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Open Access Technical advance

Sequential multiplex PCR assay for determining capsular serotypes of colonizing S. pneumoniae

Sarah Jourdain12*, Pierre-Alexandre Drèze1, Jozef Vandeven3, Jan Verhaegen3, Laurence Van Melderen1 and Pierre R Smeesters1

Author Affiliations

1 Laboratoire de Génétique et Physiologie Bactérienne, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, Bruxelles, Belgium

2 Paediatric Department, Hôpital Universitaire des Enfants Reine Fabiola HUDERF, Université Libre de Bruxelles, Bruxelles, Belgium

3 Pneumococcus Reference Laboratory, Katholieke Universiteit Leuven, Leuven, Belgium

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BMC Infectious Diseases 2011, 11:100  doi:10.1186/1471-2334-11-100

Published: 20 April 2011

Abstract

Background

Asymptomatic nasopharyngeal carriage represents an important biological marker for monitoring pneumococcal serotype distribution and evaluating vaccine effects. Serotype determination by conventional method (Quellung reaction) is technically and financially challenging. On the contrary, PCR-based serotyping represents a simple, economic and promising alternative method.

Method

We designed a novel multiplex PCR assay for specific detection of the 30 classical colonizing S. pneumoniae serogroups/types. This multiplex assay is composed of 7 consecutive PCR reactions and was validated on a large and recent collection of Streptococcus pneumoniae isolated during a prospective study conducted in Belgium at the time of PCV7 adoption.

Results

The multiplex PCR assay allowed the typing of more than 94% of the isolates of a collection of pneumococci isolated from Belgian preschool attendees (n = 332). Seventy-five percent of the isolates were typed after 3 subsequent PCR reactions. Results were in agreement with the Quellung identification.

Conclusion

Our novel multiplex assay is an accurate and reliable method which can be used in place of the conventional method for S. pneumoniae carriage studies.