Carriage of Neisseria meningitidis and Neisseria lactamica among ethnic Greek school children from Russian immigrant families in Athens

During February and March 1995, a survey of meningococcal carriage in 625 school children was carried out in a suburb of Athens in which there was a large number of ethnic Greeks who had immigrated from Russia beginning in the early 1990s. The objectives of the study were: (1) to determine if factors associated with carriage of meningococci observed in a previous study of Greek school children were similar for the immigrant population; (2) to compare phenotypic characteristics of meningococci from the immigrant population with those isolated from children in Athens. Overall isolation rate for meningococci was 82/625 (13.1%), significantly higher than that found for school children in Athens (5.8%) during the winter of 1990 1991 (5.8%) (chi=25.98, P=0.0000003). By univariate analysis, carriage was not associated with sex, number of individuals per household, blood group, secretor status, socioeconomic level or maternal smoking; however, it was associated with fathers' smoking. The high proportion of men who smoked compared with the low proportion of women smokers might contribute to this finding. The main serogroup of meningococci isolated from this population was A (28%). While serogroup A appears to be more prevalent among Russian and Kurdish immigrants (14%) than among Greek school children or military recruits (4%), there has not been an increase in group A meningococcal disease in Greece. The isolation rate for N. lactamica was high 105/625 (17.3%). A few of these strains bound some of the monoclonal antibodies used for meningococcal serotyping and subtyping, and they are being examined in greater detail.     

Epidemiological characteristics of meningococcal infection in Cuba

The results of the epidemiological analysis of the morbidity rate in meningococcal infection for 1976-1984 are presented. The maximum rise of morbidity rate, equal to 14.4 per 100000 of population, was observed in 1983. Primarily, the rise of morbidity rate in 1979 was induced by meningococci of two serogroups: C (44.6%) and B (36.4%). The vaccinal prophylaxis of the population, carried out in 1979 with the use of polysaccharide vaccine A + C, did not affect morbidity caused by group B meningococci. The isolation rate of these organisms reached 98.7% from patients and 81.0% from carriers. The characteristic feature of the epidemic process of meningococcal infection in Cuba was a considerable increase in the number of patients under 1 year of age and the absence of seasonal fluctuations in morbidity rate.     

Characterization of serogroup C meningococci isolated from 14 provinces of China during 1966-2005 using comparative genomic hybridization

Neisseria meningitidis is a major cause of bacterial meningitis and septicemia worldwide. In China, serogroup A strains were responsible for over 95% of the cases, while serogroup B strains were mainly the cause of localized outbreaks and sporadic cases. Before 2003, serogroup C strains were only recovered from a few sporadic cases. However, a sudden increase in the number of cases due to serogroup C strains occurred during 2003-2005 in Anhui Province, China. Many cases were found in other provinces at the same time. Multilocus sequence typing (MLST) results indicated that the unique sequence type 4821 clone meningococci, a new hyper-virulent lineage, was responsible for the serogroup C meningitis outbreaks. We have completed the project of sequencing the whole genome of the Chinese N. meningitidis serogroup C representative isolate 053442. We fabricated a whole-genome microarray of N. meningitidis isolate 053442 and analyzed the genome composition differences among 81 serogroup C isolates which were isolated from 14 provinces of China during 1966-2005. The comparative genomic hybridization (CGH) result shows that the genome compositions of nearly all serogroup C isolates are similar to that of 053442. The products of many absent open reading frames (ORFs) are conserved hypothetical proteins. The results will provide a valuable resource from which one can analyze the genome composition and genetic background of serogroup C meningococci in China.     

Epidemiological and Molecular Characterization of Invasive Meningococcal Disease in Italy, 2008/09-2012/13

