Neisseria meningitidis with decreased susceptibility to penicillin G and molecular characterization of the penA gene in strains isolated at University Hospital Centers of Casablanca and Marrakech (Morocco).

Introduction: the laboratory diagnosis of meningococcal meningitis relies on conventional techniques. This study aims to evaluate the correlation between the reduced sensitivity to penicillin G of Neisseria meningitidis (N.m) strains and the expression of the altered PBP 2 gene. Methods: out of 190 strains of N.m isolated between 2010 and 2021 at the bacteriology laboratories of Ibn Rochd University Hospital Centre (IR-UHC) in Casablanca and the UHC Mohammed VI in Marrakech, 23 isolates were part of our study. We first determined their state of sensitivity to penicillin G by E-Test strips and searched for the expression of the penA gene by PCR followed by Sanger sequencing. Results: of all the confirmed cases of N.m, 93.15% (n=177) are of serogroup B, 75.2% (n = 143) are sensitive to penicillin G and 24.73% (n = 47) are of intermediate sensitivity. No resistance to penicillin G was observed. Reduced sensitivity to penicillin G in N.m is characterized by mutations namely F504 L, A510 V, I515 V, G541 N and I566 V located in the C-terminal region of the penA gene encoding the penicillin-binding protein 2 (PBP2) (mosaic gene). Conclusion: our study presents useful data for the phenotypic and genotypic monitoring of resistance to penicillin G in N.m and can contribute to the analysis of genetic exchanges between different Neisseria species.

Immune interface interference vaccines: An evolution-informed approach to anti-bacterial vaccine design.

Developing protein-based vaccines against bacteria has proved much more challenging than producing similar immunisations against viruses. Currently, anti-bacterial vaccines are designed using methods based on reverse vaccinology. These identify broadly conserved, immunogenic proteins using a combination of genomic and high-throughput laboratory data. While this approach has successfully generated multiple rationally designed formulations that show promising immunogenicity in animal models, few have been licensed. The difficulty of inducing protective immunity in humans with such vaccines mirrors the ability of many bacteria to recolonise individuals despite recognition by natural polyvalent antibody repertoires. As bacteria express too many antigens to evade all adaptive immune responses through mutation, they must instead inhibit the efficacy of such host defences through expressing surface structures that interface with the immune system. Therefore, 'immune interface interference' (I3) vaccines that target these features should synergistically directly target bacteria and prevent them from inhibiting responses to other surface antigens. This approach may help us understand the efficacy of the two recently introduced immunisations against serotype B meningococci, which both target the Factor H-binding protein (fHbp) that inhibits complement deposition on the bacterial surface. Therefore, I3 vaccine designs may help overcome the current challenges of developing protein-based vaccines to prevent bacterial infections.

An isothermal CRISPR- based lateral flow assay for detection of Neisseria meningitidis.

BACKGROUND: Neisseria meningitidis can cause life-threatening meningococcal meningitis and meningococcemia. Old standard microbiological results from CSF/blood cultures are time consuming. This study aimed to combine the sensitivity of loop-mediated isothermal nucleic acid amplification (LAMP) with the specificity of CRISPR/Cas12a cleavage to demonstrate a reliable diagnostic assay for rapid detection of N. meningitidis. METHODS: A total of n = 139 samples were collected from patients with suspected meningococcal disease and were used for evaluation. The extracted DNA was subjected to qualitative real-time PCR, targeting capsular transporter gene (ctrA) of N. meningitidis. LAMP-specific primer pairs, also targeting the ctrA, were designed and the LAMP products were subjected to CRISPR/Cas12 cleavage reaction. the readout was on a lateral flow strip. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of LAMP-CRISPR/Cas was compared with real-time PCR assays. The limit of detection (LOD) was established with serial dilutions of the target N. meningitidis DNA and calculated by Probit regression analysis. RESULTS: Six LAMP assay-specific primers were developed targeting the ctrA gene of N. meningitidis, which is conserved in all meningococcal serogroups. The LAMP primers did not amplify DNA from other bacterial DNA tested, showing 100% specificity. The use of 0.4 M betaine increased the sensitivity and stability of the reaction. LAMP-CRISPR/Cas detected meningococcal serogroups (B, C, W). The assay showed no cross-reactivity and was specific for N. meningitidis. The LOD was 74 (95% CI: 47-311) N. meningitidis copies. The LAMP-CRISPR/Cas performed well compared to the gold standard. In the 139 samples from suspected patients, the sensitivity and specificity of the test were 91% and 99% respectively. CONCLUSION: This developed and optimized method can complement for the available gold standard for the timely diagnosis of meningococcal meningitis and meningococcemia.

