Impaired immune signaling and changes in the lung microbiome precede secondary bacterial pneumonia in COVID-19

A cross-sectional study in critically ill patients affected by COVID-19 in an intensive care unit: would Acinetobacter baumannii resistant to carbapenems be the biggest villain?

AIM

to describe cases of infection of Acinetobacter baumannii (A. baumannii) in critically ill patients affected by COVID-19, admitted to an intensive care unit (ICU), using dexamethasone.

METHODOLOGY

cross-sectional study conducted on patients admitted to the intensive care unit COVID-19 survey among hospitalized patients from November 2020 to March 2021.

SETTING

large hospital, reference for caring for patients with COVID-19 in Bahia (Brazil).

PATIENTS

a convenience sample of 22 patients admitted to the COVID ICU signed the consent form agreeing to participate in the study. Three patients were excluded for having decided to participate without signing the form.

RESULTS

of the 22 patients listed, 45 % (10) had blood infection or mechanical ventilation-associated pneumonia by A. baumannii in blood cultures and/or tracheal aspirate secretion. We observed that there is a moderate correlation between the length of stay and infection by A. baumannii (Spearman's ρ; 0.592; p-value<0.005) and a strong correlation between the number of days on mechanical ventilation and infection by these bacteria (Spearman's ρ; 0.740; p-value<0.001). This percentage is higher than the value of 0.62 % of infection by A. baumannii in this ICU in the same period of the year before COVID-19 (p-value<0.0001).

CONCLUSIONS

hospitals that receive patients with COVID-19 may be vulnerable to outbreaks of multi-drug resistant organisms, such as A. baumannii . It is worth reflecting on the care and operational practices in handling these patients, especially in isolation and restriction measures for those from other nosocomial areas.

Alterations in the respiratory tract microbiome in COVID-19: current observations and potential significance

SARS-CoV-2 infection causes COVID-19 disease, which can result in consequences ranging from undetectable to fatal, focusing attention on the modulators of outcomes. The respiratory tract microbiome is thought to modulate the outcomes of infections such as influenza as well as acute lung injury, raising the question to what degree does the airway microbiome influence COVID-19? Here, we review the results of 56 studies examining COVID-19 and the respiratory tract microbiome, summarize the main generalizations, and point to useful avenues for further research. Although the results vary among studies, a few consistent findings stand out. The diversity of bacterial communities in the oropharynx typically declined with increasing disease severity. The relative abundance of Haemophilus and Neisseria also declined with severity. Multiple microbiome measures tracked with measures of systemic immune responses and COVID outcomes. For many of the conclusions drawn in these studies, the direction of causality is unknown-did an alteration in the microbiome result in increased COVID severity, did COVID severity alter the microbiome, or was some third factor the primary driver, such as medication use. Follow-up mechanistic studies can help answer these questions. Video Abstract.

Relationship between corticosteroid use and incidence of ventilator-associated pneumonia in COVID-19 patients: a retrospective multicenter study

Background

Ventilator-associated pneumonia (VAP) is common in patients with severe SARS-CoV-2 pneumonia. The aim of this ancillary analysis of the coVAPid multicenter observational retrospective study is to assess the relationship between adjuvant corticosteroid use and the incidence of VAP.

Methods

Planned ancillary analysis of a multicenter retrospective European cohort in 36 ICUs. Adult patients receiving invasive mechanical ventilation for more than 48 h for SARS-CoV-2 pneumonia were consecutively included between February and May 2020. VAP diagnosis required strict definition with clinical, radiological and quantitative microbiological confirmation. We assessed the association of VAP with corticosteroid treatment using univariate and multivariate cause-specific Cox’s proportional hazard models with adjustment on pre-specified confounders.

Results

Among the 545 included patients, 191 (35%) received corticosteroids. The proportional hazard assumption for the effect of corticosteroids on the incidence of VAP could not be accepted, indicating that this effect varied during ICU stay. We found a non-significant lower risk of VAP for corticosteroid-treated patients during the first days in the ICU and an increased risk for longer ICU stay. By modeling the effect of corticosteroids with time-dependent coefficients, the association between corticosteroids and the incidence of VAP was not significant (overall effect p = 0.082), with time-dependent hazard ratios (95% confidence interval) of 0.47 (0.17–1.31) at day 2, 0.95 (0.63–1.42) at day 7, 1.48 (1.01–2.16) at day 14 and 1.94 (1.09–3.46) at day 21.

