Atypical presentation of Neisseria meningitidis serogroup W disease is associated with the introduction of the 2013 strain.

Since 2015, the incidence of invasive meningococcal disease (IMD) caused by serogroup W (MenW) has increased in Sweden, due to the introduction of the 2013 strain belonging to clonal complex 11. The aim of this study was to describe the clinical presentation of MenW infections, in particular the 2013 strain, including genetic associations. Medical records of confirmed MenW IMD cases in Sweden during the years 1995-2019 (n = 113) were retrospectively reviewed and the clinical data analysed according to strain. Of all MenW patients, bacteraemia without the focus of infection was seen in 44%, bacteraemic pneumonia in 26%, meningitis in 13% and epiglottitis in 8%, gastrointestinal symptoms in 48% and 4% presented with petechiae. Phylogenetic analysis was used for possible links between genetic relationship and clinical picture. The 2013 strain infections, particularly in one cluster, were associated with more severe disease compared with other MenW infections. The patients with 2013 strain infections (n = 68) were older (52 years vs. 25 years for other strains), presented more often with diarrhoea as an atypical presentation (P = 0.045) and were more frequently admitted for intensive care (P = 0.032). There is a risk that the atypical clinical presentation of MenW infections, with predominantly gastrointestinal or respiratory symptoms rather than neck stiffness or petechiae, may lead to delay in life-saving treatment.

Suspected cluster of Neisseria meningitidis W invasive disease in an elderly care home: do new laboratory methods aid public health action? United Kingdom, 2015.

In 2015, a suspected cluster of two invasive meningococcal disease (IMD) cases of serogroup W Neisseria meningitidis (MenW) occurred in elderly care home residents in England over 7 months; case investigations followed United Kingdom guidance. An incident control team reviewed epidemiological information. Phenotyping of case specimens informed public health action, including vaccination and throat swabs to assess carriage. Whole genome sequencing (WGS) was conducted on case and carrier isolates. Conventional phenotyping did not exclude a microbiological link between cases (case 1 W:2a:P1.5,2 and case 2 W:2a:NT). After the second case, 33/40 residents and 13/32 staff were vaccinated and 19/40 residents and 13/32 staff submitted throat swabs. Two MenW carriers and two MenC carriers were detected. WGS showed that MenW case and carrier isolates were closely related and possibly constituted a locally circulating strain. Meningococcal carriage, transmission dynamics and influence of care settings on IMD in older adults are poorly understood. WGS analyses performed following public health action helped to confirm the close relatedness of the case and circulating isolates despite phenotypic differences and supported actions taken. WGS was not sufficiently timely to guide public health practice.

Cocirculation of Hajj and non-Hajj strains among serogroup W meningococci in Italy, 2000 to 2016.

In Italy, B and C are the predominant serogroups among meningococci causing invasive diseases. Nevertheless, in the period from 2013 to 2016, an increase in serogroup W Neisseria meningitidis (MenW) was observed. This study intends to define the main characteristics of 63 MenW isolates responsible of invasive meningococcal disease (IMD) in Italy from 2000 to 2016. We performed whole genome sequencing on bacterial isolates or single gene sequencing on culture-negative samples to evaluate molecular heterogeneity. Our main finding was the cocirculation of the Hajj and the South American sublineages belonging to MenW/clonal complex (cc)11, which gradually surpassed the MenW/cc22 in Italy. All MenW/cc11 isolates were fully susceptible to cefotaxime, ceftriaxone, ciprofloxacin, penicillin G and rifampicin. We identified the full-length NadA protein variant 2/3, present in all the MenW/cc11. We also identified the fHbp variant 1, which we found exclusively in the MenW/cc11/Hajj sublineage. Concern about the epidemic potential of MenW/cc11 has increased worldwide since the year 2000. Continued surveillance, supported by genomic characterisation, allows high-resolution tracking of pathogen dissemination and the detection of epidemic-associated strains.

Emergence of Localized Serogroup W Meningococcal Disease in the United States - Georgia, 2006-2016.