BackgroundFollowing the introduction of meningococcal serogroup C conjugate vaccine in Italy in 2005, changes in the epidemiology of Invasive Meningococcal Disease (IMD) were expected. The study aims were to describe the epidemiological trend and to characterize the isolates collected during the period 2008/09-2012/13 by multilocus sequence typing (MLST). Data on laboratory confirmed meningococcal diseases from National Surveillance System of IMD were reported.MethodsPoisson regression models were used to estimate the incidence rate over time. Serogrouping and MLST were performed following published methods.ResultsThe incidence rate of laboratory confirmed meningococcal disease decreased from 0.33 per 100,000 population in 2008/09 to 0.25 per 100,000 population in 2012/13. The serogroup B incidence rate was significantly higher (p<0.01) than that of other serogroups, among all age groups. The significant decrease of the IMD incidence rate (p = 0.01) reflects the decrease of serogroup B and C, in particular among individuals aged 15–24 years old (p<0.01). On the other hand, serogroup Y incidence increased during the period (from 0.01/100,000 in 2008/09 to 0.02/100,000 in 2012/13, p = 0.05). Molecular characterizations revealed that ST–41/44 cc and ST–11 cc were the main clonal complexes identified among serogroup B and C isolates, respectively. In particular, ST–41/44 cc was predominant in all age groups, whereas ST–11 cc was not identified in infants less than 1 year of age.ConclusionsIMD incidence declined in Italy and serogroup B caused most of the IMD cases, with infants having the highest risk of disease. Continued surveillance is needed to provide information concerning further changes in circulating meningococci with special regard to serogroup distribution. Moreover, knowledge of meningococcal genotypes is essential to detect hyper-invasive strains.     

The evolution of meningococcal infection in Mongolia]

On the basis of the generalization and analysis of the results of bacteriological and immunological investigations the epidemic process of meningococcal infection (MI) in Mongolia was found to undergo definite changes during the last 20 years. Group A meningococci prevailing in the etiology of MI were replaced by strains belonging to group B affecting mainly young children (aged up to 3 years). MI morbidity rate caused by group B meningococci was found to be higher in Mongolia than in other countries of the world. These data substantiate the necessity of using more effective remedies for the control of this infection and, in particular, specific immunization with vaccines against group B meningococci; profound study of the properties of the circulating meningococcal strains is to be carried out.     

Characterization of serogroup C meningococci isolated from 14 provinces of China during 1966–2005 using comparative genomic hybridization

Neisseria meningitidis is a major cause of bacterial meningitis and septicemia worldwide. In China, serogroup A strains were responsible for over 95% of the cases, while serogroup C strains were only recovered from a few sporadic cases. However, a sudden increase in the number of cases due to serogroup C strains occurred during 2003–2005 in Anhui Province, China. Many cases were found in other provinces at the same time. Multilocus sequence typing (MLST) results indicated that the unique sequence type 4821 clone meningococci, a new hyper-virulent lineage, was responsible for the serogroup C meningitis outbreaks. We have completed the project of sequencing the whole genome of the Chinese N. meningitidis serogroup C representative isolate 053442. We fabricated a whole-genome microarray of N. meningitidis isolate 053442 and analyzed the genome composition differences among 81 serogroup C isolates which were isolated from 14 provinces of China during 1966–2005. The comparative genomic hybridization (CGH) result shows that the genome compositions of nearly all serogroup C isolates are similar to that of 053442. The products of many absent open reading frames (ORFs) are conserved hypothetical proteins. The results will provide a valuable resource from which one can analyze the genome composition and genetic background of serogroup C meningococci in China.     

Measurement of opsonophagocytic activity of antibodies specific toNeisseria meningitidis serogroup A capsular polysaccharide-serogroup B outer membrane vesicle conjugate in animal model

Neisseria meningitidis is efficiently phagocytosed by polymorphonuclear leukocytes (PMNS) following opsonization with opsonic antibodies; opsonophagocytosis is the primary mechanism for clearance of meningococci from the host. Thus, in testing meningococcal vaccines, the level of opsonophagocytic antibodies appears to correlate with vaccine-induced protection. Our previous studies demonstrated that the conjugation ofN. meningitidis serogroup A capsular polysaccharide (CPSA) to serogroup B outer membrane vesicle (OMV) could induce a high level of bactericidal antibody response against serogroup A meningococci in animals. The purpose of this study was to evaluate opsonophagocytic activity of the conjugate of CPSA to OMV (CPSA-OMV). In order to evaluate the potential efficacy of CPSA-OMV a flow cytometric opsonophagocytic assay was used. The conjugate and controls were injected intramuscularly into four groups of rabbits with boosters on days 14, 28 and 42 following primary immunization. The rabbits were bled prior to injection and two weeks after each injection. Opsonophagocytic activity of antibodies in hyperimmune sera through rabbit PMNS were measured with flow cytometer, using dihydrorhodamine-123 as a probe. The results indicated that our conjugate could induce a highly significant level of opsonophagocytic activity against serogroup A meningococci after 56 days compared to the control groups (P<0.05). We conclude that this conjugate represents a vaccine candidate against serogroups A and B meningococci after further investigation.     