Conclusions

No significant association was found between adjuvant corticosteroid treatment and the incidence of VAP, although a time-varying effect of corticosteroids was identified along the 28-day follow-up.

Elevated Rates of Ventilator-Associated Pneumonia and COVID-19 Associated Pulmonary Aspergillosis in Critically Ill Patients with SARS-CoV2 Infection in the Second Wave: A Retrospective Chart Review

Due to multiple risk factors, the rate of ventilator-associated pneumonia in critically ill COVID-19 patients has been reported in a range of 7.6% to 86%. The rate of invasive pulmonary aspergillosis in this cohort has been reported at 4% to 30%. We undertook a retrospective chart review of 276 patients who were admitted to intensive care in a large university hospital. The period studied included patients from 23 February 2014 to 12 May 2021. Four groups were collected: COVID-19 Wave 1, COVID-19 Wave 2, influenza, and community-acquired pneumonia. Clinical characteristics, outcomes, and microbiological cultures were recorded. The incidence of ventilator-associated pneumonia in COVID-19 Wave 1, COVID-19 Wave 2, influenza, and community-acquired pneumonia was 5.45%, 27.40%, 16.67%, and 3.41%, respectively (p < 0.001). The rate of invasive pulmonary aspergillosis was 0%, 9.59%, 13.33%, and 6.82%, respectively (p < 0.001). A significantly elevated rate of ventilator-associated pneumonia and invasive pulmonary aspergillosis was noted in the second wave of COVID-19 when compared to the first. This was accompanied by an increase in the mortality rate. Increased steroid use was an independent risk factor for ventilator-associated pneumonia and invasive pulmonary aspergillosis across all four groups. Despite an increased understanding of this disease, no clinical trials have shown any promising therapeutic options at present.

Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia and Ventilator-Associated Tracheobronchitis in COVID-19

Although few studies evaluated the incidence of hospital-acquired pneumonia (HAP) or ventilator-associated tracheobronchitis in COVID-19 patients, several studies evaluated the incidence of ventilator-associated pneumonia (VAP) in these patients. Based on the results of a large multicenter European study, VAP incidence is higher in patients with SARS-CoV-2 pneumonia (36.1%), as compared with those with influenza pneumonia (22.2%), or no viral infection at intensive care unit (ICU) admission (16.5%). Potential explanation for the high incidence of VAP in COVID-19 patients includes long duration of invasive mechanical ventilation, high incidence of acute respiratory distress syndrome, and immune-suppressive treatment. Specific risk factors for VAP, including SARS-CoV-2-related pulmonary lesions, and bacteria-virus interaction in lung microbiota might also play a role in VAP pathogenesis. VAP is associated with increased mortality, duration of mechanical ventilation, and ICU length of stay in COVID-19 patients. Further studies should focus on the incidence of HAP especially in ICU non-ventilated patients, better determine the pathophysiology of these infections, and evaluate the accuracy of currently available treatment guidelines in COVID-19 patients.

Comparative evaluation of ventilator-associated pneumonia in critically ill COVID- 19 and patients infected with other corona viruses: a systematic review and meta-analysis

The Coronavirus disease 19 (COVID-19) pandemic is associated with an unprecedented requirement for intensive care unit (ICU) admission, invasive mechanical ventilation, and thereby significantly increasing the risk of secondary nosocomial pneumonia, Ventilator-Associated Pneumonia (VAP). Our study aims to identify the overall incidence of VAP, common organisms associated with it, and outcome in COVID-19 patients in comparison to the non-SARS-CoV-2 infected critically ill ventilated COVID-19 patients. A comprehensive screening was conducted using major electronic databases), from January 1st 2020 to May 31st 2021, as per the PRISMA statement. In our rapid review, we included a total of 34 studies (involving 8901 cases. Overall VAP was reported in 48.15 % (95% CI 42.3%-54%) mechanically ventilated COVID-19 patients and the mortality rate was 51.4% (95% CI 42.5%-60%). COVID-19 patients had increased risk of VAP and mortality in comparison to other non-SARS-CoV-2 viral pneumonia (OR=2.33; 95%CI 1.75-3.11; I2=15%, and OR=1.46; 95%CI 1.15-1.86; I2=0% respectively). Critically ill COVID-19 patients are prone to develop VAP, which worsens the outcome.