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PubMed2006

Resistance testing of meningococci: the recommendations of the European Monitoring Group on Meningococci.

One of the most controversial topics concerning Neisseria meningitidis is the definition of antimicrobial resistance. A process of harmonization, promoted by the European Monitoring Group on Meningococci (EMGM), is already in progress. There are several aspects of the MIC definition for meningococcal strains for which a consensus is needed, as follows. (1) What methods can be used? At present, both the Etest and agar dilution methods are recommended by the EMGM. Microdilution, also a recommended method, is not used across Europe. (2) What media produce the most reliable data? The use of Mueller-Hinton medium supplemented with 5% blood is recommended for the MIC determination of N. meningitidis by both Etest and agar dilution method. (3) What is the minimum set of antimicrobial agents to be tested? A minimum set should include rifampicin, ciprofloxacin (or another quinolone), penicillin, ampicillin and ceftriaxone. (4) What are the most suitable breakpoints for definition? There is no widely accepted robust evidence base for the definition of breakpoints. Although progress has been made in achieving a standardized methodology, we are still far from obtaining common breakpoints for antimicrobial resistance definition. These differences will imply inability for building a common epidemiologic figure about drug resistance.

Anti-Bacterial Agents↗

PubMed1989

Comparative activity in vitro of 16 antimicrobial agents against penicillin-susceptible meningococci and meningococci with diminished susceptibility to penicillin.

Broad-spectrum cephalosporins were very active against strains of Neisseria meningitidis with both penicillin susceptibility and diminished penicillin susceptibility. Ceftriaxone was the most active antibiotic. Increases in MIC for 90% of meningococci with diminished susceptibility to penicillin of greater than or equal to 16-fold were observed for amdinocillin, cefuroxime, aztreonam, and imipenem; 2-fold increases were observed for ceftazidime, mezlocillin, and piperacillin. No differences were observed for non-beta-lactam antibiotics.

Anti-Bacterial Agents↗

PubMed2003

Antibody-dependent killing of meningococci by human neutrophils in serum of late complement component-deficient patients.

BACKGROUND: Thirty-one Russian patients with late complement component deficiency (LCCD) who had experienced one to five meningococcal infections were immunized with meningococcal polysaccharide vaccine (A + C + W135 + Y) and were followed for 3-8 years. We investigated the potentially protective killing effect of human neutrophils (PMNL) on serogroup A and W135 meningococci. METHODS: Meningococci were incubated in LCCD vaccine sera in the absence or presence of PMNL, and the number of live bacteria (CFU) was determined by plating onto chocolate agar. RESULTS: When meningococci were incubated in the LCCD sera alone, exponential growth of meningococci occurred despite the presence of meningococcal antibodies. After the addition of PMNL, meningococci were inhibited in their growth or even eliminated. Group A or W135 meningococci were killed effectively by PMNL in 80% of the sera which were collected 1 month to 1 year after vaccination compared to only 40% in the prevaccination LCCD sera (p < 0.05). Three years after vaccination 67% of the LCCD sera were still capable of promoting killing (and even 90% after revaccination). The rate of killing correlated with the concentration of serogroup-specific immunoglobulins. In 83% of the 72 LCCD sera with more than 5 microg/ml anti-group A immunoglobulins the killing of group A meningococci was promoted. By contrast, only 21% of 19 samples with lower specific antibody levels showed a PMNL-mediated meningococcal killing (p < 0.05). The same effect was observed for group W135 meningococci. CONCLUSION: PMNL kill meningococci during incubation in LCCD serum; this effect increases after vaccination and depends on both specific antibody and complement. Protection by vaccination may therefore be caused by an increased killing capacity of PMNL.

Adolescent↗

PubMedDate not supplied

[The bactericidal action of human neutrophils on meningococci in vitro].

