title: A Clinical Decision Tree to Predict Whether a Bacteremic Patient Is Infected With an Extended-Spectrum β-Lactamase-Producing Organism.
abstract: Timely identification of extended-spectrum β-lactamase (ESBL) bacteremia can improve clinical outcomes while minimizing unnecessary use of broad-spectrum antibiotics, including carbapenems. However, most clinical microbiology laboratories currently require at least 24 additional hours from the time of microbial genus and species identification to confirm ESBL production. Our objective was to develop a user-friendly decision tree to predict which organisms are ESBL producing, to guide appropriate antibiotic therapy.
  
  
  
  We included patients ≥18 years of age with bacteremia due to Escherichia coli or Klebsiella species from October 2008 to March 2015 at Johns Hopkins Hospital. Isolates with ceftriaxone minimum inhibitory concentrations ≥2 µg/mL underwent ESBL confirmatory testing. Recursive partitioning was used to generate a decision tree to determine the likelihood that a bacteremic patient was infected with an ESBL producer. Discrimination of the original and cross-validated models was evaluated using receiver operating characteristic curves and by calculation of C-statistics.
  
  
  
  A total of 1288 patients with bacteremia met eligibility criteria. For 194 patients (15%), bacteremia was due to a confirmed ESBL producer. The final classification tree for predicting ESBL-positive bacteremia included 5 predictors: history of ESBL colonization/infection, chronic indwelling vascular hardware, age ≥43 years, recent hospitalization in an ESBL high-burden region, and ≥6 days of antibiotic exposure in the prior 6 months. The decision tree's positive and negative predictive values were 90.8% and 91.9%, respectively.
  
  
  
  Our findings suggest that a clinical decision tree can be used to estimate a bacteremic patient's likelihood of infection with ESBL-producing bacteria. Recursive partitioning offers a practical, user-friendly approach for addressing important diagnostic questions.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Goodman
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health.
authors.forename: Justin
authors.initials: J
authors.lastname: Lessler
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Cosgrove
authors.affiliation: Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore.
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Harris
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia.
authors.forename: Ebbing
authors.initials: E
authors.lastname: Lautenbach
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia.
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Han
authors.affiliation: Department of Pediatrics, Division of Infectious Diseases.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Milstone
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Massey
authors.affiliation: Department of Pediatrics, Division of Infectious Diseases.
authors.forename: Pranita D
authors.initials: PD
authors.lastname: Tamma
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D016470:Bacteremia / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D020000:Decision Support Systems, Clinical; D003663:Decision Trees; D004926:Escherichia coli / Q000187:drug effects; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D006801:Humans; D007709:Klebsiella / Q000187:drug effects; D007710:Klebsiella Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015233:Models, Statistical; D012307:Risk Factors; D018440:beta-Lactam Resistance; D001618:beta-Lactamases
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases
keywords: ESBL; bacteremia; carbapenem; machine learning; prediction