title: Heterogeneous vancomycin-intermediate susceptibility phenotype in bloodstream methicillin-resistant Staphylococcus aureus isolates from an international cohort of patients with infective endocarditis: prevalence, genotype, and clinical significance.
abstract: BACKGROUND
  The significance of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) is unknown. Using a multinational collection of isolates from methicillin-resistant S. aureus (MRSA) infective endocarditis (IE), we characterized patients with IE with and without hVISA, and we genotyped the infecting strains.
  
  
  METHODS
  MRSA bloodstream isolates from 65 patients with definite IE from 8 countries underwent polymerase chain reaction (PCR) for 31 virulence genes, pulsed-field gel electrophoresis, and multilocus sequence typing. hVISA was defined using population analysis profiling.
  
  
  RESULTS
  Nineteen (29.2%) of 65 MRSA IE isolates exhibited the hVISA phenotype by population analysis profiling. Isolates from Oceania and Europe were more likely to exhibit the hVISA phenotype than isolates from the United States (77.8% and 35.0% vs 13.9%; P < .001). The prevalence of hVISA was higher among isolates with a vancomycin minimum inhibitory concentration of 2 mg/L (P = .026). hVISA-infected patients were more likely to have persistent bacteremia (68.4% vs 37.0%; P = .029) and heart failure (47.4% vs 19.6%; P = .033). Mortality did not differ between hVISA- and non-hVISA-infected patients (42.1% vs 34.8%, P = .586). hVISA and non-hVISA isolates were genotypically similar.
  
  
  CONCLUSIONS
  In these analyses, the hVISA phenotype occurred in more than one-quarter of MRSA IE isolates, was associated with certain IE complications, and varied in frequency by geographic region.
authors.affiliation: Duke Clinical Research Institute, Durham, North Carolina, USA.
authors.forename: In-Gyu
authors.initials: IG
authors.lastname: Bae
authors.forename: Jerome J
authors.initials: JJ
authors.lastname: Federspiel
authors.forename: José M
authors.initials: JM
authors.lastname: Miró
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Woods
authors.forename: Lawrence
authors.initials: L
authors.lastname: Park
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rybak
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Rude
authors.forename: Suzanne
authors.initials: S
authors.lastname: Bradley
authors.forename: Suzana
authors.initials: S
authors.lastname: Bukovski
authors.forename: Cristina Garcia
authors.initials: CG
authors.lastname: de la Maria
authors.forename: Souha S
authors.initials: SS
authors.lastname: Kanj
authors.forename: Tony M
authors.initials: TM
authors.lastname: Korman
authors.forename: Francesc
authors.initials: F
authors.lastname: Marco
authors.forename: David R
authors.initials: DR
authors.lastname: Murdoch
authors.forename: Patrick
authors.initials: P
authors.lastname: Plesiat
authors.forename: Marta
authors.initials: M
authors.lastname: Rodriguez-Creixems
authors.forename: Porl
authors.initials: P
authors.lastname: Reinbott
authors.forename: Lisa
authors.initials: L
authors.lastname: Steed
authors.forename: Pierre
authors.initials: P
authors.lastname: Tattevin
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Tripodi
authors.forename: Karly L
authors.initials: KL
authors.lastname: Newton
authors.forename: G Ralph
authors.initials: GR
authors.lastname: Corey
authors.forename: Vance G
authors.initials: VG
authors.lastname: Fowler
mesh_terms: D000368:Aged; D016470:Bacteremia / Q000188:drug therapy / Q000235:genetics / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D005838:Genotype; D014943:Global Health; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010641:Phenotype; D010802:Phylogeny; D011159:Population Surveillance; D015995:Prevalence; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D020713:Vancomycin Resistance / Q000187:drug effects / Q000235:genetics*