Antibody response to capsular polysaccharide antigen in an infection caused by meningococcus serogroup B in children

The continuous synchronous cultivation of serogroup B meningococci and the use of the selected clones of producer strains has made it possible to obtain the serologically active preparation of the group-specific antigen from the culture in the exponential phase. The erythrocyte diagnosticum produced on the basis of this preparation has permitted the detection of group-specific antibodies in the sera of immunized rabbits and children with generalized infection caused by serogroup B meningococci. The intensity of immune response depends on the age of children. This new technique of the passive hemagglutination test is recommended for the confirmation of generalized infection caused by serogroup B meningococci.     

Genetic subgroups of Neisseria meningitidis serogroup A isolated from patients with disseminated forms of meningococcal infection in Moscow, 1969-2006

Results of microbiological monitoring for serogroup A Neisseria meningitidis circulated in Moscow from 2002 to 2006 are presented. Using multilocus sequence-typing, molecular and epidemiologic characteristics of 32 cultures isolated from cerebro-spinal fluid of patients with generalized forms of meningococcal infection. Typed isolates belonged to 4 sequence types: CT-3349 (detected in 24 cultures), CT-2 (detected in 5 cultures), CT-75 (detected in 2 cultures), and CT-5803 (detected in 1 culture). All sequence types (except CT-5803) were detected in Moscow in previous years. Using Internet database (http://pubmlst.org/neisseria) they were genetically characterized and compared with data on serogroup A meningococci circulated in Moscow before 2002., meningococci belonging to epidemically dangerous genetic subgroup III were not detected between characterized strains. Typed isolates were distributed between subgroups VI and X, which are typical for the area under surveillance. Genetic changes in Moscow population of Neisseria meningitidis serogroup A, which manifested by shift of dominating genetic subgroup after 2002-2003, were analyzed.     

Persistence of Hyperinvasive Meningococcal Strain Types during Global Spread as Recorded in the PubMLST Database

Neisseria meningitidis is a major cause of septicaemia and meningitis worldwide. Most disease in Europe, the Americas and Australasia is caused by meningococci expressing serogroup B capsules, but no vaccine against this polysaccharide exists. Potential candidates for ‘serogroup B substitute’ vaccines are outer membrane protein antigens including the typing antigens PorA and FetA. The web-accessible PubMLST database (www.pubmlst.org) was used to investigate the temporal and geographical patterns of associations among PorA and FetA protein variants and lineages defined by combinations of housekeeping genes, known as clonal complexes. The sample contained 3460 isolates with genotypic information from 57 countries over a 74 year period. Although shifting associations among antigen variants and clonal complexes were evident, a subset of strain types associated with several serogroups persisted for decades and proliferated globally. Genetic stability among outer membrane proteins of serogroup A meningococci has been described previously, but here long-lived genetic associations were also observed among meningococci belonging to serogroups B and C. The patterns of variation were consistent with behaviour predicted by models that invoke inter-strain competition mediated by immune selection. There was also substantial geographic and temporal heterogeneity in antigenic repertoires, providing both opportunities and challenges for the design of broad coverage protein-based meningococcal vaccines.     

Synthesis and biological properties of polysaccharide-peptide conjugates as potential antigens for a vaccine against meningococci of serogroups A and B

A new approach to the development of a vaccine against meningococci of serogroups A and B was proposed. It involves the synthesis of conjugates of high-molecular capsule polysaccharides of the serogroup A meningococcus (PsA) with earlier synthesized protective fragments of membrane proteins from serogroup B meningococci. The conjugates were synthesized using a method that consists of the generation of aldehyde groups by oxidizing free vicinal hydroxyl groups of PsA and subsequent reaction of these groups with amino groups of the peptide. The reaction proceeds with the intermediate formation of the Schiff base, which is reduced to the stable secondary amine. The main parameters of the reaction were optimized in the synthesis of a PsA conjugate with a model peptide and methods of their characterization were developed. The reproducibility and efficiency of the synthetic procedure were demonstrated by the example of synthesis of PsA conjugates with fragments of protein PorA from the outer membrane of the serogroup B meningococcus. It was shown that, when administered without adjuvant, a conjugate of PsA with a protective peptide, which represents an exposed conserved fragment 306–332 of protein PorA, stimulates the formation of antibodies to the peptide and polysaccharide moieties of the molecule and is also capable of decreasing the degree of bacteremia in animals infected with serogroup A and serogroup B meningococci. The approach can be applied to the development of a complex vaccine for serogroup A and serogroup B meningococci.     

