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 cerebrospinal fluid (CSF)
Clear, colourless liquid that surrounds the brain and spinal cord and fills the spaces in them. It helps support the brain, acts as a lubricant, maintains pressure in the skull, and cushions shocks. only was associated with lower death rates (p = 0.046). This study shows evolutionary trends Noun 1. evolutionary trend - a general direction of evolutionary change
trend, drift, movement - a general tendency to change (as of opinion); "not openly liberal but that is the trend of the book"; "a broad movement of the electorate to the right" of meningococcal isolates in a relatively isolated community and highlights an association between unique STs and poor outcome.
Invasive infections caused by Neisseria meningitidis Neisseria men·in·git·i·dis
The bacteria that is the causative agent of cerebrospinal meningitis; meningococcus.
Neisseria meningitidis (meningococci) cause high rates of illness and death worldwide (1-3). Meningococci have frequently caused epidemics in Iceland, a relatively isolated community in the mid-Atlantic (4,5). To more fully understand the phylogeny of meningococcal strains, various typing methods have been used, including serogroup and serotype serotype /se·ro·type/ (ser´o-tip) the type of a microorganism determined by its constituent antigens; a taxonomic subdivision based thereon.
v. classifications. Epidemiologic studies epidemiologic study A study that compares 2 groups of people who are alike except for one factor, such as exposure to a chemical or the presence of a health effect; the investigators try to determine if any factor is associated with the health effect have used more discriminating methods, such as multilocus enzyme electrophoresis electrophoresis (ĭlĕk'trōfərē`sĭs): see colloid.
Movement of electrically charged particles in a fluid under the influence of an electric field. , based on electrophoretic e·lec·tro·pho·re·sis
1. The migration of charged colloidal particles or molecules through a solution under the influence of an applied electric field usually provided by immersed electrodes. Also called cataphoresis.
2. variation of several chromosomally encoded cytoplasmic cytoplasmic
pertaining to or included in cytoplasm.
include secretory inclusions (enzymes, acids, proteins, mucosubstances), nutritive inclusions (glycogen, lipids), pigment granules (melanin, lipofuscin, "housekeeping" enzymes (6). More recently, sequence-based molecular methods have been used to type meningococci. Multilocus sequence typing Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci. The procedure characterizes isolates of bacterial species using the DNA sequences of internal fragments of multiple (usually seven) housekeeping genes. (MLST MLST Multi Locus Sequence Typing
MLST Medical Logistics Support Team
MLST Mini Losi Super Truck (1/18th scale radio control vehicle) ) uses neutrally selected housekeeping genes (7), which are sequenced with automated equipment (8). This method gives all the information obtained by multilocus enzyme electrophoresis and improves on it in several ways (7). MLST is not dependent on the researcher's interpretation, and no reference standards are necessary. The data are portable; they are easily stored and transmitted and can therefore be easily compared.
We have generated a population-based registry of invasive meningococcal infections in Iceland since 1975. Iceland is well suited for studies of meningococcal infections, since the population is well defined, patient follow-up information is relatively accessible, and meningococcal isolates dating back to 1977 are stored centrally. We used MLST to study the evolutionary dynamics of invasive meningococcal infections in Iceland during a 28-year period, 1977-2004. The purpose of this long-term, nationwide study was 2-fold: 1) compare Icelandic strains with those circulating globally and 2) study the association between patient demographics The attributes of people in a particular geographic area. Used for marketing purposes, population, ethnic origins, religion, spoken language, income and age range are examples of demographic data. , sequence types (STs), serogroups, and outcomes.
Materials and Methods
Iceland is a 103,000-[km.sup.2] island in the mid-Atlantic, with a population of 220,918 at the beginning of the study period and 293,577 at the end of 2004. Every citizen has access to government-based health care. Currently, 2 university hospitals and 14 community hospitals exist in the country. Since 1975, blood cultures for the whole country have been processed at only 3 sites. This study was approved by the National Bioethics bioethics, in philosophy, a branch of ethics concerned with issues surrounding health care and the biological sciences. These issues include the morality of abortion, euthanasia, in vitro fertilization, and organ transplants (see transplantation, medical). Committee of Iceland and the Data Protection Authority of Iceland.
Case Definitions and Collection of Data
A prospective registry of all invasive cases of meningococcal disease since 1975 has been generated. This registry includes all patients with a diagnosis of infection, confirmed by culture of blood, cerebrospinal fluid (CSF Cerebrospinal Fluid (CSF) Analysis Definition
Cerebrospinal fluid (CSF) analysis is a laboratory test to examine a sample of the fluid surrounding the brain and spinal cord. ), or joint fluid. It also includes patients with clinical illness compatible with meningococcal disease and a positive culture from a throat specimen or a positive Gram-stain smear smear (smer) a specimen for microscopic study prepared by spreading the material across the slide.
Pap smear , Papanicolaou smear see under test. , latex agglutination test latex agglutination test
A passive agglutination test in which antigen is adsorbed onto latex particles.
latex agglutination test , or polymerase chain reaction polymerase chain reaction (pŏl`ĭmərās') (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sample of a piece of DNA; the process is (PCR PCR polymerase chain reaction.
polymerase chain reaction
Polymerase chain reaction (PCR) ) of CSF, blood, or joint fluid. The registry also includes information regarding patient age, sex, and residence and location of hospital where treatment was administered. We calculated the death ratio for patients with meningococcal disease during hospitalization hospitalization /hos·pi·tal·iza·tion/ (hos?pi-t'l-i-za´shun)
1. the placing of a patient in a hospital for treatment.
