Meningococcal serotypes and serogroup B disease in north-west Europe

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

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.

Cost-effectiveness of vaccination against meningococcal B among Dutch infants: Crucial impact of changes in incidence

OBJECTIVE

Recently, a vaccine with the capacity to protect against serogroup B meningococcal (MenB) disease received a positive opinion of the European Medicines Agency. Previously, such a vaccine was estimated to be cost-effective. However, since then, the MenB disease incidence has declined drastically in the Netherlands. Therefore, we re-assessed the potential incremental cost-effectiveness ratio (ICER) of vaccinating infants in the Netherlands with a MenB vaccine.

RESULTS

Routine infant vaccination (2, 3, 4+11 mo) could prevent 39 cases of MenB disease in a single birth cohort, corresponding to a total gain of 133 quality-adjusted life years (QALYs). However, this strategy is unlikely to be cost-effective if the vaccine costs €40 per dose (€243,778 per QALY). At a disease incidence of 5.7 per 100,000 person-years or a vaccine price of €10 per dose including administration costs, the ICER becomes more acceptable and remains below a threshold of €50,000 per QALY.

METHODS

A cohort of 185,000 Dutch newborns was followed in a Markov model to compare routine vaccination against MenB disease with no vaccination. The ICER was estimated for different disease incidences. The study was performed from a societal perspective.

CONCLUSIONS

At the current low level of disease incidence, introduction of routine infant vaccination, following a 2, 3, 4+11 mo schedule, against MenB disease is unlikely cost-effective in the Netherlands. If the MenB disease incidence increases or the vaccine price is substantially lower than €40, routine infant vaccination has the potential to be cost-effective.

Clonal analysis of Neisseria meningitidis serogroup B strains in South Africa, 2002 to 2006: emergence of new clone ST-4240/6688

From August 1999 through July 2002, hyperinvasive Neisseria meningitidis serogroup B (MenB) clonal complexes (CCs), namely, ST-32/ET-5 (CC32) and ST-41/44/lineage 3 (CC41/44), were predominant in the Western Cape Province of South Africa. This study analyzed MenB invasive isolates from a national laboratory-based surveillance system that were collected from January 2002 through December 2006. Isolates were characterized by pulsed-field gel electrophoresis (PFGE) (n = 302), and multilocus sequence typing (MLST) and PorA and FetA typing were performed on randomly selected isolates (34/302, 11%). In total, 2,400 cases were reported, with the highest numbers from Gauteng Province (1,307/2,400, 54%) and Western Cape Province (393/2,400, 16%); 67% (1,617/2,400) had viable isolates and 19% (307/1,617) were identified as serogroup B. MenB incidence remained stable over time (P = 0.77) (average incidence, 0.13/100,000 population [range, 0.10 to 0.16/100,000 population]). PFGE (302/307, 98%) divided isolates (206/302, 68%) into 13 clusters and 96 outliers. The largest cluster, B1, accounted for 25% of isolates (76/302) over the study period; its prevalence decreased from 43% (20/47) in 2002 to 13% (8/62) in 2006 (P < 0.001), and it was common in the Western Cape (58/76, 76%). Clusters B2 and B3 accounted for 10% (31/302) and 6% (19/302), respectively, and showed no significant change over time and were predominant in Gauteng. Randomly selected isolates from clusters B1, B2, and B3 belonged to CC32, CC41/44, and the new CC4240/6688, respectively. Overall, 15 PorA and 12 FetA types were identified. MenB isolates were mostly diverse with no single dominant clone; however, CC32 and CC41/44 accounted for 35% and the new CC4240/6688 was the third most prevalent clone.

Population snapshot of invasive serogroup B meningococci in South Africa from 2005 to 2008

In South Africa, serogroup B meningococcal disease is sporadic. The aim of this study was to characterize serogroup B strains causing invasive meningococcal disease (IMD) in South Africa from 2005 to 2008. Isolates, collected through a national, laboratory-based surveillance program for IMD, were characterized by multilocus sequence typing (MLST). Two thousand two hundred thirty-four cases were reported, of which 1,447 had viable isolates. Intermediate resistance to penicillin was observed in 2.8% (41/1,447) of all strains. Serogroup B was the second most common serogroup (17%, 251/1,447) and increased from 14% (58/414) in 2005 to 25% (72/290) in 2008 (P < 0.001); however, incidence remained stable during the study period (average incidence, 0.13/100,000 population) (P = 0.54). Serogroup B was predominantly characterized by three clonal complexes, namely, ST-41/44/lineage 3, ST-32/ET-5, and the new complex ST-4240/6688, which accounted for 27% (65/242), 23% (55/242), and 16% (38/242) of isolates, respectively. ST-4240/6688 was more prevalent among young children (<5 years) than other clonal complexes (27/37 [73%] versus 108/196 [55%]; P = 0.04). In the most densely populated province of South Africa, Gauteng, the prevalence of ST-32/ET-5 increased from 8% (2/24) in 2005 to 38% (9/24) in 2008 (P = 0.04). Capsular switching was observed in 8/242 (3%) strains. The newly assigned clonal complex ST-4240/6688 was more common in young children.

Vaccine herd effect

Vaccination ideally protects susceptible populations at high risk for complications of the infection. However, vaccines for these subgroups do not always provide sufficient effectiveness. The herd effect or herd immunity is an attractive way to extend vaccine benefits beyond the directly targeted population. It refers to the indirect protection of unvaccinated persons, whereby an increase in the prevalence of immunity by the vaccine prevents circulation of infectious agents in susceptible populations. The herd effect has had a major impact in the eradication of smallpox, has reduced transmission of pertussis, and protects against influenza and pneumococcal disease. A high uptake of vaccines is generally needed for success. In this paper we aim to provide an update review on the herd effect, focusing on the clinical benefit, by reviewing data for specific vaccines.

