Spread of Neisseria meningitidis serogroup W clone, China

The Epidemiology of Meningococcal Disease and Carriage, Genotypic Characteristics and Antibiotic Resistance of Neisseria meningitidis Isolates in Zhejiang Province, China, 2011–2021

Neisseria meningitidis (Nm) remains a worldwide leading cause of epidemic meningitis. During 2011–July 2021, 55 meningococcal disease (MD) cases were reported with a case fatality rate of 5.45% in Zhejiang Province, China. The median age was 7 years. The annual incidence was 0.0017–0.0183 per 100,000 population. The highest age-specific incidence was observed in the group younger than 1 year. Serogroup was identified in 30 laboratory-confirmed MD cases, and MenB was most predominant. MenB was mainly observed in two age groups: younger than 5 and older than 35 years. MenB incidence was significantly increasing from 0.0018 per 100,000 in 2013 to 0.0070 per 100,000 in 2019. During 2015–2020, 17 positive samples were detected from 2,827 throat swabs from healthy population, of which 70.59% was MenB. Twenty multilocus sequence typing sequence types (STs) containing eight newly assigned STs (ST15881–ST15888) were determined in all Nm isolates. Either in MD cases or in healthy population, MenB CC ST-4821 was the predominant ST. It was worth noting that two MenY CC ST-23 cases occurred in 2019 and 2021, respectively. MenY CC ST-23 MD cases increased gradually in China. Phylogeny results based on genome sequencing indicated that Chinese MenW CC ST-11 isolates were genetically linked and grouped together with Japanese isolates, separated from MenW CC ST-11 isolates from Saudi Arabia Hajj outbreak, Europe, South Africa, South America, North America, and Oceania. MenW CC ST-11 isolates from East Asia might have evolved locally. Antibiotic susceptibility tests revealed a relatively high resistance rate (22.86%) of Nm isolates to penicillin. This study provided valuable data for Chinese public health authorities to grasp the temporal epidemiological characteristics of MD and healthy carriage.

Meningococcal Disease Outbreaks: A Moving Target and a Case for Routine Preventative Vaccination

Outbreaks of invasive meningococcal disease (IMD) are unpredictable, can be sudden and have devastating consequences. We conducted a non-systematic review of the literature in PubMed (1997-2020) to assess outbreak response strategies and the impact of vaccine interventions. Since 1997, IMD outbreaks due to serogroups A, B, C, W, Y and X have occurred globally. Reactive emergency mass vaccination campaigns have encompassed single institutions (schools, universities) through to whole sections of the population at regional/national levels (e.g. serogroup B outbreaks in Saguenay-Lac-Saint-Jean region, Canada and New Zealand). Emergency vaccination responses to IMD outbreaks consistently incurred substantial costs (expenditure on vaccine supplies, personnel costs and interruption of other programmes). Impediments included the limited pace of transmission of information to parents/communities/healthcare workers; issues around collection of informed consents; poor vaccine uptake by older adolescents/young adults, often a target age group; issues of reimbursement, particularly in the USA; and difficulties in swift supply of large quantities of vaccines. For serogroup B outbreaks, the need for two doses was a significant issue that contributed substantially to costs, delayed onset of protection and non-compliance with dose 2. Real-world descriptions of outbreak control strategies and the associated challenges systematically show that reactive outbreak management is administratively, logistically and financially costly, and that its impact can be difficult to measure. In view of the unpredictability, fast pace and potential lethality of outbreak-associated IMD, prevention through routine vaccination appears the most effective mitigation tool. Highly effective vaccines covering five of six disease-causing serogroups are available. Preparedness through routine vaccination programmes will enhance the speed and effectiveness of outbreak responses, should they be needed (ready access to vaccines and need for a single booster dose rather than a primary series).

Household decision-making for the MenACWY vaccination: How parents and adolescents deal with an adolescent vaccination decision

OBJECTIVE

Between 2015 and 2018 The Netherlands experienced increases of invasive meningococcal disease (IMD) serogroup W (MenW), from 0.02 cases/100,000 people between 2010 and 2014 up to 0.5 cases/100,000 in 2017. Therefore in 2018 the MenACWY vaccination was introduced in the National Immunisation Programme (NIP) and a catch-up campaign was initiated among adolescents. This study aimed to gain insight into the decision-making process within households regarding the MenACWY vaccination. The focus was on the differences in the decision-making process of parents and adolescents and of those that had accepted the MenACWY vaccination and those that had not, in order to assess how these types of decisions are made within households.

METHOD

We conducted a total of 38 semi-structured interviews in 20 households (7 not vaccinated) with 20 parents and 18 adolescents (18 dyads) across The Netherlands concerning their decision-making process. Interview guides were constructed based on the Precaution Adaption Process (PAP) model. We performed thematic analysis using qualitative data analysis software (MAXQDA).

