Search

Background: Gonorrhoea can occur in the same individual on multiple occasions, with no apparent immunity. This probably results from the ability of Neisseria gonorrhoeae to exhibit antigenic variation and hence each new infection appears novel. However, there is some evidence that immunity can be acquired, particularly in women, that is directed against the major porin, Por, but this remains controversial. Methods: Patients with two or more episodes of gonorrhoea, at least one month apart, between 1998 and 2002, were randomly chosen. Each isolate was typed using a range of methods; antibiogram, auxotyping, serotyping, and molecular methods of pot sequencing, and lip typing. Results: A total of 80 gonococcal isolates were tested from 30 patients who had been infected on two (17 patients), three (seven patients), four (five patients) or five (one patient) occasions. The time between isolation ranged from one to six months. Of the 80 isolates, 57 gave unique profiles and 23 (29%) had a profile indistinguishable from at least one other isolate. There were 10 paired isolates, which were each from the same patient and one cluster of three, from different patients. The paired isolates were from nine patients, one patient was infected by two different pairs, of which four were men and five were women. Conclusion: This is the first time, to our knowledge, that highly discriminatory typing methods have demonstrated that men and women can be reinfected with indistinguishable gonococcal isolates. [ABSTRACT FROM AUTHOR]

Background: Nosocomial transmission and outbreaks of carbapenemase-producing Enterobacterales (CPE) represent a challenge to healthcare systems. In July 2018, a CPE hospital ward outbreak was declared. Our aim was to investigate transmission patterns, using social network analysis and genomics in a nosocomial CPE outbreak., Methods: A retrospective descriptive analysis of all patients (cases and contacts) admitted to a ward experiencing a CPE outbreak (2018-2019) was undertaken. A case had a negative CPE admission screen, and subsequent positive test. A contact shared a multi-bed area and/or facility with a case (>4 hours). Social networks, including genomics data and ward locations, were constructed. Network metrics were analysed., Findings: Forty-five cases and 844 contacts were analysed. The median age of cases was 78 years (IQR 67-83), 58% (n=26) were male and 100% had co-morbidities. The median outbreak ward length-of-stay (LOS) was 17 days (IQR 10-34). OXA-48 CPE was confirmed in all cases and from 26 environmental samples. Social networks identified clusters by time, gender and species/sequence type/plasmid. Network metrics indicated potential superspreading involving a subset of patients with behavioural issues., Conclusion: Social networks elucidated high resolution transmission patterns involving two related OXA-48 plasmids, multiple species/genotypes and potential super-spreading. Interventions prevented intra-hospital spread. An older patient cohort, extended hospital LOS and frequent intra-ward bed transfers, coupled with suboptimal ward infrastructure, likely prolonged this outbreak. We recommend social network analysis contemporaneously with genomics (on case and environmental samples) for complex nosocomial outbreaks and bespoke care plans for patients with behavioural issues on outbreak wards., (© 2023 The Authors.)

Mycoplasma genitalium is an emerging cause of sexually transmitted infections (STI) with a capacity to rapidly develop antibiotic resistance. The aim of this work was to carry out an evaluation and descriptive analysis of routine molecular testing of M. genitalium in symptomatic women at the Rotunda Hospital, Dublin January 2018-December 2019. 1972 specimens were tested from1291 individual symptomatic female patients > 18 years old. The median age was 29 (range 18-71). There were 10 confirmed positive specimens (0.77%); median patient age 26 (range 18-34); seven were obstetrics/gynaecology patients and three were attendees at a sexual assault treatment unit (SATU). The prevalence of positive cases in the ≥ 18 ≤ 30-year-old age group (n = 683) was six times that of the ≥ 30 year-old age group (n = 608) at 1.3% versus 0.2%. Patient symptoms included: discharge in five (50%); pelvic pain on examination in five (50%); abdominal pain in two (20%); pelvic bleeding in two (20%); dyspareunia in two (20%) patients. Co-infections were present in three patients (30%). Macrolide resistance was detected in two positives (28.6%). This initial pilot study prompts the following recommendations which require further study and consideration: 1. promotion of M. genitalium status to notifiable disease; 2 widespread screening of female population not warranted; 3. M. genitalium testing for women symptomatic for STIs; 4. antibiotic resistance testing of all positive cases. 5. Further research into other potential risk groups., (© 2021. Royal Academy of Medicine in Ireland.)

