Pneumonia

Abstract

Pneumonia is a common acute respiratory infection that affects the alveoli and distal bronchial tree of the lungs. The disease is broadly divided into community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP, which includes ventilation-associated pneumonia (VAP)) (Box 1). Aspiration pneumonia represents 5-15% of all cases of CAP; however, its prevalence amongst patients with HAP is not known 1 . The lack of robust diagnostic criteria for aspiration pneumonia may explain why the true burden of this type of pneumonia remains unknown 1 .The causative microorganisms for CAP and HAP differ substantially. The most common causal microorganisms in CAP are Streptococcus pneumoniae, respiratory viruses, Haemophilus influenzae and other bacteria such as Mycoplasma pneumoniae and Legionella pneumophila. Conversely, the most frequent microorganisms in HAP are Staphylococcus aureus (including both methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA)), Enterobacterales, non-fermenting gram-negative bacilli (for example, Pseudomonas aeruginosa), and Acinetobacter spp. 2,3 . In health-care-associated pneumonia (HCAP), owing to patient risk factors, the microbial aetiology is more similar to that in HAP than to that in CAP. However, difficulties in standardizing risk factors for this population, coupled with the heterogeneity of post-hospital health care worldwide, suggest that the concept of HCAP has little usefulness, and indeed, HCAP was not included in recent guidelines for CAP and HAP [3][4][5] .Differences in microbiology between CAP and HAP depend on whether pneumonia was acquired in the community or health care environment and on host risk factors, including abnormal gastric and oropharyngeal colonization. In addition, the aetiopathogenesis of CAP is different from that of HAP. In general, mild CAP is treated on an outpatient basis, moderately severe CAP in hospital wards, and severe CAP in intensive care units (ICUs) with or without mechanical ventilation 6 . The need for mechanical ventilation is used as a sub-classification of interest for prognosis and stratification in randomized clinical trials.Both CAP 7 and HAP 4 can occur in either immunosuppressed or immunocompetent patients. To date, most research data have been based on studies of immunocompetent patients and, therefore, we rely on such sources in this Primer. However, CAP, HAP and VAP in immunosuppressed patients have attracted the attention of researchers, and more investigation is to come.In this Primer, we cover and summarize the most important and recent updates related to epidemiology, pathophysiology, diagnostic screening, prevention, management, quality of life, and research perspectives. Additionally, owing to the profound impact of the coronavirus disease 2019 (COVID-19) pandemic caused by

Serum IL-27 Predicts the Severity and Prognosis in Patients With Community-acquired Pneumonia: A Prospective Cohort Study

“…CAP is one of common infectious diseases cause of death in the America with more than 1.5 million adults hospitalized annually [3]. The mortality was about 171.1 per 1000 people in Central Europe, eastern Europe and central Asia, 130.8 per 1000 people in Southeast Asia, eastern Asia and Oceania [4,5]. Morbidity and mortality were higher in patients with severe CAP [6].…”

Post-treatment with the PPAR-γ agonist pioglitazone inhibits inflammation and bacterial growth during Klebsiella pneumonia

“…Pneumonia is a major cause of morbidity and mortality worldwide [ 3 ]. Treatment of pneumonia by antimicrobial agents has become more difficult due to the emergence of multidrug resistant pathogens.…”

Association between delay in intensive care unit admission and the host response in patients with community-acquired pneumonia

“…The primary aim of this study was to compare the immune response upon ICU admission in CAP patients with a delayed ICU admission to those who were transferred directly from the ED. We considered this of interest since a more protracted course of severe infection and sepsis may affect host response aberrations [ 2 , 23 , 24 ] and decisions about interventions that seek to modulate the host response or the eligibility of patients for immune modulatory trials are oftentimes made shortly after ICU admission [ 25 , 26 ]. We show that, whilst overall the host response was largely similar between these two patient groups, analysis of genome-wide mRNA expression profiles established that blood leukocytes of patients with a delayed ICU admission display blunted innate and adaptive immune response signalling, as well as decreased expression of genes associated with tissue repair and extracellular matrix remodelling pathways.…”

“…Community-acquired pneumonia (CAP) is the most common infection requiring intensive care in developed countries [ 1 , 2 ]. The number of patients requiring therapy on the intensive care unit (ICU) has increased over the last decades, mostly in elderly and patients with comorbidities [ 3 , 4 ].…”