Pneumonia caused by penicillin-nonsusceptible Streptococcus pneumoniae: Clinical characteristics, prognostic factors, and outcomes

Background and purpose: Pneumococcal pneumonia caused by penicillin nonsusc eptible 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 dia gnosed from January 1993 to December 1997 were analyzed retrospectively. Pa tients were categorized into two groups according to susceptibility results . Differences between groups were evaluated with Student's t-test and the c hi-square test. Univariate analysis was used to identify factors associated with mortality. Results: Infections were caused by penicillin-susceptible S. pneumoniae (PS SP) 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 r ate (46% vs 32%) did not differ significantly between the PNSSP and PSSP gr oups. 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 lounger (9/10, 90%) p = 0.03). In patients with pneumonia caused b y PNSSP, the outcome was not significantly related to the treatment regimen (penicillin vs nonpenicillin beta-lactam antibiotics or vancomycin, 33% os 47%; p = 0.4). The only factors associated with mortality from these infec tions 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 p neumonia is more closely related to the clinical condition at presentation than the susceptibility status of the pneumococcus.