RESULTS

Parents are the main actors in the household decision-making process regarding the MenACWY vaccination. Parents start their decision-making process before adolescents are even aware of the issue. Households in the study took different approaches in involving the adolescent in the decision-making, resulting in three styles of household decision-making: parents decide without the adolescent, parents involve the adolescent, or parents leave it up to the adolescent to decide.

CONCLUSION

Parents influence adolescent reasoning, engagement and involvement during the MenACWY vaccination decision-making. And this is the case both among those that have accepted and rejected the MenACWY vaccination. Adolescent engagement with the MenACWY vaccination decision-making is either short-lived or non-existent. However, the moment offers opportunities to engage adolescents on vaccinations and decision-making, with parents as key figures to promote this.

Clinical and molecular characterization of the first culture-confirmed pediatric fulminant meningococcemia case caused by a serogroup Y clonal complex 23 strain in China

Serogroup Y Neisseria meningitidis (NmY) is rare in China, and only serogroup A and C meningococcal polysaccharide vaccines (MPVs) are included in the national vaccination schedule. We describe a case of fulminant meningococcemia caused by NmY, which occurred in a pediatric patient (2 years old) for the first time in China, confirmed by culture. Although the boy was treated in time, the dry gangrene in his toes and fingers left him with severe sequelae. An NmY isolate was cultured from the blood of the patient, and showed decreased susceptibility to penicillin (minimum inhibitory concentration of 0.125 μg/ml), with sequence type (ST) 1655 assigned to clonal complex (cc) 23. Genomic analysis showed it was clustered with isolates from Italy, UK, Finland, and South Africa, sharing designation of Y:P1.5-1,10-1:F4-1:ST-1655(cc23). The emergence of NmY invasive meningococcal disease cases challenges local immunization strategy and warrants wider usage of MPV-ACYW if there is sustained circulation of NmY.

Safety and immunogenicity of meningococcal (Groups A and C) polysaccharide vaccine in children 2 to 6 y of age in China: a randomized, active-controlled, non-inferiority study

Meningococcal serogroups A and C cause significant numbers of cases in China. The Sanofi Pasteur meningococcal polysaccharide A + C vaccine (Men-AC) was licensed in China in 1995. Immunogenicity and safety of a single dose of Men-AC against a similar marketed vaccine, the Lanzhou Institute serogroups A and C vaccine (Lanzhou-AC), were evaluated in children 2 to 6 y of age. Antibody titers were determined before and on Day 30 after vaccination using a serum bactericidal assay using baby rabbit complement (SBA-BR). Immunogenicity endpoints included rates of seroconversion (postvaccination antibody titers ≥4-fold higher) and seroprotection (postvaccination titers ≥1:8). Unsolicited systemic adverse events (AEs) within 30 minutes after vaccination, solicited injection site and systemic reactions between Days 0 and 7, unsolicited non-serious AEs within 30 d, and serious adverse events (SAEs) throughout were recorded. Seroconversion rates against serogroups A and C were 97.0% (95% confidence interval [CI], 94.5-98.6) and 94.7% (95% CI, 91.6-97.0), respectively, in the Men-AC group and 97.7% (95% CI, 95.4-99.1) and 94.8% (95% CI, 91.7-97.0), respectively, in the Lanzhou-AC group, while seroprotection rates were 98.0% (95% CI, 95.8-99.3) and 97.0% (95% CI, 94.5-98.6), respectively, in the Men-AC group and 99.0% (95% CI, 97.2-99.8) and 96.8% (95% CI, 94.1-98.4), respectively, in the Lanzhou-AC group. Non-inferiority of Men-AC with regard to immunogenicity was demonstrated since the lower bounds of the 95% CIs of the differences in rates between the two groups were > -5% for both serogroups. Both vaccines were well tolerated.

The everchanging epidemiology of meningococcal disease worldwide and the potential for prevention through vaccination

Neisseria meningitidis is a major cause of bacterial meningitis and septicaemia worldwide and is associated with high case fatality rates and serious life-long complications among survivors. Twelve serogroups are recognised, of which six (A, B, C, W, X and Y) are responsible for nearly all cases of invasive meningococcal disease (IMD). The incidence of IMD and responsible serogroups vary widely both geographically and over time. For the first time, effective vaccines against all these serogroups are available or nearing licensure. Over the past two decades, IMD incidence has been declining across most parts of the world through a combination of successful meningococcal immunisation programmes and secular trends. The introduction of meningococcal C conjugate vaccines in the early 2000s was associated with rapid declines in meningococcal C disease, whilst implementation of a meningococcal A conjugate vaccine across the African meningitis belt led to near-elimination of meningococcal A disease. Consequently, other serogroups have become more important causes of IMD. In particular, the emergence of a hypervirulent meningococcal group W clone has led many countries to shift from monovalent meningococcal C to quadrivalent ACWY conjugate vaccines in their national immunisation programmes. Additionally, the recent licensure of two protein-based, broad-spectrum meningococcal B vaccines finally provides protection against the most common group responsible for childhood IMD across Europe and Australia. This review describes global IMD epidemiology across each continent and trends over time, the serogroups responsible for IMD, the impact of meningococcal immunisation programmes and future needs to eliminate this devastating disease.

