title: Is reduced vancomycin susceptibility a factor associated with poor prognosis in MSSA bacteraemia?
abstract: OBJECTIVE
  The known data about the influence of vancomycin MIC on Staphylococcus aureus bacteraemia are contradictory. Our objective was to study the possible impact of vancomycin MIC ≥1.5 mg/L on short- and medium-term mortality.
  
  
  METHODS
  A prospective cohort study was carried out from March 2008 to January 2011 on adult patients with MSSA bacteraemia admitted to a tertiary hospital located in Seville (Spain). We studied the relationship between vancomycin MIC, accessory gene regulator (agr) type and absence of δ-haemolysin and poor prognosis. All isolates were genotyped by PFGE. Multivariate analysis, including a propensity score for having a vancomycin MIC of ≥1.5 mg/L, was performed by Cox regression.
  
  
  RESULTS
  One hundred and thirty-five episodes of bacteraemia due to MSSA were included in the analysis. Twenty-nine (21.5%) isolates had a vancomycin MIC of ≥1.5 mg/L by Etest. There were no differences in agr distribution or absence of δ-haemolysin between isolates with reduced vancomycin susceptibility (RVS) and those without. RVS was not more frequent in specific clones; RVS was not associated with higher 14 or 30 day crude mortality (relative risk = 0.44, 95% CI = 0.14-1.35; and relative risk = 1.01, 95% CI = 0.52-1.96) rates, and it did not show higher rates of complicated bacteraemia (14.2% versus 13.8%, P = 0.61). Cox regression analysis did not significantly modify the results for 14 day mortality (HR = 0.39, 95% CI = 0.11-1.34) or 30 day mortality (HR = 0.89, 95% CI = 0.39-2.04).
  
  
  CONCLUSIONS
  Contrary to previously published data, we did not find a relationship between RVS and higher mortality in patients with MSSA bacteraemia and we did not find a link with higher complicated bacteraemia rates.
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain luiselopezcortes@gmail.com.
authors.forename: L E
authors.initials: LE
authors.lastname: López-Cortés
authors.affiliation: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Velasco
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Retamar
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: del Toro
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Gálvez-Acebal
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: de Cueto
authors.affiliation: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: I
authors.initials: I
authors.lastname: García-Luque
authors.affiliation: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Caballero
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pascual
authors.affiliation: Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Spanish Network for Research in Infectious Diseases, Instituto de Salud Carlos III, Madrid, Spain Departamento de Medicina, Universidad de Sevilla, Sevilla, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Rodríguez-Baño
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D001426:Bacterial Proteins / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006460:Hemolysin Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D011379:Prognosis; D011446:Prospective Studies; D013030:Spain; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D016019:Survival Analysis; D062606:Tertiary Care Centers; D015534:Trans-Activators / Q000235:genetics; D017211:Treatment Failure; D014640:Vancomycin / Q000627:therapeutic use*; D020713:Vancomycin Resistance; D037521:Virulence Factors / Q000032:analysis / Q000235:genetics
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D015534:Trans-Activators; D037521:Virulence Factors; D014640:Vancomycin; C025994:delta hemolysin protein, Staphylococcus aureus
keywords: MICs; S. aureus; virulence factors