Molecular characteristics of Neisseria meningitidis strains isolated in Burkina Faso in 2001

In the course of an epidemic of meningitis in Burkina Faso in 2001, 27 cerebrospinal fluid samples from patients in 7 districts were forwarded to Norway for isolation and characterization of the causative agents. Neisseria meningitidis was isolated from 13 (48%) samples. The isolates were analysed using serological and genetic methods. Of the 13 strains, 4 were serogroup A, serotype 21:P1.9, sequence type (ST)-5 and belonged to clonal subgroup III, while the remaining 9 strains were serogroup W135, serotype 2a:P1.5,2, ST-11 and belonged to the electrophoretic type-37 complex. PCR analyses revealed meningococcal DNA in 13/14 culture-negative samples. Sequence analysis of the PCR products demonstrated that at least 3 different meningococcal strains were responsible for these 13 cases. Our results show that the W135 strain associated with the 2000 hajj (Muslim pilgrimage) outbreak was a significant cause of disease in Burkina Faso in 2001. Further studies are warranted to determine whether W135 is about to replace serogroup A in sub-Saharan Africa.     

Molecular characteristics and susceptibility to antibiotics of serogroup A Neisseria meningitidis strains isolated in Senegal in 1999

A total of 22 strains of Neisseria meningitidis isolated from cerebrospinal fluid samples of patients in Dakar, Senegal, in the course of an epidemic of meningococcal meningitis in 1999 were studied. All the strains were serogroup A, serotype 21:P1.9 and belonged to clonal subgroup III-1. The strains were resistant to sulphonamide, but were susceptible to ampicillin, ceftriaxone and chloramphenicol, which are used in the treatment of cerebrospinal meningitis in Senegal.     

Neisseria meningitidis serogroups A and W-135: carriage and immunity in Burkina Faso, 2003

OBJECTIVES: We sought to describe Neisseria meningitidis immunity and its association with pharyngeal carriage in Burkina Faso, where N. meningitidis serogroup W-135 and serogroup A disease are hyperendemic and most of the population received polysaccharide A/C vaccine during 2002. METHODS: We collected oropharyngeal swab samples from healthy residents of Bobo-Dioulasso (4-14 years old, n=238; 15-29 years old, n=250) monthly during February-June 2003; N. meningitidis isolates were analyzed using polymerase chain reaction and serogrouped using immune sera. Serum samples were collected at the first and last clinic visit and analyzed for anti-A, anti-C, anti-W-135, and anti-Y immunoglobulin G (IgG) concentrations and anti-A and anti-W-135 bactericidal titers. RESULTS: N. meningitidis was carried at least once by 18% of participants; this carriage included strains from serogroups W-135 (5%) and Y and X (both <1%) but not from serogroups A, B, or C. At baseline, the prevalence of putatively protective specific IgG concentrations (> or =2 microg/mL) and bactericidal titers (> or =8) was 85% and 54%, respectively, against serogroup A, and 6% and 22%, respectively, against serogroup W-135. Putatively protective anti-W-135 IgG concentrations and bactericidal titers were of short duration and were not associated with carriage. CONCLUSION: N. meningitidis serogroup W-135 strains did not induce immunity, despite their circulation. Carriage of serogroup A strains was rare despite the hyperendemic incidence of serogroup A meningitis during 2003 in Bobo-Dioulasso. A vaccine that includes serogroup W-135 antigen and eliminates serogroup A carriage is needed for sub-Saharan Africa.     