Expansion of Neisseria meningitidis Serogroup C Clonal Complex 10217 during Meningitis Outbreak, Burkina Faso, 2019.

During January 28-May 5, 2019, a meningitis outbreak caused by Neisseria meningitidis serogroup C (NmC) occurred in Burkina Faso. Demographic and laboratory data for meningitis cases were collected through national case-based surveillance. Cerebrospinal fluid was collected and tested by culture and real-time PCR. Among 301 suspected cases reported in 6 districts, N. meningitidis was the primary pathogen detected; 103 cases were serogroup C and 13 were serogroup X. Whole-genome sequencing revealed that 18 cerebrospinal fluid specimens tested positive for NmC sequence type (ST) 10217 within clonal complex 10217, an ST responsible for large epidemics in Niger and Nigeria. Expansion of NmC ST10217 into Burkina Faso, continued NmC outbreaks in the meningitis belt of Africa since 2019, and ongoing circulation of N. meningitidis serogroup X in the region underscore the urgent need to use multivalent conjugate vaccines in regional mass vaccination campaigns to reduce further spread of those serogroups.

Enhancing sensitivity of qPCR assays targeting Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae by using a mutant Taq DNA polymerase.

AIMS: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae are important causes of bacterial meningitis. In this study, the DNA binding site of the wild type Taq DNA polymerase was modified to produce a mutant enzyme with enhanced DNA affinity and PCR performance. The engineered and the wild type enzymes were integrated into qPCR-based assays for molecular detection of S. pneumoniae, N. meningitidis, H. influenzae, and serogroups and serotypes of these three pathogens. METHODS: Bio-Speedy® Bacterial DNA Isolation Kit (Bioeksen R&D Technologies, Turkiye) and 2× qPCR-Mix for hydrolysis probes (Bioeksen R&D Technologies, Turkiye) and CFX96 Instrument (Biorad Inc., USA) were used for all molecular analyses. Spiked negative clinical specimens were tested using the developed qPCR assays and the culture-based conventional methods for the analytical performance evaluation. RESULTS: All qPCR assays did not produce any positive results for the samples spiked with potential cross-reacting bacteria. Limit of detection (LOD) of the assays containing the mutant enzyme was 1 genome/reaction (10 cfu/mL sample) which is at least 3 times lower than the previously reported LOD levels for DNA amplification based molecular assays. LODs for the spiked serum and cerebrospinal fluid (CSF) samples decreased 2.3-4.7 and 1.2-3.5 times respectively when the mutant enzyme was used instead of the wild type Taq DNA polymerase. CONCLUSIONS: It is possible to enhance analytical sensitivity of qPCR assays targeting the bacterial agents of meningitis by using an engineered Taq DNA polymerase. These qPCR-based assays can be used for direct detection and serogrouping / serotyping of S. pneumoniae, N. meningitidis and H. influenzae at concentrations close to the lower limit of medical decision point.

Geographical distribution of invasive meningococcal disease and carriage: A spatial analysis.

Little information exists concerning the spatial relationship between invasive meningococcal disease (IMD) cases and Neisseria meningitidis (N. meningitidis) carriage. The aim of this study was to examine whether there is a relationship between IMD and asymptomatic oropharyngeal carriage of meningococci by spatial analysis to identify the distribution and patterns of cases and carriage in South Australia (SA). Carriage data geocoded to participants' residential addresses and meningococcal case notifications using Postal Area (POA) centroids were used to analyse spatial distribution by disease- and non-disease-associated genogroups, as well as overall from 2017 to 2020. The majority of IMD cases were genogroup B with the overall highest incidence of cases reported in infants, young children, and adolescents. We found no clear spatial association between N. meningitidis carriage and IMD cases. However, analyses using carriage and case genogroups showed differences in the spatial distribution between metropolitan and regional areas. Regional areas had a higher rate of IMD cases and carriage prevalence. While no clear relationship between cases and carriage was evident in the spatial analysis, the higher rates of both carriage and disease in regional areas highlight the need to maintain high vaccine coverage outside of the well-resourced metropolitan area.

Longitudinal study of meningococcal carriage in adolescents and young adults in South Australia 2017-2020.