Invasive meningococcal disease in Malta: an epidemiological overview, 1994-2007

Since 1996, Malta has experienced an upsurge of invasive meningococcal disease (IMD) following an almost 30 year period with a negligible number of annually reported cases. We reviewed the 233 IMD cases notified during a 14 year period (1994-2007), and analysed epidemiological and laboratory surveillance data. The crude incidence per 100,000 inhabitants peaked in 2000 at 8.1 [95 % confidence interval (CI) 5.7-11.6] and again in 2006 at 8.9 (95 % CI 6.4-12.4), thereby placing Malta amongst the countries with the highest incidence of the disease in Europe. Of the total cases, 137 (59 %) were confirmed and 30 (13 %) were classified as probable. However, 66 cases (28 %) had no laboratory evidence of the disease and were classified as possible. Information on the serogroup was available for 114 cases. Serogroup B formed the largest proportion (76 %, n=87) followed by serogroup C (16 %, n=18). B : 4 : P1.19,15 strains (n=46) predominated throughout the study period since their first identification in 1998. With 28 deaths attributed to IMD, the overall case fatality rate was 12 %. Apart from stressing the importance of maintaining high vigilance for IMD, our findings underscore the importance of enhancing laboratory surveillance of the disease, including characterization of the meningococci. Until vaccines against a broad range of serogroup B meningococci become available for universal use, the main methods of control remain the early treatment of cases and the prevention of secondary cases.

Differential in vitro infectious abilities of two common Japan-specific sequence-type (ST) clones of disease-associated ST-2032 and carrier-associated ST-2046 Neisseria meningitidis strains in human endothelial and epithelial cell lines

The Japan-specific sequence type (ST) clones, as well as several major epidemic-prone clones such as ST-32, have been identified previously among Neisseria meningitidis isolates in Japan. In this study, the infectious properties of various ST clones, including the two common Japan-specific ones, were examined and compared by in vitro infection assays using human endothelial and epithelial cell lines. The known invasive clones, as well as the Japan-specific ST-2032 strains that were frequently isolated from patients, exhibited high infectious abilities in adherence and invasion. In contrast, the Japan-specific ST-2046 and ST-198 strains, both of which were frequently isolated from carriers in Japan, were less efficient in adherence and invasion. The expression of the bacterial surface molecules such as pilin, Opc, Opa and PilC, and the lipooligosaccharide structure, did not differ between disease-associated and carrier-associated isolates. These results suggest that in vitro infection assays may discriminate between disease-associated (patient-dominant) and carrier-associated (carrier-dominant) meningococcal ST clones. The ST-2032 clone showed the highest infectious activity in vitro, suggesting that it may possess some unidentified factors necessary for the infectious ability that were not present in the ST-2046 clone with the lowest infectious ability.

Declining incidence of meningococcal disease in Denmark, confirmed by a capture-recapture analysis for 1994 and 2002

Denmark has in the past 10 years experienced a decrease in the number of notified cases of meningococcal disease. In 1994 the completeness of the Notification System for Meningococcal Disease (NSMD) was estimated as 96% (95% CI 93-98). To answer the question whether the observed decrease reflects a real decrease in the incidence; we estimated the completeness of the notification system in 2002. We estimated the completeness of registration by a capture-recapture analysis. As the first data source, we used the national NSMD, which is an integrated surveillance system between the Department of Epidemiology and the Neisseria Reference Laboratory. The second independent source was the National Patient Registry (NPR). In 2002, the completeness of the NSMD was estimated as 96% (95% CI 95-98) and for the NPR as 84% (95% CI 82-85). The 'real' incidence rate was 1.9/100 000 population, which compared to 4.4/100 000 population in 1994. We concluded that the observed decrease in incidence rate is real. The NSMD in Denmark functions well and captures almost all cases of meningococcal disease. The complete registration which includes a unique personal identification number serves as an outstanding source for nationwide registry linkage studies.

Hospital-based surveillance of meningococcal meningitis in Salvador, Brazil

This study aimed to describe the clinical, epidemiological and microbiological features of meningococcal meningitis in Salvador, Brazil. Between February 1996 and January 2001, a hospital-based surveillance prospectively identified cases of culture-positive meningococcal meningitis. Demographic and clinical data were collected through interview and medical chart review. Antisera and monoclonal antibodies were used to determine the serogroup and serotype:serosubtype of the isolates, respectively. Surveillance identified a total of 408 cases of meningococcal meningitis, with a case fatality rate of 8% (32/397). The mean annual incidence for the 304 culture-positive cases residing in metropolitan Salvador was 1.71 cases per 100,000 population. Infants <1 year old presented the highest incidence (14.7 cases per 100,000 population). Of the 377 serogrouped isolates, 82%, 16%, 2% and 0.3% were serogroups B, C, W135 and Y, respectively. A single serotype:serosubtype (4,7:P1.19,15) accounted for 64% of all cases. Continued surveillance is necessary to characterise strains and to define future prevention and control strategies.

Neisseria meningitidis sequence type and risk for death, Iceland

Invasive meningococcal infections are hyperendemic in Iceland, a relatively isolated country in the mid-Atlantic. We performed a nationwide study on all viable meningococcal strains (N = 362) from 1977 to 2004. We analyzed the association of patient's age and sex, meningococcal serogroups, and sequence types (STs) with outcomes. Overall, 59 different STs were identified, 19 of which were unique to Iceland. The most common STs were 32 (24.6%), 11 (19.9%), and 10 (10.2%). The unique ST-3492 ranked fourth (7.7%). The most common serogroups were B (56.4%), C (39.8%), and A (2.2%). Age (p<0.001) and infection with a unique ST (p = 0.011) were independently associated with increased death rates, whereas isolation of meningococci from cerebrospinal fluid only was associated with lower death rates (p = 0.046). This study shows evolutionary trends of meningococcal isolates in a relatively isolated community and highlights an association between unique STs and poor outcome.