Objectives: Molecular epidemiological description of an OXA-48 CPE outbreak affecting a tertiary-care hospital ward in Ireland over an extended period (2018-2019)., Methods: Microbiological testing and whole-genome sequencing (WGS) were performed on all 56 positive OXA-48 outbreak case isolates., Results: In total, 7 different species were identified: Enterobacter hormaechei (n = 35, 62.5%), Escherichia coli (n = 12, 21.4%), Klebsiella pneumoniae (n = 5, 8.9%), Klebsiella oxytoca (n = 1, 1.8%), Klebsiella michiganensis (n = 1, 1.8%), Citrobacter freundii (n = 1, 1.8%), and Serratia marcesens (n = 1, 1.8%). E. hormaechei ST78 was the most common genotype (n = 14, 25%). Two major pOXA-48 plasmid types were identified throughout the outbreak, 'types' 1 and 2, and 5 major E. hormaechei clonal groupings were identified: ST78, ST108, ST1126, ST135, and ST66. Within each of the ST108, ST1126, ST135 and ST66 groups, the pOXA-48 harbored within each isolate were the same. Within ST78, 9 isolates contained the pOXA48 'type 2' plasmid and 5 contained the 'type 1' plasmid. Environmental specimens were taken from different outbreak ward locations: handwash basins, sink and shower drains, and taps. Of 394 environmental specimens, OXA-48 CPE was isolated from 26 (6.6%)., Conclusions: This prolonged outbreak of OXA-48 CPE was confined to one ward, but it exemplifies the complexity and difficulty in the control of these organisms. With multiple species and genotypes involved, they may be better described as 'plasmid outbreaks.' WGS provided insights into this diversity and potential transmission among cases, though its usefulness would be enhanced by analysis as close as possible to real time so that interventions can be implemented as soon as data are available., (© The Author(s) 2021.)

The aim of this work was the establishment of a national laboratory sentinel surveillance service for human clinical Campylobacter in Ireland. This included detailed genomic molecular epidemiology of Campylobacter for 2019. For February-December 2019, 24 clinical microbiology laboratories in Ireland submitted all PCR/culture-positive clinical Campylobacter spp. specimens to Public Health Laboratory (PHL) Dublin one week out of every four. Antimicrobial susceptibility testing (AST) according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria was carried out for Campylobacter spp. isolates for ciprofloxacin, tetracycline and erythromycin. Batch whole genome sequencing (WGS) was carried out on cultures and analysis was performed to determine species, genotype, identify antimicrobial resistance (AMR) and virulence determinants and identify clusters. A total of 75 isolates and 366 PCR-positive stools were received, and 277 isolates recovered (55.7% recovery from stools). Of 257 isolates characterized by WGS, 86.4% (n = 222) were Campylobacter jejuni, 11.7% (n = 30) Campylobacter coli and 1.9% (n = 5) Campylobacter lari. There were 20 clonal complexes with ST-21 clonal complex most prevalent at 26.8% (n = 69). 50.5% (n = 140) of isolates were susceptible to all three antimicrobials tested. 39.3% (n = 109) isolates were ciprofloxacin resistant, 26.3% (n = 73) tetracycline resistant and two isolates erythromycin resistant. Congruence between phenotypic and genotypic AST was observed. There was 95.9% and 95.6% sensitivity and specificity for WGS to predict ciprofloxacin sensitivity and 98.6% and 99.5% sensitivity and specificity for WGS to predict tetracycline sensitivity. Virulence factors flaA, racR, ciaB and cdtB were detected in all isolates. WGS identified 31 potential clusters for public health alert. This sentinel surveillance of human campylobacteriosis in Ireland establishes the basis for a national reference service. Linking with other partners in a 'One Health' framework will help us better understand sources of infection to reduce disease burden and the threat of AMR., (© 2021 Wiley-VCH GmbH.)