BACKGROUND: This analysis investigated longitudinal changes in meningococcal carriage in adolescents in South Australia over 4 years. METHODS: Data from the "B Part of It" study, which included a state-wide cluster randomized controlled trial in secondary-school students (n = 34,489 in 2017 and 2018) and serial cross-sectional studies in school leavers aged 17-25 years (n = 4028 in 2019-2020). Individuals had oropharyngeal swabs collected annually. This study included two unique cohorts: (1) individuals enrolled in 2019, with three consecutive annual swabs taken in 2017, 2018 and 2019; and (2) individuals enrolled in 2020, with swabs taken in 2017, 2018, and 2020. Disease-associated N. meningitidis genogroups were identified using PCR and whole genome sequencing. Univariate analysis identified risk factors for recurrent carriage (≥2). RESULTS: Among school leavers, 50 (1.7%, total n = 2980) had carriage detected at successive visits. In participants with meningococcal carriage at successive visits, 38/50 (76.0%) had the same genogroup detected by porA PCR. Of those, 19 had the same MLST type and demonstrated minimal variation, indicating they most likely had sustained carriage of the same isolate (range 226 to 490 days, mean duration 352 [SD 51] days). In the 2019 school leaver cohort, 6.7% acquired carriage in their first year out of school compared to 3.3% in their final school year. Compared to single carriage detection, recurrent carriage was potentially more likely in older adolescents (16 compared to ≤15 years; OR = 1.97 (95%CI 1.0, 3.86); p = 0.048). CONCLUSION: Whilst carriage is typically transient, some adolescents/young adults may have persistent carriage and are likely to be an important group in the transmission of meningococci.

Obstetric and Neonatal Invasive Meningococcal Disease Caused by Neisseria meningitidis Serogroup W, Western Australia, Australia.

Three mother-baby pairs with invasive meningococcal disease occurred over 7 months in Western Australia, Australia, at a time when serogroup W sequence type 11 clonal complex was the predominant local strain. One mother and 2 neonates died, highlighting the role of this strain as a cause of obstetric and early neonatal death.

Meningococcal disease in the Middle East: A report from the Global Meningococcal Initiative.

This review details recent findings from the Global Meningococcal Initiative's (GMI) recent meeting on the surveillance and control strategies for invasive meningococcal disease in the Middle East. The nature of case reporting and notification varies across the region, with many countries using bacterial meningitis as an IMD case definition in lieu of meningitis and septicaemia. This may overlook a significant burden associated with IMD leading to underreporting or misreporting of the disease. Based on these current definitions, IMD reported incidence remains low across the region, with historical outbreaks mainly occurring due to the Hajj and Umrah mass gatherings. The use of case confirmation techniques also varies in Middle Eastern countries. While typical microbiological techniques, such as culture and Gram staining, are widely used for characterisation, polymerase chain reaction (PCR) testing is utilised in a small number of countries. PCR testing may be inaccessible for several reasons including sample transportation, cost, or a lack of laboratory expertise. These barriers, not exclusive to PCR use, may impact surveillance systems more broadly. Another concern throughout the region is potentially widespread ciprofloxacin resistance since its use for chemoprophylaxis remains high in many countries.

Enzyme mechanistic studies of NMA1982, a protein tyrosine phosphatase and potential virulence factor in Neisseria meningitidis.

Protein phosphorylation is an integral part of many cellular processes, not only in eukaryotes but also in bacteria. The discovery of both prokaryotic protein kinases and phosphatases has created interest in generating antibacterial therapeutics that target these enzymes. NMA1982 is a putative phosphatase from Neisseria meningitidis, the causative agent of meningitis and meningococcal septicemia. The overall fold of NMA1982 closely resembles that of protein tyrosine phosphatases (PTPs). However, the hallmark C(X)5R PTP signature motif, containing the catalytic cysteine and invariant arginine, is shorter by one amino acid in NMA1982. This has cast doubt about the catalytic mechanism of NMA1982 and its assignment to the PTP superfamily. Here, we demonstrate that NMA1982 indeed employs a catalytic mechanism that is specific to PTPs. Mutagenesis experiments, transition state inhibition, pH-dependence activity, and oxidative inactivation experiments all support that NMA1982 is a genuine PTP. Importantly, we show that NMA1982 is secreted by N. meningitidis, suggesting that this protein is a potential virulence factor. Future studies will need to address whether NMA1982 is indeed essential for N. meningitidis survival and virulence. Based on its unique active site conformation, NMA1982 may become a suitable target for developing selective antibacterial drugs.

Bioinformatics Analysis of Global Diversity in Meningococcal Vaccine Antigens over the Past 10 Years: Vaccine Efficacy Prognosis.

