PNEUMONIA | Community Acquired Pneumonia, Bacterial and Other Common Pathogens

Niederman, M.S.

Community-acquired pneumonia (CAP) is the number one cause of death from infectious diseases in the US, and the patient population that is affected is becoming increasingly more complex due to the presence of chronic illness which is commonly managed in outpatients who are at risk for pneumonia. The number one pathogen causing CAP is pneumococcus, which is commonly resistant to multiple antibiotics, thus complicating management. Other common pathogens include atypical organisms (Chlamydophila pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae), Hemophilus influenzae, enteric Gram-negatives (especially in those with chronic illness and aspiration risk factors), and Staphylococcus aureus. Successful management requires careful assessment of disease severity so that a site-of-care decision can be made (outpatient, inpatient, intensive care unit), appropriate samples for diagnostic testing collected, and antibiotic therapy initiated in a timely and accurate fashion. Initial antibiotic therapy is empiric, but even with extensive diagnostic testing, less than half of all patients have an etiologic pathogen identified. All patients with CAP require therapy for pneumococcus, atypical pathogens, and other organisms, as dictated by the presence of specific risk factors. Because pneumonia has both short-term and long-term impact on mortality, it is also important to focus on prevention of this illness, which requires smoking cessation, and giving at-risk individuals both pneumococal and influenza vaccines.