Towards an improved serogroup BNeisseria meningitidisvaccine

Meningococcal disease, presenting primarily as septicaemia and meningitis, continues to be a devastating problem around the world. Over the last century, vaccine development has been undertaken in earnest for the prevention of this disease. Polysaccharide vaccines have been available for almost 40 years, yet they are poorly immunogenic in young children who are at the highest risk. Since their introduction into some routine immunisation schedules in 1999, polysaccharide-protein conjugate vaccines for the prevention of serogroup C meningococcal infection have proven efficacious. A quadrivalent polysaccharide-protein conjugate vaccine against serogroups A, C, W135 and Y, which is being introduced in the US this year, is hoped to control disease caused by these serogroups. To date, however, the development of a universally safe, immunogenic and effective serogroup B Neisseria meningitidis vaccine has remained a challenge. This review details the many conventional vaccine strategies and the more recent genome-derived technological approaches being used in serogroup B vaccine development. The future prevention of serogroup B disease will rely on both outer membrane vesicle vaccines being used for serosubtype-specific outbreaks and new vaccines containing multiple other antigens. Investment by the pharmaceutical industry in preclinical research and development provides hope that an efficacious serogroup B meningococcal vaccine can be developed.

Characterization of Neisseria meningitidis isolates collected from 1974 to 2003 in Japan by multilocus sequence typing

Analysis of 182 Neisseria meningitidis strains isolated over the past 30 years in Japan by serogroup typing and multilocus sequence typing (MLST) was performed. The serogroups of the 182 Japanese isolates were B (103 isolates), Y (39), W135 (1) and non-groupable (39). By MLST analysis, 65 different sequence types (ST) were identified, 42 of which were not found in the MLST database as of January 2004 and seemed to be unique to Japan. Statistical analysis of the MLST results revealed that, although the Japanese isolates seemed to be genetically divergent, they were classified into six major clonal complexes and other minor complexes. Among these isolates, well-documented ST complexes found worldwide were present, such as ST-23 complex (49 isolates), ST-44 complex (41 isolates) and ST-32 complex (8 isolates). On the other hand, a new clonal complex designated ST-2046 complex (28 isolates), which has not been identified in other countries, was also found, suggesting that this clone was indigenous to Japan. Taken together, it was speculated that meningococcal isolates in Japan comprised heterogeneous clones, which were derived both from clones identified in other countries and clones unique to Japan.

Phylogenetic Evidence for Frequent Positive Selection and Recombination in the Meningococcal Surface Antigen PorB

Previous estimates of rates of synonymous (d(S)) and nonsynonymous (d(N)) substitution among Neisseria meningitidis gene sequences suggested that the surface loops of the variable outer membrane protein PorB were under only weak selection pressure from the host immune response. These findings were consistent with studies indicating that PorB variants were not always protective in immunological and microbiological assays and questioned the suitability of this protein as a vaccine component. PorB, which is expressed at high levels on the surface of the meningococcus, has been implicated in mechanisms of pathogenesis and has also been used as a typing target in epidemiological investigations. In this work, using more precise estimates of selection pressures and recombination rates, we have shown that some residues in the surface loops of PorB are under very strong positive selection, as great as that observed in human immunodeficiency virus-1 surface glycoproteins, whereas amino acids within the loops and the membrane-spanning regions of the protein are under purifying selection, presumably because of structural constraints. Congruence tests showed that recombination occurred at a rate that was not sufficient to erase all phylogenetic similarity and did not greatly bias selection analysis. Homology models of PorB structure indicated that many strongly selected sites encoded residues that were predicted to be exposed to host immune responses, implying that this protein is under strong immune selection and requires further examination as a potential vaccine candidate. These data show that phylogenetic inference can be used to complement immunological and biochemical data in the choice of vaccine candidates.

Development of vaccines against meningococcal disease

Neisseria meningitidis is a major cause of bacterial meningitis and sepsis. Polysaccharide-protein conjugate vaccines for prevention of group C disease have been licensed in Europe. Such vaccines for prevention of disease caused by groups A (which is associated with the greatest disease burden worldwide), Y, and W135 are being developed. However, conventional approaches to develop a vaccine for group B strains, which are responsible for most cases in Europe and the USA, have been largely unsuccessful. Capsular polysaccharide-based vaccines can elicit autoantibodies to host polysialic acid, whereas the ability of most non-capsular antigens to elicit broad-based immunity is limited by their antigenic diversity. Many new membrane proteins have been discovered during analyses of genomic sequencing data. These antigens are highly conserved and, in mice, elicit serum bactericidal antibodies, which are the serological hallmark of protective immunity in man. Therefore, there are many promising new vaccine candidates, and improved prospects for development of a broadly protective vaccine for group B disease, and for control of all meningococcal disease.

Inducible nitric oxide synthase expression in gastroduodenal diseases infected with Helicobacter pylori

BACKGROUND

Nitric oxide (NO) is synthesized enzymatically from L-arginine by NO synthase, which is measured by inducible NO synthase (iNOS). Helicobacter pylori (H. pylori) infection produces a state of chronic immunostimulation in the gastric epithelium. Infection with cagA+ H. pylori has greater degree of gastric inflammation and epithelial cell damage. Therefore, we compared the levels of iNOS in patients with H. pylori infection in relation to cagA status and H. pylori-related disease.

MATERIALS AND METHODS

One hundred and seven patients, including 51 patients with gastric cancer, 12 patients with gastric ulcer, 18 patients with duodenal ulcer and 26 patients with chronic gastritis, were enrolled in this study. Biopsies from the antrum and body were obtained for histologic examination, culture and reverse transcriptionase-PCR (RT-PCR) for detection of iNOS gene expression. The presence of H. pylori was confirmed by Giemsa staining or culture and the gene expression of cagA in H. pylori isolates was confirmed by PCR.

RESULTS

H. pylori infection was detected in 70.1% (75/107) and cagA was detected in 84.8% (28/33). iNOS expression was detected in 49.5% (53/107) and there was no significant difference in iNOS expression according to H. pylori infection nor the cagA status in the gastroduodenal diseases. However, iNOS expression was more frequently detected in gastric cancer than the other H. pylori-related diseases (64.7% vs. 35.7%, p <.05).

CONCLUSION

Although NO was thought be involved in the gastric carcinogenesis, the level of NO production was not related to H. pylori infection or cagA status.

