Bacterial infection, antibiotic use and COVID-19: Lessons from the intensive care unit

Empirical broad-spectrum antibiotics are frequently prescribed to patients with severe COVID-19, motivated by concern about bacterial coinfection. There is no evidence of benefit from such a strategy, while the dangers of inappropriate antibiotics are well described.

To investigate the frequency, profile and related outcomes of infections by bacterial pathogens in patients admitted to an intensive care unit (ICU) with severe COVID-19 pneumonia.

This was a prospective, descriptive study in a dedicated COVID-19 ICU in Cape Town, South Africa, involving all adult patients admitted to the ICU with confirmed COVID-19 pneumonia between 26 March and 31 August 2020. We collected data on patient comorbidities, laboratory results, antibiotic treatment, duration of admission and in-hospital outcome.

We included 363 patients, who collectively had 1 199 blood cultures, 308 tracheal aspirates and 317 urine cultures performed. We found positive cultures for pathogens in 20 patients (5.5%) within the first 48 hours of ICU admission, while 73 additional patients (20.1%) had positive cultures later during their stay. The most frequently isolated pathogens at all sites were Acinetobacter baumannii (n=54), Klebsiella species (n=13) and coagulase-negative staphylococci (n=9). Length of ICU stay (p<0.001) and intubation (p<0.001) were associated with positive cultures on multivariate analysis. Disease severity (p=0.5), early antibiotic use (p=0.5), diabetes mellitus (p=0.1) and HIV (p=0.9) were not associated with positive cultures. Positive cultures, particularly for tracheal aspirates (p<0.05), were associated with longer ICU length of stay and mortality. Early empirical antibiotic use was not associated with mortality (odds ratio 2.5; 95% confidence interval 0.95 - 6.81).

Bacterial coinfection was uncommon in patients at the time of admission to the ICU with severe COVID-19. Avoiding early empirical antibiotic therapy is therefore reasonable. Strategies to avoid coinfection and outbreaks in hospital, such as infection prevention and control, as well as the strict use of personal protective equipment, are important to improve outcomes.