Comparative genomic analyses of Chinese serogroup W ST-11 complex Neisseria meningitidis isolates

Although serogroup W ST-11 complex (cc11) (W:cc11) Neisseria meningitidis has been widespread in China over the past ten years, its origin and genetic relatedness has not yet been described. In this study, we described the genetic relatedness and discuss the possible origin of Chinese W:cc11 isolates by comparing their genome sequences with those of other cc11 strains globally. Comparative genomic analysis with geo-temporally diverse cc11 isolates showed that the Chinese W:cc11 isolates exclusively formed two closely related subclusters within a distinct sublineage (proposed as the Chinese-strain sublineage) of lineage 11.1 close to the interface between the Hajj-strain sublineage and the South American-strain sublineage. Several isolates from Africa and Europe were closely related to the Chinese subclusters which were largely segregated from one another among distinct provinces of China. No alleles were identified that were unique to the Chinese isolates as a whole, though each subcluster possessed unique alleles differentiating itself from the other subcluster as well as closely related isolates within the extended sublineage. Three genes differentiated the two subclusters with allele combinations that were each present among the non-Chinese isolates within the wider sublineage. These results indicate that the Chinese W:cc11 isolates formed part of a previously undescribed W:cc11 sublineage that is closely related to, but distinct from, the Hajj-strain sublineage and South American-strain sublineage. The geographical source of the Chinese subclusters was indeterminate based on available data.

The etiology of acute meningitis and encephalitis syndromes in a sentinel pediatric hospital, Shenzhen, China

Background

Acute meningitis and encephalitis syndromes (AMES) is a severe neurological infection which causes high case fatality and severe sequelae in children. To determine the etiology of childhood AMES in Shenzhen, a hospital-based study was undertaken.

Methods

A total of 240 cerebrospinal fluid (CSF) samples from 171 children meeting the case definition were included and screened for 12 common causative organisms. The clinical data and conventional testing results were collected and analyzed. Whole genome sequencing was performed on a Neisseria meningitidis isolate.

Results

A pathogen was found in 85 (49.7%) cases; Group B Streptococcus (GBS) was detected in 17 cases, Escherichia coli in 15, Streptococcus pneumoniae in 14, enterovirus (EV) in 13, herpes simplex virus (HSV) in 3, N. meningitidis in 1, Haemophilus influenzae in 1, and others in 23. Notably, HSV was found after 43 days of treatment. Twelve GBS and 6 E. coli meningitis were found in neonates aged less than 1 month; 13 pneumococcal meningitis in children aged > 3 months; and 12 EV infections in children aged > 1 year old. The multilocus sequence typing of serogroup B N. meningitidis isolate was ST-3200/CC4821. High resistance rate to tetracycline (75%), penicillin (75%), and trimethoprim/sulfamethoxazole (75%) was found in 4 of S. pneumoniae isolates; clindamycin (100%) and tetracycline (100%) in 9 of GBS; and ampicillin (75%) and trimethoprim/sulfamethoxazole (67%) in 12 of E. coli.

Conclusions

The prevalence of N. meningitidis and JEV was very low and the cases of childhood AMES were mainly caused by other pathogens. GBS and E. coli were the main causative organisms in neonates, while S. pneumoniae and EV were mainly found in older children. HSV could be persistently found in the CSF samples despite of the treatment. A better prevention strategy for GBS, the introduction of pneumococcal vaccine, and incorporation of PCR methods were recommended.

Emergence of Neisseria meningitidis Serogroup W, Central African Republic, 2015-2016

We analyzed data from the 2015 and 2016 meningitis epidemic seasons in Central African Republic as part of the national disease surveillance. Of 80 tested specimens, 66 belonged to meningococcal serogroup W. Further analysis found that 97.7% of 44 isolates belonged to the hyperinvasive clonal complex sequence type 11.

The Global Meningococcal Initiative meeting on prevention of meningococcal disease worldwide: Epidemiology, surveillance, hypervirulent strains, antibiotic resistance and high-risk populations

INTRODUCTION

The 2018 Global Meningococcal Initiative (GMI) meeting focused on evolving invasive meningococcal disease (IMD) epidemiology, surveillance, and protection strategies worldwide, with emphasis on emerging antibiotic resistance and protection of high-risk populations. The GMI is comprised of a multidisciplinary group of scientists and clinicians representing institutions from several continents.

