RESUMO
To investigate the epidemiological patterns and genetic characteristics of disease caused by group A Streptococcus (GAS), all available isolates from invasive cases in Norway during 2006 to 2007 (262 isolates) were subjected to antimicrobial susceptibility testing, T serotyping, emm typing, and multilocus sequence typing and screened for known streptococcal pyrogenic exotoxin (Spe) genes, smeZ, and ssa. The average incidence rate was 3.1 cases per 100,000 individuals. The most prevalent sequence types (STs) were STs 52, 28, and 334. In association with emm types 28, 77, and 87, the serotype T-28 comprised 24.8% of the strains. emm types 28, 1, and 82 were dominating. In 2007, a sharp increase in the number of emm-6 strains was noted. All strains were sensitive to penicillin and quinupristin-dalfopristin, while 3.4% and 6.1% of the strains were resistant to macrolides and tetracycline, respectively. Furthermore, the emm-6 strains had intermediate susceptibility to ofloxacin. Isolates displayed a wide variety of gene profiles, as shown by the presence or absence of the Spe genes, smeZ, and ssa, but 48% of the isolates fell into one of three profiles. In most cases, an emm type was restricted to one gene profile. Although the incidence decreased during this study, invasive GAS disease still has a high endemic rate, with involvement of both established and emerging emm types displaying variability in virulence gene profiles as well as differences in gender and age group preferences.
Assuntos
Antígenos de Bactérias/análise , Técnicas de Tipagem Bacteriana , Impressões Digitais de DNA , Infecções Estreptocócicas/epidemiologia , Streptococcus pyogenes/classificação , Streptococcus pyogenes/isolamento & purificação , Superantígenos/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Antígenos de Bactérias/genética , Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Transporte/genética , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Noruega/epidemiologia , Análise de Sequência de DNA , Sorotipagem , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/genética , Streptococcus pyogenes/imunologia , Fatores de Virulência/genética , Adulto JovemRESUMO
To investigate the potential herd immunity effect of MenAfriVac, a new conjugate vaccine against serogroup A Neisseria meningitidis, a multiple cross-sectional carriage study was conducted in three districts in Burkina Faso in 2009, yielding a total of 20 326 oropharyngeal samples. A major challenge was the harmonisation of operational procedures and ensuring the reliability of results. Here we describe the laboratory quality control (QC) system that was implemented. Laboratory analysis performed by three local laboratories included colony morphology assessment, oxidase test, Gram stain, ß-galactosidase activity using o-nitrophenyl-ß-galactopyranoside (ONPG), γ-glutamyl transferase (GGT) activity and slide agglutination serogrouping. Internal QC was performed on media, reagents, laboratory equipment and field conditions. Confirmation of results and molecular characterisation was performed at the Norwegian Institute of Public Health (Oslo, Norway). External QC was performed on 3% of specimens where no colonies morphologically resembling N. meningitidis had been identified and on 10% of non-ONPG-/GGT+ isolates. The QC system was a critical element: it identified logistical and operational problems in real time and ensured accuracy of the final data. The overall N. meningitidis carriage prevalence (3.98%) was probably slightly underestimated and the calculated true prevalence was 4.48%. The components of the presented QC system can easily be implemented in any other laboratory study.