• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of jcmPermissionsJournals.ASM.orgJournalJCM ArticleJournal InfoAuthorsReviewers
J Clin Microbiol. Aug 1997; 35(8): 2026–2030.
PMCID: PMC229896

Rapid characterization schemes for surveillance isolates of vancomycin-resistant enterococci.


Surveillance cultures for vancomycin-resistant enterococci (VRE) and subsequent characterization of the isolates can be extremely burdensome and difficult. Therefore, efficient and reliable schemes for the characterization of surveillance isolates are needed. In this study, a commercial agar (bile esculin azide agar with 6 microg of vancomycin per ml [BEAA]; Remel, Lenexa, Kans.) was used in the initial screening step to establish relatively rapid (i.e., in < or = 24 h from the time of isolation) phenotype-based and PCR-based schemes for the detection and characterization of VRE. The phenotype-based scheme included Gram staining of growth on BEAA and subculture of cocci on sheep blood agar plates for vancomycin disk diffusion and pyrazinamidase (PYR) testing. For the PCR scheme, inocula for van gene detection were taken directly from the BEAA plates. The phenotypic approach was applied to 378 surveillance cultures that yielded growth on BEAA. Gram staining quickly eliminated gram-positive bacilli from further testing, and a negative PYR test classified 25 additional isolates as probable pediococci. A positive PYR test reliably identified 121 single-patient VRE isolates that included 83 Enterococcus faecium, 33 E. gallinarum, and 5 E. casseliflavus strains. The vancomycin inhibition zone size clearly distinguished VanA and VanB strains from VanC strains within 24 h of BEAA isolation. All VanA and VanB strains failed to produce zones of >6 mm, while only one VanC strain produced a zone of < 15 mm. Challenging this phenotypic scheme with 47 stock VRE isolates produced similar findings. In direct PCR analyses, false-negative vanA and vanB results occurred with 12% of the specimens. Many of the false-negative reactions also failed to produce an internal control product, which underscores the need for including control primers when a PCR scheme is used. In summary, the phenotype- and the PCR-based schemes provide efficient methods for characterizing VRE within 24 h of isolation.

Full Text

The Full Text of this article is available as a PDF (162K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Arthur M, Courvalin P. Genetics and mechanisms of glycopeptide resistance in enterococci. Antimicrob Agents Chemother. 1993 Aug;37(8):1563–1571. [PMC free article] [PubMed]
  • Dutka-Malen S, Blaimont B, Wauters G, Courvalin P. Emergence of high-level resistance to glycopeptides in Enterococcus gallinarum and Enterococcus casseliflavus. Antimicrob Agents Chemother. 1994 Jul;38(7):1675–1677. [PMC free article] [PubMed]
  • Edberg SC, Hardalo CJ, Kontnick C, Campbell S. Rapid detection of vancomycin-resistant enterococci. J Clin Microbiol. 1994 Sep;32(9):2182–2184. [PMC free article] [PubMed]
  • Gordts B, Van Landuyt H, Ieven M, Vandamme P, Goossens H. Vancomycin-resistant enterococci colonizing the intestinal tracts of hospitalized patients. J Clin Microbiol. 1995 Nov;33(11):2842–2846. [PMC free article] [PubMed]
  • Green M, Barbadora K, Michaels M. Recovery of vancomycin-resistant gram-positive cocci from pediatric liver transplant recipients. J Clin Microbiol. 1991 Nov;29(11):2503–2506. [PMC free article] [PubMed]
  • Greisen K, Loeffelholz M, Purohit A, Leong D. PCR primers and probes for the 16S rRNA gene of most species of pathogenic bacteria, including bacteria found in cerebrospinal fluid. J Clin Microbiol. 1994 Feb;32(2):335–351. [PMC free article] [PubMed]
  • Landman D, Quale JM, Oydna E, Willey B, Ditore V, Zaman M, Patel K, Saurina G, Huang W. Comparison of five selective media for identifying fecal carriage of vancomycin-resistant enterococci. J Clin Microbiol. 1996 Mar;34(3):751–752. [PMC free article] [PubMed]
  • Morris JG, Jr, Shay DK, Hebden JN, McCarter RJ, Jr, Perdue BE, Jarvis W, Johnson JA, Dowling TC, Polish LB, Schwalbe RS. Enterococci resistant to multiple antimicrobial agents, including vancomycin. Establishment of endemicity in a university medical center. Ann Intern Med. 1995 Aug 15;123(4):250–259. [PubMed]
  • Sahm DF, Free L, Handwerger S. Inducible and constitutive expression of vanC-1-encoded resistance to vancomycin in Enterococcus gallinarum. Antimicrob Agents Chemother. 1995 Jul;39(7):1480–1484. [PMC free article] [PubMed]
  • Schulz JE, Sahm DF. Reliability of the E test for detection of ampicillin, vancomycin, and high-level aminoglycoside resistance in Enterococcus spp. J Clin Microbiol. 1993 Dec;31(12):3336–3339. [PMC free article] [PubMed]
  • van Horn KG, Gedris CA, Rodney KM. Selective isolation of vancomycin-resistant enterococci. J Clin Microbiol. 1996 Apr;34(4):924–927. [PMC free article] [PubMed]

Articles from Journal of Clinical Microbiology are provided here courtesy of American Society for Microbiology (ASM)


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...