AREAS COVERED

Given that the incidence and prevalence of IMD continually varies both geographically and temporally, and surveillance systems differ worldwide, the true burden of IMD remains unknown. Genomic alterations may increase the epidemic potential of meningococcal strains. Vaccination and (to a lesser extent) antimicrobial prophylaxis are the mainstays of IMD prevention. Experiences from across the globe advocate the use of conjugate vaccines, with promising evidence growing for protein vaccines. Multivalent vaccines can broaden protection against IMD. Application of protection strategies to high-risk groups, including individuals with asplenia, complement deficiencies and human immunodeficiency virus, laboratory workers, persons receiving eculizumab, and men who have sex with men, as well as attendees at mass gatherings, may prevent outbreaks. There was, however, evidence that reduced susceptibility to antibiotics was increasing worldwide.

EXPERT COMMENTARY

The current GMI global recommendations were reinforced, with several other global initiatives underway to support IMD protection and prevention.

Epidemiological Evidence and Health Risks Associated With Agricultural Reuse of Partially Treated and Untreated Wastewater: A Review

The use of partially treated and untreated wastewater for irrigation is beneficial in agriculture but may be associated with human health risks. Reports from different locations globally have linked microbial outbreaks with agricultural reuse of wastewater. This article reviews the epidemiological evidence and health risks associated with this practice, aiming toward evidence-based conclusions. Exposure pathways that were addressed in this review included those relevant to agricultural workers and their families, consumers of crops, and residents close to areas irrigated with wastewater (partially treated or untreated). A meta-analysis gave an overall odds ratio of 1.65 (95% CI: 1.31, 2.06) for diarrheal disease and 5.49 (95% CI: 2.49, 12.10) for helminth infections for exposed agricultural workers and family members. The risks were higher among children and immunocompromised individuals than in immunocompetent adults. Predominantly skin and intestinal infections were prevalent among individuals infected mainly via occupational exposure and ingestion. Food-borne outbreaks as a result of crops (fruits and vegetables) irrigated with partially or untreated wastewater have been widely reported. Contamination of crops with enteric viruses, fecal coliforms, and bacterial pathogens, parasites including soil-transmitted helminthes (STHs), as well as occurrence of antibiotic residues and antibiotic resistance genes (ARGs) have also been evidenced. The antibiotic residues and ARGs may get internalized in crops along with pathogens and may select for antibiotic resistance, exert ecotoxicity, and lead to bioaccumulation in aquatic organisms with high risk quotient (RQ). Appropriate mitigation lies in adhering to existing guidelines such as the World Health Organization wastewater reuse guidelines and to Sanitation Safety Plans (SSPs). Additionally, improvement in hygiene practices will also provide measures against adverse health impacts.

Invasive meningococcal disease in Shanghai, China from 1950 to 2016: implications for serogroup B vaccine implementation

Serogroup B invasive meningococcal disease (IMD) is increasing in China, but little is known about the causative meningococci. Here, IMD and carriage isolates in Shanghai characterised and the applicability of different vaccines assessed. Seven IMD epidemic periods have been observed in Shanghai since 1950, with 460 isolates collected including 169 from IMD and 291 from carriage. Analyses were divided according to the period of meningococcal polysaccharide vaccine (MPV) introduction: (i) pre-MPV-A, 1965–1980; (ii) post-MPV-A, 1981–2008; and (iii) post-MPV-A + C, 2009–2016. Over this period, IMD incidence decreased from 55.4/100,000 to 0.71 then to 0.02, corresponding to successive changes in meningococcal type from serogroup A ST-5 complex (MenA:cc5) to MenC:cc4821, and finally MenB:cc4821. MenB IMD became predominant (63.2%) in the post-MPV-A + C period, and 50% of cases were caused by cc4821, with the highest incidence in infants (0.45/100,000) and a case-fatality rate of 9.5%. IMD was positively correlated with population carriage rates. Using the Bexsero Antigen Sequence Type (BAST) system, fewer than 25% of MenB isolates in the post-MPV-A + C period contained exact or predicted cross reactive matches to the vaccines Bexsero, Trumenba, or an outer membrane vesicle (OMV)-based vaccine, NonaMen. A unique IMD epidemiology was seen in China, changing periodically from epidemic to hyperepidemic and low-level endemic disease. At the time of writing, MenB IMD dominated IMD in Shanghai, with isolates potentially beyond coverage with licenced OMV- and protein-based MenB vaccines.

Neisseria meningitidis carriage in Swedish teenagers associated with the serogroup W outbreak at the World Scout Jamboree, Japan 2015

The aims of the study were to estimate the carrier state of Neisseria meningitidis in Swedish teenagers and its association with an outbreak at the World Scout Jamboree in 2015 as well as to compare sensitivity of throat versus nasopharyngeal swab for optimal detection of carriage. In total, 1 705 samples (cultures n = 32, throat swabs n = 715, nasopharyngeal swabs n = 958) from 1 020 Jamboree participants were collected and sent to the National Reference Laboratory for Neisseria meningitidis for culture and molecular analysis. The overall positivity for N. meningitidis was 8% (83/1 020), whereas 2% (n = 22) belonged to a known sero/genogroup while the majority (n = 61) were non-groupable. Throat sample is clearly the sampling method of choice, in 56 individuals where both throat and nasopharynx samples were taken, N. meningitidis was detected in both throat and nasopharynx in eight individuals, in 46 individuals N. meningitidis was only detected in the throat and in two individuals only in the nasopharynx. Carriage studies are important to provide knowledge of the current epidemiology and association between carrier isolates and disease-causing isolates in a given population. Therefore, planning for a carriage study in Sweden is in progress.

