[Invasive disease caused by Streptococcus pneumoniae: a 7-year study]

The purpose of this study was to study the epidemiology of invasive childhood pneumococcal infection in our hospital.

The records of all children attending our hospital from whom Streptococcus pneumoniae was isolated from the blood or CSF were reviewed. Serotyping and MIC were performed at C.N.M.V.S. (Majadahonda).

Seventy-one pneumococci were isolated in 70 patients. The annual incidence increased from 0.14% to 0.40%. The clinical entities were: bacteremia without focus (45%), pneumonia (29.6%), meningitis (12.7%), cellulitis (5.6%), mastoiditis (5.6%) and endocarditis (1.4%). The age of 72% of the patients was less than 3 years. In 26.8% of the cases, the patient had an underlying disease and/or was previously hospitalized. The antibiotic susceptibility pattern was: penicillin (MIC < or = 0.06 microgram/ml) 45.7%, cefotaxime (MIC < or = 0.5 microgram/ml) 82.8% and erythromycin (MIC < or = 0.5 microgram/ml) 70%. Penicillin resistance of the isolated pneumococci was more often present in the group with risk factors than in those without such risk factors (p < 0.05). There were 13 different serotypes, the most prevalent were 6 (23%), 19 (17%), 14 (14%) and 23 (12%) and the most frequently penicillin-resistant (Resistant N(o)/Total N(o) were: 6 (15/15), 9 (4/4), 14 (8/9) and 23 (6/8).

Streptococcus pneumoniae is a common cause of invasive infections in children in our hospital. There was a high prevalence of serotype 6 (penicillin-resistant) as compared to in adults where serotype 3 (penicillin-susceptible) is the most prevalent. A higher rate of antibiotic resistant strains associated with risk factors (underlying disease or nosocomial acquisition), probably related to prior antibiotic use, was observed.