Neisseria meningitidis (N. meningitidis) serogroup B (MenB) is the leading cause of invasive meningococcal disease worldwide. The pathogen has a wide range of virulence factors, which are potential vaccine components. Studying the genetic variability of antigens within a population, especially their long-term persistence, is necessary to develop new vaccines and predict the effectiveness of existing ones. The multicomponent 4CMenB vaccine (Bexsero), used since 2014, contains three major genome-derived recombinant proteins: factor H-binding protein (fHbp), Neisserial Heparin-Binding Antigen (NHBA) and Neisserial adhesin A (NadA). Here, we assessed the prevalence and sequence variations of these vaccine antigens in a panel of 5667 meningococcal isolates collected worldwide over the past 10 years and deposited in the PubMLST database. Using multiple amino acid sequence alignments and Random Forest Classifier machine learning methods, we estimated the potential strain coverage of fHbp and NHBA vaccine variants (51 and about 25%, respectively); the NadA antigen sequence was found in only 18% of MenB genomes analyzed, but cross-reactive variants were present in less than 1% of isolates. Based on our findings, we proposed various strategies to improve the 4CMenB vaccine and broaden the coverage of N. meningitidis strains.

Distributed genotyping and clustering of Neisseria strains reveal continual emergence of epidemic meningococcus over a century.

Core genome multilocus sequence typing (cgMLST) is commonly used to classify bacterial strains into different types, for taxonomical and epidemiological applications. However, cgMLST schemes require central databases for the nomenclature of new alleles and sequence types, which must be synchronized worldwide and involve increasingly intensive calculation and storage demands. Here, we describe a distributed cgMLST (dcgMLST) scheme that does not require a central database of allelic sequences and apply it to study evolutionary patterns of epidemic and endemic strains of the genus Neisseria. We classify 69,994 worldwide Neisseria strains into multi-level clusters that assign species, lineages, and local disease outbreaks. We divide Neisseria meningitidis into 168 endemic lineages and three epidemic lineages responsible for at least 9 epidemics in the past century. According to our analyses, the epidemic and endemic lineages experienced very different population dynamics in the past 100 years. Epidemic lineages repetitively emerged from endemic lineages, disseminated worldwide, and apparently disappeared rapidly afterward. We propose a stepwise model for the evolutionary trajectory of epidemic lineages in Neisseria, and expect that the development of similar dcgMLST schemes will facilitate epidemiological studies of other bacterial pathogens.

Molecular characteristics of Neisseria meningitidis carriage strains in university students in Lithuania.

BACKGROUND: Neisseria meningitidis can be carried asymptomatically in the human oropharynx without causing symptoms. Meningococcal carriage is relevant to the epidemiology of invasive meningococcal disease (IMD). No carriage studies have been performed among the general population in Lithuania, whereas the incidence of IMD in Lithuania was among the highest in European countries from 2009 to 2019. RESULTS: We analyzed a total of 401 oropharyngeal samples collected from university students from December 2021 to February 2023 for N. meningitidis carriage using direct swab PCR assays and culture. The overall carriage prevalence based on both or either swab PCR or culture was 4.99%. PCR-based assays were used to characterize 15 carriage isolates, including detection of genogroup, multilocus sequence typing profile, and typing of antigens PorA and FetA. The most common carriage isolates were capsule null locus (cnl), accounting for 46.7%, followed by genogroups B (26.7%) and Y (13.3%). We also performed a molecular characterization of invasive N. meningitidis isolates collected during the COVID-19 pandemic and post-pandemic period to understand better the meningococcal carriage in the context of prevailing invasive strains. Despite the substantial decrease in the incidence of IMD during the 2020-2022 period, clonal complex 32 (CC32) of serogroup B continued to be the most prevalent IMD-causing CC in Lithuania. However, CC32 was not detected among carriage isolates. The most common CCs were CC269, CC198, and CC1136. The antigen peptide variants found in most carried isolates were classified as 'insufficient data' according to the MenDeVAR Index to evaluate the potential coverage by the 4CMenB vaccine. Nearly half of the isolates were potentially covered by the Men-Fhbp vaccine. Resistance to ciprofloxacin was detected only for one cnl isolate. All isolates were susceptible to penicillin and ceftriaxone. Our analysis identified frequent partying (≥ 4 times/month) as a risk factor for meningococcal carriage, whereas smoking, living in a dormitory, and previous COVID-19 illness were not associated with the carriage. CONCLUSIONS: Our study revealed a low prevalence of meningococcal carriage among university students in Lithuania. The carriage isolates showed genetic diversity, although almost half of them were identified as having a null capsule locus.