Characterization of serogroup C meningococci isolated from 14 provinces of China during 1966—2005 using comparative genomic hybridization

Neisseria meningitidis is a major cause of bacterial meningitis and septicemia worldwide. In China, serogroup A strains were responsible for over 95% of the cases, while serogroup B strains were mainly the cause of localized outbreaks and sporadic cases. Before 2003, serogroup C strains were only re-covered from a few sporadic cases. However, a sudden increase in the number of cases due to sero-group C strains occurred during 2003—2005 in Anhui Province, China. Many cases were found in other provinces at the same time. Multilocus sequence typing (MLST) results indicated that the unique se-quence type 4821 clone meningococci, a new hyper-virulent lineage, was responsible for the serogroup C meningitis outbreaks. We have completed the project of sequencing the whole genome of the Chi-nese N. meningitidis serogroup C representative isolate 053442. We fabricated a whole-genome mi-croarray of N. meningitidis isolate 053442 and analyzed the genome composition differences among 81 serogroup C isolates which were isolated from 14 provinces of China during 1966—2005. The com-parative genomic hybridization (CGH) result shows that the genome compositions of nearly all sero-group C isolates are similar to that of 053442. The products of many absent open reading frames (ORFs) are conserved hypothetical proteins. The results will provide a valuable resource from which one can analyze the genome composition and genetic background of serogroup C meningococci in China.     

Differential distribution of novel restriction-modification systems in clonal lineages of Neisseria meningitidis

Using representational difference analysis, we isolated novel meningococcal restriction-modification (R-M) systems. NmeBI, which is a homologue of the R-M system HgaI of Pasteurella volantium, was present in meningococci of the ET-5 complex and of lineage III. NmeAI was found in serogroup A, ET-37 complex, and cluster A4 meningococci. NmeDI was harbored by meningococci of the ET-37 complex and of cluster A4, but not by serogroup A meningococci. Two of the R-M systems, NmeBI and NmeDI, were located at homologous positions between the phenylalanyl-tRNA synthetase genes pheS and pheT, which appeared to be a preferential target for the insertion of foreign DNA in meningococci. The distribution of the three R-M systems was tested with 103 meningococcal strains comprising 49 sequence types. The vast majority of the strains had either NmeBI, NmeAI, or both NmeAI and NmeDI. Using cocultivation experiments, we could demonstrate that NmeBI, which was present in ET-5 complex meningococci, was responsible for a partial restriction of DNA transfer from meningococci of the ET-37 complex to meningococci of the ET-5 complex.     

不同地区人群咽部正常菌群抑制脑膜炎双球菌生长的调查

应用琼脂铺层技术检查了健康者咽部正常菌群对脑膜炎余瑟氏菌(Nm)生长的抑制作用。有些健康者咽部正常菌群对 A 群、B 群和 C 群 Nm 的生长均有抑制作用,而且这种抑菌作用较稳定.1989年冬～1990年春选择流脑发病高的江西宁都县青塘乡和该县未发病的东山坝乡与北京昌平县百善乡作为未发病地区的对照.在流脑发病率高的青塘乡只有8.5%的健康者咽部正常菌群具有抑菌作用;在东山坝乡和百善乡中分别有30%与50%的健康者咽部正常菌群可以抑制 A 群 Nm 生长。这种抑菌作用随年龄增长而增强。初步调查结果表明,健康者咽部正常菌群对 Nm 原发感染似乎有一定的影响。我们对调查中所收集的对 Nm 具有抑菌作用的细菌按 Bergey 氏手册进行了鉴定,现已确定它们是血液链球菌、缓症链球菌、米勒氏链球菌和唾液链球菌四种。     

Epidemiological significance of carriers of hyaluronidase-active meningococci

To find out the epidemiological role of the carriers of hyaluronidase-positive meningococcal strains, their spread in the foci of meningococcal infection, as well as outside these foci, was studied. For this purpose, altogether 5059 persons from 40 family foci of infection and 40 organized groups were examined. The number of carriers of hyaluronidase-active meningococci, detected among those of them who had contacts with sick persons, was 13 times greater than among the persons having no such contacts. In preschool institutions with unfavorable morbidity situation this number was 16 times greater than in those with favorable situation. In the family foci carriers of hyaluronidase-active meningococci constituted 80-88 %. The percentage of the carriers of hyaluronidase-active meningococci causing cases of the generalized form of meningococcal infection varied in different groups. According to the results obtained in this study, the threshold percentage of such carriers constituted 30 in preschool institutions, 36 in boarding schools and 50 in common school and in hostels for adults.     