Neuraminidase inhibitor (NAI) resistance levels globally are currently low. However, as antivirals are increasingly being used, and even in the absence of selective pressure, resistance may increase or emerge. The neuraminidase (NA) genes from influenza viruses from the Irish 2018/2019 season were sequenced: 1/144 (0.7 %) A(H1N1)pdm09 sequences harboured a substitution associated with highly-reduced susceptibility to NAIs. The very low NAI resistance we describe supports current Irish NAI use recommendations. However, continued monitoring is essential. NA characterisation also identified substitutions associated with reduced antibody effectiveness, thereby highlighting the potential of NA sequence surveillance as an additional tool for investigating influenza vaccine effectiveness (VE)., (Copyright © 2020. Published by Elsevier B.V.)

The rapid dissemination of carbapenemase-producing Enterobacterales (CPE) is a major public health concern. The role that the aquatic environment plays in this dissemination is underexplored. This study aimed to examine seawater as a reservoir for CPE. Seawater sampling took place at a bathing site throughout the 2017 bathing season. Each 30 L sample (n = 6) was filtered using the CapE filtration system. Wastewater samples (200 mL) (pre-treatment (n = 3) and post-treatment (n = 3)) were obtained from a nearby secondary wastewater treatment plant, during the same time period. All samples were examined for CPE. Whole genome sequencing of confirmed CPE was carried out using Illumina sequencing. Isolate genomes were hosted in corresponding BIGSdb databases and analyses were performed using multiple web-based tools. CPE was detected in 2/6 seawater samples. It was not detected in any wastewater samples. OXA-48-like-producing ST131 Escherichia coli (Ec_BM707) was isolated from a seawater sample collected in May 2017 and OXA-48-like-producing ST101 Klebsiella pneumoniae (Kp_BM758) was isolated from a seawater sample collected in August 2017. The genomes of the environmental isolates were compared to a collection of previously described Irish clinical OXA-48-like-producing Enterobacterales (n = 105). Ec_BM707 and Kp_BM758 harboured bla OXA-48 on similar mobile genetic elements to those identified in the clinical collection (pOXA-48 fragment in Ec_BM707 and IncL(pOXA-48) plasmid in Kp_BM758). Genetic similarities were observed between Ec_BM707 and several of the clinical ST131 E. coli, with allele matches at up to 98.2% of 2513 core genome multilocus sequence type (cgMLST) loci. In contrast, Kp_BM758 and the 34 clinical K. pneumoniae were genetically distant. The source of the CPE at this site was not identified. The detection of OXA-48-like-producing ST131 E. coli and OXA-48-like-producing ST101 K. pneumoniae in Irish recreational water is a concern. The potential for contamination of the aquatic environment to contribute to dissemination of CPE in Europe warrants further study., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives: The prevalence of infections caused by OXA-48-like carbapenemase-producing organisms in Ireland has increased dramatically since 2011 and is an urgent public health issue. Genome-based high-resolution genotyping was used to analyse clinical isolates submitted to the Irish Carbapenemase-Producing Enterobacteriaceae Reference Laboratory Service for a 13 month period (2016-17)., Methods: A total of 109 OXA-48-producing non-duplicate clinical isolates from 16 submitting centres were sequenced. Using a gene-by-gene approach, isolate genomes were characterized by MLST and core genome MLST, and the presence of antimicrobial resistance determinants was determined. Reference mapping and a novel plasmid MLST-type approach was applied to determine plasmid background., Results: The OXA-48-like-producing isolates were Escherichia coli (n = 56), Klebsiella spp. (n = 46) and Enterobacter cloacae (n = 7). Amongst the E. coli isolates there were 37 different STs and amongst the Klebsiella spp. isolates there were 27 different STs. blaOXA-48 was present in 105/109 (96.3%) of isolates. Based on mapping analysis and detection of the pOXA-48 IncL-type plasmid replicon and backbone genes, a pOXA-48-like plasmid was identified in 93/109 isolates (85.3%). The remaining isolates (n = 16; 14.7%) harboured blaOXA-48-like genes in unknown environments. Using a gene-by-gene approach two pOXA-48-like plasmid groups with 2/71 pOXA-48-like locus differences between them were identified., Conclusions: In Ireland we found a diversity of genotypes associated with OXA-48-like-producing clinical isolates with the IncL pOXA-48 plasmid type predominating as the blaOXA-48 genetic environment. A plasmid MLST approach can rapidly identify plasmids associated with outbreaks and monitor spread of types temporally and geographically., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Antimicrobial resistance is a major public health concern. Carbapenemase-producing Enterobacterales (CPE) represent a significant health threat as some strains are resistant to almost all available antibiotics. The aim of this research was to examine hospital effluent and municipal wastewater in an urban area in Ireland for CPE. Samples of hospital effluent (n = 5), municipal wastewater before (n = 5) and after (n = 4) the hospital effluent stream joined the municipal wastewater stream were collected over a nine-week period (May-June 2017). All samples were examined for CPE by direct plating onto Brilliance CRE agar. Isolates were selected for susceptibility testing to 15 antimicrobial agents in accordance with EUCAST criteria. Where relevant, isolates were tested for carbapenemase-encoding genes by real-time PCR. CPE were detected in five samples of hospital effluent, one sample of pre-hospital wastewater and three samples of post-hospital wastewater. Our findings suggest hospital effluent is a major contributor to CPE in municipal wastewater. Monitoring of hospital effluent for CPE could have important applications in detection and risk management of unrecognised dissemination of CPE in both the healthcare setting and the environment., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

