Evolution of Streptococcus pneumoniae serotypes and penicillin susceptibility in Latin America, Sireva-Vigía Group, 1993 to 1999

Background. Since 1993 the Pan American Health Organization has coordinated a surveillance network with the National Reference Laboratories of Argentina, Brazil, Chile, Colombia, Mexico and Uruguay aimed at monitoring capsular types and antimicrobial susceptibility of Streptococcus pneumoniae causing invasive disease in children <6 years of age. Methods. The surveillance system included children 6 years of age and younger with invasive disease caused by S. pneumoniae. The identification, capsular typing and susceptibility to penicillin of the isolates were conducted using a common protocol, based on standard methodologies. Results. By June, 1999, 4105 invasive pneumococcal isolates had been collected mainly from pneumonia (44.1%) and meningitis (41.1%) cases. Thirteen capsular types accounting for 86.1% of the isolates (14, 6A/6B, 5, 1, 23F, 19F, 18C, 19A, 9V, 7F, 3, 9N and 4) remained the most common types during the surveillance period. Diminished susceptibility to penicillin was detected in 28.6% of the isolates, 17.3% with intermediate and 11.3% with high level resistance. Resistance varied among countries and increased during this period in Argentina, Colombia and Uruguay. Serotypes 14 and 23F accounted for 66.6% of the resistance. Conclusion. These surveillance data clearly demonstrate the potential impact of the introduction of a conjugate vaccine on pneumococcal disease and the need for more judicious use of antibiotics to slow or reverse the development of antimicrobial resistance.