Clinical presentation of invasive disease caused by Neisseria meningitidis serogroup Y in Sweden, 1995 to 2012.

Over the period 1995-2012, the incidence of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y (NmY) increased significantly in Sweden. This is mainly due to the emergence of a predominant cluster named strain type YI subtype 1, belonging to the ST-23 clonal complex (cc). The aim of this study was to examine the clinical picture of patients with invasive disease caused by NmY and to analyse whether the predominant cluster exhibits certain clinical characteristics that might explain the increased incidence. In this retrospective observational study, the medical records available from patients with IMD caused by Nm serogroup Y in Sweden between 1995 and 2012 were systematically reviewed. Patient characteristics, in-hospital findings and outcome were studied and differences between the dominating cluster and other isolates were analysed. Medical records from 175 of 191 patients were retrieved. The median age was 62 years. The all-cause mortality within 30 days of admission was 9% (15/175) in the whole material; 4% (2/54) in the cohort with strain type YI subtype 1 and 11% (12/121) among patients with other isolates. Thirty-three per cent of the patients were diagnosed with meningitis, 19% with pneumonia, 10% with arthritis and 35% were found to have bacteraemia but no apparent organ manifestation. This survey included cases with an aggressive clinical course as well as cases with a relatively mild clinical presentation. There was a trend towards lower mortality and less-severe disease in the cohort with strain type YI subtype 1 compared with the group with other isolates.

Genomic Analysis of Serogroup Y Neisseria meningitidis Isolates Reveals Extensive Similarities Between Carriage-Associated and Disease-Associated Organisms.

BACKGROUND: Neisseria meningitidis is a frequent colonizer of the human nasopharynx, with asymptomatic carriage providing the reservoir for invasive, disease-causing strains. Serogroup Y (MenY) strains are a major cause of meningococcal disease. High-resolution genetic analyses of carriage and disease isolates can establish epidemiological relationships and identify potential virulence factors. METHODS: Whole-genome sequence data were obtained for 99 MenY carriage isolates recovered in the United Kingdom during 1997-2010. Sequences were compared to those of 73 MenY invasive isolates recovered during 2010-2011, using a gene-by-gene approach. RESULTS: Comparisons across 1605 core genes resolved 91% of isolates into one of 8 clusters containing closely related disease and carriage isolates. Six clusters contained carried meningococci isolated during 1997-2001, suggesting temporal stability. One cluster of isolates, predominately sharing the designation Y: P1.5-1,10-1: F4-1: ST-1655 (cc23), was resolved into one subcluster with 86% carriage isolates and a second with 90% invasive isolates. These subclusters were defined by specific allelic differences in 5 core genes encoding glycerate kinase (glxK), valine-pyruvate transaminase (avtA), superoxide dismutase (sodB), and 2 hypothetical proteins. CONCLUSIONS: High-resolution genetic analyses detected long-term temporal stability and temporally overlapping carriage and disease populations for MenY clones but also evidence of a disease-associated clone.

Genome-Based Characterization of Emergent Invasive Neisseria meningitidis Serogroup Y Isolates in Sweden from 1995 to 2012.

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y has increased in Europe, especially in Scandinavia. In Sweden, serogroup Y is now the dominating serogroup, and in 2012, the serogroup Y disease incidence was 0.46/100,000 population. We previously showed that a strain type belonging to sequence type 23 was responsible for the increased prevalence of this serogroup in Sweden. The objective of this study was to investigate the serogroup Y emergence by whole-genome sequencing and compare the meningococcal population structure of Swedish invasive serogroup Y strains to those of other countries with different IMD incidence. Whole-genome sequencing was performed on invasive serogroup Y isolates from 1995 to 2012 in Sweden (n = 186). These isolates were compared to a collection of serogroup Y isolates from England, Wales, and Northern Ireland from 2010 to 2012 (n = 143), which had relatively low serogroup Y incidence, and two isolates obtained in 1999 in the United States, where serogroup Y remains one of the major causes of IMD. The meningococcal population structures were similar in the investigated regions; however, different strain types were prevalent in each geographic region. A number of genes known or hypothesized to have an impact on meningococcal virulence were shown to be associated with different strain types and subtypes. The reasons for the IMD increase are multifactorial and are influenced by increased virulence, host adaptive immunity, and transmission. Future genome-wide association studies are needed to reveal additional genes associated with serogroup Y meningococcal disease, and this work would benefit from a complete serogroup Y meningococcal reference genome.

Meningococcal serogroup Y lpxL1 variants from South Africa are associated with clonal complex 23 among young adults.