2006～2010年湖北省流行性脑脊髓膜炎病原学和血清学监测分析

目的分析湖北省2006～2010年流行性脑脊髓膜炎(流脑)病原学和血清学监测结果,掌握湖北省流脑的变迁规律。方法对2006～2010年分离的脑膜炎奈瑟菌(Nm)菌株进行生化鉴定、血清学分型和药物敏感性检测,并采用多位点序列分型(MLST)和脉冲场凝胶电泳(PFGE)方法进行分子分型;对所有的脑脊液和血液标本进行Nm种属特异性荧光PCR检测;对健康人群血清,运用血清杀菌试验(SBA)进行C群杀菌力抗体水平测定。结果 2007年湖北省Nm以B群为主,2008～2010年以来C群为优势菌群;对青霉素等6种抗生素均敏感,但对环丙沙星、米诺环素、萘啶酸、复方新诺明4种抗生素出现多重耐药;分子分型结果显示,湖北省B群Nm菌株具有高度的遗传多样性,未发现明显优势的克隆群,C群优势病原株为ST-4821型。RT-PCR检测(988份脑脊液)确诊29例流脑病例,其中C群22例,A群2例、B群5例。C群杀菌力总保护率(抗体滴度≥1︰8)为38.10%。结论湖北省流脑菌株发生了从B群散发到C群流行的变迁,人群对C群Nm的免疫力不足。     

Prospective study of a serogroup X Neisseria meningitidis outbreak in northern Ghana

After an epidemic of serogroup A meningococcal meningitis in northern Ghana, a gradual disappearance of the epidemic strain was observed in a series of five 6-month carriage surveys of 37 randomly selected households. As serogroup A Neisseria meningitidis carriage decreased, an epidemic of serogroup X meningococcal carriage occurred, which reached 18% (53/298) of the people sampled during the dry season of 2000, coinciding with an outbreak of serogroup X disease. These carriage patterns were unrelated to that of Neisseria lactamica. Multilocus sequence typing and pulsed-field gel electrophoresis of the serogroup X bacteria revealed strong similarity with other strains isolated in Africa during recent decades. Three closely related clusters with distinct patterns of spread were identified among the Ghanian isolates, and further microevolution occurred after they arrived in the district. The occurrence of serogroup X outbreaks argues for the inclusion of this serogroup into a multivalent conjugate vaccine against N. meningitidis.     

Nasopharyngeal carriage of Neisseria meningitidis in general population and meningococcal disease

Nasopharyngeal carriage of Neisseria meningitidis was determined in the normal healthy population in Delhi at monthly intervals for a period of 2 years from January, 1986 to December, 1987. Of a total of 6513 individuals screened only 107 (1.64 per cent) were found to carry Neisseria meningitidis serogroup A. There was no age and sex difference in carriage. During the same period, data of laboratory confirmed cases of meningitis due to N. meningitidis serogroup A was obtained from 6 hospitals of Delhi which acted as sentinel centres. Of the total 11,870 pyogenic C.S.F. samples processed, only 557 (4.69 per cent) were due to N. meningitidis serogroup A. There was no correlation observed between the nasopharyngeal meningococcal carriage in the healthy population with the disease prevalence. There was no seasonal variation in nasopharyngeal carriage though upsurge in the number of meningococcal meningitis cases was noticed from January to April.     

Epidemiological patterns of meningococcal meningitis in Niger in 2003 and 2004: under the threat of N. meningitidis serogroup W135

Since the Neisseria meningitidis serogroup W135 epidemic in Burkina Faso in 2002, the neighbouring countries dread undergoing outbreaks. Niger has strongly enhanced the microbiological surveillance, especially by adding the polymerase chain reaction (PCR) assay to the national framework of the surveillance system. During the 2003 epidemic season, 8113 clinically suspected cases of meningitis were notified and nine districts of the 42 crossed the epidemic threshold, while during the 2004 season, the number of cases was 3521 and four districts notified epidemics. In 2003 and 2004, serogroup A was identified in most N. meningitidis from cerebrospinal fluid (CSF) specimens (89.7% of 759 and 87.2% of 406, respectively). Although serogroup W135 represented only 8.3% of the meningococcal meningitis in 2003 and 7.9% in 2004, and was not involved in outbreaks, it was widespread in various areas of the country. In the regions that notified epidemics, the proportion of serogroup W135 was tiny while it exceeded 40% in several non-epidemic regions. Despite the wide distribution of W135 serogroup in Niger and the fears expressed in 2001, the threat of a large epidemic caused by N. meningitidis W135 seems to have been averted in Niger so far. There is no clear indication whether this serogroup will play a lasting role in the epidemiology of meningococcal meningitis or not. As early as in the 1990s, a significant but transient increase in the incidence of N. meningitidis serogroup X was observed. Close microbiological surveillance is crucial for monitoring the threat and for identifying at the earliest the serogroups involved in epidemics.     