Crystal structure of an Fab fragment in complex with a meningococcal serosubtype antigen and a protein G domain

Many pathogens present highly variable surface proteins to their host as a means of evading immune responses. The structure of a peptide antigen corresponding to the subtype P1.7 variant of the porin PorA from the human pathogen Neisseria meningitidis was determined by solution of the X-ray crystal structure of the ternary complex of the peptide (ANGGASGQVK) in complex with a Fab fragment and a domain from streptococcal protein G to 1.95 A resolution. The peptide adopted a beta-hairpin structure with a type I beta-turn between residues Gly4P and Gly7P, the conformation of the peptide being further stabilised by a pair of hydrogen bonds from the side-chain of Asn2P to main-chain atoms in Val9P. The antigen binding site within the Fab formed a distinct crevice lined by a high proportion of apolar amino acids. Recognition was supplemented by hydrogen bonds from heavy chain residues Thr50H, Asp95H, Leu97H and Tyr100H to main-chain and side-chain atoms in the peptide. Complementarity-determining region (CDR) 3 of the heavy chain was responsible for approximately 50 % of the buried surface area formed by peptide-Fab binding, with the remainder made up from CDRs 1 and 3 of the light chain and CDRs 1 and 2 of the heavy chain. Knowledge of the structures of variable surface antigens such as PorA is an essential prerequisite to a molecular understanding of antigenic variation and its implications for vaccine design.

Analysis of the human Ig isotype response to lactoferrin binding protein A from Neisseria meningitidis

An effective vaccine for serogroup B meningococci has yet to be developed and attention has turned to subcapsular antigens of the meningococcus as possible vaccine candidates. Iron binding proteins are being studied, with most interest focused on the transferrin binding proteins (TbpA and TbpB) and the ferric binding protein (FbpA). This study describes the purification of lactoferrin binding protein A (LbpA) from two meningococcal strains and assesses the human isotype-specific serum antibody response to these proteins in patients with proven meningococcal disease due to a range of phenotypes. Overall, fewer than 50% of sera contained IgG that recognised LbpA isolated from either strain and this antibody response was not uniform between the two proteins. There was some evidence that the antibody response varied between meningococcal phenotypes. This study demonstrates that LbpA does not induce a highly cross-reactive antibody response, indicating that it is unlikely to be an effective vaccine antigen.

The infant rat model adapted to evaluate human sera for protective immunity to group B meningococci

The infant rat infection model previously developed to evaluate protective ability of passively administered murine antibodies to group B meningococcal (MenB) surface antigens was adapted for human sera. Several challenge doses were tested, aiming at sensitive detection of protection with little interassay variability. Doses of 10(5) and 10(6) colony forming units of strain IH5341 (MenB:15:P1.7,16) injected intraperitoneally gave consistently high levels of bacteremia and meningitis developed in 6 h in 50-100% of the pups. A monoclonal antibody mAb735 to the MenB capsule, injected 1-2 h before bacterial challenge, gave full protection at a dose of 2 microg/pup. Sera from adult volunteers immunized with a MenB outer membrane vesicle vaccine reproducibly reduced bacterial counts in the blood and cerebrospinal fluid, whereas a normal human serum, lacking bactericidal and opsonophagocidal activity, was unprotective.

Recrudescence and relapse of meningococcal meningitis and septicaemia

Three cases of recrudescence and relapse of Neisseria meningitidis group B meningitis and septicaemia are reported. The recrudescence and relapses could not be explained by infectious foci, increased bacterial penicillin resistance or immunological defects. As a supplement to antibiotic treatment, all three patients received corticosteroids for the initial 2 days of treatment, and this may have contributed to the unusual course of the disease in our patient.

Serotypes and subtypes of Neisseria meningitidis: results of an international study comparing sensitivities and specificities of monoclonal antibodies

An international study supported by the World Health Organization comparing monoclonal antibodies for serotyping and serosubtyping of Neisseria meningitidis strains was performed and the results were assessed in 1992. A collection of 6 serotype-specific (1, 2a, 2b, 4, 14, and 15) and 12 serosubtype-specific (P1.1, P1.2, P1.4, P1.5, P1.6, P1.7, P1.9, P1.10, P1.12, P1.14, P1.15, and P1.16) monoclonal antibodies was provided to 11 participating laboratories throughout the world. Monoclonal antibodies were tested on 85 Neisseria meningitidis strains with known reference results. Whole-cell enzyme-linked immunosorbent assay was used for analysis in 10 of 11 laboratories. The sensitivities and specificities of individual serotype- and subtype-specific monoclonal antibodies were evaluated. Differences in individual laboratories and with individual monoclonal antibodies were assessed. Relatively large differences in sensitivities were achieved in individual laboratories. On the contrary, the specificities remained at high levels in all laboratories. The sensitivities of serotype-specific monoclonal antibodies ranged from 72.0 to 100%. Individual serosubtype-specific monoclonal antibodies showed sensitivities ranging from 64.1 to 98.1%. The most frequent reason for the incorrect results obtained with the monoclonal antibodies were false-negative results. The collaborative study demonstrated that some monoclonal antibodies are not very sensitive. Another study to define the most suitable monoclonal antibodies is planned.

Characterization of strains of Neisseria meningitidis recovered from complement-sufficient and complement-deficient patients in the Western Cape Province, South Africa

Complement deficiency has been associated with increased susceptibility to meningococcal disease. In order to determine whether special meningococcal strains caused disease in complement-deficient (CD) patients, 17 Neisseria meningitidis strains recovered from patients in the Western Cape Province, South Africa, known to be CD were compared with 124 routine isolates obtained from patients living in the same area. Serogrouping of the strains from the CD subjects revealed that the common serogroups, particularly serogroup B, predominated. However, the prevalence of rare serogroups among isolates from CD subjects was significantly higher than that found among isolates from the control group. Sero- and subtyping of the class 1 and class 2 or 3 outer membrane proteins showed no significant difference between isolates from CD subjects and the routine clinical isolates. Multilocus enzyme electrophoresis of the 141 isolates revealed six clusters of electrophoretic types (ETs) and two unrelated ETs. The same degree of genetic diversity existed in ETs of isolates from CD subjects and the control group. However, the ET-5 complex, which is known to be associated with epidemic disease, was found in 22 (18%) of the routine clinical isolates but in none of the isolates from the CD subjects. This difference was marginally significant. What was highly significant was the finding that 8 of the 17 isolates from CD subjects were in one ET cluster, cluster F, which comprised a total of 20 isolates. Thus, our results show a difference in the clonal compositions of the strains that infect CD subjects in comparison with the clonal compositions of those that cause clinical infections in the population at large.