32 Russian patients with late complement component deficiency (LCCD) were immunize with tetravalent meningococcal polysaccharide vaccine (A + C + W135 + Y). Their immune response and infectious morbidity rate were followed for 6 years and the partial protective efficacy of vaccination was demonstrated. As the antibody-mediated complement-induced bactericidal activity of plasma was completely absent in persons with LCCD, the bactericidal action of human neutrophils on meningococci of groups A, W135 and B was studied under the conditions of incubation with serum samples collected from persons with LCCD before and after vaccination. In LCCD serum alone the exponential growth of meningococci was observed, while the addition of human neutrophils resulted in the essential inhibition of the growth of meningococci (up to their complete elimination). The proportion of serum samples stimulating the elimination of group A and W 135 meningococci by neutrophils was almost 40% of the serum samples collected before vaccination and significantly increased among the serum samples collected after vaccination (up to 84%) or revaccination (up to 90%). At the same time the capacity of an individual serum sample to promote the bactericidal effect of neutrophils against meningococci correlated with its content of specific anti-polysaccharide IgG and IgM antibodies, as well as antibodies to the inner core of lipopolysaccharide. The interaction of neutrophils with meningococci was significantly inhibited after incubation in heat-inactivated serum, suggesting that this interaction was partly mediated along the following path: the binding of IgM and IgG antibodies with bacteria--the activation of complement and the deposition of C3 complement on bacteria--the binding of meningococci with CR3 receptors of neutrophils.

Bacterial Vaccines↗

PubMed1983

Ano-genital gonorrhoea and pharyngeal colonisation with meningococci: a serogroup analysis.

Among patients attending a clinic for sexually transmitted diseases, women without gonorrhoea were significantly less likely to be colonised with meningococci than were women with gonorrhoea, men with gonorrhoea and men without gonorrhoea: the respective carriage rates (per cent) for groupable plus non-groupable meningococci were 16, 26, 23 and 31. Considering groupable and non-groupable meningococci separately it was found that women without gonorrhoea were also significantly less likely to be colonised with groupable meningococci but there were no significant differences in the carriage rates of non-groupable meningococci. The association between ano-genital gonorrhoea and meningococcal colonisation of the pharynx observed previously with certain groups of patients most likely results from increased mouth-to-mouth contact in 'high-risk' patients rather than individual susceptibility to neisserial infection. The possibility that there is a difference in the predominant means of spread of groupable and non-groupable meningococci is discussed.

Anus Diseases↗

PubMed2005

Genetic analysis of meningococci carried by children and young adults.

BACKGROUND: Neisseria meningitidis is a diverse commensal bacterium that occasionally causes severe invasive disease. The relationship between meningococcal genotype and capsular polysaccharide, the principal virulence factor and vaccine component, was investigated in carried meningococci isolated from 8000 children and young adults in Bavaria, Germany. METHODS: Of the 830 meningococci isolated (carriage rate, 10.4%) by microbiological techniques, 822 were characterized by serogrouping, multilocus sequence typing, and genetic analysis of the capsule region. Statistical and population genetic analyses were applied to these data. RESULTS: The rapid increase in carriage rates with age of carrier, the low prevalence of hyperinvasive meningococci, and the relative prevalence of the 4 disease-associated serogroups were consistent with earlier observations. There was no genetic structuring of the meningococcal population by age of carrier or sampling location; however, there was significant geographic structuring of the meningococci isolated in civil, but not military, institutions. The rate of capsule gene expression did not vary with age of carrier or meningococcal genotype, except for serogroup C, for which increased expression was associated with ST-11 (formerly ET-37) complex meningococci. CONCLUSIONS: Serogroup C capsule expression during carriage may contribute to the invasive character of ST-11 complex meningococci and to the high efficacy of meningococcal serogroup C conjugate polysaccharide vaccine.

Adolescent↗

PubMed2004

Genetics of capsule O-acetylation in serogroup C, W-135 and Y meningococci.

Capsular polysaccharides of serogroup C, W-135 and Y meningococci were previously reported to be O-acetylated at the sialic acid residues. There is evidence that O-acetylation affects the immunogenicity of polysaccharide vaccines. We identified genes indispensable for O-acetylation of serogroup C, W-135 and Y meningococci downstream of the capsule synthesis genes siaA-D. The genes were co-transcribed with the sia operon as shown by reverse transcription polymerase chain reaction analysis. The putative capsular polysaccharide O-acetyltransferases were designated OatC and OatWY. The protein OatWY of serogroups W-135 and Y showed sequence homologies to members of the NodL-LacA-CysE family of bacterial acetyltransferases, whereas no sequence homology with any known protein in the different databases was found for the serogroup C protein OatC. In serogroup W-135 and Y meningococci, several clonal lineages either lacked OatWY or OatWY was inactivated by insertion of IS1301. For serogroup C meningococci, we observed in vitro phase variation of O-acetylation, which resulted from slipped-strand mispairing in homopolymeric tracts. This finding explains the observation of naturally occurring de-O-acetylated serogroup C meningococci. Our report is the first description of sequences of sialic acid O-acetyltransferase genes that have not been cloned from either other bacterial or mammalian organisms.