OBJECTIVES: To determine the genotypes of serogroup Y meningococcus (MenY), and to determine the prevalence of and identify factors associated with MenY lpxL1 variants. METHODS: Isolates, collected from 2003 to 2007 through national surveillance for invasive meningococcal disease, were characterized by multilocus sequence typing and screened for interleukin-6 induction. LpxL1 genes were sequenced from low IL-6 inducers. RESULTS: MenY represented 13% (n = 219/1702) of meningococcal disease. Clonal complex (cc) 175, ST-23/Cluster A3 (cc23), cc11 and cc167 accounted for 82% (176/214), 11% (24/214), 3% (6/214) and 3% (7/214) respectively. Low cytokine induction was evident in 15% (32/218). Cc23 isolates (24/24) had an lpxL1 mutation, while among the remaining isolates the proportion of lpxL1 variants was 4% (8/189, p < 0.001), and these were all cc175. Compared to wild type isolates, lpxL1 variants were associated with patients aged 5-14 years [unadjusted OR (95% CI): 4.3 (1.5-12)] or 15-24 years [unadjusted OR (95% CI): 9.1 (2.8-29)] compared to children <5 years; and were more likely have been isolated from CSF than blood [unadjusted OR (95% CI): 3.5 (1-11.9)]. On multivariable analysis, age remained significant [adjusted OR (95% CI), 5-14 years: 4.2 (1.5-12); 15-24 years: 8.9 (2.7-29)]. CONCLUSION: LpxL1 variants were associated with cc23 among young adults.

Whole genome sequencing to investigate the emergence of clonal complex 23 Neisseria meningitidis serogroup Y disease in the United States.

In the United States, serogroup Y, ST-23 clonal complex Neisseria meningitidis was responsible for an increase in meningococcal disease incidence during the 1990s. This increase was accompanied by antigenic shift of three outer membrane proteins, with a decrease in the population that predominated in the early 1990s as a different population emerged later in that decade. To understand factors that may have been responsible for the emergence of serogroup Y disease, we used whole genome pyrosequencing to investigate genetic differences between isolates from early and late N. meningitidis populations, obtained from meningococcal disease cases in Maryland in the 1990s. The genomes of isolates from the early and late populations were highly similar, with 1231 of 1776 shared genes exhibiting 100% amino acid identity and an average π(N)  =  0.0033 and average π(S)  =  0.0216. However, differences were found in predicted proteins that affect pilin structure and antigen profile and in predicted proteins involved in iron acquisition and uptake. The observed changes are consistent with acquisition of new alleles through horizontal gene transfer. Changes in antigen profile due to the genetic differences found in this study likely allowed the late population to emerge due to escape from population immunity. These findings may predict which antigenic factors are important in the cyclic epidemiology of meningococcal disease.

Invasive meningococcal capsular group Y disease, England and Wales, 2007-2009.

Enhanced national surveillance for invasive meningococcal disease in England and Wales identified an increase in laboratory-confirmed capsular group Y (MenY) disease from 34 cases in 2007 to 44 in 2008 and 65 in 2009. For cases diagnosed in 2009, patient median age at disease onset was 60 years; 39% of patients had underlying medical conditions, and 19% died. MenY isolates causing invasive disease during 2007-2009 belonged mainly to 1 of 4 clonal complexes (cc), cc23 (56% of isolates), cc174 (21%), cc167 (11%), and cc22 (8%). The 2009 increase resulted primarily from sequence type 1655 (cc23) (22 cases in 2009, compared with 4 cases each in 2007 and 2008). cc23 was associated with lpxL1 mutations and meningitis in younger age groups (<25 years); cc174 was associated with nonmeningitis, particularly pneumonia, in older age groups (>65 years). The increase in MenY disease requires careful epidemiologic and molecular monitoring.

Molecular characterization of invasive serogroup Y Neisseria meningitidis strains isolated in the Latin America region.

OBJECTIVES: To improve the understanding of serogroup Y invasive meningococcal disease (IMD) in Latin America, particularly IMD molecular epidemiology; 166 Y serogroup isolates received at the National Reference Laboratories of Argentina, Brazil, Chile, Colombia, and Costa Rica during 2000-2006 were characterized by their molecular markers. METHODS: This analysis included serological assays to determine serogroup/serotype/serosubtype, DNA sequencing and genotyping of the porB and/or porA genes, multilocus sequence typing (MLST) and fetA allele determination. RESULTS: Sixteen different antigenic combinations were observed. Sixty-two (37.3%) isolates were NT:P1.5 and 36 (21.7%) isolates were 14:NST. Thirty-two different STs appeared, but 3 STs (ST-1624, ST-23, and ST-5770) accounted for 69.9% (116) of the strains. Most of the IMD isolates belonged to the ST-23, ST-167 clonal complexes or the group composed by ST-5770 and related STs. CONCLUSIONS: Isolates obtained in Colombia and Costa Rica were similar to that of the United States, in that most sequence types belonged to the ST-23 clonal complex. IMD isolates found in Argentina appear to be the result of an independent event and did not spread from nearby countries, being the sequence type ST-1624 (ST-167 clonal complex) the most frequently found. We were unable to correlate an antigenic shift of outer membrane proteins with an increase of serogroup Y meningococcal cases in our collection of isolates.

