Background and purpose: Pneumococcal pneumonia caused by penicillin-nonsusceptible Streptococcus pneumoniae (PNSSP) is increasing worldwide. To better understand this infection, patients with pneumococcal pneumonia treated at National Taiwan University Hospital during a 5-year period were evaluated to determine the clinical characteristics, prognostic factors, and outcomes of the infection.
Methods: Eighty-one patients with 81 episodes of pneumococcal pneumonia diagnosed from January 1993 to December 1997 were analyzed retrospectively. Patients were categorized into two groups according to susceptibility results. Differences between groups were evaluated with Student's t-test and the chi-square test. Univariate analysis was used to identify factors associated with mortality.
Results: Infections were caused by penicillin-susceptible S. pneumoniae (PSSP) in 57 (70%) patients and by PNSSP in the remaining 24 (30%). Nosocomial acquisition was more common in PNSSP (25%) than in PSSP patients (10%) (p = 0.05), while the frequency of bacteremia (54% vs 60%) and the mortality rate (46% vs 32%) did not differ significantly between the PNSSP and PSSP groups. Among the 24 patients with pneumonia caused by PNSSP, those 65 years of age or older had a lower incidence of bacteremia (4/14, 29%) than those who were younger (9/10, 90%) (p = 0.03). In patients with pneumonia caused by PNSSP, the outcome was not significantly related to the treatment regimen (penicillin vs nonpenicillin beta-lactam antibiotics or vancomycin, 33% vs 47%; p = 0.4). The only factors associated with mortality from these infections were shock (p = 0.003) and multilobar consolidation (p = 0.01) at the time of admission.
Conclusions: These data suggest that the clinical outcome of pneumococcal pneumonia is more closely related to the clinical condition at presentation than the susceptibility status of the pneumococcus.