Bacteremic pneumococcal infections in immunocompromised patients without AIDS: the impact of β-lactam resistance on mortality

AbstractBackground: Streptococcus pneumoniae is the leading cause of community-acquired pneumonia in the elderly, and in recent years it has arisen as an important pathogen in HIV-infected patients. However, there is a scarcity of information on clinical and therapeutic problems associated with pneumococcal infections in other immuno-compromised patients. The objective of this study was to assess the most relevant epidemiologic aspects, clinical features and prognostic factors of pneumococcal bacteremia in immunocompromised hosts without AIDS.Methods: This was a retrospective analysis of patients with pneumococcemia, carried out in a 600-bed, university-affiliated hospital in Madrid, Spain. Two-hundred and sixty patients were evaluated retrospectively; 69 (26.5%) immunocompromised patients based on strict case definitions were compared with a group composed of 191 non-immunocompromised hosts with a variety of chronic conditions. Conventional management of pneumococcal bacteremia according to clinical standards was assessed. The MICs of penicillin and other β-lactam antibiotics, and related mortality and hospital mortality at 30 days, were measured.Results: A comparison of clinical manifestations of pneumococcemia between immunocompromised patients and non-immunocompromised patients did not show differences in the presence of fever, obtundation, type of lung involvement, frequency of primary bacteremia, or meningitis. Hospital-acquired pneumococcemia was significantly more frequent in immunocompromised patients (34.7% versus 6.8%, P<0.0001), and resistance to penicillin was also more common in pneumococcal strains isolated from these patients (37.5% versus 20%, P=0.0009). Septic shock occurred more frequently in immunocompromised patients, although the overall and related mortality were not significantly different from those found in non-immunocompromised patients (33.3% versus 22.5%, P=0.07, and 28.9% versus 20.9%, P=0.7 respectively). In the multivariate analysis, multilobar pneumonia (odds ratio (OR) 15.7; 95% CI 6.00–41.30; P < 0.001), inadequate treatment (OR 12.20; 95% CI 4.10–37.20; P < 0.001), obtundation (OR 5.80; 95% CI 2.20–15.00; P<0.001) and hospital-acquired bacteremia (OR 4.80; 95% CI 1.00–14.60; P<0.006) were associated with an increased risk of mortality in patients with pneumococcemia. Only multilobar pneumonia (OR 7.90; 95% CI 4.10–15.35; P