In this study, New Delhi metallo-beta-lactamase (NDM)-producing Enterobacteriaceae were identified in Irish recreational waters and sewage. Indistinguishable NDM-producing Escherichia coli by pulsed-field gel electrophoresis were isolated from sewage, a fresh water stream and a human source. NDM-producing Klebsiella pneumoniae isolated from sewage and seawater in the same area were closely related to each other and to a human isolate. This raises concerns regarding the potential for sewage discharges to contribute to the spread of carbapenemase-producing Enterobacteriaceae., (This article is copyright of The Authors, 2017.)

A carriage study was undertaken (n = 112) to ascertain the prevalence of Neisseria spp. following the eighth case of invasive meningococcal disease in young children (5 to 46 months) and members of a large extended indigenous ethnic minority Traveller family (n = 123), typically associated with high-occupancy living conditions. Nested multilocus sequence typing (MLST) was employed for case specimen extracts. Isolates were genome sequenced and then were assembled de novo and deposited into the Bacterial Isolate Genome Sequencing Database (BIGSdb). This facilitated an expanded MLST approach utilizing large numbers of loci for isolate characterization and discrimination. A rare sequence type, ST-6697, predominated in disease specimens and isolates that were carried (n = 8/14), persisting for at least 44 months, likely driven by the high population density of houses (n = 67/112) and trailers (n = 45/112). Carriage for Neisseria meningitidis (P < 0.05) and Neisseria lactamica (P < 0.002) (2-sided Fisher's exact test) was more likely in the smaller, more densely populated trailers. Meningococcal carriage was highest in 24- to 39-year-olds (45%, n = 9/20). Evidence of horizontal gene transfer (HGT) was observed in four individuals cocolonized by Neisseria lactamica and Neisseria meningitidis One HGT event resulted in the acquisition of 26 consecutive N. lactamica alleles. This study demonstrates how housing density can drive meningococcal transmission and carriage, which likely facilitated the persistence of ST-6697 and prolonged the outbreak. Whole-genome MLST effectively distinguished between highly similar outbreak strain isolates, including those isolated from person-to-person transmission, and also highlighted how a few HGT events can distort the true phylogenetic relationship between highly similar clonal isolates., (Copyright © 2016 Mulhall et al.)