ST2859 serogroup A meningococcal meningitis outbreak in Nouna Health District, Burkina Faso: a prospective study

We analysed cerebrospinal fluid samples from suspected meningitis cases in Nouna Health District, Burkina Faso, during the meningitis seasons of 2004-2006. Serogroup A ST2859 meningococci belonging to the ST5 clonal complex of subgroup III meningococci were the predominant causative agent. ST2859 bacteria were associated with focal outbreaks in the north of the district. While >10% of the population of an outbreak village carried ST2859, the population in the south of the district was predominantly colonised by serogroup Y ST4375 meningococci, which were associated with only sporadic cases of meningitis. Colonisation with the less virulent Y meningococci may interfere with the spread of the ST2859 to the south of the district, but there are concerns that this serogroup A clone may cause a third wave of subgroup III meningococcal disease in the African Meningitis Belt.     

Antibodies against IgA1 protease are stimulated both by clinical disease and asymptomatic carriage of serogroup A Neisseria meningitidis.

IgA1 protease was purified from a strain of serogroup A Neisseria meningitidis subgroup IV-1, representative of bacteria that caused an epidemic of meningococcal meningitis in The Gambia in 1982-1983. ELISAs and immunoblot assays were done using this protease as antigen with paired acute- and convalescent-phase sera from patients from that epidemic and from one in Finland caused by other serogroup A meningococci. Paired sera were also tested from healthy Gambians who were persistent nasopharyngeal carriers, persistent noncarriers, or persons who became carriers after the first serum sample was taken. The results correlated well between the two methods: Antibodies were stimulated by disease or acquisition of carriage, and they remained at a constant level upon continued carriage.     

Outbreaks of serogroup X meningococcal meningitis in Niger 1995-2000

In the African meningitis belt, the recurrent meningococcal meningitis epidemics are generally caused by serogroup A. In the past 20 years, other serogroups have been detected, such as X or W135, which have caused sporadic cases or clusters. We report here 134 meningitis cases caused by Neisseria meningitidis serogroup X that occurred in Niamey between 1995 and 2000. They represented 3.91% of the meningococcal isolates from all CSF samples, whereas 94.4% were of serogroup A. Meningococcal meningitis cases were detected using the framework of the routine surveillance system for reportable diseases organized by the Ministry of Public Health of Niger. The strains were isolated and determined by the reference laboratory for meningitis in Niamey (CERMES) and further typed at the WHO collaborating center of the Pharo in Marseille and at the National Reference Center for the Meningococci at the Institut Pasteur. Reference laboratories in Marseille and Paris characterized 47 isolates having the antigenic formula (serogroup:serotype:sero-subtype) X:NT:P1.5. Meningitis cases due to meningococcus serogroup X did not present any clinical or epidemiological differences to those due to serogroup A. The seasonal incidence was classical; 93.3% of the cases were recorded during the dry season. The mean age of patients was 9.2 years (+/- 6 years). The sex ratio M/F was 1.3. Case fatality rate was 11.9% without any difference related to age or sex. The increasing incidence of the serogroup X was not related to the decrease of serogroup A, but seemed cyclic, and evolved independently of the recurrence of both serogroups A and C.     

