Beyond biomarkers: How enhanced CT imaging can improve the diagnostic-driven management of invasive mould disease

Sequential low-dose CT thorax scans to determine invasive pulmonary fungal infection incidence after allogeneic hematopoietic cell transplantation

Invasive fungal disease (IFD) during neutropenia goes along with a high mortality for patients after allogeneic hematopoietic cell transplantation (alloHCT). Low-dose computed tomography (CT) thorax shows good sensitivity for the diagnosis of IFD with low radiation exposure. The aim of our study was to evaluate sequential CT thorax scans at two time points as a new reliable method to detect IFD during neutropenia after alloHCT. We performed a retrospective single-center observational study in 265/354 screened patients admitted for alloHCT from June 2015 to August 2019. All were examined by a low-dose CT thorax scan at admission (CT t₀) and after stable neutrophil recovery (CT t₁) to determine the incidences of IFD. Furthermore, antifungal prophylaxis medications were recorded and cohorts were analyzed for statistical differences in IFD incidence using the sequential CT scans. In addition, IFD cases were classified according to EORTC 2008. At CT t₀ in 9.6% of the patients, an IFD was detected and antifungal therapy initiated. The cumulative incidence of IFD in CT t₁ in our department was 14%. The use of Aspergillus-effective prophylaxis through voriconazole or posaconazole decreased CT thorax t₁ suggesting IFD is statistically significant compared to prophylaxis with fluconazole (5.6% asp-azol group vs 16.3% fluconazole group, p = 0.048). In 86%, CT t₁ was negative for IFD. Low-dose sequential CT thorax scans are a valuable tool to detect pulmonary IFDs and guide antifungal prophylaxis and therapies. Furthermore, a negative CT t₁ scan shows a benefit by allowing discontinuation of antifungal medication sparing patients from drug interactions and side effects.

Aspergillosis: Emerging risk groups in critically ill patients

Information on invasive aspergillosis (IA) and other invasive filamentous fungal infections is limited in non-neutropenic patients admitted to the intensive care unit (ICU) and presenting with no classic IA risk factors. This review is based on the critical appraisal of relevant literature, on the authors' own experience and on discussions that took place at a consensus conference. It aims to review risk factors favoring aspergillosis in ICU patients, with a special emphasis on often overlooked or neglected conditions. In the ICU patients, corticosteroid use to treat underlying conditions such as chronic obstructive pulmonary disease (COPD), sepsis, or severe COVID-19, represents a cardinal risk factor for IA. Important additional host risk factors are COPD, decompensated cirrhosis, liver failure, and severe viral pneumonia (influenza, COVID-19). Clinical observations indicate that patients admitted to the ICU because of sepsis or acute respiratory distress syndrome are more likely to develop probable or proven IA, suggesting that sepsis could also be a possible direct risk factor for IA, as could small molecule inhibitors used in oncology. There are no recommendations for prophylaxis in ICU patients; posaconazole mold-active primary prophylaxis is used in some centers according to guidelines for other patient populations and IA treatment in critically ill patients is basically the same as in other patient populations. A combined evaluation of clinical signs and imaging, classical biomarkers such as the GM assay, and fungal cultures examination, remain the best option to assess response to treatment.

LAY SUMMARY

The use of corticosteroids and the presence of co-morbidities such as chronic obstructive pulmonary disease, acute or chronic advanced liver disease, or severe viral pneumonia caused by influenza or Covid-19, may increase the risk of invasive aspergillosis in intensive care unit patients.