Several countries in Europe and Australia are reporting an increasing incidence of Neisseria meningitidis serogroup W (NmW) as a consequence of the rapid expansion of a single NmW clone belonging to clonal complex 11 (1-5). Because this clone is reported to be associated with more severe disease, unusual clinical presentations, and a high case fatality ratio (CFR), it is considered a hypervirulent strain (1,6). In the United States, NmW accounts for approximately 5% of meningococcal disease reported each year, and this proportion has remained stable for several years (7). However, localized increases in NmW have been reported, most notably in Florida during 2008-2009 (8). In Georgia, NmW accounted for only 3% of meningococcal disease cases reported during 2006-2013; however, between January 2014 and December 2016, 42% of all reported cases were NmW. Surveillance data from Georgia were analyzed to describe the epidemiology and clinical characteristics of NmW cases, and whole-genome sequencing of NmW isolates was performed for comparison with NmW strains circulating in the United States and worldwide. These data indicate that the U.S. NmW strains might have evolved from the same ancestor as the hypervirulent strain that is circulating globally. Genetic analysis demonstrates that these strains are closely related, which would suggest that genetic variation led to the rise of different strains from the same ancestor. Given the recent global expansion of this potentially hypervirulent NmW lineage, clinicians and public health officials need to remain vigilant in obtaining isolates to monitor changes in circulating strains.

Characterization of strains of Neisseria meningitidis causing meningococcal meningitis in Mozambique, 2014: Implications for vaccination against meningococcal meningitis.

INTRODUCTION: In sub Saharan Africa, the epidemiology, including the distribution of serogroups of strains of N. meningitidis is poorly investigated in countries outside "the meningitis belt". This study was conducted with the aim to determine the distribution of serogroups of strains of N. meningitidis causing meningococcal meningitis in children and adults in Mozambique. METHODS: A total of 106 PCR confirmed Neisseria meningitidis Cerebrospinal Fluid (CSF) samples or isolates were obtained from the biobank of acute bacterial meningitis (ABM) surveillance being implemented by the National Institute of Health, at three central hospitals in Mozambique, from January to December 2014. Serogroups of N. meningitidis were determined using conventional PCR, targeting siaD gene for Neisseria meningitidis. Outer Membrane Proteins (OMP) Genotyping was performed by amplifying porA gene in nine samples. RESULTS: Of the 106 PCR confirmed Neisseria meningitidis samples, the most frequent serotype was A (50.0%, 53/106), followed by W/Y (18.9%, 20/106), C (8.5%, 9/106), X (7.5%, 8/106) and B (0.9%, 1/106). We found non-groupable strains in a total of 15 (14.2%) samples. PorA genotypes from nine strains showed expected patterns with the exception of two serogroup C strains with P1.19,15,36 and P1.19-36,15 and one serogroup X with P1.19,15,36, variants frequently associated to serogroup B. CONCLUSION: Our data shows that the number of cases of meningococcal meningitis routinely reported in central hospitals in Mozambique is significant and the most dominant serogroup is A. In conclusion, although serogroup A has almost been eliminated from the "meningitis belt", this serogroup remains a major concern in countries outside the belt such as Mozambique.

A cluster of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup W among university students, France, February to May 2017.

Between February and May 2017, two cases of invasive meningococcal disease caused by a new, rapidly expanding serogroup W meningococci variant were reported among students of an international university in Paris. Bacteriological investigations showed that isolates shared identical genotypic formula (W:P1.5,2:F1-1:cc11) and belonged to the South American/UK lineage. A vaccination campaign was organised that aimed at preventing new cases linked to potential persistence of the circulation of the bacteria in the students.

An international invasive meningococcal disease outbreak due to a novel and rapidly expanding serogroup W strain, Scotland and Sweden, July to August 2015.