Acetylation↗

PubMed1967

The interaction in vitro between group B meningococci and rabbit polymorphonuclear leukocytes. Demonstration of type specific opsonins and bactericidins.

The interaction in vitro between group B meningococci and rabbit polymorphonuclear leukocytes has been described. Phagocytosis did not occur in the presence of normal rabbit serum. Antiserum collected 12-21 days following one subcutaneous inoculation of living log phase meningococci exhibited opsonic activity with type specificity; this opsonic action depended on both heat-labile and heat-stable factors. Following ingestion by granulocytes, meningococci were rapidly killed. These studies suggest that group B meningococcal strains contain specific antiphagocytic surface factors of an as yet unknown chemical nature. Antisera obtained 4 or more wk after immunization showed bactericidal activity with the same type specificity as opsonic activity. This bactericidal activity was also lost after heating and restored by the addition of normal serum. Further studies on opsonins and bactericidins for meningococci may shed light on virulence factors in these microorganisms, and may prove useful for a more precise classification of meningococci according to type rather than group specificity.

Animals↗

PubMed1989

Increased adherence to vaginal epithelial cells and phagocytic killing of gonococci and urogenital meningococci associated with heat modifiable proteins.

Urogenital Neisseria meningitidis were characterized with regard to serogroup, colony morphology, the presence of heat modifiable proteins (HMP), attachment to human vaginal and buccal epithelial cells, and phagocytic killing by polymorphonuclear leukocytes. The findings were compared with those on gonococci, and with those on meningococci isolated from blood or cerebrospinal fluid, with regard to colony morphology, HMP and piliation. The opacity colony morphology characteristic could be used to predict the presence of HMP in gonococci but not in meningococci, and sodium dodecyl sulphate polyacrylamide gel electrophoresis had to be used to demonstrate this surface protein. The urogenital meningococci, serogroup Y, attached significantly more efficinetly to vaginal epithelial cells in the presence of HMP and behaved in this respect like those of gonococci. Gonococci and meningococci containing HMP were more sensitive to phagocytic killing than those without HMP. Meningococci from opaque and transparent colonies and isolated from patients with meningococcal disease had no demonstrable HMP. They showed low adherence to vaginal and buccal epithelial cells, with no difference between organisms from opaque or transparent colonies.

Bacterial Adhesion↗

PubMed1984

Human opsonins to meningococci after vaccination.

Two groups of volunteers were immunized with either a serogroup A plus C meningococcal polysaccharide vaccine or a combined serogroup B polysaccharide-serotype 2 protein vaccine. Serum opsonin responses were measured by chemiluminescence of polymorphonuclear leukocytes exposed to opsonized live meningococci. Two of the six volunteers immunized with the A plus C vaccine had an increase in serum opsonins to group A meningococci, four responded to group C meningococci, and none to group B meningococci. Five other volunteers who were immunized with the combined group B polysaccharide-serotype 2 protein vaccine responded with an increase in serum opsonins to group B meningococci of two different protein serotypes, as well as to a group C-serotype 2 meningococcal strain. Although no booster effect was observed after a second dose of the combined vaccine, both the polysaccharide and the protein components appear to be able to stimulate an opsonin response.

Bacterial Vaccines↗

PubMed1990

[Meningococcal disease: are patients carriers of meningococci after treatment with antibiotics?].

The aim of the study was to determine whether patients treated for meningococcal disease carried meningococci in the throat on discharge from hospital. If this were the case, supplementary treatment with e.g. rifampicin would be appropriate. The study comprised 106 patients: 98 patients in whom meningococci had been isolated from cerebrospinal fluid, blood or petechiae and eight patients with clinical signs of meningococcal disease in whom meningococci had been isolated only from tracheal aspirate or throat specimens. In 35% (22/62), meningococci were isolated from throat specimens on admission to hospital. From 20 throat specimens inoculated on 5% horse blood agar only, one meningococcal isolate was recovered (5%). From further 37 specimens inoculated on chocolate agar medium selective for pathogenic Neisseria, 18 meningococcal isolates were recovered (49%). This difference is statistically significant (p = 0.001). Meningococci were not isolated from any throat specimens taken on discharge from hospital; 90% (47/52) of these specimens were examined using selective chocolate agar medium. From an observed carriage rate of zero out of 47 it can be judged that the carrier rate does not exceed 6.4% (95% confidence limit). From these results, we conclude that it is unlikely that patients, who have been treated for meningococcal disease, are the source of infection in secondary cases.

