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

, Winthrop University Hospital, Mineola, NY


Medscape General Medicine. 1998;1(3) 

In This Article

Resistant Bacterial Pathogens

Resistance of bacteria to commonly used antibiotics complicates the course of severe pneumonia in the elderly. S pneumoniae resistance to penicillin approaches 25% (10% being high-level resistance) in some geographic areas.[41] A minimal inhibitory concentration (MIC) of 0.1-1.0 mcg/mL defines intermediate resistance and an MIC greater than or equal to 2.0 mcg/mL defines high-level resistance. These cutoff points are considered to be conservative and more clinically relevant when dealing with meningitis than with pneumonia. Most investigators believe that when S pneumoniae has an MIC of less than 2.0 mcg/mL, high dose penicillin G (150,000-200,000 U/kg/day) will adequately treat pneumonia. When the MIC is greater than or equal to 2.0 mcg/mL, alternative antibiotics, such as ceftriaxone or cefotaxime, should be prescribed. With a MIC greater than or equal to 2.0 mcg/mL, vancomycin, meropenem or imipenem are more appropriate antibiotic choices.[33]

Risk factors for acquiring penicillin resistant S pneumoniae infection have been identified. In a study of 374 patients with invasive pneumococcal disease (bacteremic pneumonia, sepsis, and meningitis), 74.3% due to pneumonia, 21% of these patients had penicillin resistant organisms (4% had-high level resistance and 17% had intermediate level resistance).[42] The most important risk factors for acquiring penicillin resistant infection, in this study, were immunosuppressive disease and use of beta-lactam antibiotics in the preceding 3 months. Both risk factors are commonly found in elderly patients.[42]

Risk of death from infection due to penicillin and cephalosporin resistant S pneumoniae was investigated in a prospective study[41] of 504 adults with culture-proven pneumococcal pneumonia from Barcelona, Spain. In this study, mortality associated with penicillin-resistant infection related more to concomitant medical illness and age than the sensitivity of the Pneumococcus to penicillin.

The problem of increasing drug resistance to S pneumoniae is of particular significance in the elderly population. In a recent study[5] examining bacteremic S pneumoniae infection, the incidence of drug resistant isolates increased over four years, especially in the elderly. Older individuals were also found to be at risk for invasive infection. The incidence was 9.6 per 100,000 population per year in those younger than 65 years of age, compared to 83 per 100,000 population per year in those over age 65 years 43.