Community-acquired pneumonia.

Abstract

Community-acquired pneumonia (CAP) is the most common infectious disease cause of death. We summarize recent findings regarding the epidemiology of CAP in adults, efficacy of vaccines against Streptococcus pneumoniae, diagnostics, and discuss the current controversy between CAP and healthcare-associated pneumonia (HCAP). The emergence of the Middle East respiratory syndrome coronavirus and the avian influenza A strain H7N9 are of concern but still these are infrequent causes of CAP. Recent data indicate that vaccinating children also protects adults against CAP by generating significant herd immunity, and that the conjugated pneumococcal vaccine in adults may offer some efficacy in preventing CAP caused by vaccine serotypes. The immunochromotagraphic urinary antigen test has improved the diagnostic yield for the aetiology of CAP, and initial data demonstrate that a novel multiplex urinary antigen test will further increase the sensitivity for detection of S. pneumoniae. There has been significant concern that a relatively recently described pneumonia category, HCAP, requires empirical treatment for potentially multidrug-resistant organisms (MDRO). However, new evidence shows that (at least in Europe) pneumonia caused by MDRO remains uncommon even in HCAP category patients. CAP remains a major cause of morbidity and mortality. Advances in vaccination and diagnosis should help reduce the amount of disease due to S. pneumoniae, the commonest cause of CAP. Outside of the United States, MDRO are relatively uncommon causes of CAP, and the increased mortality of HCAP category patients seems to be related to their comorbidities and age rather than microbial aetiology.