Co-Infections and Superinfections in COVID-19 Critically Ill Patients Are Associated with CT Imaging Abnormalities and the Worst Outcomes

Abstract

Background: Bacterial and fungal co-infections and superinfections have a critical role in the outcome of the COVID-19 patients admitted to the Intensive Care Unit (ICU). Methods: The present study is a retrospective analysis of 95 patients admitted to the ICU for COVID-19-related ARDS during the first (February−May 2020) and second waves of the pandemic (October 2020−January 2021). Demographic and clinical data, CT imaging features, and pulmonary and extra-pulmonary complications were recorded, as well as the temporal evolution of CT findings when more than one scan was available. The presence of co-infections and superinfections was registered, reporting the culprit pathogens and the specimen type for culture. A comparison between patients with and without bacterial and/or co-infections/superinfections was performed. Results: Sixty-three patients (66.3%) developed at least one confirmed co-infection/superinfection, with 52 (82.5%) developing pneumonia and 43 (68.3%) bloodstream infection. Gram-negative bacteria were the most common co-pathogens identified and Aspergillus spp. was the most frequent pulmonary microorganism. Consolidations, cavitations, and bronchiectasis were significantly associated with the presence of co-infections/superinfections (p = 0.009, p = 0.010 and p = 0.009, respectively); when considering only patients with pulmonary co-pathogens, only consolidations remained statistically significative (p = 0.004). Invasive pulmonary aspergillosis was significantly associated with the presence of cavitations and bronchiectasis (p < 0.001). Patients with co-infections/superinfections presented a significantly higher mortality rate compared to patients with COVID-19 only (52.4% vs. 25%, p = 0.016). Conclusions: Bacterial and fungal co-infections and superinfections are frequent in COVID-19 patients admitted to ICU and are associated with worse outcomes. Imaging plays an important role in monitoring critically ill COVID-19 patients and may help detect these complications, suggesting further laboratory investigations.

Keywords: ARDS; COVID-19; bacterial infections; bronchiectasis; cavitation; coinfection; consolidation; fungal infections; intensive care; lung CT; superinfection.

Figure 1

Flow diagram of patient selection in the study.

Figure 2

Axial HRCT images of different patients (A–C) with COVID-19 ARDS admitted to ICU showing bilateral consolidations (black arrows). In particular, all these patients developed a pulmonary superinfection by Klebsiella pneumoniae (A), Pseudomonas aeruginosa plus Acinetobacter baumannii (B) and Staphylococcus aureus plus Candida albicans.

Figure 3

Axial HRCT images of a patient admitted to ICU with confirmed superinfection by Aspergillus fumigatus showing pulmonary consolidations in the lower lobes complicated by bilateral cavitations (white and black arrows in (A)); Minimum Intensity Projection (MIP) reconstruction of the same patient demonstrating communication between the cavitations and the bronchial tree (white and black arrows in (B)). Sagittal HRCT images of a patient admitted to ICU with confirmed superinfection by Aspergillus niger showing pulmonary consolidations in the anterior-basal segment of the right lower lobe complicated by small cavitations (black arrow in (C)); Minimum Intensity Projection (MIP) reconstruction of the same patient demonstrating communication between the cavitation and the bronchial tree (black arrows in (D)).

Figure 4

Axial HRCT images of a patient with COVID-19 ARDS admitted to ICU with bronchiectasis in the middle lobe (black arrow in (A)), being more evident at Minimum Intensity Projection (MIP) reconstruction (black arrow in (B)); Aspergillus niger was later detected in the bronchoalveolar lavage of the patient. Axial HRCT image of a different patient with COVID-19 ARDS with superinfection by Klebsiella pneumoniae and bronchiectasis in the dorsal segment of the left upper lobe (black arrow in (C)). Sagittal HRCT image of a different patient with COVID-19 ARDS showing bronchiectasis in the left upper lobe (black arrow in (D)) and presenting with elevated serum-galactomannan levels compatible with Aspergillus spp. superinfection.