Antimicrobial De-Escalation in Critically Ill Patients.

Antimicrobial de-escalation (ADE) is defined as the discontinuation of one or more antimicrobials in empirical therapy, or the replacement of a broad-spectrum antimicrobial with a narrower-spectrum antimicrobial. The aim of this review is to provide an overview of the available literature on the effectiveness and safety of ADE in critically ill patients, with a focus on special conditions such as anti-fungal therapy and high-risk categories. Although it is widely considered a safe strategy for antimicrobial stewardship (AMS), to date, there has been no assessment of the effect of de-escalation on the development of resistance. Conversely, some authors suggest that prolonged antibiotic treatment may be a side effect of de-escalation, especially in high-risk categories such as neutropenic critically ill patients and intra-abdominal infections (IAIs). Moreover, microbiological documentation is crucial for increasing ADE rates in critically ill patients with infections, and efforts should be focused on exploring new diagnostic tools to accelerate pathogen identification. For these reasons, ADE can be safely used in patients with infections, as confirmed by high-quality and reliable microbiological samplings, although further studies are warranted to clarify its applicability in selected populations.

Lung microbiota composition, respiratory mechanics, and outcomes in COVID-19-related ARDS.

Few data are available on the lung microbiota composition of patients with coronavirus disease 2019-related acute respiratory distress syndrome (C-ARDS) receiving invasive mechanical ventilation (IMV). Moreover, it has never been investigated whether there is a potential correlation between lung microbiota communities and respiratory mechanics. We performed a prospective observational study in two intensive care units of a university hospital in Italy. Lung microbiota was investigated by bacterial 16S rRNA gene sequencing, performed on bronchoalveolar lavage fluid samples withdrawn after intubation. The lung bacterial communities were analyzed after stratification by respiratory system compliance/predicted body weight (Crs) and ventilatory ratio (VR). Weaning from IMV and hospital survival were assessed as secondary outcomes. In 70 C-ARDS patients requiring IMV from 1 April through 31 December 2020, the lung microbiota composition (phylum taxonomic level, permutational multivariate analysis of variance test) significantly differed between who had low Crs vs those with high Crs (P = 0.010), as well as in patients with low VR vs high VR (P = 0.012). As difference-driving taxa, Proteobacteria (P = 0.017) were more dominant and Firmicutes (P = 0.040) were less dominant in low- vs high-Crs patients. Similarly, Proteobacteria were more dominant in low- vs high-VR patients (P = 0.013). After multivariable regression analysis, we further observed lung microbiota diversity as a negative predictor of weaning from IMV and hospital survival (hazard ratio = 3.31; 95% confidence interval, 1.52-7.20, P = 0.048). C-ARDS patients with low Crs/low VR had a Proteobacteria-dominated lung microbiota. Whether patients with a more diverse lung bacterial community may have more chances to be weaned from IMV and discharged alive from the hospital warrants further large-scale investigations. IMPORTANCE: Lung microbiota characteristics were demonstrated to predict ventilator-free days and weaning from mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). In this study, we observed that in severe coronavirus disease 2019 patients with ARDS who require invasive mechanical ventilation, lung microbiota characteristics were associated with respiratory mechanics. Specifically, the lung microbiota of patients with low respiratory system compliance and low ventilatory ratio was characterized by Proteobacteria dominance. Moreover, after multivariable regression analysis, we also found an association between patients' microbiota diversity and a higher possibility of being weaned from mechanical ventilation and discharged alive from the hospital. For these reasons, lung microbiota characterization may help to stratify patient characteristics and orient the delivery of target interventions. (This study has been registered at ClinicalTrials.gov on 17 February 2020 under identifier NCT04271345.).Registered at ClinicalTrials.gov, 17 February 2020 (NCT0427135).

Update on vitamin D role in severe infections and sepsis.

Severe infections frequently require admission to the intensive care unit and cause life-threatening complications in critically ill patients. In this setting, severe infections are acknowledged as prerequisites for the development of sepsis, whose pathophysiology implies a dysregulated host response to pathogens, leading to disability and mortality worldwide.Vitamin D is a secosteroid hormone that plays a pivotal role to maintain immune system homeostasis, which is of paramount importance to resolve infection and modulate the burden of sepsis. Specifically, vitamin D deficiency has been widely reported in critically ill patients and represents a risk factor for the development of severe infections, sepsis and worse clinical outcomes. Several studies have demonstrated the feasibility, safety and effectiveness of vitamin D supplementation strategies to improve vitamin D body content, but conflictual results support its benefit in general populations of critically ill patients. In contrast, small randomised clinical trials reported that vitamin D supplementation may improve host-defence to pathogen invasion via the production of cathelicidin and specific cytokines. Nonetheless, no large scale investigations have been designed to specifically assess the impact of vitamin D supplementation on the outcome of critically ill septic patients admitted to the intensive care unit.