Pneumocystis pneumonia risk among viral acute respiratory distress syndrome related or not to COVID 19

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Lymphopenia, corticosteroids and immunomodulatory therapeutics frequently used in COVID-19 patients with acute respiratory distress syndrome (C-ARDS) may be contributing factors to opportunistic infection such as Pneumocystis jirovecii pneumonia (PCP). We conducted a retrospective study to compare the prevalence of PCP between patients with C-ARDS and those with non-SARS-CoV-2 viral ARDS (NC-ARDS). Methods and some data from this cohort have been previously published [1]. There was no systematic protocol to search for PCP but in case of suspicion of PCP (respiratory symptoms with any consistent radiographic features), several analyses were performed on respiratory samples, such as broncho-alveolar lavage (BAL), blind protected sample, or sputum. It included direct examination (using May-Grünwald Giemsa (MGG), or immunofluorescence staining), detection of Pneumocystis jirovecii DNA by real-time polymerase chain reaction (qPCR) [2], and serum (1–3)-β-D-glucan. During the COVID-19 outbreak, immunofluorescence staining was not performed. PCP was defined as per the revised EORTC/MSGERC definition [3] as follows: proven in case of suspicion with positive direct examination; possible in case of suspicion with positive qPCR and positive BDG in ≥ 2 consecutive serum samples provided other etiologies have been excluded. SARS-CoV-2 and other viruses were not considered a priori as host factors. Patients with positive qPCR but lacking the other criteria for possible PCP were classified as colonized. The primary endpoint was the difference in prevalence of PCP between C-ARDS and NC-ARDS patients. No statistical sample size calculation was performed a priori, and sample size was equal to the number of patients treated during the study period. All patients were included only once. Between October 1, 2009, and April 29, 2020, ninety patients had C-ARDS (positive RT PCR test for SARSCoV-2), while 82 patients had viral NC-ARDS. Our study comprises 120 patients with fungal analyses on respiratory samples obtained from 81 C-ARDS and 39 NC-ARDS patients. NC-ARDS patients had more comorbidities were more often immunocompromised, and had lower lymphocyte counts than C-ARDS patients (Table 1). C-ARDS patient received less steroid than NCARDS patients because they were included before randomized trials demonstrating decreased mortality with dexamethasone. Pneumocystis analyses were performed on a mean of 3.1 respiratory sample per patient (range 1–15). Direct examination was performed in a total of 72 samples, with two positive cases. qPCR was performed in a total of 368 samples (294 blind protected samples, 72 BAL, and three sputum). All qPCR were negative in C-ARDS patients, while five (13%) NC-ARDS patients had at least Open Access

Lymphopenia, corticosteroids and immunomodulatory therapeutics frequently used in COVID-19 patients with acute respiratory distress syndrome (C-ARDS) may be contributing factors to opportunistic infection such as Pneumocystis jirovecii pneumonia (PCP).
We conducted a retrospective study to compare the prevalence of PCP between patients with C-ARDS and those with non-SARS-CoV-2 viral ARDS (NC-ARDS).
Methods and some data from this cohort have been previously published [1]. There was no systematic protocol to search for PCP but in case of suspicion of PCP (respiratory symptoms with any consistent radiographic features), several analyses were performed on respiratory samples, such as broncho-alveolar lavage (BAL), blind protected sample, or sputum. It included direct examination (using May-Grünwald Giemsa (MGG), or immunofluorescence staining), detection of Pneumocystis jirovecii DNA by real-time polymerase chain reaction (qPCR) [2], and serum (1-3)-β-D-glucan. During the COVID-19 outbreak, immunofluorescence staining was not performed. PCP was defined as per the revised EORTC/MSGERC definition [3] as follows: proven in case of suspicion with positive direct examination; possible in case of suspicion with positive qPCR and positive BDG in ≥ 2 consecutive serum samples provided other etiologies have been excluded. SARS-CoV-2 and other viruses were not considered a priori as host factors. Patients with positive qPCR but lacking the other criteria for possible PCP were classified as colonized.
The primary endpoint was the difference in prevalence of PCP between C-ARDS and NC-ARDS patients.
No statistical sample size calculation was performed a priori, and sample size was equal to the number of patients treated during the study period. All patients were included only once.
Between October 1, 2009, and April 29, 2020, ninety patients had C-ARDS (positive RT PCR test for SARS-CoV-2), while 82 patients had viral NC-ARDS. Our study comprises 120 patients with fungal analyses on respiratory samples obtained from 81 C-ARDS and 39 NC-ARDS patients. NC-ARDS patients had more comorbidities were more often immunocompromised, and had lower lymphocyte counts than C-ARDS patients ( Table 1). C-ARDS patient received less steroid than NC-ARDS patients because they were included before randomized trials demonstrating decreased mortality with dexamethasone.
Pneumocystis analyses were performed on a mean of 3.1 respiratory sample per patient (range 1-15). Direct examination was performed in a total of 72 samples, with two positive cases. qPCR was performed in a total of 368 samples (294 blind protected samples, 72 BAL, and three sputum). All qPCR were negative in C-ARDS patients, while five (13%) NC-ARDS patients had at least COPD = chronic obstructive pulmonary disease, HIV = human immunodeficiency virus, SAPS II = Simplified Acute Physiology Score II, SOFA = sequential organ failure assessment, ICU = intensive care unit; *two missing values because two patients received dexamethasone or placebo in a randomized controlled trial; #denotes more than 1 mg/kg of prednisone or equivalent   Two NC-ARDS patients fulfilled proven PCP diagnostic criteria, with a positive direct examination, a single ß-D-glucan > 80 pg/mL (Table 2), and received treatment for PCP.
Three other NC-ARDS patients were classified as colonized, while no patient fulfilled possible PCP diagnostic criteria. Time between ICU admission and positive sample for PCP (Table 2) was short (< 2 days) like in other invasive fungal infections (i.e. invasive pulmonary aspergillosis) in severe influenza infection or ARDS.
In this study of patients with viral ARDS, we found a low risk for possible or proven PCP. Our findings are in accordance with two smaller studies in France [4,5] retrieving a low risk of Pneumocystis colonisation in COVID-19 patients. In our cohort, qPCR was positive in 13% of NC-ARDS. This result is in accordance with a previous study showing 7% of positive qPCR in ICU-admitted influenza patients [6].
The strengths of our study are the analysis of a large ARDS cohort with fungal analyses. Our study also has limitations: monocentric design, NC-ARDS patients more frequently immunocompromised, and a long cohort period.