Meningococcal disease and control in China: Findings and updates from the Global Meningococcal Initiative (GMI)

The Global Meningococcal Initiative (GMI) is a global expert group, including scientists, clinicians and public health officials from a wide range of specialities. The goal of the GMI is to prevent meningococcal disease worldwide through education, research, and co-operation. The Chinese GMI roundtable meeting was held in June 2017. The GMI met with local experts to gain insight into the meningococcal disease burden in China and current prevention and vaccination strategies in place. China experienced five epidemics of serogroup A meningococcal disease (MenA) between 1938 and 1977, with peak incidence of 403/100,000 recorded in 1967. MenA incidence rates have significantly declined following the universal introduction of the MenA polysaccharide vaccine in China in the 1980s. Further, surveillance data indicates changing meningococcal epidemiology in China with the emergence of new clones of serogroup B from serogroup C clonal complex (cc) 4821 due to capsular switching, and the international spread of serogroup W cc11. The importance of carriage and herd protection for controlling meningococcal disease was highlighted with the view to introduce conjugate vaccines and serogroup B vaccines into the national immunization schedule. Improved disease surveillance and standardized laboratory techniques across and within provinces will ensure optimal epidemiological monitoring.

Prevalence of factor H Binding Protein sub-variants among Neisseria meningitidis in China

OBJECTIVE

To study the prevalence of the fHbp genes in Neisseria meningitidis (N. meningitidis) isolates for further evaluation and development of serogroup B meningococcal vaccines in China.

METHODS

A panel of 1012 N. meningitidis strains was selected from the national culture collection from 1956 to 2016, according to the years of isolation, locations, and strain sources. These were tested by FHbp variant typing. Multi-locus sequence typing (MLST) was performed on 822 of these samples, including 242 strains from clinical strains and 580 carrier-derived strains. Analysis based on sequence types, serogroups, and FHbp variations were used to summarize the prevalence and characteristics of N. meningitidis.

RESULTS

There were 8 serogroups of N. meningitidis as well as a collection of nongroupable strains in this study. 1008 of 1012 N. meningitidis strains tested were positive for the fHbp gene. Serogroup A N. meningitidis (MenA) strains belonging to ST-1 and ST-5 clonal complexes harbored genes only encoding variant 1 (v1) FHbp. All MenW strains encoded v2 FHbp. 61.9% of clinical MenB strains were positive for v2 FHbp vs. 32.1% that were positive for v1. Among fHbp-positive carrier-derived MenB strains, v2 FHbp accounted for 90.8%. 79.7% of clinical MenC strains were positive for v1 FHbp and 20.3% were positive for v2 FHbp. Among carrier-derived MenC strains, v2 FHbp predominated. The number of major serogroups of N. meningitidis analyzed by MLST was 822, and the encoded FHbp showed CC- or ST-specific characteristics.

CONCLUSION

fHbp genes were detected in almost all N. meningitidis strains in this study. Therefore, it is possible that a vaccine against MenB or meningococci irrespective of serogroups, which includes FHbp, could be developed. Meningococcal vaccine development for China is a complex issue and these findings warrant further attention with respect to vaccine development.

Invasive serogroup W Neisseria meningitidis (MenW) in Ontario, Canada shows potential clonal replacement during the period January 1, 2009 to June 30, 2016

Background

In Ontario, serogroup W Neisseria meningitidis (MenW) accounts for a small percentage of all invasive meningococcal disease (IMD) and between 2010 and 2014, only zero to three confirmed cases occurred per year. However, between August 2015 and June 2016, six culture confirmed MenW IMD cases were reported in Ontario.

Objective

All MenW IMD cases in Ontario between January 1, 2009 and June 30, 2016 were reviewed and the N. meningitidis strains involved were characterized.

Methods

MenW cases were identified in the Integrated Public Health Information System byf Public Health Ontario. MenW isolates were characterized at the National Microbiology Laboratory.

Results

Of the thirteen MenW IMD cases, six were due to isolates typed as sequence type (ST)-22 clonal complex (cc), six were of ST-11 cc, and one ST-167 cc. Most (83%) MenW cases due to the ST-22 cc occurred prior to 2012 while all six MenW cases due to ST-11 cc happened since May 2014. The six MenW ST-11 isolates appeared to be clonal.

Conclusion

It appears that a genetic shift in the invasive MenW isolates has occurred in Ontario in 2014 with the ST-11 clone replacing the traditional ST-22 clone.

