1599. Comparative Performance of Screening Microdilution Test for Detection of  ESBL Phenotype in Enterobacteriacea Clinical Isolates
Session: Poster Abstract Session: ESBL and CRE Diagnostics
Saturday, October 10, 2015
Room: Poster Hall
Posters
  • Poster IDSA.pdf (616.4 kB)
  • Background:

    To evaluate the predictive power of screening microdilution tests  for detection of ESBL phenotype using  MIC criteria  of Ceftriaxone, Ceftazidime and Cefotaxime in clinical isolates of enterobacteriaceae.

    Methods:

    Results of MIC microdilution test for Ceftriaxone, Ceftazidime and Cefotaxime (MIC > = 1 ug was considered as ESBL predictor), were compared to confirmation phenotypic criteria (using CLSI 2010 criteria: 3 fold increase comparing Ceftazidime´s MIC 0,25-128 ug/ml with Ceftazidime /Clavulanate 0,25-4 y 128-4 ug/ml) , 3 multivariate logistic regression models (One model for each antibiotic) were tested as  predictors  for screening test in order to detect ESBL phenotype (dependent variable). Independent variables were: 1) 1832 Clinical isolates of E.coli, K.pneumoniae or K.Oxitoca collected from patients with intraabdominal or urinary tract infection  (Venezuela SMART project) in the period 2009-2014  2) epidemiologic data: patient age, year of sample collection (YOC) ,gender, location and sample type . Each model was evaluated separately using forward stepwise multivariate logistic regression methodology, estimating sensitivity, specificity and ROC (Receiver Operating Characteristic). Sub analysis for E.coli and K.pneumoniae prediction model was also evaluated. General significance criteria were 0.05. STATA 11.0 was used as statistical package

    Results: 

    Even although every model has a good prediction capacity, Ceftazidime model shows the best ROC (0,98) p 0,001, independently of other covariates ( gender , age, YOC, location and type of sample 

    Model

    Variables

     

    P

    Sensib

    Specif

    ROC

    Ceftriaxone

    Ceftriaxone, Age, Gender , YOC 

     

    0,001

    91

    97

    94

    Ceftazidime

    Cefatizidime, age,gender YOC

     

    0,001

     

    99

    96

    98

    Cefotaxime

    Cefotaxime , age , gender, YOC ,

     

    0,001

     

    92

    96

    95

    Conclusion:

    In settings were confirmation with secondary test for ESBL detection are not available, MIC >=1 of Ceftazidime is a good predictor of ESBL phenotype.

    Julio Castro, MD, Infectious Diseases, Universidad Central De Venezuela, Caracas, Venezuela

    Disclosures:

    J. Castro, None

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