Antipseudomonal Monotherapy Efficacious in Pneumonia

Antipseudomonal combination therapy has shown poorer efficacy than antipseudomonal monotherapy in individuals with suspected pseudomonal pneumonia.
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SAN FRANCISCO — Antipseudomonal combination therapy has shown poorer efficacy than antipseudomonal monotherapy among individuals with suspected pseudomonal pneumonia. This research was recently presented at IDWeek 2018, held October 3-7, 2018, in San Francisco, California.

This population-based cohort study included 31,027 individuals, 77% of whom were given antipseudomonal monotherapy and 23% of whom were given antipseudomonal combination therapy. The 2 groups were similar in the demographics of age, race, and sex. Individuals were stratified according to their risk profiles, with 59% classified low-risk, 24% medium risk, and 18% high risk. The 30-day mortality for these groups was 13%, 21%, and 36%, respectively. 

The low-risk group displayed the greatest disparity in unadjusted mortality between the 2 cohorts, with individuals receiving antipseudomonal combination therapy at 18% risk and those receiving antipseudomonal monotherapy at 8% risk; the medium-risk group showed 24% and 18% mortality risk respectively, and the high-risk group showed 39% and 33% mortality risk, respectively. Overall, antipseudomonal combination therapy was linked with a 1.54 times higher adjusted risk of 30-day mortality than the antipseudomonal monotherapy (95% CI, 1.43-1.66). Among the low-risk group, the adjusted odds ratio (aOR) was 1.69 (95% CI, 1.50-1.89); among the medium-risk group aOR was1.30 (95% CI, 1.14-1.48), and among the high-risk group, aOR was1.21 (95% CI, 1.04-1.40).

Data for this study was collected from over 150 Veteran Health Administration hospitals. A published rule was used to classify individuals into risk groups for drug-resistant pathogens. Assignment to antipseudomonal combination therapy or antipseudomonal monotherapy was decided depending on which antibiotics had been administered in the initial 2 days of hospitalization. To investigate whether treatment choice was linked with 30-day mortality, distinct multivariable logistic regression models were built and adjusted for varying baseline features.

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The study researchers concluded that “[older] adults who received empiric combination antipseudomonal therapy for community-onset pneumonia fared worse than those who received monotherapy. Empiric combination antipseudomonal therapy should not be routinely offered to all patients suspected of having pseudomonal pneumonia.”

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Obodozie-Ofoegbu O, Teng C, Mortensen EM, Frei CR. Empiric pseudomonal monotherapy versus combination therapy for community-onset pneumonia in older adults. Poster presented at: Infectious Diseases Week; October 3-7, 2018; San Francisco, CA. Abstract 1881.