Lab Med Online.  2013 Oct;3(4):264-268.

Occurrence of a PCR-Positive but Culture-Negative Case for vanB Vancomycin-Resistant Enterococci in Stool Surveillance

  • 1Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
  • 2Department of Laboratory Medicine, Seoul Medical Center, Seoul, Korea.


We present here occurence of PCR-positive but culture-negative for vanB vancomycin-resistant enterococci (VRE) from an enrichment broth of a stool surveillance culture in a patient suffering from Parkinson's disease, who was transferred from a long-term care facility because of aspiration pneumonia. He developed VRE bacteriuria at the hospital day 42. vanA and vanB genes were detected from 6 microg/mL vancomycin-containing BBL Enterococcosel broth (BD), of which color changed to black after overnight incubation, by both Seeplex VRE detection (Seegene, Seoul, Korea) and Anyplex VanR real-time PCR (Seegene). Subculture of an aliquot of the blackened broth on blood agar plate produced only vanA VRE. All of the four subsequent consecutive surveillance cultures for 1 month until discharge at hospital day 75 resulted in PCR-positive but culture-negative for vanB VRE from the enrichment broths. Therefore, the presence of a non-enterococcal intrinsic reservoir bearing vanB is more likely than low burden of vanB VRE. Considering the rare occurrence of vanB VRE in Korea, vanB-positive PCR results from the enrichment broth requires confirmation by microbiological studies.


Vancomycin; Enterococcus; vanB; PCR; Enrichment; Broth; Surveillance; Culture; Stool
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