Molecular epidemiology of Streptococcus pneumoniae causing invasive disease in 5 countries

A multicenter study was done during 1993-1995 to investigate prospectively the influence of several prognostic factors for predicting the risk of deat h among patients with pneumococcal bacteremia. Five centers located in Cana da, the United Kingdom, Spain, Sweden, and the United States participated. Clinical parameters were correlated to antibiotic susceptibility and seroty ping of the 354 invasive pneumococcal isolates collected and to molecular t yping of 173 isolates belonging to the 5 most common serotypes (14, 9V, 23F , 3, and 7F). Serotype 14 was the most common among all isolates, but serot ype 3 dominated in fatal cases and in isolates from Spain and the United St ates, the countries with the highest case-fatality rates. Fewer different p atterns were found among the type 3 isolates, which suggests a closer clona l relationship than that among isolates belonging to other serotypes. Of ty pe 3 isolates from fatal cases, 1 clone predominated. Other penicillin-susc eptible invasive clones were also shown to spread in and between countries.