International external quality assurance for laboratory identification and typing of Streptococcus agalactiae (group B streptococci)

Baharak Afshar*, Karen Broughton, Roberta Creti, Antoaneta Decheva, Markus Hufnagel, Paula Kriz, Lotte Lambertsen, Marguerite Lovgren, Pierrette Melin, Graziella Orefici, Claire Poyart, Andreas Radtke, Javier Rodriguez-Granger, Uffe B.Skov Sørensen, John Telford, Lea Valinsky, Levantia Zachariadou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


We report the results from the first international multicenter 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 program. A questionnaire-based surveillance was undertaken among eight laboratories participating in DEVANI and six laboratories not participating in DEVANI from 13 countries in order to assess their current microbiological procedures for GBS screening, diagnosis, and typing. GBS strains from three EQA distributions were characterized 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. The 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 2 of 14 centers, which achieved a typeability value of 93%; this assay detected only 9 of 10 GBS capsular polysaccharide genes. From the second and third EQA studies, standardized 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 that detected all 10 GBS capsular types (Ia to IX). These standardized protocols are being used by many European laboratories, and as the use of these methods increases, it is imperative to continuously improve and assess laboratory performance and offer training to any laboratories that have technical difficulties.

Original languageEnglish
Pages (from-to)1475-1482
Number of pages8
JournalJournal of Clinical Microbiology
Issue number4
Publication statusPublished - Apr 2011


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