2. the term of confinement in a hospital. or within 4 weeks of diagnosis by hospital records and the national population registry of Iceland (http://www.statice.is/). Imported cases were excluded.
Microbiology microbiology: see biology.
Scientific study of microorganisms, a diverse group of simple life-forms including protozoans, algae, molds, bacteria, and viruses.
All invasive meningococcal isolates are sent for serogrouping and susceptibility testing susceptibility test Antimicrobial susceptibility test, see there at the Department of Clinical Microbiology Clinical microbiology
The adaptation of microbiological techniques to the study of the etiological agents of infectious disease. Clinical microbiologists determine the nature of infectious disease and test the ability of various antibiotics to inhibit or kill at Landspitali University Hospital, the national reference laboratory for the country. The oldest invasive isolates in the collection date from 1977. In total, 362 isolates from January l, 1977, to December 31, 2004, were viable and thus available for further study. Serogrouping was performed by using standard antisera (Difco Laboratories, Detroit, MI, USA). When an unusual relationship was observed between serogroups and STs, serogrouping was performed at least twice. MICs for penicillin penicillin, any of a group of chemically similar substances obtained from molds of the genus Penicillium that were the first antibiotic agents to be used successfully in the treatment of bacterial infections in humans. , sulfadiazine sulfadiazine /sul·fa·di·a·zine/ (-di´ah-zen) a sulfonamide antibacterial, used as the base or the sodium salt in the treatment of infections including nocardiosis, toxoplasmosis, otitis media, and chloroquine-resistant falciparum malaria. , and rifampin rifampin (rĭfăm`pĭn), antibiotic used in the treatment of tuberculosis. It is also used to eliminate the meningococcus microorganism from carriers and to treat leprosy, or Hansen's disease. were measured by using the Etest (AB Biodisk, Solna, Sweden) according to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. Clinical Laboratory Standards Institute criteria (9).
MLST was performed by determining the nucleotide nucleotide (n`klēətīd', ny`–), organic substance that serves as a monomer in forming nucleic acids. sequences of 7 housekeeping genes (abcZ, adk, aroE, fumC, gdh, pdhC, pgm) as previously described (8). Alleles and sequences were assigned by using the MLST database (http://neisseria.org/nm/typing/mlst/). Sequence typing data were analyzed as described previously (10). Data were submitted to the MLST database from January 30, 2004, to August 10, 2004, and STs that had not been previously described were assigned a new number. Strains with STs that were found exclusively in Iceland were classified as "unique" in the context of statistical analysis. The allelic al·lele
One member of a pair or series of genes that occupy a specific position on a specific chromosome.
[German Allel, short for Allelomorph, allelomorph, from English profiles were used to study the relatedness of the STs by using the unweighted pair-group method with arithmetic mean (mathematics) arithmetic mean - The mean of a list of N numbers calculated by dividing their sum by N. The arithmetic mean is appropriate for sets of numbers that are added together or that form an arithmetic series. (UPGMA UPGMA Unweighted Pair Group Method, Arithmetic Mean ). Phylogenetic trees phylogenetic tree
Diagram showing the evolutionary interrelations of a group of organisms that usually originated from a shared ancestral form. The ancestor is in the tree trunk; organisms that have arisen from it are placed at the ends of tree branches. were constructed with the Sequence Type Analysis and Recombinational Tests (START) suite of programs (http://pubmlst.org/software/).
BURST (Based Upon Related Sequence Types, http://pubmlst.org/software/) was also used to examine the relationships within clonal complexes, while the relationships between different clonal complexes were ignored. BURST required allelic profile data only, and these also contained their ST numbers. For MLST data based on 7 loci loci
[L.] plural of locus.
loci Plural of locus, see there , a cutoff point Cutoff point
The lowest rate of return acceptable on investments. of 5 identical loci allows inclusion of strains that belong to a single clonal complex, while excluding those that do not.
The collective term "ST group" was used to differentiate unique STs, defined as strains found exclusively in Iceland, from other STs, which have been described elsewhere. We used the Pearson [chi square chi square (kī),
n a nonparametric statistic used with discrete data in the form of frequency count (nominal data) or percentages or proportions that can be reduced to frequencies. ] test and the Fisher exact test as appropriate to assess the bivariate bi·var·i·ate
Mathematics Having two variables: bivariate binomial distribution.
Adj. 1. relationship between categorical That which is unqualified or unconditional.
A categorical imperative is a rule, command, or moral obligation that is absolutely and universally binding.
Categorical is also used to describe programs limited to or designed for certain classes of people. variables, in particular how death rate was related to the other variables, including ST group. Patient age, based on ST group of the isolate and patient status, was compared by using the Mann-Whitney test. To further assess factors associated with death, we performed multivariable logistic regression In statistics, logistic regression is a regression model for binomially distributed response/dependent variables. It is useful for modeling the probability of an event occurring as a function of other factors. analysis with death as the dependent variable. Controlling for age, we tested each of the following variables in separate models: sex of the patients, serogroup (B, C, and others), ST group (unique STs vs. other STs), residence (capitol area vs. rural), hospital location (capitol area vs. rural), and finally, we examined the site of the positive bacterial culture in 2 different ways, in 4 categories (blood, CSF only, both blood and CSF, and other sites), and in 2 categories (CSF only vs. all other sites). Variables that remained significant in the model after controlling for age were evaluated in further models to assess independent associations with death. Level of significance was set at p<0.05. All tests were 2-tailed. Statistical analysis was performed by using SPSS A statistical package from SPSS, Inc., Chicago (www.spss.com) that runs on PCs, most mainframes and minis and is used extensively in marketing research. It provides over 50 statistical processes, including regression analysis, correlation and analysis of variance. version 10.5 (SPSS Inc., Chicago, IL, USA).