Anti-Bacterial Agents↗

PubMed1986

[Electron microscopic study of the cytopathogenic action of meningococci in a continuous human amnion cell culture].

The electron-microscopic study of the interaction of meningococci with continuous human amnion cell culture F1 has revealed that this process comprises 3 stages. The study has shown that, following the adhesion of meningococci to the surface of cells F1, these cells are invaded by individual coccal forms of meningococci. In response to infection vacuoles appear in the cytoplasm of the cells. Meningococci are either phagocytosed inside these vacuoles, or their release into the intercellular space and the death of the infected by meningococci are observed. When the cells are infected by cytopathogenic strains, the infectious process results in the appearance of degenerative changes in the cells.

Amnion↗

PubMed1986

Class 1/3 outer membrane protein vaccine against group B, type 15, subtype 16 meningococci.

Neisseria meningitidis capsular polysaccharides and outer membrane proteins have been incorporated in vaccines and the potential of these vaccines has been evaluated in man. Polysaccharides are the most attractive candidates for a vaccine against group A and C meningococci whereas outer membrane proteins may have a potential for a vaccine against group B meningococci. This paper describes the characteristics of the five classes of outer membrane proteins of group B meningococci and the protective (bactericidal) activity of monoclonal antibodies against class 1 and 2 or 3 outer membrane proteins. Monoclonal antibodies against class 1 outer membrane proteins were bactericidal irrespective of the growth conditions of the bacterium. On the other hand, these conditions influenced the bactericidal activity of monoclonal antibodies against class 2 or 3 outer membrane proteins. These data indicate that class 1 outer membrane protein is an attractive component of a vaccine. The Blake and Gotschlich procedure for the isolation of gonococcal outer membrane protein II (1) was adapted for the isolation of a combination of class 1 and 3 outer membrane proteins from group B, type 15 meningococci. The combination of both outer membrane proteins was adsorbed to ALPO4 in the presence of the detergent Zwittergent 3-14. The vaccine was injected into mice. The antibodies were strongly bactericidal and Western blot analysis indicated that both outer membrane proteins induced antibodies. The vaccine may have a potential to combat an epidemic caused by group B, type 15 meningococci. Such an epidemic was observed in some N.W. - European countries.

Animals↗

PubMed2006

Survival of meningococci outside of the host: implications for acquisition.

Meningococci are regarded as being unlikely to survive outside of their human host although this has possibly been more assumed than demonstrated. Seven strains of meningococci were tested for their ability to survive on glass or plastic while retaining expression of their capsule and important outer membrane proteins. A known number of colony-forming units of each strain were dried onto glass and onto plastic and tested for viability over time. Survival on glass was significantly better than on plastic (P<0.0001). Isolates of the New Zealand epidemic strain, B:4:P1.7-2,4 survived better on glass than all other strains tested. Recovered isolates still expressed their capsules and outer membrane proteins. These findings raise the question of whether meningococci can be transferred from person to person via fomites contaminated with oropharyngeal secretions containing meningococci.

Bacterial Capsules↗

PubMed1994

Complement deficiency predisposes for meningitis due to nongroupable meningococci and Neisseria-related bacteria.

Nongroupable meningococci or bacteria related to the genus Neisseria rarely cause meningitis. Complement deficiency has been identified as a major predisposing factor for meningococcal disease. To assess whether patients with meningitis due to such strains have a complement deficiency, we studied 12 persons. Six patients had meningitis due to nongroupable strains of meningococci, and six patients had meningitis due to Moraxella species or Acinetobacter species. Inherited complement component C7 or C8 deficiency was found in two persons who had had meningitis due to nongroupable meningococci, and one C8-deficient person had had meningitis caused by Moraxella osloensis. Hypocomplementemia resulting from CSF drain-associated shunt nephritis was found in one person with meningitis due to Moraxella nonliquefaciens and in one person with meningitis due to Acinetobacter lwoffi. This rather high frequency of inherited or acquired complement deficiencies among patients with meningitis due to nongroupable meningococci, Moraxella species, and Acinetobacter species justifies the recommendation that such patients must be studied for complement deficiency.