Serogroup B is the only major disease-associated capsular group of Neisseria meningitidis for which no protein-polysaccharide conjugate vaccine is available. This has led to the development of multi-component protein-based vaccines that target serogroup B invasive meningococcal disease (IMD), including Bexsero®, which was implemented for UK infants in 2015, and Trumenba®. Given the diversity of meningococcal protein antigens, post-implementation surveillance of IMD isolates, including characterisation of vaccine antigens, is essential for assessing the effectiveness of such vaccines. Whole genome sequencing (WGS), as realised in the Meningitis Research Foundation Meningococcus Genome Library (MRF-MGL), provides a rapid, comprehensive, and cost-effective approach to this. To facilitate the surveillance of the antigen targets included in Bexsero® (fHbp, PorA, NHBA and NadA) for protective immunity, a Bexsero® Antigen Sequence Type (BAST) scheme, based on deduced peptide sequence variants, was implemented in the PubMLST.org/neisseria database, which includes the MRF-MGL and other isolate collections. This scheme enabled the characterisation of vaccine antigen variants and here the invasive meningococci isolated in Great Britain and Ireland in the epidemiological years 2010/11 to 2013/14 are analysed. Many unique BASTs (647) were present, but nine of these accounted for 39% (775/1966) of isolates, with some temporal and geographic differences in BAST distribution. BASTs were strongly associated with other characteristics, such as serogroup and clonal complex (cc), and a significant increase in BAST-2 was associated with increased prevalence of serogroup W clonal complex 11 meningococci. Potential coverage was assessed by the examination of the antigen peptide sequences present in the vaccine and epidemiological dataset. There were 22.8-30.8% exact peptide matches to Bexsero® components and predicted coverage of 66.1%, based on genotype-phenotype modelling for 63.7% of serogroup B isolates from 2010/14 in UK and Ireland. While there are many caveats to this estimate, it lies within the range of other published estimates., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Following the introduction of effective protein-polysaccharide conjugate vaccines against capsular group C meningococcal disease in Europe, meningococci of capsular group B remain a major cause of death and can result in debilitating sequelae. The outer membrane proteins PorA and FetA have previously been shown to induce bactericidal antibodies in humans. Despite considerable antigenic variation among PorA and FetA OMPs in meningococci, systematic molecular epidemiological studies revealed this variation is highly structured so that a limited repertoire of antigenic types is congruent with the hyperinvasive meningococcal lineages that have caused most of the meningococcal disease in Europe in recent decades. Here we describe the development of a prototype vaccine against capsular group B meningococcal infection based on a N. meningitidis isolate genetically engineered to have constitutive expression of the outer membrane protein FetA. Deoxycholate outer membrane vesicles (dOMVs) extracted from cells cultivated in modified Frantz medium contained 21.8% PorA protein, 7.7% FetA protein and 0.03 μg LPS per μg protein (3%). The antibody response to the vaccine was tested in three mouse strains and the toxicological profile of the vaccine was tested in New Zealand white rabbits. Administration of the vaccine, MenPF-1, when given by intramuscular injection on 4 occasions over a 9 week period, was well tolerated in rabbits up to 50 μg/dose, with no evidence of systemic toxicity. These data indicated that the MenPF-1 vaccine had a toxicological profile suitable for testing in a phase I clinical trial.