Epidemiology of Invasive Meningococcal Disease
The number of registered cases in Iceland varied greatly from 1977 to 2004, ranging from 55 cases/year during the epidemic of 1977 to 7-8 cases/year in 1988 and 2003. The average incidence of invasive meningococcal disease during this 28-year period was 7.1 cases/100,000 population/year, but if the epidemic year of 1977 is excluded, it drops to 6.4 cases/100,000 population/year. A detailed description of the study cohort and serogroups of the organisms is given in Table 1. Meningococci were most commonly isolated from CSF only (39.7%). Serogroups varied substantially within the study period (Figure 1).
[FIGURE 1 OMITTED]
Sequence Typing of Meningococcal Isolates
MLST was performed on all 362 viable strains, which were responsible for 72.7% of all documented cases of invasive meningococcal disease in the country during the study period. Overall, 59 STs were observed. A summary of the MLST results is given in Table 2, and the association between STs and serogroups is shown in Table 3. Missing isolates were predominantly from the first 2 years of the study. During the epidemic of 1977, pathogens were genetically homogenous homogenous - homogeneous , however, as all strains were ST-10 (Table 2).
Strains of 8 different STs caused 75% of all infections. ST-32 was most common, causing 24.6% of all cases. It was predominantly of serogroup B and endemic during almost the entire period. ST-32 also caused a small epidemic in the country in 1993 and 1994. The second most common ST was ST-11 (19.9% of all cases), which was predominantly of serogroup C. It was first seen in Iceland in 1989 and was the main culprit in invasive meningococcal disease from 1999 to 2002. ST-10 caused 10.2% of all infections and dominated during the first 3 years of the study, but it has not been seen since 1983. In 1983, a new type emerged, ST-3492 from the ST-41/44 complex; it was the fourth most common ST in Iceland overall and caused 7.7% of all infections. ST-3492 was predominantly serogroup C. This ST was the most common cause of invasive disease in 1989 and 1990 but disappeared after 1996.
During the study, 19 STs that were unique to Iceland were described, and these accounted for 14.6% of all invasive infections. Most of these emerging STs (14 of 19) caused only single infections (3.9% of all episodes). The remaining 5 STs caused 10.8% of all invasive disease in the country.
In general, good concordance concordance /con·cor·dance/ (-kord´ins) in genetics, the occurrence of a given trait in both members of a twin pair.concor´dant
n. was seen between STs and serogroups. Nevertheless, isolates exhibiting both serogroup B and C capsules were observed among the 4 most common STs (Table 3).
Dendrogram A dendrogram is a tree diagram frequently used to illustrate the arrangement of the clusters produced by a clustering algorithm (see cluster analysis). Dendrograms are often used in computational biology to illustrate the clustering of genes. and Clonal Complexes
The phylogenetic tree of isolates in this study is shown in Figure 2. All STs that were encountered in [greater than or equal to] 3 clinical cases and all new STs are shown. ST-2148 was remarkably similar to ST-32, differing only at 1 locus. This clone emerged in 1999 and, like ST-32, was found in both serogroups B and C. ST-11 was most closely related to ST-8 and ST-10, which had 4 and 3 genes, respectively, in common with ST-11. However the ST-8 and ST-10 clones had different serogroups. The relationships within clonal complexes and their association with death is shown in Table 4. We identified 9 complexes and 17 singletons; most isolates (26.5%) fell within group 2, in which ST-32 was the ancestral ANCESTRAL. What relates to or has, been done by one's ancestors; as homage ancestral, and the like. strain.
[FIGURE 2 OMITTED]
Routine vaccination vaccination, means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of live, killed, or altered antigens that stimulate the body to produce antibodies against more dangerous forms. was initiated among children and young adults (< 18 years of age) in late 2002 with a conjugated conjugated
estrogens, conjugated Warning - Hazardous drug!
C.E.S. meningococcal vaccine against serogroup C (NeisVac-C, Baxter, Orth/Donau, Austria); >90% of all Icelanders <18 years of age were vaccinated. Three years later, no evidence has been seen for capsule switching.
Antimicrobial antimicrobial /an·ti·mi·cro·bi·al/ (-mi-kro´be-al)
1. killing microorganisms or suppressing their multiplication or growth.
2. an agent with such effects. Drug Susceptibility
All meningococcal isolates were susceptible to penicillin (MIC 0.012-0.125 [micro]tg/mL). All strains were also susceptible to rifampin (MIC 0.008-0.19 [micro]g/mL) (9). In contrast, 148 isolates (40.9%) were resistant to sulfadiazine (MIC >8 [micro]g/mL). Most commonly, these meningococci were ST-32, ST-1, and ST-11.