PCR identification of the group A Neisseria meningitidis gene in cerebrospinal fluid

The aim of this study was to develop a PCR method for direct identification of Neisseria meningitidis serogroup A in cerebrospinal fluid. The assay makes use of unique sites within the gene cassette responsible for expression of the (alpha1 --> 6)-linked N-acetyl-D-mannosamine-1-phosphate serogroup A capsule. A total of 67 different N. meningitidis strains and 12 clinical samples of CSF, culture positive for N. meningitidis, were examined. All the strains and samples of N. meningitidis serogroup A were correctly identified by an amplified PCR product of 519 bp. The PCR method for identification is specific for the group A gene of N. meningitidis. The assay may contribute to reducing recurrent, devastating epidemics of meningococcal infection by providing a diagnostic tool for grouping in developing countries where problems with false negative cultures are common and vaccination against serogroup A meningococci may be required.     

Mutator clones of Neisseria meningitidis in epidemic serogroup A disease

Serogroup A Neisseria meningitidis has repeatedly caused widespread epidemics of meningitis and septicemia throughout the 20th century. Recently, in a limited collection of strains, epidemic serogroup A isolates were found to have elevated mutation rates that was caused by defects in mismatch repair pathways. To ascertain the role of these mutators in the epidemic spread of this serogroup, the prevalence of hypermutability in a collection of 95 serogroup A N. meningitidis invasive isolates was determined. Overall mutability in Neisseriae can be described by measuring both missense mutation rates as well as phase variation frequencies of "contingency loci." Fifty-seven percent of serogroup A isolates possessed elevated mutability, which could be divided into two classes: intermediate and high level. Eleven of 20 high-level mutators, with phase variation rates >100-fold higher than wild-type isolates, were defective in mismatch repair. Ten of the 34 intermediate mutators possessing >10-fold increases in phase variation rates could be partially complemented by a wild-type mutL allele. A high prevalence of mutators in epidemic isolates indicates that hypermutability may play a major role in the transmission of this pathogen. The added diversity derived from increased phase variation rates may allow fixation of mutator alleles more frequently during epidemic spread.     

Another Swedish family with complete properdin deficiency: association with fulminant meningococcal disease in one male family member

Inherited deficiency of the complement component properdin is described in a Swedish family without any previous history of meningococcal infections. The properdin-deficient index patient died from a fulminant infection caused by Neisseria meningitidis serogroup Y. Family investigation revealed properdin deficiency in the patient's half-brother and in the maternal grandfather. The half-brother had a history of pneumococcal pneumonia and meningitis probably caused by Borrelia burgdorferi. Opsonic and bactericidal functions of serum were examined in the half-brother after immunization with tetravalent meningococcal vaccine. Vaccination promoted opsonization of N. meningitidis serogroups C and Y but not of serogroups A and W-135. The serum bactericidal activity increased against serogroup C and to some extent against serogroup W-135. This report emphasizes the importance of investigating the complement system even in families with single cases of fulminant meningococcal disease. Individuals with properdin deficiency might be protected from infection by immunization.     

A comparison of the variable antigens expressed by clone IV-1 and subgroup III of Neisseria meningitidis serogroup A.

Serogroup A Neisseria meningitidis of subgroup III has caused two pandemics of meningococcal meningitis since 1966 and recently spread to East Africa. The last epidemics in West Africa in the early 1980s were caused by clone IV-1. Surface antigens of clone IV-1 strains from West Africa and subgroup III strains from both pandemic waves were analyzed. Lipopolysaccharide was stable within clone IV-1 but variable in subgroup III. Pili from clone IV-1 possessed class I epitopes, while those from subgroup III also possessed class IIa epitopes. Certain class 5 protein variants were expressed by both bacterial clones, possibly reflecting either inheritance of primeval genes or horizontal transmission. Exposure of Gambians to clone IV-1 bacteria stimulated production of bactericidal antibodies cross-reactive with subgroup III bacteria in some individuals but of type-specific antibodies in others. Gambians without bactericidal antibodies usually became healthy carriers rather than developing meningococcal disease on exposure to virulent meningococci.     

