Clinical and microbiological epidemiology of Streptococcus pneumoniae bacteremia in cancer patients.

OBJECTIVES: In the current era of changing epidemiology of invasive pneumococcal disease, we aimed to assess the clinical features, antimicrobial susceptibility, vaccination status, serotypes, genotypes and outcomes of pneumococcal bacteremia in cancer patients.
METHODS: Prospective observational analysis of all consecutive cancer adults admitted to a university hospital (January 2006-April 2011).
RESULTS: Of 971 episodes of bacteremia, 63 (6.5%) were caused by Streptococcus pneumoniae. Pneumonia was the most common source of pneumococcal bacteremia (84.1%). Although all isolated pneumococci were penicillin-susceptible, resistance to ceftazidime was high (43%). The serotypes most frequently isolated were 19A and 14, and the most common genotypes were Spain(9V)-ST156 and Denmark(14)-ST230. Only 23% of patients had received the 23-valent polysaccharide pneumococcal vaccine. This polysaccharide vaccine was found to cover 72.4% of the serotypes identified, whereas the 7-valent, 10-valent and the 13-valent conjugate vaccines covered 24.1%, 29.3%, and 53.5% of serotypes respectively. The early case-fatality rate (<48 h) was 4.8% and overall case-fatality rate (<30 days) 14.3%.
CONCLUSIONS: Pneumococcal bacteremia, which complicates mainly pneumonia, is frequent in cancer patients and causes significant morbidity and case-fatality rate. Resistance to ceftazidime is particularly high. These findings should be considered when selecting antibiotic treatment for cancer patients presenting pneumonia.