Vancomycin Resistant Enterococci (VRE) are an important and well reported nosocomial pathogen which is increasing in incidence worldwide. However, there have only been a handful of case reports describing the isolation of Vancomycin-dependant Enterococci (VDE) on clinical specimens since it was first identified.
We describe the case of a 54 year old patient with Acute Myeloid Leukaemia and chemotherapy induced neutropenia in whom we isolated VDE on screening swabs. The patient was previously known to be VRE colonised and had an admission with VRE bacteraemia. More recently, the patient had been hospitalised several times with recurrent Clostridium difficile diarrhoea unresponsive to conventional antibiotics. The patient was therefore treated with a prolonged course of oral Vancomycin to offer symptomatic relief.
During the patient’s admission, two routine rectal surveillance swabs for Multi Resistant Organisms (MRO) and VRE screening were performed. As per our laboratory protocol, the swabs were inoculated on to Biomerieux ESBL chromID agar, Thermofisher Scientific HBA + GENT agar, MacConkey agar and VRE chromID agar. We observed significant growth at 48 hours on the VRE chromID agar and the ESBL chromID agar. The 3 different colonies isolated were identified by the MALDI-TOF as Enterococcus faecium. All 3 colonies were subsequently subcultured to HBA agar with a Vancomycin disc. Two colonies had a heavy growth resistant to Vancomycin and one of the colonies isolated from the ESBL chromID agar grew interestingly only around the Vancomycin disc. Real-Time PCR genotyping of this Vancomycin-dependant isolate identified it as a Van B VDE.
We postulate that the prior and prolonged use of Vancomycin has increased the risk of VDE colonisation in our patient and advocate for greater awareness and testing for this organism in patients at risk.