Bacterial superinfection detected in 21% of patients with COVID-19 pneumonia

Bacterial superinfection was present at the time of intubation in 21% of patients with severe COVID-19 pneumonia, according to new research published in the American Journal of Respiratory and Critical Care Medicine.

“More accurate assessment other than just reviewing clinical parameters is needed to enable clinicians to avoid using antibiotics in the majority of these patients, but appropriately use antibiotics in the 20% to 25% who have a bacterial infection as well,” Richard G. Wunderink, MD, professor of medicine in the division of pulmonary and critical care at Northwestern University Feinberg School of Medicine, said in a related press release.

Current guidelines that recommend that patients with SARS-CoV-2 pneumonia receive empirical antibiotics initially based on hospital admission for suspected bacterial superinfection are based on weak evidence, according to the authors. Rates of superinfection pneumonia in other published clinical trials of patients with SARS-CoV-2 pneumonia are unexpectedly low, according to the release.

The observational, single-center study included 386 bronchoscopic bronchoalveolar lavage samples from 179 patients with SARS-CoV-2 pneumonia (median age, 62.4 years; 61.5% men) who required mechanical ventilation at Northwestern Memorial Hospital in Chicago from March to June 2020. Researchers compared actual antibiotic use with the current guideline-recommended therapy.

Within 48 hours of intubation, bacterial superinfection was observed among 21.1% of patients. Seventy-two patients (44.4%) developed at least one ventilator-association pneumonia episode. Of those patients, 15 (20.8%) of the initial ventilator-associated pneumonia cases were caused by difficult-to-treat pathogens. The first ventilator-associated pneumonia case occurred an average of 10.8 days after intubation.

Researchers observed that the use of guideline-recommended antibiotic therapy at the time of intubation among these patients would have resulted in antibiotic overuse. In addition, among patients with bacterial superinfection during the first 10 days of intubation, early antibiotic use could be avoided in more than 75% of cases, according to the results.

The overall hospital mortality rate was 19%, with a higher mortality rate among patients transferred for quaternary care compared with patients admitted through the ED (34.3% vs. 15.3%; OR = 2.87; 95% CI, 1.13-7.11; P = .01). However, the mortality rate of patients with bacterial superinfection at intubation was not higher than patients with only SARS-CoV-2 (10.7% vs. 16.2%), according to the results.

“An accurate diagnosis of suspected pneumonia allows clinicians to safely avoid or use narrow spectrum antibiotics for many patients,” Wunderink said in the release. “While multiple interventions impact mortality in these critically ill patients, the low mortality in our study with more limited antibiotic treatment suggests that our approach was safe.”