International External Quality Assurance for Laboratory Identification and Typing of Streptococcus agalactiae (group B streptococci)

We report the results from the first international multicentre external quality assessment (EQA) studies for molecular and serological typing of group B streptococcus (GBS) strains as part of DEVANI (DEsign of a Vaccine Against Neonatal Infections), a pan-European programme. A questionnaire-based surveillance was undertaken amongst eight DEVANI and six non-DEVANI participating laboratories from 13 countries in order to assess their current microbiological procedures for GBS screening, diagnosis and typing. GBS strains from three EQA distributions were characterised using molecular and serological methods based on GBS capsular polysaccharide typing. Participants were asked to test the first distribution using their current serotyping and genotyping methods. Strep-B-Latex agglutination method was the most widely used method with a typeability value of >90%. A multiplex PCR assay for GBS capsular gene typing was also used by two of 14 centres who achieved a typeability value of 93%; this assay only detected 9 of 10 GBS capsular polysaccharide genes. From the second and third EQA studies standardised protocols were prepared for serological and molecular typing of GBS strains based on the Strep-B-Latex agglutination method and a novel multiplex PCR assay which detected all ten GBS capsular types (Ia to IX). These standardised protocols are being used by many European laboratories and as the use of these methods increase, it is imperative to continuously improve and assess laboratory performance and offer training to any laboratories that have technical difficulties.