Prevalence of serotypes and antimicrobial resistance of invasive strains of pneumococcus in children: analysis of 9 years

Abstract

To determine the prevalence of serotypes and antimicrobial susceptibility of strains of pneumococcus in children and to evaluate the implications for vaccine formulation. Strains of pneumococcus obtained from children admitted with invasive diseases were isolated at Hospital de Clínicas of Universidade Federal de Uberlândia, Uberlândia, Brazil, and sent to Instituto Adolfo Lutz, São Paulo, Brazil, for further identification, serotyping, and determination of antimicrobial susceptibility. From April 1999 to December 2008, 142 strains of pneumococcus, obtained from children under 5 years of age, were analyzed. Seventy-five (52.8%) patients were male, and the age ranged from 1 to 60 months (mean age = 19+/-15.4 months; median = 15 months). The most common diagnoses were pneumonia [92 cases (64.8%)] and meningitis [33 cases (23.2%)]. The strains were mostly isolated from blood [61 samples (43%)], pleural fluid [52 samples (36.6%)], and cerebrospinal fluid [28 samples (19.7%)]. The most common serotypes were 14, 5, 6B, 1, 6A, 18C, 19A, 3, 9V, 19F, 23F, 9N, and 10A. There were 14 [9.9%] penicillin-resistant strains, which was detected only in the following serotypes: 14, 6B, 19F, 19A, and 23F, being predominant from 2004 to 2008 (p = 0.000). There was reduced susceptibility to co-trimoxazole (79.5%), erythromycin and clindamycin (11.3% each), and ceftriaxone (5.6%). Penicillin resistance was detected in 9.9% of the strains, being predominant from 2004 to 2008. Twenty different pneumococcal serotypes were identified, and 71.9% of the serotypes were represented in the 7-valent conjugate vaccine (PN CRM7) currently available.