References of "Members of the DEVANI Study Group"
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See detailCapsular Gene Typing of Streptococcus agalactiae Compared to Serotyping by Latex Agglutination
Yao, Kaihu; Poulsen, Knud; Maione, Domenico et al

in Journal of Clinical Microbiology (2012), 51(2), 503-507

We evaluated three different PCR-based capsular gene typing methods applied to 312 human and bovine Streptococcus agalac- tiae (group B Streptococcus [GBS]) isolates and compared the results to serotyping ... [more ▼]

We evaluated three different PCR-based capsular gene typing methods applied to 312 human and bovine Streptococcus agalac- tiae (group B Streptococcus [GBS]) isolates and compared the results to serotyping results obtained by latex agglutination. Among 281 human isolates 27% could not be typed by latex agglutination. All 312 isolates except 5 could be typed by the three PCR methods combined. Two of these methods were multiplex assays. Among the isolates that were typeable by both latex ag- glutination and capsular gene typing, 94% showed agreement between the two methods. However, each of the PCR methods showed limitations. One of the methods did not include all 10 recognized serotypes, one misidentified eight isolates of serotypes Ib and IV as serotype Ia, and one did not distinguish between serotypes VII and IX. For five isolates that showed aberrant pat- terns in the capsular gene typing, long-range PCR targeting the cps operon disclosed large insertions or deletions affecting the cps gene cluster. A sensitive flow cytometric assay based on serotype-specific antibodies applied to 76 selected isolates that were nontypeable by latex agglutination revealed that approximately one-half of these did express capsular polysaccharide. A proce- dure for convenient and reliable capsular gene typing to be included in epidemiological and surveillance studies of S. agalactiae is proposed. [less ▲]

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See detailInternational External Quality Assurance for Laboratory Identification and Typing of Streptococcus agalactiae (group B streptococci)
Afshar, Baharak; Broughton, Karen; Creti, Roberta et al

in Journal of Clinical Microbiology (2011)

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 ... [more ▼]

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. [less ▲]

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