Validation of a Prediction Score for Drug-Resistant Microorganisms in Community-acquired Pneumonia
Adrian Ceccato1,2, Raul Mendez3,4, Santiago Ewig5
1Centro de Investigacíon Biomédica en Red de Enfermedades Respiratorias (CB06/06/0028), Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universidad de Barcelona, Barcelona, Spain.
Abstract:
Rationale: Recommended initial empiric antimicrobial treatment covers the most common bacterial pathogens; however, community-acquired pneumonia (CAP) may be caused by microorganisms not targeted by this treatment. Developed in 2015, the PES (Pseudomonas aeruginosa, extended-spectrum β-lactamase-producing Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus) score was developed in 2015 to predict the microbiological etiology of CAP caused by PES microorganisms.Objective: To validate the usefulness of the PES score for predicting PES microorganisms in two cohorts of patients with CAP from Valencia and Mataró.Methods: We analyzed two prospective observational cohorts of patients with CAP from Valencia and Mataró. Patients in the Mataró cohort were all admitted to an intensive care unit (ICU).Results: Of the 1,024 patients in the Valencia cohort, 505 (51%) had a microbiological etiology and 31 (6%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.81 (95% confidence interval [95% CI], 0.74-0.88). For a PES score ≥5, sensitivity, specificity, the negative and positive predictive values as well as the negative and positive likelihood ratios were 72%, 74%, 98%, 14%, 0.38, and 2.75, respectively. Of the 299 patients in the Mataró cohort, 213 (71%) had a microbiological etiology and 11 (5%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.73 (95% CI 0.61-0.86). For a PES score ≥ 5, sensitivity, specificity, the negative and positive predictive values, and the negative and positive likelihood ratios were 36%, 83%, 96%, 11%, 0.77, and 2.09, respectively. The best cutoff for patients admitted to the ICU was 4 points, which improved sensitivity to 86%. The hypothetical application of the PES score showed high rates of overtreatment in both cohorts (26% and 35%, respectively) and similar rates of undertreatment.Conclusions: The PES score showed good accuracy in predicting the risk for microorganisms that required different empirical therapy; however, its use as a single strategy for detecting noncore pathogens could lead to high rates of overtreatment. Given its high negative predictive value, the PES score may be used as a first step of a wider strategy that includes subsequent advanced diagnostic tests.
Insights
The PES score helps predict uncommon pneumonia pathogens, but using it alone may lead to overtreatment. Its high negative predictive value makes it a useful first step in diagnostic strategies.
Area of Science:
- Infectious Diseases
- Pulmonology
- Microbiology
Background:
- Standard community-acquired pneumonia (CAP) treatment may not cover all causative pathogens.
- The PES score (Pseudomonas aeruginosa, extended-spectrum β-lactamase-producing Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus) was developed to identify these specific microorganisms.
- Validating the PES score's utility in diverse patient cohorts is crucial for refining empirical antimicrobial therapy.
Purpose of the Study:
- To validate the PES score's effectiveness in predicting PES microorganisms in two distinct CAP patient cohorts.
- To assess the PES score's performance in both general CAP patients and those in an intensive care unit (ICU).
Main Methods:
- Analysis of two prospective observational cohorts of CAP patients from Valencia and Mataró.
- Inclusion of all Mataró cohort patients admitted to the ICU.
- Calculation of the PES score and evaluation of its predictive accuracy using receiver operating characteristic curves and associated metrics.
Main Results:
- In the Valencia cohort (n=1024), 6% had PES microorganisms; the PES score showed an AUC of 0.81.
- In the Mataró ICU cohort (n=299), 5% had PES microorganisms; the PES score showed an AUC of 0.73.
- A PES score cutoff of ≥5 demonstrated varying sensitivity and specificity across cohorts, with a cutoff of ≥4 being optimal for ICU patients (86% sensitivity).
- Hypothetical application indicated high overtreatment rates (26-35%) and similar undertreatment rates.
Conclusions:
- The PES score demonstrates good accuracy in predicting the need for broader empirical therapy in CAP.
- Solely relying on the PES score may result in significant overtreatment of non-core pathogens.
- Its high negative predictive value suggests the PES score can serve as an initial step in a comprehensive diagnostic approach for CAP.
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