Bacterial co-infection and secondary infection in critically ill patients with acute respiratory failure of coronavirus disease 2019.

Abstract

Objectives: The objective of the study is to understand the prevalence of bacterial co-infection and secondary infection in severe coronavirus disease 2019 (COVID-19) pneumonia in a tertiary hospital intensive care unit (ICU), the spectrum of pathogens, and the impact of these infections on clinical outcomes.

Materials and methods: Retrospective analysis of all patients with COVID-19 with acute hypoxemic respiratory failure who were admitted to the ICU requiring invasive mechanical ventilation (IMV) or high-flow nasal cannula (HFNC) from January 2021 to August 2022.

Results: Of the 123 cases, 59.3% had culture-confirmed bacterial co-infection, mostly lower respiratory tract infections (LRTIs). Patients with bacterial co-infection had higher 30-day mortality (28.8% vs. 12%, hazard ratio [HR] = 2.96, %95 confidence interval [CI] =1.1-7.99; adjusted HR [aHR] = 1.34, %95 CI = 0.43-4.17). Klebsiella pneumoniae, Staphylococcus aureus, and Pseudomonas aeruginosa were the most common co-infection pathogens. Of the 108 cases who stayed in the ICU for >2 days, 34 (31.5%) cases developed secondary bacterial infections within 30 days, of whom all cases had LRTI, 4 had bacteremia, and 8 had urinary tract infections. IMV users had a higher 1-month incidence of secondary bacterial infections than HFNC users (47.5% vs. 8.9%, P < 0.0001). Patients with secondary bacterial infections had higher 60-day mortality (32.4% vs. 11.2% HR = 3.45, 95% CI = 1.27-9.4; aHR = 2.29, %95 CI =0.8-6.67). The most common secondary infection pathogens were Acinetobacter species, P. aeruginosa, Stenotrophomonas maltophilia, and K. pneumoniae. At the 30-day follow-up, 54 events of ICU-acquired secondary bacterial LRTI were noted in 34 patients, 18 (33.3%) events, and 15 (44%) patients were infected by carbapenem-resistant Gram-negative bacilli.

Conclusion: The high incidence of bacterial co-infection and secondary infection in critically ill patients with COVID-19 might associated with increased mortality. Infection by drug-resistant pathogens may develop during the treatment course.