Search

Serological surveys for diphtheria were conducted in six European countries including Czech Republic, Hungary, Ireland, Latvia, Luxembourg, Slovakia and one country outside Europe, Israel. For each country, a nationally representative population sample was collected across the entire age range and was tested for antibodies to diphtheria toxin. Although each national laboratory used its preferred assay, the results were all standardized to those of the in vitro neutralization test and expressed in international units (IU) which allowed comparative analyses to be performed. The results showed that increasing age is related to a gradual increase in seronegative subjects (<0·01 IU/ml of diphtheria antitoxin antibodies). This may reflect waning immunity following childhood vaccination without repeated booster vaccinations in adults. Differences in seronegativity were also found according to gender. In subjects aged 1-19 years, geometric mean titres of antitoxin are clearly related to the different vaccination schedules used in the participating countries. Although clinical disease remains rare, the susceptibility to diphtheria observed in these serosurveys highlights the importance of strengthened surveillance.

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.