Evolution and exchange of plasmids in pathogenic Neisseria.

IMPORTANCE: Horizontal gene transfer (HGT) is a major influence in driving the spread of antimicrobial resistance (AMR) in many bacteria. A conjugative plasmid which is widespread in Neisseria gonorrhoeae, pConj, prevented the use of tetracycline/doxycycline for treating gonococcal infection. Here, we show that pConj evolved in the related pathogen, Neisseria meningitidis, and has been acquired by the gonococcus from the meningococcus on multiple occasions. Following its initial acquisition, pConj spread to different gonococcal lineages; changes in the plasmid's conjugation machinery associated with another transfer event limit spread in the gonococcal populations. Our findings have important implications for the use of doxycycline to prevent bacterial sexually transmitted disease which is likely to exacerbate the spread of AMR through HGT in pathogenic bacteria.

Comparison of bacterial culture with BioFire® FilmArray® multiplex PCR screening of archived cerebrospinal fluid specimens from children with suspected bacterial meningitis in Nigeria.

BACKGROUND: Diagnosis of bacterial meningitis remains a challenge in most developing countries due to low yield from bacterial culture, widespread use of non-prescription antibiotics, and weak microbiology laboratories. The objective of this study was to compare the yield from standard bacterial culture with the multiplex nested PCR platform, the BioFire® FilmArray® Meningitis/Encephalitis Panel (BioFire ME Panel), for cases with suspected acute bacterial meningitis. METHODS: Following Gram stain and bacterial culture on cerebrospinal fluid (CSF) collected from children aged less than 5 years with a clinical suspicion of acute bacterial meningitis (ABM) as defined by the WHO guidelines, residual CSF specimens were frozen and later tested by BioFire ME Panel. RESULTS: A total of 400 samples were analyzed. Thirty-two [32/400 (8%)] of the specimens were culture positive, consisting of; three Salmonella spp. (2 Typhi and 1 non-typhi), three alpha hemolytic Streptococcus, one Staphylococcus aureus, six Neisseria meningitidis, seven Hemophilus influenzae, 11 Streptococcus pneumoniae and 368 were culture negative. Of the 368 culture-negative specimens, the BioFire ME Panel detected at least one bacterial pathogen in 90 (24.5%) samples, consisting of S. pneumoniae, N. meningitidis and H. influenzae, predominantly. All culture positive specimens for H. influenzae, N. meningitidis and S. pneumoniae also tested positive with the BioFire ME Panel. In addition, 12 specimens had mixed bacterial pathogens identified. For the first time in this setting, we have data on the viral agents associated with meningitis. Single viral agents were detected in 11 (2.8%) samples while co-detections with bacterial agents or other viruses occurred in 23 (5.8%) of the samples. CONCLUSIONS: The BioFire® ME Panel was more sensitive and rapid than culture for detecting bacterial pathogens in CSF. The BioFire® ME Panel also provided for the first time, the diagnosis of viral etiologic agents that are associated with meningoencephalitis in this setting. Institution of PCR diagnostics is recommended as a routine test for suspected cases of ABM to enhance early diagnosis and optimal treatment.

Detection of Novel US Neisseria meningitidis Urethritis Clade Subtypes in Japan.

Neisseria meningitidis causes invasive meningococcal diseases and has also been identified as a causative agent of sexually transmitted infections, including urethritis. Unencapsulated sequence type 11 meningococci containing the gonococcal aniA-norB locus and belonging to the United States N. meningitidis urethritis clade (US_NmUC) are causative agents of urethral infections in the United States, predominantly among men who have sex with men. We identified 2 subtypes of unencapsulated sequence type 11 meningococci in Japan that were phylogenetically close to US_NmUC, designated as the Japan N. meningitidis urethritis clade (J_NmUC). The subtypes were characterized by PCR, serologic testing, and whole-genome sequencing. Our study suggests that an ancestor of US_NmUC and J_NmUS urethritis-associated meningococci is disseminated worldwide. Global monitoring of urethritis-associated N. meningitidis isolates should be performed to further characterize microbiologic and epidemiologic characteristics of urethritis clade meningococci.

Emergence of ciprofloxacin- and penicillin-resistant Neisseria meningitidis isolates in Japan between 2003 and 2020 and its genetic features.

