Introduction

An enduring pathogen since its discovery in 1881, Streptococcus pneumoniae (pneumococcus) ranks first among all causes of community-acquired pneumonia (CAP), second as a cause of bacterial meningitis among adults, and is a frequent cause of sepsis and meningitis among children. The high case-fatality rates from invasive (bacteremic) pneumococcal disease (IPD) attest to its importance as a pervasive pathogen. Case-fatality rates in IPD approach about one in six cases of pneumonia among elderly and about one in ten among middle-aged adults, about one in three cases of meningitis among adults and one in 20 cases of meningitis in children, and nearly nil in cases of bacteremia without localization among children 4 years of age or younger. Persistent high case-fatality rates from IPD during the second half of the twentieth century, despite effective antibiotic treatment regimens, drove the development and licensure of polysaccharide vaccines for adults and children.

Pneumonia

The antibiotic treatment of CAP among patients admitted to hospital must be initiated without delay and should be started before the patient leaves the emergency department, based on expert empiric treatment guidelines, even before the causative organism is established by diagnostic laboratory procedures. The diagnosis of S. pneumoniae pneumonia initially represents a presumptive clinical judgment taking into account its common occurrence, symptoms and signs, age of the patient, and the results of rapid laboratory tests, when available. Unequivocal evidence of the specific etiologic diagnosis of S. pneumoniae pneumonia requires isolation of the organism from blood or another otherwise sterile site, such as pleural fluid, with results not available usually until the next day. Blood cultures should be done to assess the invasive nature of the infection and to test the isolated strain for antibiotic sensitivity, because of the increasing emergence of intermediate and high resistant strains worldwide. A single set of cultures obtained before the start of antibiotic treatment is adequate for recovery of the organism.