At a recent (18 November 2004) meeting of the Australian Group on Antimicrobial Resistance (AGAR), a number of members described problems with the detection and confirmation of vancomycin resistance in enterococci, especially the vanB phenotype. After discussion, it was agreed that AGAR should make this problem widely known to assist pathologists and medical laboratory scientists.
The problem appears to be method and/or media related and some antimicrobial susceptibility testing (AST) methods may fail to detect vancomycin resistant enterococci (VRE). AGAR recommends that if you have an Enterococcus growing on VRE screening media, the isolate should be submitted for vanB gene detection testing. AGAR also recommends enterococci isolated from sterile sites (e.g. blood, CSF) should be tested for vancomycin susceptibility and forwarded for the vanB gene detection testing. The vanA phenotype should not be a problem to detect in MIC or routine testing, but because the most common phenotype in Australia is E. faecium vanB, we suspect some VRE isolates may be missed.
For further information please contact the Chair of AGAR, Prof. Graeme Nimmo (graeme_nimmo@health.qld.gov.au)
AGAR laboratories that perform vanB PCR testing:
