Oropharyngeal Carriage of Meningococcus in Portugal by Group and Clonal Complex 6 Years After Adolescent Vaccine Campaign

Morales-Aza, Begonia; Christensen, Hannah; Giles, Jessica; Ferreira, Muriel; Sikora, Paulina; Madanelo, Ines; Lucidarme, Jay; Januário, Luís; Finn, Adam

doi:10.1097/inf.0000000000000860

Cited by 9 publications

(19 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Putting swabs into broth, storing them frozen and processing them later in batches has been the norm for many years in pneumococcal carriage studies and is now becoming established in meningococcal swabbing studies as well. 10,20,22 Genogrouping is more efficient than conventional serogrouping techniques using antisera in studies of carriage bacteria, which often express only low levels of capsular antigens. 9,10 The use of "lawn cultures" as a means to amplify DNA for molecular detection has been described in the literature on pneumococcal carriage studies.…”

Section: A C C E P T E Dmentioning

confidence: 99%

“…10,20,22 Genogrouping is more efficient than conventional serogrouping techniques using antisera in studies of carriage bacteria, which often express only low levels of capsular antigens. 9,10 The use of "lawn cultures" as a means to amplify DNA for molecular detection has been described in the literature on pneumococcal carriage studies. 24 In our hands it seems to compensate almost entirely for the deficits in sensitivity of genogrouping qPCRs when compared to standard culture and testing of isolates.…”

Section: A C C E P T E Dmentioning

confidence: 99%

“…qPCR assays may also be used to identify capsular groups more reliably than agglutination antisera in pharyngeal Nm in which levels of capsular expression are often downregulated. 9,10 We applied qPCR to the detection, quantification and characterization of Nm from oropharyngeal swabs, to compare the performance of this approach with conventional techniques and to work out how best to apply it to the study of the potential impact of new generation meningococcal vaccines on carriage and transmission. We describe for the first time the distribution of density of Nm oropharyngeal colonization in a sample of healthy young adults.…”

Section: A C C E P T E Dmentioning

confidence: 99%

“…The same approach was used for experiments examining different broths and for samples from study 2. 10 Briefly, broth was inoculated onto G.C. agar plates (E&O Laboratories, Cumbernauld, UK) and after overnight growth at 37°C in 5% CO 2 and thereafter, if negative, at 24h intervals until 72h, plates were examined and oxidase-positive, Gram-negative diplococcal isolates were tested using the API NH strip test (bioMérieux, Lyon, France) for the identification Copyright © 2016 Wolters Kluwer Health, Inc.…”

Section: Bacterialmentioning

confidence: 99%

See 3 more Smart Citations

Density Distribution of Pharyngeal Carriage of Meningococcus in Healthy Young Adults

Finn

Morales-Aza

Sikora

et al. 2016

Pediatric Infectious Disease Journal

Self Cite

View full text Add to dashboard Cite

Background: Improved understanding of Neisseria meningitidis (Nm) carriage biology and better methods for detection and quantification would facilitate studies of potential impact of new vaccines on colonization and transmission in adolescents. Methods:We performed plate cultures on 107 oropharyngeal swabs stored frozen in STGG broth and previously positive for Nm. We compared quantitative (q)PCR detection of Nm in 601 STGG-swabs with culture. Using qPCR (n=87), a log-phase broth culture standard curve and semi-quantitative plate cultures (n=68), we measured density of carriage. We compared qPCR genogrouping of DNA extracts from STGG-swabs and from plate culture lawns (n=110) with purified isolates (n=80).Results: Swab storage resulted in only 10% loss of culture sensitivity. Direct sodC qPCR Nm detection yielded more positives (87/601, 14.5%) than culture (80/601, 13.3%). Most samples (57/110) positive by culture were also positive by qPCR and vice versa, but discrepancies (single positives) were frequent among low density samples. sodC qPCR was positive in 79/80 isolates but in only 65 by ctrA qPCR. Density both by culture and qPCR varied across 4 orders of magnitude with the majority being low (<50 bacteria-gene copies/mL) and a minority being high (>1000). Genogrouping qPCRs yielded more positive results when performed on DNA extracts from lawn cultures. Conclusions:We provide the first description of the distribution of Nm carriage density. This could be important for understanding transmission dynamics and population-level effectiveness of adolescent vaccine programs. Storage of swabs frozen in STGG for batched laboratory analysis facilitates carriage studies and direct sodC qPCR for Nm combined with qPCR genogrouping of lawn culture extracts provides accurate, detailed description of colonization.

show abstract

Section: A C C E P T E Dmentioning

confidence: 99%

Section: A C C E P T E Dmentioning

confidence: 99%

Section: A C C E P T E Dmentioning

confidence: 99%

Section: Bacterialmentioning

confidence: 99%

See 2 more Smart Citations

Density Distribution of Pharyngeal Carriage of Meningococcus in Healthy Young Adults

Finn

Morales-Aza

Sikora

et al. 2016

Pediatric Infectious Disease Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Most studies have focused on the optimization of methods for collecting pharyngeal swabs; these studies have shown that a peroral swab taken behind the uvula is most likely to yield a positive result and that taking two sequential swabs increases sensitivity (4–6). Until recently, little has been done to improve methods of transport (7, 8), and we are aware of only two studies aimed at improving the identification of meningococci by using molecular methods (9, 10). PCR testing on DNA extracted directly from a swab has been employed in some studies, but a recent investigation of UK adolescents showed that this method was less sensitive than conventional culture followed by PCR (11).…”

Section: Introductionmentioning

confidence: 99%

Alternative Molecular Methods for Improved Detection of Meningococcal Carriage and Measurement of Bacterial Density

et al. 2016

View full text Add to dashboard Cite

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.

show abstract

Neisseria meningitidis

Pollard¹,

Finn²,

Bijker³

et al. 2023

Principles and Practice of Pediatric Infectious Diseases

View full text Add to dashboard Cite

Oropharyngeal Carriage of Meningococcus in Portugal by Group and Clonal Complex 6 Years After Adolescent Vaccine Campaign

Cited by 9 publications

References 14 publications

Density Distribution of Pharyngeal Carriage of Meningococcus in Healthy Young Adults

Density Distribution of Pharyngeal Carriage of Meningococcus in Healthy Young Adults

Alternative Molecular Methods for Improved Detection of Meningococcal Carriage and Measurement of Bacterial Density

Neisseria meningitidis

Contact Info

Product

Resources

About