Impact of Invasive Quantitative Respiratory Cultures on Antimicrobial Therapy for Suspected Pneumonia in Trauma

Invasive quantitative respiratory cultures are generally not recommended because of a lack of demonstrated benefit. There is insufficient literature regarding specific populations such as trauma. The objective of this study was to evaluate the effect of invasive quantitative respiratory sampling on de-escalation to targeted antimicrobial therapy for the management of pneumonia in a trauma population.

This was a single-center retrospective cohort study conducted at an American College of Surgeons-verified Level II Trauma Center in Nashville, TN. Adult patients admitted to the trauma service and diagnosed with pneumonia from July 2013 to August 2018 were divided into 2 groups: invasive quantitative respiratory sampling versus noninvasive respiratory sampling. The primary endpoint was rate of targeted antimicrobial therapy. Secondary endpoints included in-hospital mortality, antibiotic days of therapy, and frequency of discontinuation of antibiotics when quantitative cultures were below the diagnostic threshold.

A total of 88 patients were sampled, with 27 in the invasive quantitative group and 66 in the noninvasive group. There was no difference in rates of targeted therapy in patients with invasive quantitative sampling (17 [63%] vs. 35 [57%]; relative risk = 1.10; 95% confidence interval [0.76, 1.57]). No statistically significant differences were observed for in-hospital mortality (8 patients vs. 6 patients, p = .35) or antimicrobial days of therapy (10.3 ± 8.8 vs. 7.8 ± 3.6, p = .161). Only 2 patients (17%) had antibiotics withheld when below the diagnostic threshold.

Invasive quantitative respiratory sampling did not result in significant changes in targeted antibiotic therapy in a trauma population.