Genomic Investigation Reveals Highly Conserved, Mosaic, Recombination Events Associated with Capsular Switching among Invasive Neisseria meningitidis Serogroup W Sequence Type (ST)-11 Strains

Neisseria meningitidis is an important cause of meningococcal disease globally. Sequence type (ST)-11 clonal complex (cc11) is a hypervirulent meningococcal lineage historically associated with serogroup C capsule and is believed to have acquired the W capsule through a C to W capsular switching event. We studied the sequence of capsule gene cluster (cps) and adjoining genomic regions of 524 invasive W cc11 strains isolated globally. We identified recombination breakpoints corresponding to two distinct recombination events within W cc11: A 8.4-kb recombinant region likely acquired from W cc22 including the sialic acid/glycosyl-transferase gene, csw resulted in a C→W change in capsular phenotype and a 13.7-kb recombinant segment likely acquired from Y cc23 lineage includes 4.5 kb of cps genes and 8.2 kb downstream of the cps cluster resulting in allelic changes in capsule translocation genes. A vast majority of W cc11 strains (497/524, 94.8%) retain both recombination events as evidenced by sharing identical or very closely related capsular allelic profiles. These data suggest that the W cc11 capsular switch involved two separate recombination events and that current global W cc11 meningococcal disease is caused by strains bearing this mosaic capsular switch.

Meningococcal Vaccinations

Neisseria meningitidis, a gram-negative diplococcal bacterium, is a common asymptomatic nasopharyngeal colonizer that may infrequently lead to invasive disease in the form of meningitis or bacteremia. Six serogroups (A, B, C, W, X and Y) are responsible for the majority of invasive infections. Increased risk of disease occurs in specific population groups including infants, adolescents, those with asplenia or complement deficiencies, and those residing in crowded living conditions such as in college dormitories. The incidence of invasive meningococcal disease varies geographically with some countries (e.g., in the African meningitis belt) having both high endemic disease rates and ongoing epidemics, with annual rates reaching 1000 cases per 100,000 persons. Given the significant morbidity and mortality associated with meningococcal disease, it remains a major global health threat best prevented by vaccination. Several countries have implemented vaccination programs with the selection of specific vaccine(s) based on locally prevalent serogroup(s) of N. meningitidis and targeting population groups at highest risk. Polysaccharide meningococcal vaccines became available over 40 years ago, but are limited by their inability to produce immunologic memory responses, poor immunogenicity in infants/children, hyporesponsiveness after repeated doses, and lack of efficacy against nasopharyngeal carriage. In 1999, the first meningococcal conjugate vaccines were introduced and have been successful in overcoming many of the shortcomings of polysaccharide vaccines. The implementation of meningococcal conjugate vaccination programs in many areas of the world (including the massive campaign in sub-Saharan Africa using a serogroup A conjugate vaccine) has led to dramatic reductions in the incidence of meningococcal disease by both individual and population protection. Progressive advances in vaccinology have led to the recent licensure of two effective vaccines against serogroup B [MenB-4C (Bexsero) and MenB-FHbp (Trumenba)]. Overall, the evolution of novel meningococcal vaccines and the effective implementation of targeted vaccination programs has led to a substantial decrease in the burden of disease worldwide representing a major public health accomplishment.

Global epidemiology of capsular group W meningococcal disease (1970-2015): Multifocal emergence and persistence of hypervirulent sequence type (ST)-11 clonal complex

Following an outbreak in Mecca Saudi Arabia in 2000, meningococcal strains expressing capsular group W (W) emerged as a major cause of invasive meningococcal disease (IMD) worldwide. The Saudi Arabian outbreak strain (Hajj clone) belonging to the ST-11 clonal complex (cc11) is similar to W cc11 causing occasional sporadic disease before 2000. Since 2000, W cc11 has caused large meningococcal disease epidemics in the African meningitis belt and endemic disease in South America, Europe and China. Traditional molecular epidemiologic typing suggested that a majority of current W cc11 burden represented global spread of the Hajj clone. However, recent whole genome sequencing (WGS) analyses revealed significant genetic heterogeneity among global W cc11 strains. While continued spread of the Hajj clone occurs in the Middle East, the meningitis belt and South Africa have co-circulation of the Hajj clone and other unrelated W cc11 strains. Notably, South America, the UK, and France share a genetically distinct W cc11 strain. Other W lineages persist in low numbers in Europe, North America and the meningitis belt. In summary, WGS is helping to unravel the complex genomic epidemiology of group W meningococcal strains. Wider application of WGS and strengthening of global IMD surveillance is necessary to monitor the continued evolution of group W lineages.

