Pneumococcal bacteremia in patients aged over 65 years. A study of 161 cases

BACKGROUND: Here we present the results from a prospective analysis of pneumococcal bacteremia in patients older than 65 years, highlighting its differences with regard to patients aged from 15 to 64 years. PATIENTS AND METHOD: We performed a prospective follow-up study (1988-1999) of patients older than 14 years who had blood cultures positive for Streptococcus pneumoniae (S, pneumoniae). S. pneumoniae was identified using standard techniques. The antimicrobial sensitivity was analysed using the broth midrodilution technique and the serotype was studied in a reference laboratory. Statistical analyses were performed by means of the SPSS(R) program, version 9.0. RESULTS: 161 out of 321 bacteremias occurred in 154 patients older than 65 years (86 males). Most frequent underlying diseases were chronic obstructive pulmonary disease (COPD), diabetes and neoplasia. Most patients had pneumonia, 29.7% with ilfiltrates involving at least two lung lobes. 9.4% of bacteremias were nosocomial. Among patients older than 65 years, 32.5% of strains were resistant to penicillin, compared to 21.7% in patients younger than 65 years (p = 0.034). Mortality in patients over 65 years was higher than in younger patients (25.3% vs 11.5%; p = 0.002) and mortality predictive factors in a multivariate analysis were age, nosocomial bacteremia and multi-lobe involvement (in patients with pneumonia), CONCLUSIONS: There is a high incidence of pneumococcal bacteremia in patients over 65 years of age. These patients have a higher rate of resistance to penicillin and a higher mortality rate than younger patients. Mortality predictive factors are age, nosocomial bacteremia and multilobe involvement.