Advances in severe community-acquired pneumonia.

Abstract

Community-acquired pneumonia (CAP) is a common respiratory disease and is considered to be the leading cause of mortality among various infectious diseases.[1,2] A large population-based study showed that among hospitalized patients diagnosed with pneumonia, 21% of them required the intensive care unit (ICU) admission, 6% required invasive mechanical ventilation, and 2% died.[3] Although therapeutic strategies have been significantly improved over recent years, the morbidity and mortality of CAP, especially severe CAP (SCAP), remain high. Mortality of SCAP has been reported to range from 17% to 49% by different multi-center cohort studies.[4] The Infectious Diseases Society of America (IDSA), American Thoracic Society (ATS) and the Infectious Disease Assembly, Chinese Thoracic Society, have published consensus guidelines for CAP (IDSA/ATS 2007, CTS 2016), which clearly defined SCAP criteria.[5] According to IDSA/ATS SCAP criteria, patients with SCAP requiring ICU admission should have at least one major criteria (invasive mechanical ventilation or septic shock with the need for vasopressors) or at least three minor criteria (respiratory rate ≥30 breaths/min, oxygenation index (PaO2/FiO2) ratio ≤250, multi-lobe infiltrates, hypothermia (core temperature <36°C), leukopenia (white blood cell count <4000 cells/mm3), thrombocytopenia (platelet count <100,000 cells/mm3), hypotension requiring aggressive fluid resuscitation, confusion/disorientation, and uremia (blood urea nitrogen (BUN) ≥20 mg/dL).[5] To date, confusion, uremia, respiratory rate, low blood pressure, age 65 years or greater (CURB-65) and pneumonia severity index (PSI), the two primary clinical assessment tools utilized, have been widely used to evaluate the mortality risk of CAP patients in clinical practice.[6,7] Several risk factors associated with high mortality in SCAP have been identified, including anti-microbial resistance, increased age, septic shock, and acute respiratory failure.[8] It is thus greatly beneficial to distinguish high-risk patients with SCAP and formulate personalized treatment strategies. Optimal ICU management and rational application of antibiotics were reported to be two key factors determining outcomes of patients with SCAP.[1] Recently, several advances in SCAP have been made and here we summarized the updated knowledge of diagnostic and therapeutic strategies for SCAP.