Open AccessIncreased Mortality with Accessory Gene Regulator ( agr ) Dysfunction in Staphylococcus aureus among Bacteremic Patients
Author(s) -
Marin L. Schweizer,
Jon P. Furuno,
George Sakoulas,
J. Kristie Johnson,
Anthony D. Harris,
Michelle Shardell,
Jessina C. McGregor,
Kerri A. Thom,
Eli N. Perencevich
Publication year - 2011
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.00918-10
Subject(s) - staphylococcus aureus , bacteremia , medicine , hazard ratio , confidence interval , staphylococcal infections , proportional hazards model , retrospective cohort study , blood culture , cohort study , mortality rate , surgery , microbiology and biotechnology , biology , antibiotics , bacteria , genetics
Accessory gene regulator (agr ) dysfunction inStaphylococcus aureus has been associated with a longer duration of bacteremia. We aimed to assess the independent association betweenagr dysfunction inS. aureus bacteremia and 30-day in-hospital mortality. This retrospective cohort study included all adult inpatients withS. aureus bacteremia admitted between 1 January 2003 and 30 June 2007. Severity of illness prior to culture collection was measured using the modified acute physiology score (APS).agr dysfunction inS. aureus was identified semiquantitatively by using a δ-hemolysin production assay. Cox proportional hazard models were used to measure the association betweenagr dysfunction and 30-day in-hospital mortality, statistically adjusting for patient and pathogen characteristics. Among 814 patient admissions complicated byS. aureus bacteremia, 181 (22%) patients were infected withS. aureus isolates withagr dysfunction. Overall, 18% of patients withagr dysfunction inS. aureus died, compared to 12% of those with functionalagr inS. aureus (P = 0.03). There was a trend toward higher mortality among patients withS. aureus withagr dysfunction (adjusted hazard ratio [HR], 1.34; 95% confidence interval [CI], 0.87 to 2.06). Among patients with the highest APS (scores of >28),agr dysfunction inS. aureus was significantly associated with mortality (adjusted HR, 1.82; 95% CI, 1.03 to 3.21). This is the first study to demonstrate an independent association betweenagr dysfunction and mortality among severely ill patients. The δ-hemolysin assay examiningagr function may be a simple and inexpensive approach to predicting patient outcomes and potentially optimizing antibiotic therapy.