The 23rd World Scout Jamboree in 2015 took place in Japan and included over 33,000 scouts from 162 countries. Within nine days of the meeting ending, six cases of laboratory-confirmed invasive serogroup W meningococcal disease occurred among scouts and their close contacts in Scotland and Sweden. The isolates responsible were identical to one-another by routine typing and, where known (4 isolates), belonged to the ST-11 clonal complex (cc11) which is associated with large outbreaks and high case fatality rates. Recent studies have demonstrated the need for high-resolution genomic typing schemes to assign serogroup W cc11 isolates to several distinct strains circulating globally over the past two decades. Here we used such schemes to confirm that the Jamboree-associated cases constituted a genuine outbreak and that this was due to a novel and rapidly expanding strain descended from the strain that has recently expanded in South America and the United Kingdom. We also identify the genetic differences that define the novel strain including four point mutations and three putative recombination events involving the horizontal exchange of 17, six and two genes, respectively. Noteworthy outcomes of these changes were antigenic shifts and the disruption of a transcriptional regulator.

Cluster of serogroup W-135 meningococcal disease in 3 military recruits.

We describe a group of 3 cases of invasive meningococcal disease that occurred in a military training camp in April 2011. All three patients were hospitalized. Ultimately, two patients recovered and one died. One patient had meningitis, one patient had septicemia and meningitis, and the other had no definite septicemia or meningitis. Neisseria meningitidis serogroup W-135 was detected in the serum and cerebrospinal fluid (CSF) of all patients by real-time polymerase chain reaction. In the one case of mortality, two strains were isolated from the patient's blood and CSF. Using multilocus sequence typing analysis, these strains were identified as a novel sequence type, ST-8912. Special attention is required for the meningococcal disease in military camp because the military personnels are in high risk of contact transmission.

Cluster of Serogroup W-135 Meningococcal Disease in 3 Military Recruits

We describe a group of 3 cases of invasive meningococcal disease that occurred in a military training camp in April 2011. All three patients were hospitalized. Ultimately, two patients recovered and one died. One patient had meningitis, one patient had septicemia and meningitis, and the other had no definite septicemia or meningitis. Neisseria meningitidis serogroup W-135 was detected in the serum and cerebrospinal fluid (CSF) of all patients by real-time polymerase chain reaction. In the one case of mortality, two strains were isolated from the patient's blood and CSF. Using multilocus sequence typing analysis, these strains were identified as a novel sequence type, ST-8912. Special attention is required for the meningococcal disease in military camp because the military personnels are in high risk of contact transmission.

A broadly-protective vaccine against meningococcal disease in sub-Saharan Africa based on generalized modules for membrane antigens (GMMA).

INTRODUCTION: Neisseria meningitidis causes epidemics of meningitis in sub-Saharan Africa. These have mainly been caused by capsular group A strains, but W and X strains are increasingly contributing to the burden of disease. Therefore, an affordable vaccine that provides broad protection against meningococcal disease in sub-Saharan Africa is required. METHODS: We prepared Generalized Modules for Membrane Antigens (GMMA) from a recombinant serogroup W strain expressing PorA P1.5,2, which is predominant among African W isolates. The strain was engineered with deleted capsule locus genes, lpxL1 and gna33 genes and over-expressed fHbp variant 1, which is expressed by the majority of serogroup A and X isolates. RESULTS: We screened nine W strains with deleted capsule locus and gna33 for high-level GMMA release. A mutant with five-fold increased GMMA release compared with the wild type was further engineered with a lpxL1 deletion and over-expression of fHbp. GMMA from the production strain had 50-fold lower ability to stimulate IL-6 release from human PBMC and caused 1000-fold lower TLR-4 activation in Human Embryonic Kidney cells than non-detoxified GMMA. In mice, the GMMA vaccine induced bactericidal antibody responses against African W strains expressing homologous PorA and fHbp v.1 or v.2 (geometric mean titres [GMT]=80,000-200,000), and invasive African A and X strains expressing a heterologous PorA and fHbp variant 1 (GMT=20-2500 and 18-5500, respectively). Sera from mice immunised with GMMA without over-expressed fHbp v.1 were unable to kill the A and X strains, indicating that bactericidal antibodies against these strains are directed against fHbp. CONCLUSION: A GMMA vaccine produced from a recombinant African N. meningitidis W strain with deleted capsule locus, lpxL1, gna33 and overexpressed fHbp v.1 has potential as an affordable vaccine with broad coverage against strains from all main serogroups currently causing meningococcal meningitis in sub-Saharan Africa.

