Ventilator-Associated Lower Respiratory Tract Bacterial Infections in COVID-19 Compared With Non-COVID-19 Patients.

OBJECTIVES: Ventilator-associated lower respiratory tract infections (VA-LRTIs) are associated with prolonged length of stay and increased mortality. We aimed to investigate the occurrence of bacterial VA-LRTI among mechanically ventilated COVID-19 patients and compare these findings to non-COVID-19 cohorts throughout the first and second wave of the pandemic. DESIGN: Retrospective cohort study. SETTING: Karolinska University Hospital, Stockholm, Sweden. PATIENTS: All patients greater than or equal to 18 years treated with mechanical ventilation between January 1, 2011, and December 31, 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The cohort consisted of 20,223 ICU episodes (479 COVID-19), with a VA-LRTI incidence proportion of 30% (129/426) in COVID-19 and 18% (1,081/5,907) in non-COVID-19 among patients ventilated greater than or equal to 48 hours. The median length of ventilator treatment for COVID-19 patients was 10 days (interquartile range, 5-18 d), which was significantly longer than for all other investigated specific diagnoses. The VA-LRTI incidence rate per 1,000 ventilator days at risk was 31 (95% CI, 26-37) for COVID-19 and 34 (95% CI, 32-36) for non-COVID-19. With COVID-19 as reference, adjusted subdistribution hazard ratios for VA-LRTI was 0.29-0.50 (95% CI, < 1) for influenza, bacterial pneumonia, acute respiratory distress syndrome, and severe sepsis, but 1.38 (95% CI, 1.15-1.65) for specific noninfectious diagnoses. Compared with COVID-19 in the first wave of the pandemic, COVID-19 in the second wave had adjusted subdistribution hazard ratio of 1.85 (95% CI, 1.14-2.99). In early VA-LRTI Staphylococcus aureus was more common and Streptococcus pneumoniae, Haemophilus influenzae, and Escherichia coli less common in COVID-19 patients, while Serratia species was more often identified in late VA-LRTI. CONCLUSIONS: COVID-19 is associated with exceptionally long durations of mechanical ventilation treatment and high VA-LRTI occurrence proportions. The incidence rate of VA-LRTI was compared with the pooled non-COVID-19 cohort, however, not increased in COVID-19. Significant differences in the incidence of VA-LRTI occurred between the first and second wave of the COVID-19 pandemic.

Bacterial co-infections in community-acquired pneumonia caused by SARS-CoV-2, influenza virus and respiratory syncytial virus.

BACKGROUND: A mismatch between a widespread use of broad-spectrum antibiotic agents and a low prevalence of reported bacterial co-infections in patients with SARS-CoV-2 infections has been observed. Herein, we sought to characterize and compare bacterial co-infections at admission in hospitalized patients with SARS-CoV-2, influenza or respiratory syncytial virus (RSV) positive community-acquired pneumonia (CAP). METHODS: A retrospective cohort study of bacterial co-infections at admission in SARS-CoV-2, influenza or RSV-positive adult patients with CAP admitted to Karolinska University Hospital in Stockholm, Sweden, from year 2011 to 2020. The prevalence of bacterial co-infections was investigated and compared between the three virus groups. In each virus group, length of stay, ICU-admission and 30-day mortality was compared in patients with and without bacterial co-infection, adjusting for age, sex and co-morbidities. In the SARS-CoV-2 group, risk factors for bacterial co-infection, were assessed using logistic regression models and creation of two scoring systems based on disease severity, age, co-morbidities and inflammatory markers with assessment of concordance statistics. RESULTS: Compared to influenza and RSV, the bacterial co-infection testing frequency in SARS-CoV-2 was lower for all included test modalities. Four percent [46/1243 (95% CI 3-5)] of all SARS-CoV-2 patients had a bacterial co-infection at admission, whereas the proportion was 27% [209/775 (95% CI 24-30)] and 29% [69/242 (95% CI 23-35)] in influenza and RSV, respectively. S. pneumoniae and S. aureus constituted the most common bacterial findings for all three virus groups. Comparing SARS-CoV-2 positive patients with and without bacterial co-infection at admission, a relevant association could not be demonstrated nor excluded with regards to risk of ICU-admission (aHR 1.53, 95% CI 0.87-2.69) or 30-day mortality (aHR 1.28, 95% CI 0.66-2.46) in adjusted analyses. Bacterial co-infection was associated with increased inflammatory markers, but the diagnostic accuracy was not substantially different in a scoring system based on disease severity, age, co-morbidities and inflammatory parameters [C statistic 0.66 (95% CI 0.59-0.74)], compared to using disease severity, age and co-morbidities only [C statistic 0.63 (95% CI 0.56-0.70)]. CONCLUSIONS: The prevalence of bacterial co-infections was significantly lower in patients with community-acquired SARS-CoV-2 positive pneumonia as compared to influenza and RSV positive pneumonia.