title: Urinary tract infection with an Enterococcus faecalis isolate that requires vancomycin for growth.
abstract: OBJECTIVE
  To characterize the nutritional requirements and potential origin of a fastidious urinary tract Enterococcus faecalis isolate that apparently requires the antimicrobial agent vancomycin to grow.
  
  
  METHODS
  Case report and detailed microbiologic and molecular epidemiologic analysis.
  
  
  METHODS
  University teaching hospital.
  
  
  METHODS
  Growth of the vancomycin-dependent strain was monitored using various standard laboratory media with and without supplementation with vancomycin and other substrates. This strain was compared with other vancomycin-resistant but nondependent E. faecalis strains by examining plasmid profiles and pulsed-field gel electrophoresis patterns of genomic DNA and by analyzing vancomycin-resistance genes identified by the polymerase chain reaction.
  
  
  RESULTS
  An E. faecalis isolate, strain TJ310, was isolated repeatedly from the urine of a patient receiving long-term vancomycin therapy. This strain grew in primary culture but not on subculture, suggesting an unusual growth requirement, and ultimately was found to require the glycopeptide antibiotic vancomycin to grow. Strain TJ310 appeared to be closely related to other vancomycin-resistant but nondependent E. faecalis isolates with the vanB genotype previously isolated from the same patient, suggesting that vancomycin dependence may have evolved in vivo in a vancomycin-resistant enterococcal strain during continuous exposure to high concentrations of vancomycin in the urine.
  
  
  CONCLUSIONS
  This is the first reported example of a clinical bacterial isolate that requires an antimicrobial agent to grow.
authors.affiliation: Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: H S
authors.initials: HS
authors.lastname: Fraimow
authors.forename: D L
authors.initials: DL
authors.lastname: Jungkind
authors.forename: D W
authors.initials: DW
authors.lastname: Lander
authors.forename: D R
authors.initials: DR
authors.lastname: Delso
authors.forename: J L
authors.initials: JL
authors.lastname: Dean
mesh_terms: D004352:Drug Resistance, Microbial; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D008875:Middle Aged; D014552:Urinary Tract Infections / Q000382:microbiology*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D014640:Vancomycin