[Rapid and accurate diagnosis of severe pneumonia: similarities and differences between severe community-acquired pneumonia and hospital-acquired pneumonia/ventilator-associated pneumonia].

Abstract

Severe pneumonia, as a critical and prevalent condition of the respiratory system, poses a significant threat to patient survival and health outcomes. This article focuses on the similarities and differences between community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP)/ventilator-associated pneumonia (VAP). There is significant divergence in the predominant pathogens between severe community-acquired pneumonia (SCAP) and HAP/VAP. Epidemiologic data from China has identified the six most prevalent SCAP pathogens as influenza virus, Streptococcus pneumoniae, Enterobacteriaceae, Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydia psittaci (listed in descending order of frequency). In contrast, HAP/VAP cases in China are predominantly bacterial, with Gram-negative bacilli accounting for the majority of isolates. The antimicrobial resistance profiles of SCAP and HAP/VAP pathogens are markedly distinct: HAP/VAP pathogens exhibit substantially higher resistance rates than their CAP counterparts, necessitating different therapeutic approaches. In terms of severity assessment criteria, SCAP has well-established severity stratification systems, whereas HAP/VAP currently lacks standardized diagnostic criteria for severe cases. This discrepancy may lead to reduced inter-rater reliability and diagnostic accuracy when evaluating clinical severity compared to CAP. For etiological diagnosis, SCAP and HAP/VAP require distinct diagnostic approaches. Culture combined with antimicrobial susceptibility testing (AST) plays a pivotal role in HAP/VAP diagnosis. Proper lower respiratory tract specimens are a prerequisite for accurate identification. In contrast, most SCAP pathogens are difficult to culture; therefore, rapid and sensitive molecular detection methods, such as polymerase chain reaction (PCR) and next-generation sequencing (NGS), are essential for SCAP pathogen identification. Clinicians should develop a rapid and precise diagnostic approach for pneumonia management, applying distinct strategies for SCAP versus HAP/VAP. While initiating appropriate empirical therapy, active identification of causative pathogens through advanced diagnostics should be pursued in order to achieve the goals of precision medicine and ultimately improve patient outcomes.