Annual report of the Australian Meningococcal Surveillance Programme, 2007.

In 2007 there were 242 laboratory-confirmed cases of invasive meningococcal disease analysed by the National Neisseria Network, a nationwide network of reference laboratories. The phenotypes (serogroup, serotype and serosubtype) and antibiotic susceptibility of 127 isolates of Neisseria meningitidis from invasive cases of meningococcal disease were determined and an additional 115 cases were confirmed by non-culture based methods. Nationally, 192 (85%) confirmed cases where a serogroup was determined were infected with serogroup B and 14 (6.2%) with serogroup C meningococci. The total number of confirmed cases was 29 fewer than the 271 cases identified in 2006. The only jurisdiction to record a substantial increase in laboratory confirmed cases was New South Wales and this was in sporadic cases of serogroup B infection. Typical primary and secondary disease peaks were observed in those aged 4 years or less and in adolescents and young adults respectively. Serogroup B cases predominated in all age groups and jurisdictions. The common phenotypes circulating in Australia were B:15:P1.7, B:4:P1.4 and C:2a:P1.5. No evidence of meningococcal capsular 'switching' was detected. About three-quarters of all isolates showed decreased susceptibility to the penicillin group of antibiotics (minimum inhibitory concentration [MIC] 0.06-0.5 mg/L). All isolates remained susceptible to rifampicin. A single serogroup B isolate had decreased susceptibility to ciprofloxacin (MIC 0.06 mg/L). This was the first local isolate of this type since the original report of this phenomenon in Australia in 2000.

Serological and genetic characterization of meningococcal isolates in Korea.

Meningococcal disease has been regarded as a very rare infection in Korea. Until now, there have been no reports on the serological or genetic characterization of Neisseria meningitidis isolates in Korea. This study was the first report of the serogroup, PorA VR subtype, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and antimicrobial susceptibility of N. meningitidis isolates collected from 2002 to 2003. Of 11 meningococcal isolates, serogroup Y was found to be the most frequent (nine isolates). In addition, one isolate was from serogroup B and one was from serogroup 29E. Four isolates showed a reduced sensitivity to penicillin G. However, all strains tested were susceptible to chloramphenicol, cefotaxime, ciprofloxacin, and rifampin. Among the 11 isolates, seven PorA types were identified. P1.5-1, 2-2 was the most prevalent PorA type, accounting for 55.6% of the serogroup Y isolates. In terms of PFGE patterns, nine isolates of serogroup Y were divided into three clusters, but the isolates shared a high level of PFGE pattern similarity. The serogroup Y isolates were characterized as ST-1625 (five strains) and ST-23 (four). They belonged to the ST-23 complex/Cluster A3. In this study, the ST-23 complex/Cluster A3 was prevalent, with the PorA type P1.5-1, 2-2 accounting for 55.6% of the nine serogroup Y strains. Also, we identified the hypervirulent lineage strain such as ST-6667 of ST-41/44 complex/Lineage 3 in Korea. The results of this study show the need for comprehensive epidemiological surveillance to monitor any changes in the meningococcal disease situation so that prompt intervention can be initiated.

Characterization of invasive serogroup Y meningococci in Italy: prevalence of ST-23 Complex/Cluster A3.

The percentage of Neisseria meningitidis serogroup Y isolated from patients with invasive meningococcal disease (IMD) in Italy has increased from 1998 to 2006. In this study, phenotypic features and genetic relatedness have been investigated in all serogroup Y meningococci isolated during that period. Multilocus sequence typing (MLST) identified the ST-23 complex/Cluster A3 as the major clonal complex in 88.8% of the strains. That complex included all strains belonging to the sequence type (ST) 23 isolated from 1998 to 2004, whereas the ST-3171 was prevalent among strains in the years 2005 and 2006. The STs 23 and 3171 differ for only one nucleotide in the phosphoglucomutase (pgm) housekeeping gene. Over 80% of serogroup Y ST-23 complex/Cluster A3 strains showed phenotype Y:14:NST and 85% of the latter resulted indistinguishable by pulsed-field gel electrophoresis analysis. In 2005, serogroup Y meningococci with decreased susceptibility to penicillin were isolated for the first time in Italy. In the following year, three of the seven strains showed this phenotype. The results of this study allow us to draw a profile of the molecular characteristics of invasive serogroup Y in Italy and will be helpful to monitor the spread of this serogroup in the next years.

