External Quality Assurance for Laboratory Identification and Capsular Typing of Streptococcus pneumoniae

Abstract

An external quality assessment (EQA) scheme for pneumococcal serotype identification has been performed over a period of 11 years, by a network of European pneumococcal reference laboratories. We report the results from the EQA, and present an assessment of the acceptability and utility of the EQA scheme. Reports from 22 EQA panels distributed in 2005–2016 were analysed. Each EQA panel consisted of seven isolates. A questionnaire including seven questions related to the acceptability and utility of the EQA scheme was distributed to all participating laboratories. Altogether, 154 pneumococcal isolates were tested. Of the 92 serologically distinct serotypes currently defined, 49 serotypes were included in the rounds. Discrepant results were observed in eight EQA rounds, involving 11 isolates (7.1%, 95% CI: 4% to 12%). All participating laboratories reported that the EQA scheme was useful for quality assurance purposes. Our results show that comparable serotyping data can be obtained in different laboratories. The EQA participation helps to keep the typing procedures at a high standard and provides data for accreditation purposes. The EQA is helpful when new technologies are introduced, and reveal limitations of both genotypic and phenotypic methods. Continuation of the presented EQA scheme is planned.

Molecular characterization and epidemiology of Streptococcus pneumoniae serotype 24F in Denmark

“…The pneumococci isolates were phenotypically identified by optochin susceptibility and bile solubility tests 1,11 . All isolates were serotyped either by the Quellung reaction alone or by the Pneumotest Latex kit (SSI-Diagnostica, Copenhagen, Denmark) combined with the Quellung reaction using type-specific pneumococcal rabbit-antisera as previously described (SSIDiagnostica, Copenhagen, Denmark) 11 .…”

Molecular characterization and epidemiology of Streptococcus pneumoniae serotype 8 in Denmark

“…The serotype 8 IPD isolates were phenotypically species-confirmed based on optochin susceptibility and identification of the serotype. Serotyping was performed either by the Quellung reaction alone or by the ImmuLex™ Pneumotest Kit ( SSIDiagnostica.com , Hillerød, Denmark) combined with the Quellung reaction using type-specific pneumococcal rabbit-antisera ( SSIDiagnostica.com , Hillerød, Denmark) [ 12 , 14 ].…”

Discovery and description of a new serogroup 7 Streptococcus pneumoniae serotype, 7D, and structural analysis of 7C and 7D

“…Briefly, cultures were grown in 5 ml of MAST Todd Hewitt Broth (PHE media services) for four hours, at 35°C with 5% CO 2 , centrifuged at 453 xg for 30 min, and the supernatant removed. Cell pellets were re-suspended in a small residual volume of broth and subjected to slide agglutination tests with latex absorbed pool antisera (ImmuLex™ Pneumotest kit) or standard group and factor sera (SSI Diagnostica A/S, Hilleroed, Denmark) [24].…”