Changing needs of community-acquired pneumonia.

Community-acquired pneumonia (CAP) is a serious condition associated with significant morbidity and potential long-term mortality. Although the majority of patients with CAP are treated as outpatients, the greatest proportion of pneumonia-related mortality and healthcare expenditure occurs among the patients who are hospitalized. There has been considerable interest in determining risk factors and severity criteria assessments to assist with site-of-care decisions. For both inpatients and outpatients, the most common pathogens associated with CAP include Streptococcus pneumoniae, Haemophilus influenzae, group A streptococci and Moraxella catarrhalis. Atypical pathogens, Gram-negative bacilli, methicillin-resistant Staphylococcus aureus (MRSA) and viruses are also recognized aetiological agents of CAP. Despite the availability of antimicrobial therapies, the recent emergence of drug-resistant pneumococcal and staphylococcal isolates has limited the effectiveness of currently available agents. Because early and rapid initiation of empirical antimicrobial treatment is critical for achieving a favourable outcome in CAP, newer agents with activity against drug-resistant strains of S. pneumoniae and MRSA are needed for the management of patients with CAP.