Serotype and serosubtype distribution of strains of Neisseria meningitidis isolated in South Australia and the Northern Territory of Australia: 1971-1989

Strains of meningococci isolated from patients in South Australia (SA) and the Northern Territory (NT) with either bacteremia or meningitis (or both) were serotyped and serosubtyped using monoclonal antibodies in a whole cell ELISA technique. From SA, 144 isolates were examined for the period 1971 through 1989 and from the NT, 38 isolates from 1975 through 1977 and 1983 through 1989 were examined. During the periods of study the principal serogroups were group B in South Australia and group A in the Northern Territory. About 60% of the SA strains were typable and subtypable: the predominant types were 4, 2a, 15 and 14, in that order; the predominant subtypes were P1.2, P1.1 and P1.10, in that order. Of the strains from the NT about 80% were typable, the predominant type was type 4 and all 19 group A strains were identified as type 4, subtype P1.10.

Molecular characterization of rifampin-resistant Neisseria meningitidis

Primers were designed to amplify the rpoB gene of Neisseria meningitidis. The region of the gene amplified covered clusters I and II of the rifampin resistance (Rifr) mutation sites identified in Escherichia coli. DNAs from six Rifr isolates and 21 rifampin-susceptible isolates from the United Kingdom representing a number of serogroups were amplified and sequenced. All six Rifr isolates had identical DNA sequences and the same amino acid change, a His to an Asn change at position 35 (H35N). This His residue is equivalent to the His residue at position 526 in E. coli, one of the known Rifr mutation sites. DNAs from an additional six Rifr mutations generated in vitro were amplified and sequenced. Three had H35Y changes, one had an H35R change, one had an H35N change and one had an S40F change. The predominance of mutations at the His residue at position 35 in Rifr N. meningitidis isolates suggests that it plays a critical role in the selection of antibiotic-resistant variants. All six Rifr isolates belonged to the same clonal group when analyzed by restriction enzyme analysis and pulsed-field gel electrophoresis. These data suggest that a single clone of Rifr N. meningitidis is present and widespread throughout the United Kingdom.

Group B meningococcal meningitis in India

The first case of infection with Group B meningococcus in India is reported. The patient was a 4-month-old boy who presented with meningitis and died within 6 h of admission. Gram stain of CSF showed meningococci and latex particle agglutination test on CSF was strongly positive for Neisseria meningitidis serogroup B. The CSF was also positive for meningococcus by polymerase chain reaction using primers NM1 and NM6, which amplify a 650 bp region of the dihydropteroate synthase (dhps) gene of N. meningitidis.

Prognostic factors in meningococcal disease and a new scoring system

One-hundred-and-forty patients diagnosed as having meningococcal disease have been investigated retrospectively with respect to prognostic factors. The overall mortality was 8.6%, the mortality rate of the infants under 6 months of age being higher than that of the other groups. In cases where there was no meningitis or leucocytosis, the presence of hypotension, disturbed consciousness and diffuse petechiae increased the mortality rate significantly. High fever did not have any effect on mortality. We propose a new practical and reliable scoring system for meningococcal disease for determining the influence of prognostic factors on mortality.

Expression of meningococcal epitopes in LamB of Escherichia coli and the stimulation of serosubtype-specific antibody responses

The class 1 outer membrane protein (OMP), a major variable surface antigen of Neisseria meningitidis, is a component of novel meningococcal vaccines currently in field trials. Serological variants of the protein are also used to serosubtype meningococci. Most of the amino acid changes that give rise to antigenic variants of the protein occur in two variable regions (VR1 and VR2) that are thought to form loops on the cell surface. The polymerase chain reaction (PCR) was used to amplify the nucleotide sequences encoding VR1 and VR2 from the chromosomal DNA of N. meningitidis strain M1080. These were cloned in frame into the lamB gene of the Escherichia coli expression vector pAJC264. Whole-cell enzyme-linked immunosorbent assays (ELISAs), using monoclonal antibodies, and SDS-PAGE confirmed that, upon induction, strains of E. coli carrying these constructs expressed hybrid LamB proteins containing the N. meningitidis surface loops. These strains were used to immunize rabbits and the resultant polyclonal antisera reacted specifically with the class 1 OMP of reference strain M1080 (P1.7). Immunogold labelling of meningococcal cells and whole-cell dot-blot analyses with these antisera showed that the variable epitopes were exposed on the cell surface and confirmed that this approach could be used to obtain serosubtype-specific antisera. The binding profiles of the antisera were determined from their reactions with overlapping synthetic peptides and their reactivity compared with that of relevant serosubtype-specific monoclonal antibodies. This approach was used successfully to raise antisera against two other class 1 OMP VR2s. A fourth antiserum raised against a VR2, including the P1.1 epitope, was not subtype specific.

Epidemic meningococcal meningitis in central Australia, 1987-1991

OBJECTIVE

To describe an outbreak of meningococcal meningitis and the impact of rifampicin chemoprophylaxis on secondary attack rates among Aboriginal people in central Australia.

DESIGN

Prospective study of patients admitted to hospital between September 1987 and May 1991.

SETTING

The Alice Springs Health Region of the Northern Territory and the Anangu Pitjantjatjara Lands of South Australia, covering a population of 13,228 Aboriginal people.

SUBJECTS

Patients admitted to the Alice Springs Hospital with clinical signs or autopsy findings of meningococcal disease. Rifampicin chemoprophylaxis was given to close contacts of all cases. Mencevax AC vaccine was offered to children aged 1 to 15 years in the Region.

MAIN OUTCOME MEASURES

Blood or cerebrospinal fluid (CSF) with Neisseria meningitidis, or a positive result of latex agglutination testing on CSF. Positive isolates were serogrouped.

