Evolution of an international external quality assurance model to support laboratory investigation of Streptococcus pneumoniae, developed for the SIREVA project in Latin America, from 1993 to 2005.

In 1993 the Pan American Health Organization initiated a laboratory-based surveillance system, called the SIREVA project, to learn about Streptococcus pneumoniae invasive disease in Latin American children. In 1994, National Laboratories in six countries were trained to perform serotyping and antibiotic susceptibility testing using broth microdilution to determine the MIC for specified antibiotics. An international External Quality Assurance (EQA) program was developed to monitor and support ongoing laboratory performance. The EQA program was coordinated by the National Centre for Streptococcus (NCS), Edmonton, Canada, and included external proficiency testing (EPT) and a validation process requiring regular submission of a sample of isolates from each laboratory to the NCS for verification of the serotype and MIC. In 1999, the EQA program was decentralized to use three of the original laboratories as regional quality control centers to address operational concerns and to accommodate the growth of the laboratory network to more than 20 countries including the Caribbean region. The overall EPT serotyping accuracies for phase I (1993 to 1998) and phase II (1999 to 2005) were 88.0 and 93.8%, respectively; the MIC correlations within +/-1 log(2) dilution of the expected result were 83.0 and 91.0% and the interpretive category agreements were 89.1 and 95.3%. Overall, the validation process serotyping accuracies for phases I and II were 81.9 and 88.1%, respectively, 80.4 and 90.5% for MIC agreement, and 85.8 and 94.3% for category agreement. These results indicate a high level of testing accuracy in participating National Laboratories and a sustained increase in EQA participation in Latin America and the Caribbean.

Characterization of haemophilus influenzae isolated from invasive disease in Brazil from 1990 to 1999.

The Haemophilus influenzae serotype b (Hib) conjugate vaccine was introduced in the National Immunization Program in Brazil in the second half of 1999. A retrospective analysis on serotypes, biotypes, and antimicrobial resistance of Hi invasive strains obtained through Hi survey was conducted to document the characteristics of this pathogenic agent during a decade prior the use of Hib vaccine. A total 3,204 strains from 1990 to 1999 were studied, being 88.2% isolated from cerebrospinal fluid, 10.7% from blood, and 1.1% from pleural fluid. The rate of 90.9% of strains was obtained from children up to 4 years old, and the age group >6 months old to 1 year was the higher risk to Hi infection. Type b was, by far, the most common type (97.8%), followed in frequency by type a (0.5%); only 1.5% was a nontypable strain. Biotypes I and II accounted for 97.8% of isolates. Resistance to ampicillin (AM) and chloramphenicol (CO) was detected at rates of 18.1% and 19.1%, respectively, whereas simultaneous resistance to AM and CO was identified in 13.9% of strains. Total concordance was found between AM resistance and beta-lactamase production. No strain showed resistance to ceftriaxone and rifampicin. In conclusion, the data generated through this laboratory-based surveillance should serve as a reference for assessing the impact of Hib vaccination and to detect changes on the pattern of Hi diseases in the country.

Dot-Enzyme-Linked immunosorbent assay (Dot-ELISA) for detection of pneumococcal polysaccharide antigens in pleural fluid effusion samples: comparison with bacterial culture, counterimmunoelectrophoresis and latex agglutination

Dot-ELISA para deteccao de antigenos polissacaridicos de pneumococos foi padronizado em vista da necessidade de se ter um diagnostico rapido e eficaz para pneumonia pneumococica aguda. Um total de 480 amostras de liquido pleural sendo 442 de criancas com diagnostico clinico e laboratorial de pneumonia bacteriana e 38 de pacientes com tuberculose, mais 20 amostras dos soros sanguineos de criancas sadias foram avaliados no Dot-ELISA. As amostras foram tratadas previamente a 90ºC por 10 min com EDTA 0,1 M de pH 7,5 e aplicadas sobre membrana de nitrocelulose. Para a deteccao de antigeno pneumococico foi empregado omniserum pneumococico diluido a 1:200. Os resultados de Dot-ELISA avaliados em comparacao com os resultados de cultura bacteriana, contra-imunoeletroforese e latex-aglutinacao apresentaram indices de 0,940 para a sensibilidade, 0,830 para especificidade e 0,760 para concordancia. Omniserum pneumococico mostrou ser um otimo soro polivalente para a deteccao de antigenos pneumococicos em Dot-ELISAe, essa tecnica provou se uma alternativa pratica e eficaz para o diagnostico de pneumonias pneumococicas.