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

    Research output: Contribution to journalA1: Web of Science-article

    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 genogroups W(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
    JournalJournal of Clinical Microbiology
    Volume54
    Issue number11
    Pages (from-to)2743-2748
    Number of pages6
    ISSN0095-1137
    DOIs
    Publication statusPublished - 2016

    Keywords

    • DRIED BLOOD SPOTS
    • REAL-TIME PCR
    • ADOLESCENTS
    • TRANSPORT

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