Biochemical and biophysical characterization of the sialyl-/hexosyltransferase synthesizing the meningococcal serogroup W135 heteropolysaccharide capsule.

Neisseria meningitidis (Nm) is a leading cause of bacterial meningitis and sepsis. Crucial virulence determinants of pathogenic Nm strains are the polysaccharide capsules that support invasion by hindering complement attack. In NmW-135 and NmY the capsules are built from the repeating units (→ 6)-α-D-Gal-(1 → 4)-α-Neu5Ac-(2 →)n and (→ 6)-α-D-Glc-(1 → 4)-α-Neu5Ac-(2 →)n, respectively. These unusual heteropolymers represent unique examples of a conjugation between sialic acid and hexosyl-sugars in a polymer chain. Moreover, despite the various catalytic strategies needed for sialic acid and hexose transfer, single enzymes (SiaDW-135/Y) have been identified to form these heteropolymers. Here we used SiaDW-135 as a model system to delineate structure-function relationships. In size exclusion chromatography active SiaDW-135 migrated as a monomer. Fold recognition programs suggested two separate glycosyltransferase domains, both containing a GT-B-fold. Based on conserved motifs predicted folds could be classified as a hexosyl- and sialyltransferase. To analyze enzyme properties and interplay of the two identified glycosyltransferase domains, saturation transfer difference NMR and mutational studies were carried out. Simultaneous and independent binding of UDP-Gal and CMP-Sia was seen in the absence of an acceptor as well as when the catalytic cycle was allowed to proceed. Enzyme variants with only one functionality were generated by site-directed mutagenesis and shown to complement each other in trans when combined in an in vitro test system. Together the data strongly suggests that SiaDW-135 has evolved by fusion of two independent ancestral genes encoding sialyl- and galactosyltransferase activity.

[Emergence of W135 meningococcal serogroup in Chile during 2012]. / Emergencia de la cepa W135 causante de enfermedad meningocócica invasora en Chile 2012.

The epidemiologic behavior of the Invasive Meningococcal Disease (IMD) in Chile has changed. At the end of 2011, the W135 serogroup belonging to the hypervirulent clone ST-11 emerged. It affected diverse countries of the world, after the Mecca pilgrimage in 2000. In Chile, there have been 133 IMD cases during 2012. These figures represent an incidence of 0.7 per 100,000 inhabitants, which is 30% higher than expected. Eighty eight percent of cases were confirmed by the National Reference Laboratory at the Chilean Public Health Institute. The serogroup was determined in 103 strains and 58% belonged to the W135 serogroup, surpassing for the first time the B serogroup (37%). The Metropolitan Region concentrated 80% of these cases, and the remaining 20% affected other seven regions of the country. Forty seven percent of cases corresponded to children less than 5 years of age. The predominant clinical presentation of the W135 serogroup was a sepsis in 67% of cases. The fatality ratio of IDM during 2012 was 27%, the highest in the past 20 years. With this information, the Chilean Ministry of Health decreed a sanitary alert and implemented an integrated approach to control and prevent W-135 IDM, denominated "W-135 Action Plan".

An evaluation of the role of properdin in alternative pathway activation on Neisseria meningitidis and Neisseria gonorrhoeae.

Properdin, a positive regulator of the alternative pathway (AP) of complement is important in innate immune defenses against invasive neisserial infections. Recently, commercially available unfractionated properdin was shown to bind to certain biological surfaces, including Neisseria gonorrhoeae, which facilitated C3 deposition. Unfractionated properdin contains aggregates or high-order oligomers, in addition to its physiological "native" (dimeric, trimeric, and tetrameric) forms. We examined the role of properdin in AP activation on diverse strains of Neisseria meningitidis and N. gonorrhoeae specifically using native versus unfractionated properdin. C3 deposition on Neisseria decreased markedly when properdin function was blocked using an anti-properdin mAb or when properdin was depleted from serum. Maximal AP-mediated C3 deposition on Neisseriae even at high (80%) serum concentrations required properdin. Consistent with prior observations, preincubation of bacteria with unfractionated properdin, followed by the addition of properdin-depleted serum resulted in higher C3 deposition than when bacteria were incubated with properdin-depleted serum alone. Unexpectedly, none of 10 Neisserial strains tested bound native properdin. Consistent with its inability to bind to Neisseriae, preincubating bacteria with native properdin followed by the addition of properdin-depleted serum did not cause detectable increases in C3 deposition. However, reconstituting properdin-depleted serum with native properdin a priori enhanced C3 deposition on all strains of Neisseria tested. In conclusion, the physiological forms of properdin do not bind directly to either N. meningitidis or N. gonorrhoeae but play a crucial role in augmenting AP-dependent C3 deposition on the bacteria through the "conventional" mechanism of stabilizing AP C3 convertases.

