Max is a 65-year-old man who presents with a “terrible cough” and fever of several days' duration. He has just returned from a business trip and is feeling quite run down. His cough is productive with rusty colored sputum. He is otherwise healthy and is a nonsmoker. His chest x-ray is similar to the one shown in Figure 53-1. He is diagnosed with probable bacterial pneumonia and is placed on antibiotics. You note that he has never had vaccinations against influenza or pneumococcus and you offer these to him at a follow-up visit when he is well.
Chest x-ray (CXR) showing right upper lobe consolidation. (From Miller WT Jr. Diagnostic Thoracic Imaging. New York, NY: McGraw-Hill; 2006:218, Figure 5-1 B. Copyright 2006.)
Pneumonia refers to an infection in the lower respiratory tract (distal airways, alveoli, and interstitium of the lung). Community-acquired pneumonia (CAP) has traditionally referred to pneumonia occurring outside of the hospital setting. More recently, a subgroup of CAP has been identified that is associated with healthcare risk factors (e.g., prior hospitalization, dialysis, nursing home residence, immunocompromised state); this form of pneumonia has been classified as a healthcare-associated pneumonia (HCAP), although definitions of HCAP vary. While severity and excess mortality are associated with HCAP, as well as a slight increase in multidrug resistant (MDR) pathogens, most studies do not support either a causal relationship between MDR and excess mortality or demonstrate benefit from broad-spectrum antibiotic coverage.1 It is likely that excess mortality is a result of underlying patient-related factors (e.g., older age, comorbidities, higher initial severity).1,2
- Three to 4 million adults per year in United States are diagnosed with CAP (8 to 15 per 1000 persons/year).3,4
- Annual incidence rate of CAP requiring hospitalization: 267 per 100,000 population and 1012 per 100,000 individuals older than 65 years of age.5
- Ten percent to 20% of patients are admitted to the hospital.3,4,6 Of those, 10% to 20% are admitted to the intensive care unit (ICU).7
- Increased incidence in men and in blacks versus whites.3
- CAP is the most frequent cause of death caused by infectious disease in the United States and the eighth leading cause of death overall (2007).7,8
- Economic burden associated with CAP is estimated at more than $12 billion annually in the United States.7
- In a study of children hospitalized with CAP (N = 254), the cause of the disease (identified in 85% of cases) was most often viral (62%, with 30% having evidence of both viral and bacterial pathogens).9 The most common pathogens were Streptococcus pneumoniae (37%), respiratory syncytial virus (29%), and rhinovirus (24%). Dual bacterial infections were found in 19 patients; only 1 patient of 125 tested had a ...