecium (VRE) colonies that grew only on media supplemented with vancomycin. The patient finally succumbed to her injuries.
The isolate's dependence on vancomycin was observed by its sparse growth in vancomycin-free media and dense growth in vancomycin containing media and around vancomycin disc [Figure 1]a. The isolate was simultaneously resistant to vancomycin (MIC ≥256 μg/ml, teicoplanin (MIC ≥32 μg/ml), gentamicin (≥500 μg/ml), streptomycin (≥2000 μg/ml), ampicillin (≥16 μg/ml) and ciprofloxacin (≥16 μg/ml). PCR detected the presence of vanA gene in the isolate [Figure 1]b. Rate of spontaneous revertants without vancomycin dependence  were found in the frequency of 1 in 10 5 and the revertant strain was also identified as vanA positive E. faecium.
Though the exact prevalence of VDE carriage or those causing infections is not yet known, reports of VDE isolated either from stool as gut colonizers as this one or from clinical specimens have been documented.  One of the major reasons for these infrequent reports  is the requirement of vancomycin enriched medium, which usually is done only as a part of hospital infection control protocol. Even outbreaks due to VDE were identified due to ongoing VRE surveillance programme  and clinical isolates mostly following radiometric monitoring of a repeatedly culture negative sample. 
|Figure 1: (a) Growth of colonies only around vancomycin disc. (b) Agarose gel electrophoresis of PCR amplifi ed vancomycin resistance genes in the VDE isolate and its revertant|
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As proposed, widespread use of third generation cephalosporin along with other broad spectrum antibiotics causes selective pressure to convert the resistant gut commensals to dependents.  In this case, both the risk factors of third generation cephalosporin and vancomycin were present. Outbreaks due to such strains emphasize the need for their laboratory screening, especially in the ICU, where empirical use of antibiotics is unavoidable.  Even though the clinical importance of the isolate could not be established, its isolation may be considered as an indirect indication of excessive and prolonged use of broad spectrum antibiotics with the need to review the effectiveness of the ongoing antibiotic policy.
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