RESULTS

Seventy-seven cases of meningococcal disease were diagnosed in Aboriginal people over four years compared with one to two cases per year previously; of these, 60 were definite, 7 probable and 10 suspected cases. Seventy-six subjects had meningitis, of whom one also had the clinical features of meningococcal septicaemia; one other subject had positive blood cultures with a mild febrile illness without features of meningitis. The annual attack rate of meningococcal disease in the Aboriginal population was 1.6/1000. The relative risk for secondary cases was estimated to be between 0.3 (95% confidence interval [CI], 0.09-0.92) and 0.5 (95% CI, 0.15-1.53). The annual attack rate in the non-Aboriginal population was 0.04/1000.

CONCLUSIONS

The epidemic closely resembled those in sub-Saharan Africa, and in socioeconomically marginalised groups in developed countries. The relative risk for secondary cases was lower than generally reported, and was attributed to chemoprophylaxis for close contacts and the mass vaccination program for children. Until there are major improvements in living conditions, infectious diseases such as those transmitted by airborne droplets will continue to occur in Aboriginal communities.

Comparative studies on pharyngeal carriage of Neisseria meningitidis during a localized outbreak of serogroup C meningococcal disease

An outbreak involving 20 cases of serogroup C meningococcal disease, predominantly among teenagers, occurred over a 7-month period in the Randers area of Denmark. The cases were caused by serogroup C:2a:P1.2 sulphonamide-resistant strains. The available evidence was against the transmission being related to particular schools. The outbreak was experienced as 3 clusters. At 2 schools involved in the first and the third cluster of the outbreak, 351 students were examined regarding pharyngeal carriage of meningococci, 282 of whom were tested again 17 weeks later; 308 students attending two similar schools in a nearby area were examined once. The majority of strains isolated from group C carriers in the high-risk area were serologically indistinguishable from the outbreak strain (13/14 = 95%), but less often sulphonamide-resistant (5/13 = 38%). In both areas, the overall rate (30%), the overall group C rate (3%), the carrier rate for the outbreak strain (1%) were the same. The attack rate for the outbreak strain differed significantly: 1/40 in the high-risk area versus 1/2,500 in the normal risk area. No conditions that might explain this difference were revealed. Immediately after recognition of the first and the third cluster, 780 and 13,300 students, respectively, were vaccinated with meningococcal polysaccharide vaccine A+C. It was concluded that the definition of target groups for vaccination should be liberal, because the "at risk" population may be difficult to recognize at the onset of an outbreak.

Phylogenetic and epidemiological analysis of Neisseria meningitidis using DNA probes

The genetic relationships between various serotypes and serogroups of meningococcal strains were investigated by restriction fragment-length polymorphism (RFLP) analysis using a number of random DNA probes and a probe containing a truncated copy of the meningococcal insertion sequence IS1106. The data were used to estimate genetic distance between all pairs of strains and to construct phylogenetic trees for meningococcal strains. B15:P1.16R strains isolated from cases of systemic meningococcal disease in two health districts with a high incidence of disease were clonal in contrast to similar strains from cases occurring in other parts of the UK. Strains from these areas, which contain a similar genomic deletion, were found to be derived from two distinct lineages within the B15:P1.16R phylogenetic group. RFLP data demonstrated that present serological typing systems for the meningococcus do not necessarily reflect true genetic relationships.

Identification of meningococcal serosubtypes by polymerase chain reaction

The polymerase chain reaction was used as the basis of a novel typing method for Neisseria meningitidis. Southern hybridization experiments demonstrated that it was possible to identify genes encoding different serological variants of the meningococcal class 1 outer membrane protein by probing with polymerase chain reaction products corresponding to known epitopes. A set of 14 defined variable regions was prepared in bacteriophage M13mp19 by the cloning of polymerase chain reaction products. The phage were dot blotted onto membrane filters, which were used as targets for hybridization of radiolabeled amplified class 1 outer membrane protein genes. Thus, the presence of many different subtype-specific epitopes could be investigated in one experiment. This technique was evaluated with a set of serological reference strains, mainly of serogroup B organisms, and provided an alternative, rapid, and comprehensive typing system that was capable of distinguishing known serosubtypes and also of defining currently untypeable strains independently of sodium dodecyl sulfate-polyacrylamide gel electrophoresis or serological analysis. An additional advantage of this technique was that in the case of an unknown serosubtype (i.e., one that did not hybridize with any of the known samples), the DNA amplified from the original sample could be used to determine the nucleotide sequence of the novel serosubtype and to clone the corresponding variable region into bacteriophage M13. It may be possible to develop this procedure for the diagnostic detection and typing of meningococci directly from clinical samples even when culture is not possible because of antibiotic treatment of an acute case.

Meningococcal disease in Wales: clinical features, outcome and public health management

In Wales, in 1988, 119 patients with meningococcal disease were identified, so giving a crude annual incidence of 4.2 patients per 100,000 population. The combined classical clinical features of fever, vomiting, neck stiffness, headache and purpuric rash were identified in only 9% of patients. Fever and vomiting were the commonest symptoms, both being present in 60% of patients. A rash was noted in 77% of patients but neck stiffness in only 39%. Rash was more common in children, headache and photophobia in adults. A total of 13 patients died, the fatality rare increasing with age from 3% in infants to 20% in older teenagers and adults. Only 15% of 75 patients admitted to hospital by general practitioners were known to have received intravenous or intramuscular penicillin before admission as recommended by the Chief Medical Officers of the Health Departments in the U.K. Only 24% of patients received rifampicin to clear nasopharyngeal carriage before or at discharge from hospital. Altogether, 375 household contacts of patients were identified. At least 84% of them received chemoprophylaxis.

The lipooligosaccharide immunotype as a virulence determinant in Neisseria meningitidis

We have studied the antigenic (immunotype) and physical characteristics of the lipooligosaccharide (LOS) of epidemiologically related Neisseria meningitidis case (36) and carrier (76) isolates associated with a virulent clone of meningococci (ET-5 complex). LOS immunotypes were determined by dot blotting using immunotype specific monoclonal antibodies and physical characteristics were determined from silver stained SDS-PAGE following proteinase K digestion. The genetic similarity of the different isolates was confirmed by analysis of the restriction fragment length polymorphisms. An association between LOS immunotype expression and invasive disease was found; 97% of case isolates expressed the L3,7,9 immunotype, of which 13% additionally expressed the L1,8,10 determinant. The LOS immunotypes of carrier strains were much more heterogeneous. The predominant immunotype was L1,8,10 (70%) and only 24% expressed L3,7,9 alone. Genotypically related case isolates from Norway (6) and Austria (18) expressed the L3,7,9 immunotype with similar frequency to the U.K. isolates. The combination of LOS immunotype and capsule expression appears to be related to the virulence of these meningococcal strains.

