Severe Pneumonia in the Elderly: Risks, Treatment, and Prevention

, Winthrop University Hospital, Mineola, NY


Medscape General Medicine. 1998;1(3) 

In This Article


The etiology of pneumonia can not be predicted based on standard clinical, laboratory or radiographic data. The "classic" clinical presentations such as the bulging fissure sign of Klebsiella pneumoniae, the hyponatremia associated with Legionella infection, and the "atypical" presentation of Mycoplasma-induced pneumonia are neither sensitive nor specific enough to allow diagnosis of an inciting microbial pathogen to be made. Recently the American Thoracic Society has published practice guidelines for the management of both community-acquired and hospital-acquired pneumonia. These guidelines suggest evaluation, therapy, and work-up of pneumonia patients based upon patient specific risk factors, age and site of treatment.[27]

For older (> 60 years) outpatients, the likely causative organisms are S pneumoniae, respiratory viruses, and Haemophilus influenzae (especially in smokers). Aerobic gram-negative bacilli including P aeruginosa are increasingly common as a cause of pneumonia in the community. S aureus, Moraxella catarrhalis, Legionella species, Mycobacterium tuberculosis, and the endemic fungi must also be considered, especially in compromised hosts. Based upon this probable spectrum of inciting pathogens the following antibiotic regimens are recommended: a second-generation cephalosporin, or a beta-lactam/beta-lactamase inhibitor, or trimethoprim-sulfamethoxazole, with or without the addition of a macrolide or quinolone antibiotic to cover the so-called atypical pathogens (Table I).

Recent reports suggest that more than 50% of community-acquired pneumonia occurs in individuals with impaired host defenses.[27] Approximately 10% of all AIDS cases manifest in the elderly. Therefore Pneumocystis carinii pneumonia (PCP) must also be included in the clinical differential.

In more severely ill elderly, patients who require hospitalization and have significant comorbid medical illness, infections are often polymicrobial, and common inciting pathogens include S pneumoniae, H influenzae, aerobic gram-negative bacilli, Legionella species, and S aureus. Chlamydia pneumoniae with M pneumoniae have been increasingly identified as causative in elderly hospitalized patients with pneumonia (Fig. 2). Recommended therapy in this patient population consists of a second or third-generation cephalosporin or a beta-lactam/beta-lactamase inhibitor, again with or without the addition of a macrolide or quinolone antibiotic (Table II).

Microbiologic diagnosis of community-acquired pneumonia in the 71% of cases with an etiology documented by sputum culture. Adapted from Neill AM, Martin IR, Weir R, et al: Community-acquired pneumonia: Aetiology and usefulness of severity criteria on admission. Thorax 51:1010-1016, 1996.

If the patient has severe community-acquired pneumonia (Table III), S pneumoniae, Legionella species, aerobic gram-negative bacilli (especially P aeruginosa in the setting of chronic lung disease), and M pneumoniae (Fig. 3) are likely inciting pathogens.[38,39,40] Therapy should include a macrolide or quinolone and a third-generation cephalosporin with anti-pseudomonal activity or another anti-pseudomonal agent, such as imipenem/cilastatin, meropenem, or ciprofloxacin (Table IV). The incidence of P aeruginosa-induced severe community-acquired pneumonia has been as high as 10%, but probably occurs primarily in patients with structural lung disease such as bronchiectasis.

Pathogens in patients with severe community-acquired pneumonia.