Alternative molecular methods for improved detection of meningococcal carriage and measurement of bacterial density
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Author(s)
Type
Journal Article
Abstract
BACKGROUND: Conventional methods for detecting pharyngeal carriage of Neisseria meningitidis (Nm) are complex. There is a need for simpler methods with improved performance. We have investigated two alternative approaches. METHODS: Three pharyngeal swabs were collected from 999 pupils aged 10 to 18 years in The Gambia. Carriage of Nm was investigated 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 overnight culture, testing by PCR, (iii) compression of the swab on filter paper and, after DNA concentration, testing by PCR. RESULTS: PCR after culture in THB was more than twice as sensitive as conventional methods in detecting Nm (13.2% versus 5.7%; p<0.0001). PCR after DNA extraction from filter paper had a similar sensitivity to that of conventional methods (4.9% vs 5.7%, p=0.33). Capsular genogroups detected by broth culture were W (21), B (12), Y (8), E (3), and X (2), and 68 meningococci had the capsule null intergenic region. The distribution of genogroups and of capsule null organisms was similar with each of the three methods. Carriage density in samples extracted from filter paper ranged from 1 to 25,000 DNA copies. CONCLUSIONS: PCR of overnight broth culture doubled the yield of Nm 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.
Date Issued
2016-08-31
Date Acceptance
2016-08-31
Citation
Journal of Clinical Microbiology, 2016, 54 (11), pp.2743-2748
ISSN
1098-660X
Publisher
American Society for Microbiology
Start Page
2743
End Page
2748
Journal / Book Title
Journal of Clinical Microbiology
Volume
54
Issue
11
Copyright Statement
© 2016 Manigart et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
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Subjects
Science & Technology
Life Sciences & Biomedicine
Microbiology
06 Biological Sciences
07 Agricultural And Veterinary Sciences
11 Medical And Health Sciences
Publication Status
Published