Deficiency of the Eighth Component of Complement and Recurrent Meningococcal Disease: A Case and Family Study

Abstract: A 16-year-old boy presented on four occasions to a New Zealand hospital. On the first admission he had severe Neissera meningitidis (group Y) meningitis requiring treatment. Sixteen, 17 and 26 months later he presented with similar but less severe symptoms which resolved spontaneously. On the latter admission the same meningococcal serogroup was isolated from his blood. He had no detectable serum C8 activity: investigation of his close family revealed four maternal and two paternal relatives tentatively designated heterozygotes for C8 deficiency.     

Chronicle of an outbreak foretold: meningococcal meningitis W135 in Burkina Faso

Burkina Faso lies within the African meningitis belt. Until recently, serogroup A of Neisseria meningitidis was the most common cause of epidemic meningitis in Burkina Faso. However, during the epidemic that started in January 2002, W135 was the predominant serogroup of meningococcus. Vaccine against the W135 serogroup is expensive and in short supply. Strategies to react to a future African epidemic of W135 meningococcal meningitis with a sufficient and affordable supply of vaccine must be put into place now.     

Meningococcal disease caused by Neisseria meningitidis: epidemiological, clinical, and preventive perspectives

Bacterial meningitis constitutes a significant global public health problem. In particular, Neisseria meningitidis continues to be a public health problem among human populations in both developed and developing countries. Meningococcal infection is present as an endemic and an epidemic disease. Meningococcal disease is manifested not only as meningitis, but also as meningococcemia. The latter is usually fulminant. The global persistence of N. meningitidis is due to the significant number of carriers and the dynamics of transmission and disease. Approximately 500 million people worldwide are carriers of the bacterium in their nasopharynx. Multiple factors have been identified that predispose to the transmissibility of N. meningitidis, including active or passive inhalation tobacco smoking, upper viral respiratory tract infections, drought seasons, and overcrowding. These factors explain the frequent occurrence of outbreaks in military barracks, schools, prisons, and dormitories. Some of the determinants of invasiveness of the bacteria include nasopharyngeal mucosal damage in colonized individuals, virulence of the strains, absence of bactericidal antibodies, and deficiencies of the complement system. During both endemic and epidemic scenarios of meningococcal disease, control measures should include treating the cases with appropriate antimicrobial therapy (penicillin, ceftriaxone, or chloramphenicol); providing chemoprophylactic drugs to contacts (rifampin or ciprofloxacin), and close observation of contacts. Nevertheless, the key to effective control and prevention of meningococcal disease is immunoprophylaxis. Available vaccines include the polysaccharide monovalent, bivalent (serogroups A, C), or tetravalent (A, C, Y, W-135 serogroups) vaccines; conjugate vaccine (serogroup C); and the combined vaccine with outer membrane proteins and polysaccharide (serogroups B, C). Due to a recent increase in case reporting of serogroup C N. meningitidis in Mexico, we have developed a national response strategy that includes availability of vaccines and medications for chemoprophylaxis. This review aims at providing health care workers with updated information regarding the epidemiological, clinical, and preventive aspects of meningococcal disease. The English version of this paper is available at: http://www.insp.mx/salud/index.html.     

Antigenic diversity of Neisseria meningitidis isolated in Taiwan between 1995 and 2002