Although we previously reported that some meningococcal isolates in Japan were resistant to penicillin (PCG) and ciprofloxacin (CIP), the antibiotic susceptibilities of Neisseria meningitidis isolates obtained in Japan remained unclear. In the present study, 290 N. meningitidis isolates in Japan between 2003 and 2020 were examined for the sensitivities to eight antibiotics (azithromycin, ceftriaxone, ciprofloxacin, chloramphenicol, meropenem, minocycline, penicillin, and rifampicin). All isolates were susceptible to chloramphenicol, ceftriaxone, meropenem, minocycline, and rifampicin while two were resistant to azithromycin. Penicillin- and ciprofloxacin-resistant and -intermediate isolates (PCGR, CIPR, PCGI and CIPI, respectively) were also identified. Based on our previous findings from whole genome sequence analysis, approximately 40% of PCGI were associated with ST-11026 and cc2057 meningococci, both of which were unique to Japan. Moreover, the majority of ST-11026 meningococci were CIPR or CIPI. Sensitivities to PCG and CIP were closely associated with genetic features, which indicated that, at least for Japanese meningococcal isolates, PCGR/I or CIPI/R would be less likely to be horizontally conferred from other neisserial genomes by transferring of the genes responsible (penA and gyrA genes, respectively), but rather that ancestral N. meningitidis strains conferring PCGR/I or CIPI/R phenotypes clonally disseminated in Japan.

Genetic variants linked to the phenotypic outcome of invasive disease and carriage of Neisseria meningitidis.

Neisseria meningitidis can be a human commensal in the upper respiratory tract but is also capable of causing invasive diseases such as meningococcal meningitis and septicaemia. No specific genetic markers have been detected to distinguish carriage from disease isolates. The aim here was to find genetic traits that could be linked to phenotypic outcomes associated with carriage versus invasive N. meningitidis disease through a bacterial genome-wide association study (GWAS). In this study, invasive N. meningitidis isolates collected in Sweden (n=103) and carriage isolates collected at Örebro University, Sweden (n=213) 2018-2019 were analysed. The GWAS analysis, treeWAS, was applied to single-nucleotide polymorphisms (SNPs), genes and k-mers. One gene and one non-synonymous SNP were associated with invasive disease and seven genes and one non-synonymous SNP were associated with carriage isolates. The gene associated with invasive disease encodes a phage transposase (NEIS1048), and the associated invasive SNP glmU S373C encodes the enzyme N-acetylglucosamine 1-phosphate (GlcNAC 1-P) uridyltransferase. Of the genes associated with carriage isolates, a gene variant of porB encoding PorB class 3, the genes pilE/pilS and tspB have known functions. The SNP associated with carriage was fkbp D33N, encoding a FK506-binding protein (FKBP). K-mers from PilS, tbpB and tspB were found to be associated with carriage, while k-mers from mtrD and tbpA were associated with invasiveness. In the genes fkbp, glmU, PilC and pilE, k-mers were found that were associated with both carriage and invasive isolates, indicating that specific variations within these genes could play a role in invasiveness. The data presented here highlight genetic traits that are significantly associated with invasive or carriage N. meningitidis across the species population. These traits could prove essential to our understanding of the pathogenicity of N. meningitidis and could help to identify future vaccine targets.

Meningococcal carriage in children and young adults: a cross-sectional and longitudinal study, Iceland, 2019 to 2021.

BackgroundNeisseria meningitidis is a commensal bacterium which can cause invasive disease. Colonisation studies are important to guide vaccination strategies.AimThe study's aim was to determine the prevalence of meningococcal colonisation, duration of carriage and distribution of genogroups in Iceland.MethodsWe collected samples from 1 to 6-year-old children, 15-16-year-old adolescents and 18-20-year-old young adults. Carriers were sampled at regular intervals until the first negative swab. Conventional culture methods and qPCR were applied to detect meningococci and determine the genogroup. Whole genome sequencing was done on groupable meningococci.ResultsNo meningococci were detected among 460 children, while one of 197 (0.5%) adolescents and 34 of 525 young adults (6.5 %) carried meningococci. Non-groupable meningococci were most common (62/77 isolates from 26/35 carriers), followed by genogroup B (MenB) (12/77 isolates from 6/35 carriers). Genogroup Y was detected in two individuals and genogroup W in one. None carried genogroup C (MenC). The longest duration of carriage was at least 21 months. Serial samples from persistent carriers were closely related in WGS.ConclusionsCarriage of pathogenic meningococci is rare in young Icelanders. Non-groupable meningococci were the most common colonising meningococci in Iceland, followed by MenB. No MenC were found. Whole genome sequencing suggests prolonged carriage of the same strains in persistent carriers.