[Impact of Streptococcus pneumoniae on pneumonia in Latin American children. SIREVA-Vigía Group]

Abstract

Community-acquired pneumonia is one of the leading causes of infant morbidity and mortality. Studies conducted in developing countries indicate that the most serious symptoms of pneumonia are associated with bacterial causes, mainly Streptococcus pneumoniae, followed by Haemophilus influenzae type b. Managing those infections in children under two years of age is hindered by the lack of appropriate vaccines and by the decreased susceptibility of S. pneumoniae to penicillin and other antibiotics. In 1993, at the initiative of the Regional System for Vaccines of the Pan American Health Organization, and with funding from the Canadian International Development Agency, a study was designed to identify the S. pneumoniae capsular types that cause invasive disease in Latin American children under 5 years of age. The objective of the study was to determine the ideal composition of a conjugate vaccine that could be used in Latin America, and the penicillin susceptibility of the S. pneumoniae isolates. The initiative was undertaken in Argentina, Brazil, Chile, Colombia, Mexico, and Uruguay. This report analyzes the information that the participating countries generated on pneumococcal pneumonia. A total of 3,393 children were found with systemic S. pneumoniae infections, of which 1,578 corresponded to pneumonias. The analysis focused on 1,409 cases of pneumonia in Argentina, Brazil, Colombia, Mexico, and Uruguay. Of the children, 63.8% of them were under two years of age. Twelve prevalent capsular types were identified, of which serotypes 14, 5, and 1 were the three most common in the majority of the countries. At the beginning of the study the highest level of penicillin resistance was found in Mexico (47.0%), and the lowest in Colombia (12.1%). Over the 1993-1998 period, resistance to penicillin increased in the five countries. Penicillin resistance was associated with a small number of capsular serotypes, mainly 14 and 23F. The first of those serotypes was resistant to penicillin and to trimethoprim-sulfamethoxazole, and the second was multiresistant. The frequency of resistance to trimethoprim-sulfamethoxazole was high in all of the countries; Argentina had the highest level, 58.0%. A decrease in susceptibility to chloramphenicol was uncommon, except in Colombia, where there was a resistance level of 23.4%. Resistance to erythromycin was low in all the countries, and all the isolates were susceptible to vancomycin.