The geographic distribution of N. meningitidis is diverse. Information on the antigenic variation of N. meningitidis is important for the development of an outer membrane protein-based vaccine. As a first step towards vaccine development, serological typing was performed to determine the antigenic properties of 127 invasive N. meningitidis isolates collected in Taiwan between 1995 and 2002. With 31.5% non-serotypeable and 32.3% non-serosubtypeable, the 127 isolates fell into 51 phenotypes, with W135:NT:P1.5,2:L3,7,9, Y:14P1.5,2, and B:1:NST:L3,7,9 being the 3 most prevalent. Among the 37 serogroup B isolates, 15 serosubtypes were found, with P1.5,2 and P1.12,13 being the most prevalent. The high diversity of Por A among serogroup B isolates circulating in Taiwan poses a great challenge for the development of a PorA-based vaccine. Because 85% of the serogroup B isolates had the L3,7,9 immunotype, inclusion of L3,7,9 lipooligosaccharides in a PorA-based vaccine may be a promising approach. In addition, based on the phenotypic characterization, we suggest that both serogroup B and W135 isolates were endemic and that serogroup A, C, and Y isolates were imported, which may reflect increased international travel.     

Emergence of serogroup C meningococcal disease associated with a high mortality rate in Hefei, China

ABSTRACT: BACKGROUND: Neisseria meningitidis serogroup C has emerged as a cause of epidemic disease in Hefei. The establishment of serogroup C as the predominant cause of endemic disease has not been described. METHODS: We conducted national laboratory-based surveillance for invasive meningococcal disease during 2000--2010. Isolates were characterized by pulsed-field gel electrophoresis and multilocus sequence typing. RESULTS: A total of 845 cases of invasive meningococcal disease were reported. The incidence increased from 1.25 cases per 100,000 population in 2000 to 3.14 cases per 100,000 in 2003 (p < 0.001), and peaked at 8.43 cases per 100,000 in 2005. The increase was mainly the result of an increase in the incidence of serogroup C disease. Serogroup C disease increased from 2/23 (9%) meningococcal cases and 0.11 cases per 100,000 in 2000 to 33/58 (57%) cases and 1.76 cases per 100,000 in 2003 (p < 0.01). Patients infected with serogroup C had serious complications more frequently than those infected with other serogroups. Specifically, 161/493 (32.7%) cases infected with serogroup C had at least one complication. The case-fatality rate of serogroup C meningitis was 11.4%, significantly higher than for serogroup A meningitis (5.3%, p = 0.021). Among patients with meningococcal disease, factors associated with death in univariate analysis were age of 15--24 years, infection with serogroup C, and meningococcemia. CONCLUSIONS: The incidence of meningococcal disease has substantially increased and serogroup C has become endemic in Hefei. The serogroup C strain has caused more severe disease than the previously predominant serogroup A strain.     

Analysis of the genetic differences between Neisseria meningitidis and Neisseria gonorrhoeae: two closely related bacteria expressing two different pathogenicities.

We have investigated genetic differences between the closely related pathogenic Neisseria species, Neisseria meningitidis and Neisseria gonorrhoeae, as a novel approach to the elucidation of the genetic basis for their different pathogenicities. N. meningitidis is a major cause of cerebrospinal meningitis, whereas N. gonorrhoeae is the agent of gonorrhoea. The technique of representational difference analysis was adapted to the search for genes present in the meningococcus but absent from the gonococcus. The libraries achieved are comprehensive and specific in that they contain sequences corresponding to the presently identified meningococcus-specific genes (capsule, frp, rotamase, and opc) but lack genes more or less homologous between the two species, e.g., ppk and pilC1. Of 35 randomly chosen clones specific to N. meningitidis, DNA sequence analysis has confirmed that the large majority have no homology with published neisserial sequences. Mapping of the cloned DNA fragments onto the chromosome of N. meningitidis strain Z2491 has revealed a nonrandom distribution of meningococcus-specific sequences. Most of the genetic differences between the meningococcus and gonococcus appear to be clustered in three distinct regions, one of which (region 1) contains the capsule-related genes. Region 3 was found only in strains of serogroup A, whereas region 2 is present in a variety of meningococci belonging to different serogroups. At a time when bacterial genomes are being sequenced, we believe that this technique is a powerful tool for a rapid and directed analysis of the genetic basis of inter- or intraspecific phenotypic variations.