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Pneumonia and other respiratory infections
INTRODUCTION
Streptococcus pneumoniae is an important cause of community-acquired pneumonia, bacteraemia, and meningitis. Invasive pneumococcal disease (IPD) is defined as isolation of S. pneumoniae from a normally sterile body site (typically blood or cerebrospinal fluid), and carries with it significant morbidity and mortality, even in the modern antibiotic era. The mortality rate of pneumococcal bacteraemia in a large prospective international study was 16·9% in those with age >65 years and the presence of underlying disease or risk factors for immunosuppression significantly associated with increased mortality [1]. Pneumococcal meningitis also leads to poor outcomes, carrying a mortality rate of 21% [2]. Various states of immunodeficiency, including underlying malignancy, are recognized as risk factors for IPD [3, 4]. Vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPV23) is efficacious against IPD and recommended for patients in high-risk groups, including all patients with malignancy [5-7]. Unfortunately, many patients with IPD who have an indication for vaccination are not vaccinated despite multiple encounters with the healthcare system [8].
Large-scale population studies have found increased rates of IPD in paediatric and adult patients with haematological and solid-organ malignancies [9-11], but condition-specific data is lacking. We conducted a large 5-year retrospective study of all adult patients aged [= or >, slanted]18 years with IPD in the province of Alberta and obtained provincial prevalence data for various malignancies from the Alberta Cancer Board to determine the rates of IPD in patients with selected underlying malignancies.
METHODS
Demographics and definitions
The study was conducted in the province of Alberta from 2000 to 2004, which at the time of the study was divided into nine health regions. The population was 2 967 755 in 2000 and 3 179 036 in 2004 [12]. Cases of IPD were defined as the isolation of S. pneumoniae from any normally sterile body site, including blood, cerebrospinal fluid, pleural fluid, biopsy tissue, synovial fluid, pericardial fluid, and peritoneal fluid [13]. In Alberta, IPD is a notifiable disease reportable to the Provincial Health Office. S. pneumoniae isolates recovered from patients with IPD are submitted to the National Centre for Streptococcus (NCS) located in Edmonton, Alberta, for capsular serotyping and antimicrobial resistance profiling for trending analysis. Isolates were submitted to...