Population structure and capsular switching of invasive Neisseria meningitidis isolates in the pre-meningococcal conjugate vaccine era--United States, 2000-2005.

BACKGROUND: A quadrivalent meningococcal conjugate vaccine (MCV4) was licensed in the United States in 2005; no serogroup B vaccine is available. Neisseria meningitidis changes its capsular phenotype through capsular switching, which has implications for vaccines that do not protect against all serogroups. METHODS: Meningococcal isolates from 10 Active Bacterial Core surveillance sites from 2000 through 2005 were analyzed to identify changes occurring after MCV4 licensure. Isolates were characterized by multilocus sequence typing (MLST) and outer membrane protein gene sequencing. Isolates expressing capsular polysaccharide different from that associated with the MLST lineage were considered to demonstrate capsular switching. RESULTS: Among 1160 isolates, the most common genetic lineages were the sequence type (ST)-23, ST-32, ST-11, and ST-41/44 clonal complexes. Of serogroup B and Y isolates, 8 (1.5%) and 3 (0.9%), respectively, demonstrated capsular switching, compared with 36 (12.9%) for serogroup C (P < .001); most serogroup C switches were from virulent serogroup B and/or serogroup Y lineages. CONCLUSIONS: A limited number of genetic lineages caused the majority of invasive meningococcal infections. A substantial proportion of isolates had evidence of capsular switching. The high prevalence of capsular switching requires surveillance to detect changes in the meningococcal population structure that may affect the effectiveness of meningococcal vaccines.

Phenotypic and molecular characterization of invasive serogroup W135 Neisseria meningitidis strains from 1990 to 2005 in Brazil.

OBJECTIVE: Neisseria meningitidis serogroup W135 has been associated with global outbreaks since the 2000 Hajj. Considering that N. meningitidis serogroup W135 is the third most prevalent serogroup isolated in Brazil in the last 10 years, and the possibility that the Hajj-related N. meningitidis serogroup W135 clone has been causing disease in Brazil, the present study characterized invasive N. meningitidis serogroup W135 isolates recovered in Brazil from 1990 to 2005. METHODS: The isolates were characterized by serotyping, PorA and PorB VR typing, FetA and 16S rRNA typing, multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE). RESULTS: Based on MLST, 73% of the isolates were clustered in one major clone of ST-11 complex/ET37 complex. Strains of this clone had the same STs, serotypes and PorA VR types as found in Hajj-related N. meningitidis serogroup W135 clone. One of these strains had the Hajj-2000 outbreak strain genotype, including 16S rRNA gene sequence 31 and 84% relatedness by PFGE. CONCLUSION: Taken together, these data suggest that the Hajj-related N. meningitidis serogroup W135 clone is present in Brazil but has not yet caused a substantial number of infections. Given the emergence of N. meningitidis serogroup W135 globally and the unpredictability of meningococcal disease epidemiology, continued surveillance for this invasive N. meningitidis serogroup W135 clone is needed for control and prevention strategies.

[Genotypic characteristics of Neisseria meningitidis serogroup W-135 strains isolated as the agent of fatal meningitis in a military hospital]. / Bir askeri hastanede fatal menenjit etkeni olarak izole edilen Neisseria meningitidis serogrup W-135 suslarinin genotipik özellikleri.

