Antibiotic De-escalation Patterns and Outcomes in Critically Ill Patients with Suspected Pneumonia as Informed by Bronchoalveolar Lavage Results

Abstract

Background: Antibiotic stewardship in critically ill pneumonia patients is crucial yet challenging, partly due to the limited diagnostic yield of noninvasive infectious tests. In this study, we report an antibiotic prescription pattern informed by bronchoalveolar lavage (BAL) results, where clinicians de-escalate antibiotics based on the combination of quantitative cultures and multiplex PCR rapid diagnostic tests.

Methods: We analyzed data from SCRIPT, a single-center prospective cohort study of mechanically ventilated patients who underwent a BAL for suspected pneumonia. We used the novel Narrow Antibiotic Therapy (NAT) score to quantify day-by-day antibiotic prescription pattern for each suspected pneumonia episode etiology (bacterial, viral, mixed bacterial/viral, microbiology-negative, and non-pneumonia control). We also analyzed and compared clinical outcomes for each pneumonia etiology, including unfavorable outcomes (a composite of in-hospital mortality, discharge to hospice, or requiring lung transplantation during hospitalization), duration of ICU stay, and duration of intubation. Clinical outcomes were compared with the Mann-Whitney U test and Fisher's exact test.

Results: We included 686 patients with 927 pneumonia episodes. NAT score analysis indicated that an antibiotic de-escalation pattern was evident in all pneumonia etiologies except resistant bacterial pneumonia. Microbiology-negative pneumonia was treated similarly to susceptible bacterial pneumonia in terms of antibiotic spectrum. Over a quarter of the time in viral pneumonia episodes, antibiotics were completely discontinued. Unfavorable outcomes were comparable across all pneumonia etiologies. Patients with viral and mixed bacterial/viral pneumonia had longer durations of ICU stay and intubation.

Conclusions: BAL quantitative cultures and multiplex PCR rapid diagnostic tests resulted in prompt antibiotic de-escalation in critically ill pneumonia patients. There was no evidence of increased incidence of unfavorable outcomes.

Figure 1.

(A) Examples of the NAT score scenarios and (B) day by day examples of different clinical scenarios. The example NAT table and scenarios are adapted from our group’s prior work, references [11] and [22].

Figure 2.

Flow diagram of patients included in the different analyses. All patients with suspected pneumonia episodes were included in the antibiotic de-escalation analysis. Patients who had exactly one suspected pneumonia episode was included in the outcomes analysis.

Figure 3.

Variable patterns of antibiotic de-escalation, by category of pneumonia. Median NAT score per pneumonia episode day, with error bars representing IQR. If a patient died or was discharged before day 7, the days after death or discharge are not included in the plot. Plots B and C are subcategories of plot A, plots H and I are subcategories of plot G.

Figure 4.

The average NAT score of days 1–7 relative to BAL collection shows the range of antibiotic de-escalation patterns across different episode etiologies. ‘Bacterial (resistant)’ and ‘bacterial (susceptible)’ are subcategories of ‘bacterial’ episodes.

Figure 5.

Average NAT score of days 1–7 relative to BAL collection, stratified by cure status on day 7. (*: P<0.05; **: P<0.01; ***: P<0.001; ****: P<0.0001)

Figure 6.

Average NAT score of days 1–7 relative to BAL collection, stratified by the presence or absence of extra-pulmonary infections. (ns: not statistically significant; *: P<0.05; **: P<0.01; ***: P<0.001; ****: P<0.0001)