title: Comparison of the clinical features, bacterial genotypes and outcomes of patients with bacteraemia due to heteroresistant vancomycin-intermediate Staphylococcus aureus and vancomycin-susceptible S. aureus.
abstract: OBJECTIVE
  We compared the clinical characteristics and outcomes of, and the bacterial genotypes in, patients with bacteraemia due to heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) and vancomycin-susceptible S. aureus (VSSA).
  
  
  METHODS
  A total of 268 consecutive patients with methicillin-resistant S. aureus (MRSA) bacteraemia were prospectively enrolled. All isolates were selected on the first day of bacteraemia and subjected to population analysis profiling for identification of hVISA phenotype and PCR analysis for 41 virulence factors.
  
  
  RESULTS
  Of 268 MRSA isolates, 101 (37.7%) were identified as hVISA. Overall mortality was similar in hVISA- and VSSA-infected patients (45/101 versus 65/167; P = 0.36). The following factors were independently associated with the presence of hVISA: a vancomycin MIC ≥2 mg/L by Etest [adjusted OR (aOR), 9.98; 95% CI, 4.22-23.59], rifampicin resistance (aOR, 5.74; 95% CI, 1.35-24.37), prior vancomycin therapy (aOR, 3.04; 95% CI, 1.49-6.17) and use of immunosuppressive therapy (aOR, 2.41; 95% CI, 1.12-5.17). Among patients with hVISA, bacteraemia was more likely to persist for ≥7 days in patients with an initial vancomycin trough <15 mg/L than in those with an initial trough ≥15 mg/L (13/34 versus 5/35; P = 0.02). The hVISA and VSSA isolates were genotypically similar.
  
  
  CONCLUSIONS
  The hVISA phenotype was present in more than one-third of MRSA isolates and was independently associated with several baseline factors. Although this phenotype did not affect patient outcomes, our results indicate that targeting an initial vancomycin trough of 15-20 mg/L may be beneficial in patients with hVISA bacteraemia.
authors.affiliation: Department of Infectious Diseases, Asan Medical Center,  University of Ulsan College of Medicine, Seoul,  Republic of Korea.
authors.forename: Ki-Ho
authors.initials: KH
authors.lastname: Park
authors.forename: Eun Sil
authors.initials: ES
authors.lastname: Kim
authors.forename: Hee Seung
authors.initials: HS
authors.lastname: Kim
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Bang
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: So-Youn
authors.initials: SY
authors.lastname: Park
authors.forename: Song Mi
authors.initials: SM
authors.lastname: Moon
authors.forename: Yong Pil
authors.initials: YP
authors.lastname: Chong
authors.forename: Sung-Han
authors.initials: SH
authors.lastname: Kim
authors.forename: Sang-Oh
authors.initials: SO
authors.lastname: Lee
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Jeong
authors.forename: Mi-Na
authors.initials: MN
authors.lastname: Kim
authors.forename: Jun Hee
authors.initials: JH
authors.lastname: Woo
authors.forename: Yang Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000368:Aged; D016470:Bacteremia / Q000382:microbiology* / Q000401:mortality / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008875:Middle Aged; D011446:Prospective Studies; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000401:mortality / Q000473:pathology; D016019:Survival Analysis; D016896:Treatment Outcome; D020713:Vancomycin Resistance