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Population structure of invasive Streptococcus pneumoniae in The Netherlands in the pre-vaccination era assessed by MLVA and capsular sequence typing.

Elberse KE, van de Pol I, Witteveen S, van der Heide HG, Schot CS, van Dijk A, van der Ende A, Schouls LM - PLoS ONE (2011)

Bottom Line: MLVA and CST were used to create a snapshot of the Dutch pneumococcal population causing invasive disease before the introduction of the 7-valent pneumococcal conjugate vaccine in The Netherlands in 2006.The CST was successful in discriminating most serotypes present in our collection.MLVA demonstrated that isolates belonging to some serotypes had a relatively high genetic diversity whilst other serotypes had a very homogeneous genetic background.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Infectious Diseases and Perinatal Screening, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands. Karin.Elberse@RIVM.nl

ABSTRACT
The introduction of nationwide pneumococcal vaccination may lead to serotype replacement and the emergence of new variants that have expanded their genetic repertoire through recombination. To monitor alterations in the pneumococcal population structure, we have developed and utilized Capsular Sequence Typing (CST) in addition to Multiple-Locus Variable number tandem repeat Analysis (MLVA).To assess the serotype of each isolate CST was used. Based on the determination of the partial sequence of the capsular wzh gene, this method assigns a capsular type of an isolate within a single PCR reaction using multiple primersets. The genetic background of pneumococcal isolates was assessed by MLVA. MLVA and CST were used to create a snapshot of the Dutch pneumococcal population causing invasive disease before the introduction of the 7-valent pneumococcal conjugate vaccine in The Netherlands in 2006. A total of 1154 clinical isolates collected and serotyped by the Netherlands Reference Laboratory for Bacterial Meningitis were included in the snapshot. The CST was successful in discriminating most serotypes present in our collection. MLVA demonstrated that isolates belonging to some serotypes had a relatively high genetic diversity whilst other serotypes had a very homogeneous genetic background. MLVA and CST appear to be valuable tools to determine the population structure of pneumococcal isolates and are useful in monitoring the effects of pneumococcal vaccination.

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Related in: MedlinePlus

Minimum spanning tree of the results obtained by MLVA of 1154 pneumococcal isolates.The minimum spanning tree is based on the entire MLVA database (last accessed on October 20, 2010) with only the results from the current collection plotted within. The circles indicate the types and the size of the circles indicate the number of isolates. Lines linking two types denote a single locus difference between those types. The colors of the circles indicate the serotype of the isolates and complexes were indicated by grey halos.
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pone-0020390-g002: Minimum spanning tree of the results obtained by MLVA of 1154 pneumococcal isolates.The minimum spanning tree is based on the entire MLVA database (last accessed on October 20, 2010) with only the results from the current collection plotted within. The circles indicate the types and the size of the circles indicate the number of isolates. Lines linking two types denote a single locus difference between those types. The colors of the circles indicate the serotype of the isolates and complexes were indicated by grey halos.

Mentions: In Figure 2, a minimum spanning tree displays the 444 MLVA types that were obtained by MLVA of the 1154 isolates. In general, there was a strong correlation between MLVA type and serotype. However, several serotypes were distributed over various MLVA complexes. An example is serotype 14 which is divided into 2 distinct MLVA complexes. For some serotypes, e.g. 19F, the MLVA profiles were highly diverse. To illustrate the serotype dependent variation in MLVA the minimum spanning tree based on the MLVA of serotypes 7F, 14, 19A and 19F are depicted in Figure 3. Of the 139 serotype 7F isolates 108 (78%) had an identical MLVA profile and 136 (97%) isolates belonged to a single MLVA complex. Serotype 14 isolates clustered in 2 large complexes. Remarkably, the CST also yielded 2 CTs (CT14-01 and CT14-02) and the separation into the CTs was in full agreement with separation into 2 complexes obtained by MLVA. The distribution of the serotype 7F and 14 isolates over the MVLA complexes was similar irrespective of the age of the patients from which the strains were isolated. In contrast, more diversity was observed within the serotype 19A and 19F isolates. The MLVA of serotype 19F yielded many different MLVA types that were distributed over various complexes. Among the 36 serotype 19F isolates there were 35 different MLVA types. As a result virtually each isolate had its own MLVA type leading to a very high degree of diversity with a DI of 99.5%. However, the majority of the isolates belonging to CT19F-01 were closely related based on MLVA. Also, BOX_4 was absent in 12 of the 36 serotype 19F isolates. The collection contained 75 serotype 8 and 15 serotype 11A isolates. Although 21 different MLVA types were found, serotypes 8 and 11A were indistinguishable by MLVA. Inspection of the MLST profiles of serotypes 8 and 11A in the S. pneumoniae database (www.mlst.net) showed that the profiles of serotypes 8 and 11A are related but distinct. To verify this for our isolates, we performed MLST on 4 serotype 8 isolates and 4 serotype 11A isolates and this resulted also in related but distinct profiles.