Sequence Type 4821 Clonal Complex Serogroup B Neisseria meningitidis in China, 1978-2013

Serogroup B Neisseria meningitidis strains belonging to sequence type 4821 clonal complex (CC4821), a hyperinvasive lineage first identified for serogroup C in 2003, have been increasingly isolated in China. We characterized the outer membrane protein genes of 48 serogroup B and 214 serogroup C strains belonging to CC4821 and analyzed the genomic sequences of 22 strains. Four serogroup B strains had porin A (i.e., PorA), PorB, and ferric enterobactin transport (i.e., FetA) genotypes identical to those for serogroup C. Phylogenetic analysis of the genomic sequences showed that the 22 CC4821 strains from patients and healthy carriers were unevenly clustered into 2 closely related groups; each group contained serogroup B and C strains. Serogroup B strains appeared variable at the capsule locus, and several recombination events had occurred at uncertain breakpoints. These findings suggest that CC4821 serogroup C N. meningitidis is the probable origin of highly pathogenic CC4821 serogroup B strains.

Genomic Epidemiology of Hypervirulent Serogroup W, ST-11 Neisseria meningitidis

Neisseria meningitidis is a leading bacterial cause of sepsis and meningitis globally with dynamic strain distribution over time. Beginning with an epidemic among Hajj pilgrims in 2000, serogroup W (W) sequence type (ST) 11 emerged as a leading cause of epidemic meningitis in the African ‘meningitis belt’ and endemic cases in South America, Europe, Middle East and China. Previous genotyping studies were unable to reliably discriminate sporadic W ST-11 strains in circulation since 1970 from the Hajj outbreak strain (Hajj clone). It is also unclear what proportion of more recent W ST-11 disease clusters are caused by direct descendants of the Hajj clone. Whole genome sequences of 270 meningococcal strains isolated from patients with invasive meningococcal disease globally from 1970 to 2013 were compared using whole genome phylogenetic and major antigen-encoding gene sequence analyses. We found that all W ST-11 strains were descendants of an ancestral strain that had undergone unique capsular switching events. The Hajj clone and its descendants were distinct from other W ST-11 strains in that they shared a common antigen gene profile and had undergone recombination involving virulence genes encoding factor H binding protein, nitric oxide reductase, and nitrite reductase. These data demonstrate that recent acquisition of a distinct antigen-encoding gene profile and variations in meningococcal virulence genes was associated with the emergence of the Hajj clone. Importantly, W ST-11 strains unrelated to the Hajj outbreak contribute a significant proportion of W ST-11 cases globally. This study helps illuminate genomic factors associated with meningococcal strain emergence and evolution.

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Genomic characterization of serogroup W ST-11 of Neisseria meningitidis.

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Epidemic W ST-11 strain (Hajj clone) emerged through recombination affecting virulence genes.

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Both the Hajj clone and W ST-11 strains unrelated to the Hajj outbreak have persisted globally.

Neisseria meningitidis, a bacterial cause of frequently fatal brain (meningitis) and blood stream (sepsis) infections, has variable strain distribution over time. Serogroup W sequence type 11 (W ST-11) lineage is associated on one hand with strains causing only rare (sporadic) disease cases, and the Hajj clone – a major global cause of epidemic and endemic meningococcal disease. In this study we analyzed complete genome sequences of a global collection of 270 W ST-11 isolates causing meningococcal disease from 1970-2013. The Hajj clone acquired novel gene sequences within genes involved in nitrogen metabolism (nitrogen oxide reductase, nitrite reductase) and evasion of human immune response (factor H binding protein). These genes may be the cause of increased virulence of the Hajj clone and can be used to trace continuing spread of the clone. These results shed light on mechanisms of meningococcal strain emergence.

Shifts in the Antibiotic Susceptibility, Serogroups, and Clonal Complexes of Neisseria meningitidis in Shanghai, China: A Time Trend Analysis of the Pre-Quinolone and Quinolone Eras

BACKGROUND

Fluoroquinolones have been used broadly since the end of the 1980s and have been recommended for Neisseria meningitidis prophylaxis since 2005 in China. The aim of this study was to determine whether and how N. meningitidis antimicrobial susceptibility, serogroup prevalence, and clonal complex (CC) prevalence shifted in association with the introduction and expanding use of quinolones in Shanghai, a region with a traditionally high incidence of invasive disease due to N. meningitidis.