The epidemiological characteristics of meningococcal infection in the USSR

The epidemiological analysis of morbidity in meningococcal infection in the USSR in the period of 1969-1987 showed that the second rise of the morbidity level occurred in 1984 and was followed by its decrease in most of the regions of the USSR. This study also revealed that the characteristic feature of the second rise of morbidity in meningococcal infection was a considerable involvement of young children (aged up to 3 years), as well as the increased etiological role of group B meningococci in cases of meningococcal infection and the circulation of these microorganisms among the population. Besides, the preservation of the etiological importance of group A meningococci in many regions of the USSR, especially among adults, was noted. In this connection, the use of Soviet group A meningococcal polysaccharide vaccine on epidemiological indications was considered to be epidemiologically substantiated.     

Prospective survey on carriage of Neisseria meningitidis and protective immunity to meningococci in schoolchildren in Niamey (Niger): focus on serogroup W135

We investigated the carriage of serogroup W135 meningococci and its relationship with protective immunity in Niamey. Between February and May 2003, three oropharyngeal swabs and two serum samples were each taken from 287 school children. Serogroup W135 isolates were obtained from 8.9% of children. Specific IgG > or = 2 microg/ml using ELISA or serum bactericidal assay (SBA) titre > or = 8 were supposed to represent the protective immunity to a serogroup. The proportion of children with serogroup W135-specific IgG > or = 2 microg/ml increased significantly during follow-up (13.9% to 19.1%), but not the proportion of those with SBA titre > or = 8 (10.1% to 11.6%). At the end of the follow-up, we observed a significant association between carriage of serogroup W135 strains and presumed protective immunity to this serogroup, using either ELISA or SBA. Among 240 children having an initial SBA titre < 8, 20 carried serogroup W135 strains at least once. In May, 25% of carriers had an SBA titre > or = 8, vs. 2.3% of non-carriers. For ELISA, 230 children had specific IgG < 2 microg/ml in February, with 22 having at least one swab positive for serogroup W135 meningococci later. In May, 45.5% of them had specific IgG > or = 2 microg/ml vs. 5.3% among non-carriers.     

Etiology of suppurative bacterial meningitis

The results of the laboratory examination of 2034 patients with meningococcal infection and purulent meningitides, hospitalized during the period of June 1980 to October 1983, revealed that three main etiological agents were responsible for these diseases: meningococci, pneumococci and Haemophilus influenzae. The susceptibility of the patients to different etiological agents was found to depend on their age. Children aged up to 3 years constituted 75% of the patients with meningitis caused by H. influenzae; 50% of the patients with meningococcal infection were children aged up to 5 years; pneumococcal meningitis occurred more frequently in adults. Serogroup A meningococci were found to prevail in patients with meningococcal infection. Besides, in children serogroup C meningococci could be isolated in 24% of cases. Since 1983 the cases of the isolation of strains belonging to serogroup B increased in number. Among the pneumococci responsible for the disease serotypes 1, 19, 6 and in children serotype 12 occurred most frequently.     

Nucleotide sequence analysis of the sialyltransferase genes of meningococcal serogroups B,C, Y and W135

A rapid method for serogrouping meningococci is essential for the characterization of phenotypically non-groupable meningococcal isolates and clinical samples, particularly for public health management purposes. The Scottish Meningococcus and Pneumococcus Reference Laboratory (SMPRL) provides serogrouping results of meningococcal isolates and clinical samples using a PCR assay which detects restriction fragment length polymorphisms in meningococcal serogroups B, C, Y and W135. Although this PCR system was invaluable when first introduced, it has several drawbacks and lacks the required sensitivity for detecting DNA in clinical samples. Due to the recent introduction of the meningococcal group C conjugate vaccine and an impending group B vaccine, a more robust and informative method for serogroup determination is required. A protocol was devised allowing PCR amplification of the siaD gene of serogroup B, C, Y and W135 meningococci. This system was multiplexed and allowed serogroup differentiation between serogroups B and C and also between B/C and Y/W135 by product size analysis. A nested stage was incorporated into the system for enhanced detection of meningococci in clinical samples, and finally a sequencing protocol was designed allowing detection of any nucleotide changes within the siaD gene. This system allows rapid serogrouping results for use within an agarose gel system as well as more informative results when used for sequencing within the siaD gene.