The aim of this study was to describe the genetic characterization of a total of 6 Neisseria meningitidis serogroup W-135 strains isolated from patients with meningitis and carriers in a military hospital in 2007-2008. Suspected colonies on modified Thayer-Martin medium plates were screened for oxidase reactivity and Gram stain. If gram-negative diplococci were present, a biochemical profile by the API NH system was used for species confirmation. Pulse field gel electrophoresis typing of Nhel-digested DNA was performed by a previously described method. Multi-locus sequence typing (MLST) was performed using the standard primers as listed on the Neisseria MLST website. Three distinct sequence types (STs) were identified: ST-11, ST-2754, ST-3751. One of the clinical isolates was identified as the same sequence type with Hajj isolate (ST-11) and the isolate with ST-2754 was the same as the first Turkish clinical strain isolated in 2003. These data demonstrated that along with ST-11 which is a known Hajj isolate, the ST-2754 strain causing meningococcal disease in Turkey beginning from the year 2003, should be carefully monitored.

[Molecular characters of epidemic cerebrospinal W135 Neisseria meningitidis strain firstly isolated in Guangdong province].

OBJECTIVE: To analyze the molecular characters of the W135 Neisseria meningitidis strain firstly isolated from patients in Guangdong province. METHODS: Biochemical profile by using the API NH system (bio-Merieux, France) was used for confirmation,and sero-grouping of the meningococcal isolates including one serogroup W135, one serogroup C and three serogroups of a Neisseria meningitidis isolated from patients in Guangdong province in recent two years were performed. The subtype was determined after amplifying porA and porB respectively from the genome DNA of Neisseria meningitidis. Multilocus sequence typing (MLST) was performed for determining the allele profiles and the sequence types (STs). The polygenetic tree was obtained by analyzing the allele profiles with program Splits tree online. The molecular characters of the serogroup W135 Neisseria meningitidis was analyzed by its evolution relationship and the variable regions in porA and porB which encoding the outer membranes proteins (OMPs). RESULTS: The subtype determined by porA variable regions of the serogroup W135 Neisseria meningitidis was P1.5,2, which was one of the most invasive types. The types of variable regions (VRs) I, IV, V, VII with porB were 1, 1, 1, 17, and there was no VI and VIII in porB. The allele profile of the W135 strain in this study was 2, 123, 4, 3, 8, 4, 6, and its sequence type was ST-2960, which belonged to ST-11/ET-37 clone complex. The subtypes of the serogroup C and serogroup A strains were P1.20, while their types of VR IV were all 7, and they all hadn't VR VII in porB. The strain serogroup C belonged to ST-4821 clone complex, and the 3 serogroup A strains belonged to ST-5 clone complex. CONCLUSION: The molecular character of the serogroup W135 Neisseria meningitidis should be the same with the strains isolated in foreign country, and be different from the epidemic types in the area. This serogroup W135 Neisseria meningitis isolated from patients in Guangdong for the first time was thought to be a new type appearing in the local area.

Meningococcal factor H-binding protein variants expressed by epidemic capsular group A, W-135, and X strains from Africa.

BACKGROUND: Meningococcal epidemics in Africa are generally caused by capsular group A strains, but W-135 or X strains also cause epidemics in this region. Factor H-binding protein (fHbp) is a novel antigen being investigated for use in group B vaccines. Little is known about fHbp in strains from other capsular groups. METHODS: We investigated fHbp in 35 group A, W-135, and X strains from Africa. RESULTS: The 22 group A isolates, which included each of the sequence types (STs) responsible for epidemics since 1963, and 4 group X and 3 group W-135 isolates from recent epidemics had genes encoding fHbp in antigenic variant group 1. The remaining 6 W-135 isolates had fHbp variant 2. Within each fHbp variant group, there was 92%-100% amino acid identity, and the proteins expressed conserved epitopes recognized by bactericidal monoclonal antibodies. Serum samples obtained from mice vaccinated with native outer membrane vesicle vaccines from mutants engineered to express fHbp variants had broad bactericidal activity against group A, W-135, or X strains. CONCLUSIONS: Despite extensive natural exposure of the African population, fHbp is conserved among African strains. A native outer membrane vesicle vaccine that expresses fHbp variants can potentially elicit protective antibodies against strains from all capsular groups that cause epidemics in the region.