Background Few small studies have described hospital-acquired infections (HAIs) during COVID-19. Research Question What patient characteristics in critically ill patients with COVID-19 are associated with HAIs and how do HAIs associate with outcomes in these patients? Study Design and Methods Multicenter retrospective analysis of prospectively collected data including adult patients with severe COVID-19, admitted to 8 Italian hub hospitals from February 20, 2020, to May 20, 2020. Descriptive statistics, univariable and multivariable Weibull regression models were used to assess incidence, microbial etiology, resistance patterns, risk factors (i.e., demographics, comorbidities, exposure to medication), and impact on outcomes (i.e., ICU survival, length of ICU and hospital stay and duration of mechanical ventilation) of microbiologically-confirmed HAIs. Results Of the 774 included patients, 359 (46%) patients developed 759 HAIs (44.7 infections/1000 ICU patient-days, 35% multi-drug resistant (MDR) bacteria). Ventilator-associated pneumonia (VAP) (389, 50%), bloodstream infections (183, 34%), and catheter related blood stream infections (74, 10%) were the most frequent HAIs, with 26.0 (23.6-28.8) VAPs/1000 patient intubation-days, 11.7(10.1-13.5) BSIs/1000 ICU patient-days, and 4.7 (3.8-5.9) CRBSIs/1000 patient-days. Gram-negative bacteria (especially Enterobacterales ) and Staphylococcus aureus caused 64% and 28% of VAPs. Variables independently associated with infection were age, PEEP and treatment with broad-spectrum antibiotic at admission. 234 patients (30%) died in ICU (15.3 deaths/1000 ICU patient-days). Patients with HAIs complicated by septic shock had almost doubled mortality (52% vs. 29%), while non-complicated infections did not affect mortality. HAIs prolonged mechanical ventilation (24(14-39) vs. 9(5-13) days; p<0.001), ICU and hospital stay (24(16-41) vs. 9(6-14) days, p=0.003; and (42(25-59) vs. 23(13-34) days, p<0.001). Interpretation Critically-ill COVID-19 patients are at high risk for HAIs, especially VAPs and BSIs due to MDR organisms. HAIs prolong mechanical ventilation and hospitalization, and HAIs complicated by septic-shock almost doubled mortality.

Purpose The present study hypothesised that whole-body [18F]FDG-PET/CT might provide insight into the pathophysiology of long COVID. Methods We prospectively enrolled 13 adult long COVID patients who complained for at least one persistent symptom for >30 days after infection recovery. A group of 26 melanoma patients with negative PET/CT matched for sex/age was used as controls (2:1 control to case ratio). Qualitative and semi-quantitative analysis of whole-body images was performed. Fisher exact and Mann-Whitney tests were applied to test differences between the two groups. Voxel-based analysis was performed to compare brain metabolism in cases and controls. Cases were further grouped according to prevalent symptoms and analysed accordingly. Results In 4/13 long COVID patients, CT images showed lung abnormalities presenting mild [18F]FDG uptake. Many healthy organs/parenchyma SUVs and SUV ratios significantly differed between the two groups ( p ≤ 0.05). Long COVID patients exhibited brain hypometabolism in the right parahippocampal gyrus and thalamus (uncorrected p < 0.001 at voxel level). Specific area(s) of hypometabolism characterised patients with persistent anosmia/ageusia, fatigue, and vascular uptake (uncorrected p < 0.005 at voxel level). Conclusion [18F]FDG PET/CT acknowledged the multi-organ nature of long COVID, supporting the hypothesis of underlying systemic inflammation. Whole-body images showed increased [18F]FDG uptake in several “target” and “non-target” tissues. We found a typical pattern of brain hypometabolism associated with persistent complaints at the PET time, suggesting a different temporal sequence for brain and whole-body inflammatory changes. This evidence underlined the potential value of whole-body [18F]FDG PET in disclosing the pathophysiology of long COVID. Supplementary Information The online version contains supplementary material available at 10.1007/s00259-021-05294-3.

Purpose Several patients experience unexplained persistent symptoms after SARS-CoV-2 recovering. We aimed at evaluating if 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) was able to demonstrate a persistent inflammatory process. Methods Recovered adult COVID-19 patients, who complained unexplained persisting symptoms for more than 30 days during the follow-up visits, were invited to participate in the study. Patients fulfilling inclusion criteria were imaged by [ 18 F]FDG positron emission tomography/computed tomography ([ 18 F]FDG-PET/CT). Whole-body [ 18 F]FDG-PET/CT, performed according to good clinical practice, was qualitatively (comparison with background/liver) and semi-quantitatively (target-to-blood pool ratio calculated as average SUVmax artery/average SUVmean inferior vena cava) analyzed. Negative follow-up [ 18 F]FDG-PET/CT images of oncologic patients matched for age/sex served as controls. Mann-Whitney test was used to test differences between groups. SPSS version 26 was used for analyses. Results Ten recovered SARS-CoV-2 patients (seven male and three females, median age 52 years, range 46–80) with persisting symptoms were enrolled in the study. Common findings at visual analysis were increased [ 18 F]FDG uptake in bone marrow and blood vessels (8/10 and 6/10 cases, respectively). [ 18 F]FDG uptake in bone marrow did not differ between cases and controls ( p = 0.16). The total vascular score was similar in the two groups ( p = 0.95). The target-to-blood pool ratio resulted higher in recovered SARS-CoV-2 patients than in controls. Conclusion Although the total vascular score was similar in the two groups, the target-to-blood pool ratio was significantly higher in three vascular regions (thoracic aorta, right iliac artery, and femoral arteries) in the recovered COVID-19 cohort than in controls, suggesting that SARS-CoV-2 induces vascular inflammation, which may be responsible for persisting symptoms.