New research has shown that less than a quarter of patients with severe COVID-19 pneumonia on mechanical ventilation actually have a documented bacterial superinfection.

An observational single center study was conducted to estimate the prevalence of bacterial superinfection within 48 hours of initial intubation.¹ The study also attempted to find out the incidence and cause of subsequent bacterial ventilator-associated pneumonia (VAP) in 179 patients with severe COVID-19 pneumonia for the entire duration of mechanical ventilation.  

Towards this end, quantitative bacterial cultures and a multiplex polymerase chain reaction (PCR) panel were used to analyse 386 bronchoscopic bronchoalveolar lavage (BAL) fluid samples. BAL cultures and multiplex bacterial PCR detected bacterial superinfection in 21% of mechanically ventilated patients with COVID-19 pneumonia within 48 hours of intubation.

The study further compared the actual use of antibiotics with the treatment recommended by the guidelines. Adopting an approach of using BAL-guided antibiotics significantly decreased the use of antibiotics vis-à-vis complying with the guidelines, which recommend that patients with SARS-CoV-2 pneumonia receive empirical antibiotics for suspected bacterial superinfection.

It has been postulated that empirical antibiotics may increase the incidence of ventilator-associated pneumonia (VAP) caused by difficult-to-treat pathogens. This study recorded a high prevalence of VAP (44%), but the etiopathogens were not difficult-to-treat pathogens. This could be due to the rational use of antibiotics based on the results of BAL cultures and PCR.

Because they share many clinical features, an accurate microbiologic diagnosis is key to the diagnosis of bacterial superinfection pneumonia in intubated patients with severe COVID-19 pneumonia.

This study has shown that using BAL fluid analysis to identify bacterial superinfection in patients with severe COVID-19 pneumonia requiring mechanical ventilation promotes rational use of antibiotics, which is also the need of the hour because antibiotic resistance is fast becoming a major public health crisis. All patients with COVID-19 pneumonia must be closely monitored for development of bacterial superinfection.

Reference

1. Pickens CO, et al; NU COVID Investigators. Bacterial superinfection pneumonia in patients mechanically ventilated for COVID-19 pneumonia. Am J Respir Crit Care Med. 2021 Aug 19. doi: 10.1164/rccm.202106-1354OC.