Genetic and antigenic analysis of invasive serogroup Y Neisseria meningitidis isolates collected from 1999 to 2003 in Canada.

One hundred forty serogroup Y Neisseria meningitidis isolates recovered from patients with invasive meningococcal disease (IMD) in Canada from 1999 to 2003 were analyzed by genetic and serological methods. Seventy-four isolates (52.9%) belonged to serotype 2c, and most have serosubtype antigen P1.5,2 (37 isolates, 26%) or P1.5 (31 isolates, 22%). Forty-eight isolates (34.3%) belonged to serotype 14 and have serosubtype antigen P1.5,2 (13 isolates, 9%) or P1.5 (7 isolates, 5%) or were nonserosubtypeable (27 isolates, 19%). Thirteen isolates (9.3%) were nonserotypeable. Multilocus sequence typing identified two unrelated clonal populations of serogroup Y meningococci causing invasive disease in Canada: ST-23 and ST-167 clonal complexes. Almost all ST-167-related isolates were typed as 2c:P1.5, while strains of the ST-23 clonal complex were either serotype 14 or 2c but with the serosubtype antigen P1.5,2. In contrast to previous reports that patients with serogroup Y disease are usually older, 26% of the Canadian serogroup Y cases were found in the 10-to-19-year-old age group and another 11% were in the 20-to-39-year-old age group.

Consecutive use of two multiplex PCR-based assays for simultaneous identification and determination of capsular status of nine common Neisseria meningitidis serogroups associated with invasive disease.

We developed two Neisseria meningitidis multiplex PCR assays to be used consecutively that allow determination of the serogroup and capsular status of serogroup A, B, C, 29E, W135, X, and Y cnl-3/cnl-1-like-containing N. meningitidis isolates by direct analysis of the amplicon size. These assays offer a rapid and simple method of serogrouping N. meningitidis.

Assignment of Neisseria meningitidis serogroups A, C, W135, and Y anticapsular total immunoglobulin G (IgG), IgG1, and IgG2 concentrations to reference sera.

Meningococcal serogroup-specific immunoglobulin G (IgG), IgG1, and IgG2 concentrations were assigned to three reference sera, CDC 1992, 89-SF, and 96/562, for meningococcal serogroups A, C, Y, and W135 via the method of cross standardization. The sum of the serogroup-specific IgG1 and IgG2 concentrations determined for the four meningococcal serogroups showed good agreement with the serogroup-specific IgG either determined here or as previously represented. Following the assignment of meningococcal serogroup-specific IgG1 and IgG2 concentration to these reference sera, a meningococcal serogroup-specific IgG1 and IgG2 enzyme-linked immunosorbent assay protocol was developed. The serogroup A and C specific subclass distribution of a panel of adult sera collected following vaccination with any combination of meningococcal serogroup C conjugate, bivalent, or tetravalent polysaccharide vaccines was determined. For the determination of serogroup W135 and Y specific subclass distribution, an adolescent panel 28 days following a single dose of either tetravalent polysaccharide or conjugate vaccine was used. The sum of the serogroup-specific IgG1 and IgG2 showed strong correlation with the serogroup-specific total IgG determined. The assignment here of IgG1 and IgG2 subclasses to these reference sera will allow more detailed evaluation of meningococcal conjugate and polysaccharide vaccines.

Identification of Neisseria meningitidis serogroups Y and W135 by siaD nucleotide sequence analysis.

Rapid serogrouping of meningococci is essential for the effective public health management of cases of the disease and the contacts of infected patients. Here we describe an accurate nucleotide-sequencing method for the confirmation of serogroup Y and W135 meningococci by siaD gene analysis from cultures of Neisseria meningitidis.

5' exonuclease assay for detection of serogroup Y Neisseria meningitidis.

The incidence of serogroup Y meningococcal disease has increased recently in the United States. Here, we describe the development of a 5' exonuclease assay for the detection of serogroup Y Neisseria meningitidis and demonstrate the usefulness of this assay for resolving serogroup identification of strains that are resistant to conventional serogrouping and for the nonculture identification of serogroup Y meningococcal disease.