During the 28-year study period, 31 (8.6%) of 362 patients died after the infection. Higher case-fatality ratios case-fatality ratio Epidemiology A value calculated as 100 cases of a disease 'X', divided by the number of persons with the disease who died in a given period of time; the resulting ratio is equal to the rate of a disease's occurrence. See Cause-fatality ratio. were associated with higher age (p = 0.001), but no significant difference was seen between men and women (p = 0.953), residents in the capitol area and rural areas (p = 0.259), or patients who received treatment in hospitals in the capitol area versus in rural hospitals (p = 0.239). When results were analyzed by source of culture, patients with a positive culture from CSF only had significantly lower death ratios than other patients in the cohort (4.2% vs 11.5%, p = 0.02). These patients were younger than the remainder of the cohort, and as a result, this difference was of borderline borderline /bor·der·line/ (-lin) of a phenomenon, straddling the dividing line between two categories.
borderline significance when age was corrected for (p = 0.059).
The association between the most common STs, serogroups, and patient outcomes is summarized in Table 3. Unique STs were more frequently found in isolates with serogroup C capsule (19 of 204 with B, 33 of 144 with C, and 1 of 13 with other serogroups; p = 0.001). Death was not associated with particular serogroups, however (14 of 204 with B, 14 of 144 with C, and 3 of 14 with other serogroups, p = 0.138). The case-fatality ratio among patients infected by meningococci with previously described STs was 7.1% (22/309) compared to 17.0% (9/53) of patients infected by unique STs (p = 0.03). No significant difference was found between the age of patients with unique and previously described STs (p = 0.686) and source of isolates among patients with unique and previously described STs (p = 0.511).
We then performed multivariable logistic regression analysis to study the association of these parameters with outcome, age and sex of the patient, residence, location of hospital, source of positive culture, serogroup of the isolates, and ST group (unique STs in comparison to other STs). In the final model (Table 5) 3 parameters were independently associated with outcomes. Higher age was highly significantly associated with death, followed by infection with a unique ST. Isolation of meningococci from CSF only was associated with lower case-fatality ratios. Age and ST group remained significant when epidemic cases from 1977 were excluded from the analysis (data not shown).
To our knowledge, this population-based, longitudinal study longitudinal study
a chronological study in epidemiology which attempts to establish a relationship between an antecedent cause and a subsequent effect. See also cohort study. is the first of its kind to examine the molecular epidemiology molecular epidemiology Molecular medicine An evolving field that combines the tools of standard epidemiology–case studies, questionnaires and monitoring of exposure to external factors with the tools of molecular biology–eg, restriction endonucleases, of all viable invasive meningococcal strains by using MLST. The 28-year observation period started in 1977, during an epidemic of meningococcal disease in Iceland. The well defined population of Iceland, with excellent follow-up information on patients and its relative isolation make it an ideal setting for studies of this nature.
In the current study, the 362 isolates had 59 different STs, and of those, 19 were exclusively found in Iceland. These unique STs accounted for 14.4% of all infections during the 28-year period, and ST-3492 was by far the most common.
Although both long-term studies and population-based studies are lacking, other investigators have used MLST to study selected meningococcal strains from individual countries (8,11-13). For example, Murphy et al. analyzed 56 Irish meningococcal strains by this method, collected during a 4-year period. Of the invasive isolates, 26 different STs were identified, including 5 new ones (12). Takahasi et al. found 65 different STs among 182 isolates, 42 of which were unique to Japan, in a survey of Japanese strains (13). The distribution of some STs therefore seems to be fairly restricted geographically, which is also manifested by the fact that 41.1% of the Icelandic isolates characterized in this study are exclusively associated with Scandinavia.
ST-32 was the most common type found in Iceland, causing almost one fourth of all infections. It has been reported to cause numerous outbreaks worldwide and has a tendency to cause hyperendemic disease, particularly septicemia septicemia (sĕptĭsē`mēə), invasion of the bloodstream by virulent bacteria that multiply and discharge their toxic products. The disorder, which is serious and sometimes fatal, is commonly known as blood poisoning. with a high death rate (12). However, in our study, the case-fatality ratio in patients infected by ST-32 did not differ from that in patients infected by other STs. The second most common type, ST- 11, caused most cases of serogroup C disease during the second half of the study. This type has also been reported in several countries, with a propensity to spread rapidly once introduced into the population (8,12,14). The third most common type, ST-10, was mostly serogroup B. It was the primary cause of the meningococcal outbreak in 1977, but it disappeared after 1983. The most closely related type, ST-8, was first detected in the country more than a decade later, but this ST uniformly belonged to serogroup C. ST-3492 was the fourth most common type; it had not been described previously. It was almost uniformly serogroup C, with a tendency to cause worse outcomes.
By comparing the 7 housekeeping genes used in MLST, a close relationship between ST-11, ST-8, and ST-10 was observed. However, ST-11 and ST-8 are primarily serogroup C, whereas ST-10 is primarily serogroup B. These results could indicate genetic transfer and possible capsular cap·su·lar
Of, relating to, or resembling a capsule.
Adj. 1. capsular - resembling a capsule; "the capsular ligament is a sac surrounding the articular cavity of a freely movable joint and attached to the bones" switch. Analysis of genetic relatedness also shows a close relationship between ST-206 and ST-3492, which were most commonly serogroup C. However, both ST-206 and ST-3492 are part of the ST41/44 complex, which is predominantly associated with serogroup B meningococci, thus highlighting genetic transfer between closely related STs.
All of our strains were susceptible to penicillin. This contrasts with the situation in southern Europe Southern Europe or sometimes Mediterranean Europe is a region of the European continent. There is no clear definition of the term which can vary depending on whether geographic, cultural, linguistic or historical factors are taken into account. , in particular, where resistance is increasingly reported (15-17). Likewise, none of the isolates in our study exhibited resistance to rifampin, which still seems to be rare (18).
