Vancomycin-Dependent Enterococci: A Clinical and Laboratory Assessment
Bacterial organisms with unusual nutritional requirements are occasionally isolated from clinical specimens, and their detection provides a major challenge to the clinical microbiology laboratory.1 Among the more unusual nutritionally deficient organisms are those that demonstrate a specific growth requirement for antimicrobial agents. Although strains with a wide variety of antibiotic growth requirements can be constructed in vitro, clinical “antibiotic-dependent” isolates appear to occur only infrequently.2,3,4 The most well known examples of “antibiotic-dependent” organisms are streptomycin-dependent bacteria, which were first recognized shortly after the introduction of streptomycin.2,4,5 Dependence on other antibiotics such as tetracyclines and chloramphenicol has also been noted in vivo, but these phenomena have been only poorly characterized.2,6 We and others have recently reported on the isolation of strains of Enterococcus faecalis and Enterococcus faecium demonstrating specific requirements for glycopeptide antimicrobial agents.7–10 In this chapter, the clinical and laboratory features and proposed mechanism of vancomycin-dependence of the first of these isolates, strain TJ310, is described in detail, and the available information on several other clinical vancomycin-dependent isolates is reviewed. In addition to their importance as examples of extreme bacterial adaptation in the face of ongoing selective antimicrobial pressure, such strains may also provide significant clues to the basic mechanisms of glycopeptide resistance.
KeywordsVancomycin Resistance Chocolate Agar 34th Interscience vanE Gene Enterococcal Isolate
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- 4.C.P. Miller and M. Bohnhoff. Development of streptomycin-resistant and streptomycin -dependent bacteria. In Waksman SA. Streptomycin: it’s nature and practical applications. Williams and Wilkins, Baltimore, MD 1949 pp 15876.Google Scholar
- 6.T.M. Gocke and M. Finland. Development of chloramphenicol-resistant and chloramphenicol dependent varients of a strain of Klebsielia pneumoniae. Proc. Soc. Exper. Biol. and Med. 1950; 74: 824–829.Google Scholar
- 8.M. Green, J.H. Shlaes, K. Barbadors, and D.M. Shlaes DM. Vancomycin-dependent E. faecium: a preliminary characterization. In: Program and Abstracts of the 33rd Interscience Congress of Antimicrobial Agents and Chemotherapy. Washington DC: American Society for Microbiology 1993: p 241.Google Scholar
- 10.L.L. Dever, S.M. Smith SM, R.H.K. Eng, and S. Flandwerger. Vancomycindependent Enterococcus faecium isolated from stool following oral vancomycin therapy. In: Program Addendum for 34th Interscience Congress of Antimicrobial Agents and Chemotherapy. Washington DC, American Society for Microbiology 1994.Google Scholar
- 12.E. Venuti, J. Dean, and H.S. Fraimow. Characterization of vancomycin-resistant enterococci of the vanB genotype by PCR for vanB 1 and vanB2. Abstracts of the 1994 American Society for Microbiology Annual Meeting; Washington DC, American Society for Microbiology 1994, p. 527.Google Scholar
- 13.H.S. Gold, S. Unal, E. Cercenado, C. Thauvin-Eliopoulos, G.M. Eliopoulos, C.B. Wennersten, and R.C. Moellering Jr. A gene conferring resistance to vancomycin but not teicoplanin in isolates of Enterococcus faecalis demonstrates homology with vanA vanB and vanC genes of enterococci. Antimicrob Agents Chemother. 1993; 37: 1604–1609.PubMedCrossRefGoogle Scholar
- 15.S. Evers, R. Quintiliani Jr., P.E. Reynolds, and P. Courvalin. Phenotypic and genotypic differences between vanA and vanB type glycopeptide resistance in enterococci. Abstracts of the 34th Interscience Conference on Antimicrobial Agents and Chemotherapy, American Society for Microbiology, 1994, p 293.Google Scholar
- 17.M. Green, J.H. Shlaes, K. Barbadora, and D.M. Shlaes. Vancomycin-dependent Enterococcus faecium: a preliminary characterization. Clin. Infect. Dis. 1995.Google Scholar