METHODS AND FINDINGS

A total of 374 N. meningitidis isolates collected by the Shanghai Municipal Center for Disease Control and Prevention between 1965 and 2013 were studied. Shifts in the serogroups and CCs were observed, from predominantly serogroup A CC5 (84%) in 1965-1973 to serogroup A CC1 (58%) in 1974-1985, then to serogroup C or B CC4821 (62%) in 2005-2013. The rates of ciprofloxacin nonsusceptibility in N. meningitidis disease isolates increased from 0% in 1965-1985 to 84% (31/37) in 2005-2013 (p < 0.001). Among the ciprofloxacin-nonsusceptible isolates, 87% (27/31) were assigned to either CC4821 (n = 20) or CC5 (n = 7). The two predominant ciprofloxacin-resistant clones were designated ChinaCC4821-R1-C/B and ChinaCC5-R14-A. The ChinaCC4821-R1-C/B clone acquired ciprofloxacin resistance by a point mutation, and was present in 52% (16/31) of the ciprofloxacin-nonsusceptible disease isolates. The ChinaCC5-R14-A clone acquired ciprofloxacin resistance by horizontal gene transfer, and was found in 23% (7/31) of the ciprofloxacin-nonsusceptible disease isolates. The ciprofloxacin nonsusceptibility rate was 47% (7/15) among isolates from asymptomatic carriers, and nonsusceptibility was associated with diverse multi-locus sequence typing profiles and pulsed-field gel electrophoresis patterns. As detected after 2005, ciprofloxacin-nonsusceptible strains were shared between some of the patients and their close contacts. A limitation of this study is that isolates from 1986-2004 were not available and that only a small sample of convenience isolates from 1965-1985 were available.

CONCLUSIONS

The increasing prevalence of ciprofloxacin resistance since 2005 in Shanghai was associated with the spread of hypervirulent lineages CC4821 and CC5. Two resistant meningococcal clones ChinaCC4821-R1-C/B and ChinaCC5-R14-A have emerged in Shanghai during the quinolone era. Ciprofloxacin should be utilized with caution for the chemoprophylaxis of N. meningitidis in China.

CC4821 serogroup W meningococcal disease in China

Neisseria meningitidis is a major public health concern worldwide, including China. A few cases of serogroup W meningococcal disease have been reported in southeast China in recent years. Thus far, invasive disease due to W isolates has involved sequence type 11. We report two cases of N. meningitidis infection caused by CC4821 serogroup W strains.

Genetic diversity and clonal characteristics of ciprofloxacin-resistant meningococcal strains in China

The purpose of the present study was to identify the clonal characteristics and gyrA gene diversity of ciprofloxacin-resistant meningococcal strains in China. One hundred and forty-one ciprofloxacin-resistant and 103 ciprofloxacin-susceptible meningococcal strains were selected for multilocus sequence typing. Of these, 54 ciprofloxacin-resistant and 42 ciprofloxacin-susceptible strains were selected for gyrA gene sequencing. Of the three clonal complexes prevalent in China, serogroup A of ST-5 complex (CC5) and serogroup C/B strains of CC4821 had a high proportion of ciprofloxacin resistance, whereas CC11 serogroup W strains were all susceptible. Nucleotide and amino acid sequences of the gyrA gene among ciprofloxacin-resistant strains showed more diversity than those among ciprofloxacin-susceptible strains. All ciprofloxacin-resistant strains had a T91I mutation and the ciprofloxacin-susceptible strains had no T91I mutation. Phylogenetic analysis showed that the gyrA gene sequences of CC4821 serogroup B/C strains, CC11 serogroup W, CC1 serogroup A, ciprofloxacin-susceptible CC5 serogroup A and reference strains had high similarity. By contrast, the ciprofloxacin-resistant CC5 serogroup A strains had a highly conserved gyrA gene sequence which was different (94.8% similarity) from that in the above strains. The results of our investigation showed that the high proportion of ciprofloxacin resistance in Neisseria meningitidis is associated with certain sequence types (STs) or clonal complexes (CCs). The prevalence of certain CCs with a high proportion of ciprofloxacin resistance can facilitate the spread of ciprofloxacin resistance.

Serogroup W meningococcal disease: global spread and current affect on the Southern Cone in Latin America

Meningococcal serogroup W strains have been emerging throughout the current century with most of the isolates belonging to the sequence type (ST11)/electrophoretic type (ET37) clonal complex (ST11/E37 CC), particularly since the international outbreak following Hajj 2000. That outbreak appears to have triggered off that trend, contributing to the spread of W ST11/ET37 CC strains globally; however, local strains could be also responsible for increases in the percentage and/or incidence rates of this serogroup in some countries. More recently, unexpected increases in the percentage and incidence rate of W has been noticed in different countries located in the South Cone in Latin America, and W ST11/ET37 CC strains now appear as endemic in the region and an extensive immunization programme with tetravalent conjugate vaccine (covering serogroups A, C, Y and W) has been recently implemented in Chile. It is difficult to ascertain whether we are observing the emergence of W ST11 CC strains in different geographical areas or whether the Hajj 2000 strain is still spreading globally. Several aspects of the evolution of that situation are analysed in this paper, reviewing also the implications in immunization programmes. Closely related with the analysis of this potential evolution, it will be very interesting to monitor the evolution of serogroup W in the African meningitis belt after implementation of the extensive immunization programme with serogroup A conjugate vaccine that is currently underway. More data about carriers, transmission, clonal lineages, etc. are needed for taking decisions (target groups, outbreak control, defining the extent, etc.) to adapt the response strategy with potential interventions with broad coverage vaccines against the emergent serogroup W.