To our knowledge, this is the first study to look at associations between STs and patient outcomes. By multivariable analysis, age and infection by a unique ST were independently associated with higher death rates. Lower death rates were observed among patients with a positive culture from CSF only than among other patients. Age has previously been shown to be associated with worse outcome in patients with meningitis meningitis (mĕnĭnjī`tĭs) or cerebrospinal meningitis (sĕr'əbrōspī`nəl), acute inflammation of the meninges, the membranes that cover and protect the brain and spinal cord. (19), but infection with a novel or unique ST has not. At least 2 potential explanations could explain this difference. First, these strains likely represent evolutionary changes within the meningococcal population; therefore, a lower level of immunity against the unique STs within the population could translate into greater disease severity. In the case of pneumococcal pneumococcal /pneu·mo·coc·cal/ (-kok´al) pertaining to or caused by pneumococci. infections, for example, the spread of clonal types can be influenced by herd immunity herd immunity
1. Resistance to the spread of infectious disease in a group because susceptible members are few, making transmission from an infected member unlikely.
2. (20). Second, the difference in outcomes may indicate greater virulence Virulence
The ability of a microorganism to cause disease. Virulence and pathogenicity are often used interchangeably, but virulence may also be used to indicate the degree of pathogenicity. of unique STs. Although data on this topic are lacking for meningococci, Sandgren et al. have shown that pneumococci with identical serotypes but different clonal types can have different invasive potentials (21,22). We therefore propose that meningococcal expression of virulence traits, other than the capsule type, may be linked to certain STs. Indeed, recent data suggest that serogroup C capsule expression may contribute to the invasive character of ST-11 meningococci (23). A more detailed analysis of virulence properties of specific meningococcal STs, including capsule expression, and their association with clinical characteristics is warranted. Judging from clinical experience, increased awareness during meningococcal epidemics may speed diagnosis and improve prognosis, which could bias our results since an epidemic of meningococcal infections was ongoing in 1977, when this study began. The epidemic was primarily caused by ST-10, an "old" ST, which accordingly could be associated with lower death ratio. However, the 2 risk factors for poor outcome remained significant even when epidemic cases were excluded, which argues against this hypothesis. When the outcomes were analyzed by source of the isolate, having a positive culture from CSF only was associated with lower risk for death. Although patients with CSF isolates were younger, this parameter remained significant when we corrected for age and ST category of the isolate. We do not have detailed information regarding patients' clinical signs and symptoms. Nevertheless, this part of the cohort most likely represents patients with meningitis, who generally have lower death ratios than do those with sepsis Sepsis Definition
Sepsis refers to a bacterial infection in the bloodstream or body tissues. This is a very broad term covering the presence of many types of microscopic disease-causing organisms. .
One limitation of the study is that submission date of MLST data ultimately determined whether we classified STs as old or new, which may bias the results. However, most data were submitted within a relatively short period, which should minimize this risk. As a result, more than a year from the original submission of the data (December 2005), we checked whether subsequent isolates with these novel STs had been identified, and none were found. Since routine vaccination was implemented in Iceland, meningococcal C disease has only been seen among unvaccinated adults. The rise in serogroup B is of concern, but a longer observation period is required before a conclusion can be reached regarding the issue of serogroup replacement.
In summary, this long-term, nationwide study looked at evolutionary trends of invasive meningococcal isolates in a well-defined setting, where invasive meningococcal disease has been hyperendemic. Although the most common STs have been described previously, we describe a high number of emerging STs. In particular, one ST, unique to Iceland, ranked fourth in prevalence. This study highlights the interplay between epidemiologic and evolutionary processes, which ultimately may produce unique meningococcal strains that lead to worse outcomes. More studies on virulence properties and host immunity are warranted to advance preventive strategies against meningococcal disease.
The authors thank Olafur Skuli Indridason for assistance with statistical analysis of the data and the staffs at the Scottish Meningococcus meningococcus
Neisseria meningitidis, the bacterium that causes meningococcal meningitis in humans, the only natural hosts in which it causes disease. Meningococci are spherical, frequently occur in pairs, and are strongly gram-negative (see gram stain). and Pneumococcus pneumococcus
Spheroidal bacterium (Streptococcus pneumoniae) that causes human diseases including pneumonia, sinusitis, ear infection, and meningitis. Usually occurring in the upper respiratory tract, this gram-positive (see Reference Laboratory, Glasgow, and Landspitali University Hospital, Reykjavik, for assistance in this project.
This project was supported in part by the Landspitali University Hospital Science Fund, the Director of Public Health, and Alcan, Reykjavik, Iceland, and the Meningitis Association and National Services Division of the Scottish Executive, Scotland, United Kingdom. Robotic liquid handling systems and DNA sequencers A DNA sequencer is an instrument used to automate the DNA sequencing process.
DNA sequencers have become more important due to large genomics projects and the need to increase productivity. were funded by the Meningitis Association and National Services of the Scottish Executive. This study made use of the Neisseria Multi Locus Sequence Typing website, developed by Keith Jolley and Man-Suen Chan at the University of Oxford. The development of this site has been funded by the Wellcome Trust The Wellcome Trust is a United Kingdom-based charity established in 1936 to administer the fortune of the American-born pharmaceutical magnate Sir Henry Wellcome. Its income was derived from what was originally called Burroughs Wellcome & Co, later renamed in the UK as the and the European Union European Union (EU), name given since the ratification (Nov., 1993) of the Treaty of European Union, or Maastricht Treaty, to the
European Community .
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(3.) Robbins JB, Schneerson R, Gotschlich EC, Mohammed I Mohammed I, or the equivalent in the local language, can refer to the following Muslim rulers:
An acute infectious disease affecting children and young adults characterized by inflammation of the meninges of the brain and spinal cord, headache, vomiting, convulsions, stiff neck, light sensitivity, and purpuric in sub-Saharan Africa: the case for mass and routine vaccination with available polysaccharide polysaccharide: see carbohydrate.
Any of a large class of long-chain sugars composed of monosaccharides. Because the chains may be unbranched or branched and the monosaccharides may be of one, two, or occasionally more kinds, vaccines. Bull World Health Organ. 2003;81:745-50.
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1. Having the capability to cause disease.
2. Producing disease.
3. Relating to pathogenesis. microorganisms. Proc Natl Acad Sci U S A. 1998;95:3140-5.
(8.) Clarke SC, Diggle MA, Edwards GFS See Google File System.
GFS - Grandfather, Father, Son . Semiautomation of multilocus sequence typing for the characterization of clinical isolates of Neisseria meningitidis. J Clin Microbiol. 2001 ;39:3066-71.
(9.) Clinical and Laboratory Standards Institute. M100-S15 performance standard for antimicrobial susceptibility testing, 15th informational supplement. Wayne (PA): The Institute; 2005.
(10.) Diggle MA, Clarke SC. Rapid assignment of nucleotide sequence data to allele allele (əlēl`): see genetics.
Any one of two or more alternative forms of a gene that may occur alternatively at a given site on a chromosome. types for multi-locus sequence analysis (MLSA MLSA Montana Legal Services Association
MLSA Ministry of Labour and Social Affairs
MLSA Muslim Law Students Association
MLSA Multilocus Sequence Analysis
MLSA Modern Language Studies Abroad
MLSA Money Laundering Suppression Act of 1994 ) of bacteria using an adapted database and modified alignment program. J Mol Microbiol Biotechnol. 2002;4:515-7.
(11.) Diggle MA, Clarke SC. Increased genetic diversity of Neisseria meningitidis isolates after the introduction of meningococcal serogroup C polysaccharide conjugate vaccines A conjugate vaccine is created by covalently attaching a poor antigen to a carrier protein, thereby conferring the immunological attributes of the carrier on the attached antigen. . J Clin Microbiol. 2005;43:4649-53.
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(13.) Takahashi H, Kuroki T, Watanabe Y, Tanaka H, Inouye H, Yamai S Yamai devi or Shree Yamai devi temple is situated in a hill complex in the town of Aundh, Satara district, Maharashtra. There are steps which take you to the top of hill. A rather perilous road can also be used to reach the top by car. , et al. Characterization of Neisseria meningitidis isolates collected from 1974 to 2003 in Japan by multilocus sequence typing. J Med Microbiol. 2004;53:657-62.
(14.) Pollard pollard
fine protein-rich feed supplement for farm animals; a byproduct from the milling of wheat for flour. Called also shorts. AJ, Ochnio J, Ho M, Callaghan M, Bigham M, Dobsong S. Disease susceptibility to ST11 complex meningococci bearing serogroup C or W135 polysaccharide capsules, North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. . Emerg Infect infect /in·fect/ (in-fekt´)
1. to invade and produce infection in.
2. to transmit a pathogen or disease to.
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(17.) Saezo-Nieto JA, Lujan R, Berron S, Campos Campos (käm`ps), city (1996 pop. 391,299), Rio de Janeiro state, SE Brazil, on the Paraíba River near its mouth. J, Vinas M, Fuste C, et al. Epidemiology and molecular basis of penicillin-resistant Neisseria meningitidis in Spain: a 5-year history (1985-1989). Clin Infect Dis. 1992;14:394-402.
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(19.) van de Beek D, de Gans J, Spanjaard L, Weisfelt M, Reitsma JB, Vermeulen M. Clinical features and prognostic factors prognostic factor Medtalk Any factor–eg, Pt age, family Hx, lifestyle, stage of presentation, that is weighed in determining a prognosis. See Prognosis. in adults with bacterial meningitis bacterial meningitis Acute bacterial meningitis Neurology Meningeal inflammation caused by bacteria which, if untreated, is often fatal, or associated with significant sequelae Epidemiology 60% are community-acquired–CM, 40% nosocomial–NM Predisposing . N Engl J Med. 2004;351:1849-59.
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Streptococcus pneumoniae Microbiology A pathogenic streptococcus with 90 serotypes associated with pneumonia, bacteremia, meningitis Transmission Person to person Incidence . J Infect Dis. 2004;189:785-96.
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Magnus Gottfredsson, * ([dagger]) Mathew A. Diggle, ([double dagger double dagger
A reference mark () used in printing and writing. Also called diesis.
Noun 1. ]) David I David I, king of Scotland
David I, 1084–1153, king of Scotland (1124–53), youngest son of Malcolm III and St. Margaret of Scotland. During the reign of his brother Alexander I, whom he succeeded, David was earl of Cumbria, ruling S of the Clyde . Lawrie, ([double dagger]) Helga Erlendsdottir, * Hjordis Hardardottir, * Karl G Kristinsson,* ([dagger]) and Stuart C. Clarke ([double dagger]) ([section])
* Landspitali University Hospital, Reykjavik, Iceland; ([dagger]) University of Iceland (body, education) University of Iceland - The Home of Fjolnir.
http://rhi.hi.is/. , Reykjavik, Iceland; ([double dagger]) Scottish Meningococcus and Pneumococcus Reference Laboratory, Glasgow, United Kingdom; and ([section]) University of Glasgow The University of Glasgow (Scottish Gaelic: Oilthigh Ghlaschu, Latin: Universitas Glasguensis) was founded in 1451, in Glasgow, Scotland. , Glasgow, United Kingdom
Address for correspondence: Magnus Gottfredsson, Landspitali University Hospital, Fossvogur, 108 Reykjavik, Iceland; email: firstname.lastname@example.org
Dr Gottfredsson is consultant in infectious diseases infectious diseases: see communicable diseases. at Landspitali University Hospital and associate professor of internal medicine and infectious diseases at the University of Iceland School of Medicine. His research interests include epidemiology and pathogenesis pathogenesis /patho·gen·e·sis/ (path?ah-jen´e-sis) the development of morbid conditions or of disease; more specifically the cellular events and reactions and other pathologic mechanisms occurring in the development of disease. of invasive infections, including meningitis, sepsis, and nosocomial infections Nosocomial infections
Infections that were not present before the patient came to a hospital, but were acquired by a patient while in the hospital.
Mentioned in: Enterobacterial Infections, Staphylococcal Infections .
Table 1. Description of the patient cohort Parameter No. (%) Patients 362 Male 185 (51.1) Female 177 (48.9) Children * 244 (67.4) Adults 118 (32.6) Strain isolated from cerebrospinal fluid only 144 (39.8) Strain isolated from blood only 105 (29.0) Strain isolated from cerebrospinal fluid and blood 78 (21.5) Strain isolated from joint fluid 10 (2.8) Strain grown from throat culture ([dagger]) 25 (6.9) Serogroup A 8 (2.2) Serogroup B 204 (56.4) Serogroup C 144 (39.8) Serogroup Y 3 (0.8) Serogroup W135 3 (0.8) * <16 years of age at the time of diagnosis. ([dagger]) Positive throat culture in the setting of invasive meningococcal disease, diagnosed clinically. Table 2. Epidemiology of invasive meningococcal disease in Iceland * Sequence type (ST) Year No. (no. cases) isolates 1 8 10 11 32 40 1977 (55) 9 9^ 1978 (21) 13 10^ 1979 (25) 18 13^ 1 1980 (16) 6 3^ 1 1981 (18) 11 4^ 2 2 1982 (10) 7 1 1 2^ 1983 (19) 10 1 2^ 1984 (13) 8 6^ 1985 (13) 12 1986 (11) 10 1 1987 (9) 5 1988 (7) 6 1 1989 (14) 9 1 1990 (17) 10 2 1991 (18) 17 1 5^ 1992 (21) 19 4^ 4^ 1993 (23) 22 5 13^ 1994 (30) 26 1 5 16^ 1995 (14) 10 2 5^ 1996 (17) 16 1 3 8^ 1997 (20) 18 6^ 2 5^ 1998 (16) 15 4 3 7^ 1999 (20) 20 1 10^ 4 2000 (18) 16 3 6^ 2 2001 (19) 17 12^ 1 2002 (16) 14 13^ 2003 (8) 8 2^ 2004 (10) 10 3^ 2 3^ Total 362 8 16 37 72 89 3 Sequence type (ST) Year (no. cases) 41 44 60 162 206 275 1314 1977 (55) 1978 (21) 1979 (25) 1980 (16) 1981 (18) 1982 (10) 1 1983 (19) 1 2^ 1984 (13) 1985 (13) 2 1 1986 (11) 2 1 1987 (9) 1 2^ 1 1988 (7) 2^ 1 1989 (14) 1 1990 (17) 1 1 1991 (18) 1 2 1 1992 (21) 3 1 1 1993 (23) 2 1 1994 (30) 1 1995 (14) 1 1996 (17) 1 1997 (20) 1 1 1998 (16) 1999 (20) 1 2000 (18) 1 2001 (19) 1 2002 (16) 2003 (8) 1 2004 (10) Total 3 4 7 3 9 4 11 Sequence type (ST) Year (no. cases) 1323 2148 2266 3435 3464 3492 1977 (55) 1978 (21) 1979 (25) 2 1980 (16) 1981 (18) 1982 (10) 1 1 1983 (19) 2^ 1 1984 (13) 1 1 1985 (13) 3^ 1 3^ 1986 (11) 2 3^ 1987 (9) 1 1988 (7) 2^ 1989 (14) 5^ 1990 (17) 4^ 1991 (18) 3 1992 (21) 3 1993 (23) 1 1994 (30) 1 1995 (14) 1 1996 (17) 1 1997 (20) 1998 (16) 1 1999 (20) 1 2000 (18) 1 2001 (19) 1 2002 (16) 1 2003 (8) 3^ 2004 (10) Total 