Identification and characterization of a novel insertion sequence, IS1106, downstream of the porA gene in B15 Neisseria meningitidis

Examination of Neisseria meningitidis strains associated with endemic meningococcal disease demonstrated differences in the number of copies of a repetitive sequence. Characterization of a copy of this repetitive sequence present in B15 strains has revealed the presence of a novel insertion sequence (IS1106) located within a complex repetitive region downstream of the gene for the major surface antigen (porA). IS1106 has a length of 1137 bp and is flanked by 36bp inverted repeats. Two open reading frames (ORF1 and ORF2) are present in opposite strands in codon-codon register with ORF2 entirely located within ORF1. The predicted protein from ORF1 demonstrates homology with the 5A protein of IS5 (Kroger and Hobom, 1982). Strains from two independent outbreaks of B15 meningococcal disease in the UK were found to contain the same genomic deletion removing a copy of IS1106 downstream of the porA gene.

Antibiotic sensitivities of Neisseria meningitidis isolates from patients and carriers in Greece

Usage of antibiotics in southern Europe is less well regulated than in northern countries. The proportion (48%) of meningococci in Spain insensitive to pencillin (MIC greater than or equal to 0.1 mg/l) prompted this investigation of antibiotic sensitivities of isolates from Greek patients with meningitis (31) and carriers (47 school-children and 472 recruits). The agar dilution method was used to determine MIC to penicillin G (PN), sulphamethoxazole (SU), rifampicin (RF), cefaclor (CF) and ciprofloxacin (CP). The proportion of isolates insensitive to PN was 48% for isolates from patients, 19% from school-children and 36.6% from recruits. Resistance to SU (MIC greater than or equal to 16 mg/l) was found in 16% of those from patients, 10.6% from children and 40% from recruits. None of the isolates from patients was resistant to RF (greater than or equal to 1 mg/l) but 6% of those from carriers were. Resistance to CF (greater than or equal to 4 mg/l) was found in 9.2% of patient isolates, 6.4% from children and 23.7% from recruits. All isolates except one were sensitive to CP (MIC range less than 0.0015-0.125 mg/l). Resistances to PN, SU and RF were analysed by serogroup, serotype and subtype of the bacteria. The proportion of resistant isolates showed some variation between different areas of Greece, but it was not statistically significant.

Carriage of Neisseria species in communities with different rates of meningococcal disease

A single clone, Neisseria meningitidis serogroup C (C:2a:P1.2), was isolated from seven patients during a cluster of cases of meningococcal disease in Ontario in 1989. To determine whether the clone was present in asymptomatic individuals in the same population, pharyngeal swabs were taken from 7% (644 of 9125) of residents who were vaccinated during the outbreak. Rates of isolation of Neisseria species were also compared to those in two other geographical areas which did not have an elevated incidence of meningococcal disease. The rate of carriage of N meningitidis in the asymptomatic individuals sampled was between 1.9% and 5.4%. The clone isolated from patients was not present among the carrier strains as determined by sero- and subtyping and electrophoretic analysis of metabolic enzymes. Age greater than six years was the only factor associated with colonization with N meningitidis.

An outbreak of serogroup B:15:P1.16 meningococcal disease, Frederiksborg County, Denmark, 1987-9

Epidemiological features of an outbreak of group B:15:P1.16 meningococcal disease (MD) in Frederiksborg county, Denmark, 1987-9, were investigated. The study comprised 149 cases notified during the outbreak and the two preceding years; 115 were confirmed by the isolation of Neisseria meningitidis. In 1989 the incidence had increased to 14.1 per 100,000 population. Among group B strains, B:15:P1.16 accounted for 80% (77/97). The overall mortality rate was 10% (15/149). Regarding cases due to group B:15:P1.16 strains a significant time-space clustering, which exclusively occurred within the 10-19 years age group, was demonstrated. The link between cases within clusters was indirect or unknown, except for ten patients with contact to one particular school. The prophylactic measures used included administration of rifampicin to household contacts. During the outbreak the proportion of secondary cases was high (6-15%). All secondary cases occurred outside the household indicating that the household had been protected.

ELISA test for antimeningococcal IgG and IgM antibodies: application to epidemiology and diagnosis

We have developed an enzyme-linked immunosorbent assay (ELISA) in order to quantitate antimeningococcal IgM and IgG serum antibodies. The B:15 meningococcal strain was used as coating antigen, and class specific antibodies were detected by using alkaline phosphatase labelled rabbit anti-human IgM or IgG as conjugate. The specific IgG activity was higher in sera from healthy meningococcal carriers than non-carriers, but the difference was not statistically significant. Antimeningococcal IgM serum antibodies were more frequent in carriers that in non-carriers. Acute sera from 34 patients with fulminant meningococcal disease contained less specific IgG and had a higher prevalence of IgM than healthy carriers and non-carriers. By combining measurement of antimeningococcal IgG and IgM antibodies in both acute and convalescent sera 15/18 meningococcal patients demonstrated an increase in either IgG and IgM antibodies during the hospital stay, giving a sensitivity of 83%. 8/118 individuals without meningococcal disease had detectable specific IgM antibodies in their serum, giving a clinical specificity of the test of 93%. We conclude that quantitation of specific IgG antimeningococcal antibodies by a whole bacteria ELISA test may be a useful test for the study of immunity against meningococcal disease in single individuals as well as in epidemiological studies. The combined use of the IgG and IgM tests is helpful in the diagnosis of meningococcal disease when blood or cerebrospinal fluid cultures are negative.

