title: Prediction of failure in vancomycin-treated methicillin-resistant Staphylococcus aureus bloodstream infection: a clinically useful risk stratification tool.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of bloodstream infection (BSI) and is often associated with invasive infections and high rates of mortality. Vancomycin has remained the mainstay of therapy for serious Gram-positive infections, particularly MRSA BSI; however, therapeutic failures with vancomycin have been increasingly reported. We conducted a comprehensive evaluation of the factors (patient, strain, infection, and treatment) involved in the etiology and management of MRSA BSI to create a risk stratification tool for clinicians. This study included consecutive patients with MRSA BSI treated with vancomycin over 2 years in an inner-city hospital in Detroit, MI. Classification and regression tree analysis (CART) was used to develop a risk prediction model that characterized vancomycin-treated patients at high risk of clinical failure. Of all factors, the Acute Physiology and Chronic Health Evaluation II (APACHE-II) score, with a cutoff point of 14, was found to be the strongest predictor of failure and was used to split the population into two groups. Forty-seven percent of the population had an APACHE-II score < 14, a value that was associated with low rates of clinical failure (11%) and mortality (4%). Fifty-four percent of the population had an APACHE-II score ≥ 14, which was associated with high rates of clinical failure (35%) and mortality (23%). The risk stratification model identified the interplay of three other predictors of failure, including the vancomycin MIC as determined by Vitek 2 analysis, the risk level of the source of BSI, and the USA300 strain type. This model can be a useful tool for clinicians to predict the likelihood of success or failure in vancomycin-treated patients with MRSA bloodstream infection.
authors.affiliation: Division of Infectious Diseases, Henry Ford Hospital, 2799 West Grand Blvd., CFP 314, Detroit, MI 48202, USA. cmoore2@hfhs.org
authors.forename: Carol L
authors.initials: CL
authors.lastname: Moore
authors.forename: Mei
authors.initials: M
authors.lastname: Lu
authors.forename: Faiqa
authors.initials: F
authors.lastname: Cheema
authors.forename: Paola
authors.initials: P
authors.lastname: Osaki-Kiyan
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Perri
authors.forename: Susan
authors.initials: S
authors.lastname: Donabedian
authors.forename: Nadia Z
authors.initials: NZ
authors.lastname: Haque
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Zervos
mesh_terms: D018806:APACHE; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D018570:Risk Assessment; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D017211:Treatment Failure; D014640:Vancomycin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin