Microbiologic workload and clinical significance of Streptococcus pneumoniae isolated during one week in Spain

Most studies reporting Streptococcus pneumoniae (Sp) infections select either specific populations/diseases, or refer to a single or a low number of institutions. A nationwide point-prevalence study including 147 hospitals from which we collected all the isolates of Sp reported in a single week (February 16-22, 2004). Workload and clinical data were studied, and susceptibility testing and serotyping of all isolates were performed. The participating institutions had an estimated catchment population of 37,534,750 inhabitants. During the study week, microbiology laboratories received 224,956 samples of which 34,647 were positive and 360 had S. pneumoniae. Overall, 69% of the isolates were from adults (> or = 15 years). Most of the isolates (89%) were considered clinically significant. Infection was community-acquired in 88% of infections and monomicrobial in 79%. We calculated that S. pneumoniae was isolated 38 times per 100,000 inhabitants/year and it was present in 1% of all samples with one or more bacterial isolates. We also calculated that pneumococcal disease (invasive and noninvasive) was present in 34 patients per 100,000 inhabitants/year. Penicillin resistance (I+R) was 42%, and erythromycin resistance was 35%. The most frequent serotypes were 3, 19F, and 19A. Considering only invasive isolates, the estimated coverage of the 7-valent vaccine was 61% in children and 41% in adults, and the estimated coverage of the 23-valent vaccine in adults was 79%. A nationwide point-prevalence study is an efficient tool for surveying pneumococcal infection in a large population.