9 3 5 3 3 28 Year (no. cases) Other STs 1977 (55) 1978 (21) 334, 2986, 3333 1979 (25) 13, 1011 1980 (16) 3501#, 4013# 1981 (18) 1423, 2320, 3471 1982 (10) 1983 (19) 43 1984 (13) 1985 (13) 1328 (x2) 1986 (11) 23 1987 (9) 1988 (7) 1989 (14) 785, 3502 1990 (17) 2843, 3508 1991 (18) 1015, 1154, 3509#, 5119# 1992 (21) 34, 3710# (x2) 1993 (23) 1994 (30) 286, 3756# 1995 (14) 46 1996 (17) 43, 467 1997 (20) 22, 944, 1671 1998 (16) 1999 (20) 352, 3757#, 3758# 2000 (18) 23, 34, 3759# 2001 (19) 33, 1943 2002 (16) 2003 (8) 1163, 3334# 2004 (10) 1281, 4178# Total 45 * The total number of cases is shown with the number of ST isolates available for multilocus sequence typing. Unique STs, those found exclusively in Iceland, are shown in italics. The most prevalent STs for each year are shown in shaded cells. Note: Unique STs, those found exclusively in Iceland is indicated with #. Note: The most prevalent STs for each year is indicated with ^. Table 3. Association between meningococcal sequence types (STs), serogroups, and death, Iceland. 1977-2004 * Serogroup A Serogroup B ST No. isolates No. deaths No. isolates No. deaths 32 86 7 11 5 10 36 1 3492# 2 8 1314 11 206 1 1 1323 1 8 60 7 2266 5 44 4 275 4 1 40 3 41 3 1 162 3 2148# 2 1 3435# 3 2 3464# 23 34 1 43 1 1328 3710# 2 Total Serogroup C No. deaths ST No. isolates No. deaths No. isolates (%) 32 3 89 7 (8) 11 67 6 72 6 (8) 10 1 1 37 2 (5) 3492# 26 4 28 4 (14) 8 16 16 1314 11 206 8 9 1 (11) 1323 9 9 1 8 60 7 2266 5 44 4 275 4 1 (25) 40 3 41 3 1 (33) 162 3 2148# 1 3 1 (33) 3435# 3 2 (67) 3464# 3 3 23 2 ([dagger]) 1 (50) 34 1 2 43 1 2 1328 2 1 2 1 (50) 3710# 2 * All STs that were encountered more than once are shown. Blank cells indicate zero values. Unique STs are shown in italics; 19 unique STs were found. Of 362 cases, 53 were caused by strains with unique STs and 309 by other STs. ([dagger]) Both isolates were serogroup Y. Note: Unique STs is indicated with #. Table 4. Association between Neisseria meningitidis CC, ST, and patient deaths, Iceland, 1977-2004 * ([dagger]) CC ST Deaths (freq) SLV DLV SAT 1 10 2 (37) 0 1 0 8 0 (16) 0 1 0 2 32# 7 (89)# 3# 1# 0# 34 0 (2) 1 2 1 1015 0 (1) 2 2 0 2148 1 (3) 1 2 1 33 0 (1) 3 1 0 3 3756^ 0 (1) 0 1 14 3492^ 4 (28) 1 6 8 43 0 (2) 3 5 7 44 0 (4) 1 5 9 46 0 (1) 1 2 12 206# 1 (9)# 4# 4# 7# 3509^ 0 (1) 1 4 10 41 1 (3) 3 4 8 2266 0 (5) 2 1 12 2320 0 (1) 0 1 14 1423 0 (1) 0 1 14 3502^ 1 (1) 1 4 10 3508^ 0 (1) 4 4 7 1328 0 (2) 0 1 14 2843 0 (1) 1 4 10 40 0 (3) 2 1 12 4 1314 0 (11) 0 1 0 3757^ 0 (1) 0 1 0 5 467 0 (1) 0 1 0 13 0 (1) 0 1 0 6 275# 1 (4)# 3# 1# 1# 1163 0 (1) 2 1 2 1671 0 (1) 1 2 2 3758^ 0 (1) 0 1 4 352 0 (1) 2 2 1 3435^ 2 (3) 0 1 4 7 1154 0 (1) 1 0 0 60# 0 (7)# 1# 0# 0# 8 3710^ 0 (2) 0 2 1 1323 0 (9) 1 2 0 3464^ 0 (3) 1 0 2 334 0 (1) 0 2 1 9 3501^ 0 (1) 1 0 0 2986 0 (1) 1 0 0 * CC, clonal complex; ST, sequence type; freq, frequency of isolates with the ST; SLV, single locus variant; DLV, double locus variant; SAT, satellite. ([dagger]) We identified 9 clonal complexes and 17 singletons (11, 286, 5119, 162, 1, 3759, 23, 1943, 22, 944, 3471, 3333, 1011, 785, 3334, 4178, and 4013), defined as strains that do not fit in any group in the collection. Some groups have an ST that is the ancestral strain for that group (shown in boldface). Unique STs are shown in italics. Note: Some groups have an ST that is the ancestral strain for that group is indicated with #. Note: Unique STs is indicated with ^. Table 5. Multivariate analysis of death rate in patients with invasive meningococcal disease, Iceland, 1977-2004 * Variable OR (95% CI) p value Age 1.031 (1.016-1.048) 0.0001 Unique ST ([dagger]) 3.225 (1.311-7.934) 0.011 Positive CSF culture ([double dagger]) 0.381 (0.147-0.984) 0.046 * OR, odds ratio; CI, confidence interval; ST, sequence type; CSF, cerebrospinal fluid. ([dagger]) Infection with an isolate with an ST unique to the country, in comparison to other, previously described STs. ([double dagger]) Positive CSF culture only, in comparison to all other sources of positive culture, including blood only and blood and CSF.