Acinetobacter Infections↗

PubMed2003

Age dependence of in vitro survival of meningococci in whole blood during childhood.

OBJECTIVES: To determine the association between the ability of a different strains of meningococci to survive in whole blood and the age of the donor. METHODS: A panel of serogroup B and a serogroup C strain of Neisseria meningitidis was tested in an ex vivo whole blood model. Blood from 81 healthy children and 20 adults and from children during convalescence from serogroup B (55 patients) or serogroup C (43 patients) meningococcal infection was assessed. RESULTS: Age-dependent acquisition of whole blood killing of serogroup B and C bacterial isolates was demonstrated in healthy children with an inverse relationship to the reported incidence of disease. After infection with serogroup B or C meningococci, evidence of whole blood killing of the bacteria was found even in blood from children <2 years of age, the survival of a serogroup B strain, MC58, being reduced compared with that in healthy children (median, 64% compared with 194.5% survival at 90 min). In both affected children and controls, there was a significant correlation between whole blood killing of strain MC58 and of other serogroup B and C meningococci. CONCLUSIONS: The whole blood model measures both humoral and cellular mechanisms responsible for the bactericidal activity of blood. The model was first described 80 years ago, but this is the first description of its age dependency. Acquisition of bactericidal activity was more rapid in children infected and is directed at various strains of meningococci, indicating the presence of a cross-reactive antigen(s).

Adolescent↗

PubMed1987

Standardization of a chemiluminescence method for the measurement of meningococcal opsonins using ethanol fixed meningococci.

A chemiluminescence (CL) method using polymorphonuclear leukocytes (PMNLs) and an automatic photoluminometer was used to measure serum opsonins to viable and inactivated group B meningococci. Continuous mixing at 37 degrees C both during opsonization and phagocytosis was essential for optimal CL responses. The CL response increased rapidly during an opsonization time up to 7.5 min, and with PMNL and bacteria concentrations up to 37.5 X 10(5) and 3.8 X 10(7) cells/ml, respectively. Opsonized ethanol fixed meningococci gave CL responses similar to those of viable meningococci, but had a better reproducibility. Using the ethanol fixed bacteria, the variation of PMNLs from different donors, the day-to-day variation, and the coefficient of variation of the CL responses, were all less than 10%. The opsonic activity of convalescent sera from 10 patients with meningococcal disease was markedly higher than that of sera obtained during the acute phase of the disease. Thus, this standardized CL assay using ethanol fixed bacteria is a highly reproducible and sensitive method for measuring serum opsonins to meningococci.

Ethanol↗

PubMed2002

[Universal vaccination against group-C meningococci and pneumococci; summary of the advice from the Health Counsil of the Netherlands].

The Health Council of the Netherlands (Gezondheidsraad) assessed the vaccination of infants against both group-C meningococci and pneumococci in terms of general criteria and basic principles for inclusion in the national vaccination programme. Vaccination against meningococci C in the Netherlands is expected to prevent about 300 cases of meningococcal disease (meningitis or sepsis), 22 deaths and 12 cases of severe lasting problems (neurological problems or amputations) per year. Vaccination against pneumococci may prevent about 100 cases of meningitis or sepsis, 3200 cases of pneumonia, 36,000 cases of acute otitis media, 11 deaths, 11 cases of severe permanent damage (neurological problems, deafness) per year. The Health Council advised implementing vaccination against group-C meningococci as soon as possible, through 2 injections at the ages of 5 and 6 months or through 1 injection shortly after the child's first birthday, and to carry out a catch-up programme for all children and adolescents up to and including 18 years of age. The council also advised starting a vaccination programme against pneumococci, at ages 2, 3 and 4 months, as soon as the current vaccinations against diphtheria, tetanus, pertussis and polio and against Haemophilus influenzae type b are combined into 1 injection (in 2002 or 2003). In view of the concentration of pneumococci disease in the first years of life, a catch-up programme is not indicated in this case. The Health Council emphasised the importance of microbiological and clinical monitoring of potential adverse effects and of public education programmes. The cost of vaccination against group-C meningococci is comparable to that of other accepted programmes for primary prevention. Compared to other programmes and at the current vaccine price, the cost of vaccination against pneumococci is high.

Adolescent↗