title: Accessory Gene Regulator Polymorphism and Vancomycin Minimum Inhibitory Concentration in Methicillin-Resistant Staphylococcus aureus.
abstract: BACKGROUND
  Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with a vancomycin minimum inhibitory concentration (MIC) of 2 µg/mL presents a high rate of therapeutic failure in response to vancomycin. In addition, polymorphism in accessory gene regulator (agr) is associated with vancomycin therapeutic effects. The association between agr polymorphism and vancomycin MICs was investigated in MRSA isolates.
  
  
  METHODS
  Agr group-specific PCR was conducted on 118 MRSA bloodstream isolates. Vancomycin susceptibility tests were conducted, while E-test GRD (bioMérieux SA, France) was used to detect heterogeneous vancomycin-intermediate S. aureus (hVISA).
  
  
  RESULTS
  Of the 118 MRSA isolates, 59 (50.0%), 43 (36.4%), and 10 (8.5%) isolates belonged to agr group I, II, and III, respectively. Six isolates could not be classified. Twenty-six, 73, and 19 isolates presented a vancomycin MIC of 2, 1, and 0.5 µg/mL, respectively. Nine (34.6%), 14 (53.8%), and 2 (7.7%) isolates with MICs of 2 µg/mL belonged to agr group I, II, and III, respectively. Thirty-seven (50.6%), 26 (35.6%), and 6 (8.2%) isolates with MICs of 1 µg/mL belonged to agr group I, II, and III, respectively. Thirteen (68.4%), 3 (15.8%), and 2 (10.5%) isolates with MICs of 0.5 µg/mL belonged to agr group I, II, and III, respectively. The agr group II presented more isolates with MIC of 2 µg/mL (32.6%) than the agr non-group II (16%). Four isolates tested positive for hVISA. Three of them belonged to agr group II.
  
  
  CONCLUSIONS
  MRSA isolates with vancomycin MIC of 2 µg/mL were more common in agr group II than in agr non-group II.
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Jae-Seok
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Song
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Young Kyung
authors.initials: YK
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Anyang, Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Kang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D060885:Multiplex Polymerase Chain Reaction; D009154:Mutation; D015534:Trans-Activators / Q000235:genetics*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: C095698:Agr protein, Staphylococcus aureus; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015534:Trans-Activators; D014640:Vancomycin
keywords: Agr polymorphism; Staphylococcus aureus; Vancomycin