Population structure of invasive Streptococcus pneumoniae in The Netherlands in the pre-vaccination era assessed by MLVA and capsular sequence typing.

Elberse KE, van de Pol I, Witteveen S, van der Heide HG, Schot CS, van Dijk A, van der Ende A, Schouls LM - PLoS ONE (2011)

Minimum spanning tree of the results obtained by MLVA of 1154 pneumococcal isolates.The minimum spanning tree is based on the entire MLVA database (last accessed on October 20, 2010) with only the results from the current collection plotted within. The circles indicate the types and the size of the circles indicate the number of isolates. Lines linking two types denote a single locus difference between those types. The colors of the circles indicate the serotype of the isolates and complexes were indicated by grey halos.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102707&req=5

pone-0020390-g002: Minimum spanning tree of the results obtained by MLVA of 1154 pneumococcal isolates.The minimum spanning tree is based on the entire MLVA database (last accessed on October 20, 2010) with only the results from the current collection plotted within. The circles indicate the types and the size of the circles indicate the number of isolates. Lines linking two types denote a single locus difference between those types. The colors of the circles indicate the serotype of the isolates and complexes were indicated by grey halos.
Mentions: In Figure 2, a minimum spanning tree displays the 444 MLVA types that were obtained by MLVA of the 1154 isolates. In general, there was a strong correlation between MLVA type and serotype. However, several serotypes were distributed over various MLVA complexes. An example is serotype 14 which is divided into 2 distinct MLVA complexes. For some serotypes, e.g. 19F, the MLVA profiles were highly diverse. To illustrate the serotype dependent variation in MLVA the minimum spanning tree based on the MLVA of serotypes 7F, 14, 19A and 19F are depicted in Figure 3. Of the 139 serotype 7F isolates 108 (78%) had an identical MLVA profile and 136 (97%) isolates belonged to a single MLVA complex. Serotype 14 isolates clustered in 2 large complexes. Remarkably, the CST also yielded 2 CTs (CT14-01 and CT14-02) and the separation into the CTs was in full agreement with separation into 2 complexes obtained by MLVA. The distribution of the serotype 7F and 14 isolates over the MVLA complexes was similar irrespective of the age of the patients from which the strains were isolated. In contrast, more diversity was observed within the serotype 19A and 19F isolates. The MLVA of serotype 19F yielded many different MLVA types that were distributed over various complexes. Among the 36 serotype 19F isolates there were 35 different MLVA types. As a result virtually each isolate had its own MLVA type leading to a very high degree of diversity with a DI of 99.5%. However, the majority of the isolates belonging to CT19F-01 were closely related based on MLVA. Also, BOX_4 was absent in 12 of the 36 serotype 19F isolates. The collection contained 75 serotype 8 and 15 serotype 11A isolates. Although 21 different MLVA types were found, serotypes 8 and 11A were indistinguishable by MLVA. Inspection of the MLST profiles of serotypes 8 and 11A in the S. pneumoniae database (www.mlst.net) showed that the profiles of serotypes 8 and 11A are related but distinct. To verify this for our isolates, we performed MLST on 4 serotype 8 isolates and 4 serotype 11A isolates and this resulted also in related but distinct profiles.

Bottom Line: MLVA and CST were used to create a snapshot of the Dutch pneumococcal population causing invasive disease before the introduction of the 7-valent pneumococcal conjugate vaccine in The Netherlands in 2006.The CST was successful in discriminating most serotypes present in our collection.MLVA demonstrated that isolates belonging to some serotypes had a relatively high genetic diversity whilst other serotypes had a very homogeneous genetic background.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Infectious Diseases and Perinatal Screening, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands. Karin.Elberse@RIVM.nl

ABSTRACT
The introduction of nationwide pneumococcal vaccination may lead to serotype replacement and the emergence of new variants that have expanded their genetic repertoire through recombination. To monitor alterations in the pneumococcal population structure, we have developed and utilized Capsular Sequence Typing (CST) in addition to Multiple-Locus Variable number tandem repeat Analysis (MLVA).To assess the serotype of each isolate CST was used. Based on the determination of the partial sequence of the capsular wzh gene, this method assigns a capsular type of an isolate within a single PCR reaction using multiple primersets. The genetic background of pneumococcal isolates was assessed by MLVA. MLVA and CST were used to create a snapshot of the Dutch pneumococcal population causing invasive disease before the introduction of the 7-valent pneumococcal conjugate vaccine in The Netherlands in 2006. A total of 1154 clinical isolates collected and serotyped by the Netherlands Reference Laboratory for Bacterial Meningitis were included in the snapshot. The CST was successful in discriminating most serotypes present in our collection. MLVA demonstrated that isolates belonging to some serotypes had a relatively high genetic diversity whilst other serotypes had a very homogeneous genetic background. MLVA and CST appear to be valuable tools to determine the population structure of pneumococcal isolates and are useful in monitoring the effects of pneumococcal vaccination.

Show MeSH
Related in: MedlinePlus