Incidence, serogroups and case-fatality rate of invasive meningococcal infections in a Swedish region 1975-1989

In a retrospective study of invasive meningococcal infections in Greater Gothenburg, Sweden, 213 cases of culture-verified meningitis or septicaemia were identified during the 15-year period 1975-1989. The annual incidence was 2.0/100,000. Cases were seen in all age-groups with the highest rates in the 0-4 and 15-19 year-old groups, 9.5 and 6.2/100,000 respectively. 20% of the patients were less than 2 years. 91% of the patients had no known risk factors. In only 10 cases (5%) was contact with another case of meningococcal infection known. The main clinical manifestations were meningitis (57%), septicaemia with no sign of focal infection (25%) and septic shock (17%). The case-fatality rate for all the patients was 6.6% and did not change during the 15-year period. One-third of the patients who presented with septic shock died. The serogroup was known for strains from 192 patients. 51% of the strains belonged to serogroup B, 10% to group A and 23% to group C. In conclusion, the incidence of meningococcal infection was low but the relatively high case-fatality rate warrants a search for effective prophylaxis. About 30% of the cases were potentially preventable by the currently available tetravalent (A, C, Y and W135) polysaccharide vaccine, which is immunogenic in children greater than 2 years. Widespread use of antibiotic prophylaxis to close contacts of known cases would not lower the incidence markedly.

Antibodies to poly[(2----8)-alpha-N-acetylneuraminic acid] and poly[(2----9)-alpha-N-acetylneuraminic acid] are elicited by immunization of mice with Escherichia coli K92 conjugates: potential vaccines for groups B and C meningococci and E. coli K1

Meningitis and other systemic infections caused by group B Neisseria meningitidis and Escherichia coli K1 remain important problems. The capsular polysaccharides (CPs) of these pathogens (poly[(2----8)-alpha-N-acetylneuraminic acid] or poly(alpha 2-8NeuNAc] are identical and are virulence factors and protective antigens for both. CP vaccines for these pathogens are not available because poly(alpha 2-8NeuNAc) alone, as a complex or a conjugate, is poorly immunogenic. Because oligomers of poly(alpha 2-8NeuNAc) in fetal brain and other tissues bind antibodies in vitro, it has been suggested that antibodies to this CP might be pathologic. We synthesized conjugates of this CP with tetanus toxoid under conditions that avoid lactone formation. Using this scheme, we also synthesized conjugates of group C meningococcal CP (poly[(2----9)-alpha-N-acetylneuraminic acid] or poly(alpha 2-9NeuNAc] and of E. coli K92 CP [poly(alpha 2-8, alpha 2-9NeuNAc)]. When injected s.c. in saline into mice, conjugates of poly(alpha 2-8NeuNAc) or poly(alpha 2-9NeuNAc) elicited homologous antibodies. E. coli K92 conjugates elicited both poly(alpha 2-8NeuNAc) and poly(alpha 2-9NeuNAc) antibodies. Both components of the conjugates expressed T-dependent immunologic properties under conditions and dosages acceptable for clinical evaluation. Poly(alpha 2-8NeuNAc) antibodies elicited by the homologous or the K92 conjugates had lower binding activities at 37 degrees C than at 22 degrees C. "Natural" poly(alpha 2-8NeuNAc) antibodies were present in almost all matched pairs of human maternal and cord sera; most cord levels were higher than in corresponding maternal sera. These findings suggest that increased levels of poly(alpha 2-8NeuNAc) IgG antibodies elicited by our conjugates will confer protective immunity to group B meningococci and E. coli K1 and will not be pathologic.

Pharyngeal carriage of Neisseria meningitidis and Neisseria lactamica in households with infants within areas with high and low incidences of meningococcal disease

In a household survey in the Faroe Islands, an isolated community with hyperendemic occurrence of meningococcal disease due to serogroup B 15, 1604 persons were examined for pharyngeal carriage of Neisseria meningitidis and N. lactamica. Two areas were chosen having experienced high (HIA), and two having experienced low incidences (LIA) of disease. Living in HIA compared with LIA was associated with higher risk of N. meningitidis B 15 carriage and lower risk of N. lactamica carriage, with odds ratios of 2.7 (95% confidence interval (CI) 1.4-5.1, P = 0.003) and 0.41 (95% CI 0.31-0.53, P less than 0.0001), respectively. In HIA the risk of N. meningitidis carriage was much lower in non-carriers than carriers of N. lactamica, with an odds ratio of 0.19 (95% CI 0.08-0.47, P = 0.0003); in LIA this association (odds ratio 0.51, P = 0.05) was much weaker. Children 0-14 years had substantially higher risk of being carriers of N. meningitidis group B 15 if the mothers were so, with an odds ratio of 11 (95% CI 4-29, P less than 0.0001).

A change in meningococcal serogroups in the west of Ireland?

Admission of patients to University College Hospital, Galway over a five month period commencing December 1989 indicates an increase in the incidence of Neisseria Meningitidis Serogroup C. Seven cases of Group CN. Meningitidis have been identified, five of them occurring over a four week period. A review of Meningococcal isolates occurring at this hospital over eleven years since 1979 shows, serogroup B as the predominant serogroup. Thirty-six isolates identified by serogrouping shows the distribution of serogroups as follows: Serogroup B 69.4%, Serogroup C 19.4%, Serogroup A 8.3%, Serogroup Z 2.7%. Serogrouping, and when available, further serotyping of meningococcal isolates is very important in order to follow epidemiological trends in the disease and to monitor the serogroups that cause outbreaks. This information can influence measures that can be taken in the prevention of spread of the disease as for example the use of vaccination as appropriate.

Point mutation in meningococcal por A gene associated with increased endemic disease

The por A gene, which encodes expression of meningococcal class 1 outer membrane protein, responsible for antigenic subtype specificity, has been cloned and sequenced in an isolate of Neisseria meningitidis (B:15:P1.7,16) from a patient in the Gloucester area with meningococcal meningitis. Comparison of the sequence with that of the equivalent gene from the P1.7,16 reference strain reveals a point mutation which generates a single aminoacid change in the epitope responsible for P1.16 specificity. Monoclonal antibodies with P1.16 specificity do not react with synthetic peptides that correspond to the altered epitope, and do not promote complement-mediated bactericidal killing of the isolate. Analysis of other strains shows widespread distribution of infections due to B:15:P1.7,16 meningococci with the altered epitope (P1.16b) in England and Wales.