Clinical Risk Score for Prediction of Extended-Spectrum β-Lactamase–Producing Enterobacteriaceae in Bloodstream Isolates

Abstract

OBJECTIVE To develop a risk score to predict probability of bloodstream infections (BSIs) due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBLE). DESIGN Retrospective case-control study. SETTING Two large community hospitals. PATIENTS Hospitalized adults with Enterobacteriaceae BSI between January 1, 2010, and June 30, 2015. METHODS Multivariate logistic regression was used to identify independent risk factors for ESBLE BSI. Point allocation in extended-spectrum β-lactamase prediction score (ESBL-PS) was based on regression coefficients. RESULTS Among 910 patients with Enterobacteriaceae BSI, 42 (4.6%) had ESBLE bloodstream isolates. Most ESBLE BSIs were community onset (33 of 42; 79%), and 25 (60%) were due to Escherichia coli. Independent risk factors for ESBLE BSI and point allocation in ESBL-PS included outpatient procedures within 1 month (adjusted odds ratio [aOR], 8.7; 95% confidence interval [CI], 3.1-22.9; 1 point), prior infections or colonization with ESBLE within 12 months (aOR, 26.8; 95% CI, 7.0-108.2; 4 points), and number of prior courses of β-lactams and/or fluoroquinolones used within 3 months of BSI: 1 course (aOR, 6.3; 95% CI, 2.7-14.7; 1 point), ≥2 courses (aOR, 22.0; 95% CI, 8.6-57.1; 3 points). The area under the receiver operating characteristic curve for the ESBL-PS model was 0.86. Patients with ESBL-PSs of 0, 1, 3, and 4 had estimated probabilities of ESBLE BSI of 0.7%, 5%, 24%, and 44%, respectively. Using ESBL-PS ≥3 to indicate high risk provided a negative predictive value of 97%. CONCLUSIONS ESBL-PS estimated patient-specific risk of ESBLE BSI with high discrimination. Incorporation of ESBL-PS with acute severity of illness may improve adequacy of empirical antimicrobial therapy and reduce carbapenem utilization. Infect Control Hosp Epidemiol 2017;38:266-272.

Impact of Penicillin Allergy on Empirical Carbapenem Use in Gram‐Negative Bloodstream Infections: An Antimicrobial Stewardship Opportunity

“…The current study also identified prior β‐lactam use and higher BSIMRS as independent predictors of empirical carbapenem therapy. Prior use of β‐lactams has been consistently demonstrated as a risk factor for infections due to ESBLE . High BSIMRS reflects guarded prognosis at initial presentation, which may lower the threshold to initiate empirical carbapenem therapy in patients with minor risk factors for ESBLE infections .…”

“…Because penicillin allergy is more frequently reported in elderly women, patients with penicillin allergy in this study were matched to those without penicillin allergy based on age (±10 years) and sex . Matching by site of acquisition was applied because extended‐spectrum β‐lactamase–producing Enterobacteriaceae (ESBLE) and P. aeruginosa are relatively more common in health care–associated than in community‐acquired BSI . Finally, to allow examination of the impact of antimicrobial stewardship interventions on carbapenem utilization, matching by time period before (January 1, 2010, to December 31, 2013) and after (January 1, 2014, to June 30, 2015) full implementation of antimicrobial stewardship interventions was performed.…”

“…The guidelines emphasized the safety of third‐ and fourth‐generation cephalosporins in patients with minor penicillin allergy, citing < 3% risk of cross‐reactivity . The guidelines also discouraged the use of empirical carbapenems in the absence of major risk factors for BSIs due to ESBLE . Second, the antimicrobial stewardship team performed allergy reconciliation for every hospitalized patient with documented penicillin allergy who triggered an antimicrobial stewardship alert for medication use, microbiology, or clinical infectious syndrome.…”

“…Third, the following preapproved indications were required for all inpatient carbapenem orders: (i) documented infections with ESBLE, multidrug‐resistant (MDR) P. aeruginosa , or nontuberculous mycobacteria; (ii) presence of both penicillin and cephalosporin allergies; or (iii) high risk of ESBLE or MDR P. aeruginosa infections. High risk of ESBLE was defined as prior infections or colonization with ESBLE within the past 12 months or receipt of two or more courses of β‐lactams and/or fluoroquinolones within the previous 90 days . High risk of MDR P. aeruginosa was defined as prior infections or colonization with MDR P. aeruginosa within the past 12 months or receipt of one or more courses of antipseudomonal β‐lactams within the previous 30 days .…”

“…Finally, audit and feedback were performed on all inpatient carbapenem orders on the same day if ordered during business hours or the next business day if ordered in the evening or weekend. This review ensured appropriateness of carbapenem use and provided antimicrobial recommendations based on available patient data (e.g., microbiology results or predicted probability of infections due to MDR gram‐negative bacilli based on clinical risk assessment) …”