Alternative molecular methods for improved detection of meningococcal carriage and measurement of bacterial density

Olivier Manigart*, Jacinta Okeakpu, Aderonke Odutola, Sheikh Jarju, Ebenezer Foster-Nyarko, Kanny Diallo, Anna Roca, Beate Kampmann, Umberto D'Alessandro, Samba Sow, Martin Antonio, Martin J. Maiden, Ray Borrow, James M. Stuart, Caroline L. Trotter, Brian M. Greenwood

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Conventional methods for detecting pharyngeal carriage of Neisseria meningitidis are complex. There is a need for simpler methods with improved performance. We have investigated two alternative approaches. Three pharyngeal swabs were collected from 999 pupils aged 10 to 18 years in The Gambia. Carriage of N. meningitidis was investigated by using three different methods: (i) plating on Thayer-Martin selective medium and testing by conventional microbiological methods followed by PCR testing; (ii) seeding in Todd-Hewitt broth (THB) and, after culture overnight, testing by PCR; and (iii) compression of the swab on filter paper and, after DNA concentration, testing by PCR. PCR after culture in THB was more than twice as sensitive as conventional methods in detecting N. meningitidis (13.2% versus 5.7%; P<0.0001). PCR after DNA extraction from filter paper had a sensitivity similar to that of conventional methods (4.9% versus 5.7%; P=0.33). Capsular genogroups detected by broth culture were genogroupsW(21 isolates), B (12 isolates), Y (8 isolates), E (3 isolates), and X (2 isolates), and 68 meningococci had the capsule-null intergenic region. The distributions of genogroups and of capsule-null organisms were similar with each of the three methods. The carriage density in samples extracted from filter paper ranged from 1 to 25,000 DNA copies. PCR of broth cultures grown overnight doubled the yield of N. meningitidis carriage isolates compared with conventional methods. This approach could improve the efficiency of carriage studies. Collection on filter paper followed by quantitative PCR could be useful for density measurement and for carriage studies in areas with limited resources.

Original languageEnglish
Pages (from-to)2743-2748
Number of pages6
JournalJournal of Clinical Microbiology
Volume54
Issue number11
DOIs
Publication statusPublished - Nov 2016

Bibliographical note

Funding Information:
This work, including the efforts of Brian M. Greenwood, was funded by Wellcome Trust. This work, including the efforts of Brian M. Greenwood, was funded by Bill and Melinda Gates Foundation (Bill & Melinda Gates Foundation) (51251). This work, including the efforts of Olivier Manigart, was funded by Meningitis Research Foundation (MRF)

Publisher Copyright:
Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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