The lack of an anti-capsular vaccine against serogroup B meningococcal disease has necessitated the exploration of alternative vaccine candidates, mostly proteins exhibiting varying degrees of antigenic variation. Analysis of variants of antigen-encoding genes is facilitated by publicly accessible online sequence repositories, such as the Neisseria PubMLST database and the associated Meningitis Research Foundation Meningococcus Genome Library (MRF-MGL). We investigated six proposed meningococcal vaccine formulations by deducing the prevalence of their components in the isolates represented in these repositories. Despite high diversity, a limited number of antigenic variants of each of the vaccine antigens were prevalent, with strong associations of particular variant combinations with given serogroups and genotypes. In the MRF-MGL and globally, the highest levels of identical sequences were observed with multicomponent/multivariant vaccines. Our analyses further demonstrated that certain combinations of antigen variants were prevalent over periods of decades in widely differing locations, indicating that vaccine formulations containing a judicious choice of antigen variants have potential for long-term protection across geographic regions. The data further indicated that formulations with multiple variants would be especially relevant at times of low disease incidence, as relative diversity was higher. Continued surveillance is required to monitor the changing prevalence of these vaccine antigens.

Neisseria adhesin A (NadA), involved in the adhesion and invasion of Neisseria meningitidis into host tissues, is one of the major components of Bexsero, a novel multicomponent vaccine licensed for protection against meningococcal serogroup B in Europe, Australia, and Canada. NadA has been identified in approximately 30% of clinical isolates and in a much lower proportion of carrier isolates. Three protein variants were originally identified in invasive meningococci and named NadA-1, NadA-2, and NadA-3, whereas most carrier isolates either lacked the gene or harbored a different variant, NadA-4. Further analysis of isolates belonging to the sequence type 213 (ST-213) clonal complex identified NadA-5, which was structurally similar to NadA-4, but more distantly related to NadA-1, -2, and -3. At the time of this writing, more than 89 distinct nadA allele sequences and 43 distinct peptides have been described. Here, we present a revised nomenclature system, taking into account the complete data set, which is compatible with previous classification schemes and is expandable. The main features of this new scheme include (i) the grouping of the previously named NadA-2 and NadA-3 variants into a single NadA-2/3 variant, (ii) the grouping of the previously assigned NadA-4 and NadA-5 variants into a single NadA-4/5 variant, (iii) the introduction of an additional variant (NadA-6), and (iv) the classification of the variants into two main groups, named groups I and II. To facilitate querying of the sequences and submission of new allele sequences, the nucleotide and amino acid sequences are available at http://pubmlst.org/neisseria/NadA/., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

New vaccines targeting meningococci expressing serogroup B polysaccharide have been developed, with some being licensed in Europe. Coverage depends on the distribution of disease-associated genotypes, which may vary by age. It is well established that a small number of hyperinvasive lineages account for most disease, and these lineages are associated with particular antigens, including vaccine candidates. A collection of 4,048 representative meningococcal disease isolates from 18 European countries, collected over a 3-year period, were characterized by multilocus sequence typing (MLST). Age data were available for 3,147 isolates. The proportions of hyperinvasive lineages, identified as particular clonal complexes (ccs) by MLST, differed among age groups. Subjects <1 year of age experienced lower risk of sequence type 11 (ST-11) cc, ST-32 cc, and ST-269 cc disease and higher risk of disease due to unassigned STs, 1- to 4-year-olds experienced lower risk of ST-11 cc and ST-32 cc disease, 5- to 14-year-olds were less likely to experience ST-11 cc and ST-269 cc disease, and ≥25-year-olds were more likely to experience disease due to less common ccs and unassigned STs. Younger and older subjects were vulnerable to a more diverse set of genotypes, indicating the more clonal nature of genotypes affecting adolescents and young adults. Knowledge of temporal and spatial diversity and the dynamics of meningococcal populations is essential for disease control by vaccines, as coverage is lineage specific. The nonrandom age distribution of hyperinvasive lineages has consequences for the design and implementation of vaccines, as different variants, or perhaps targets, may be required for different age groups., (Copyright © 2014 Brehony et al.)

Factor H binding protein (fHbp) is a major antigenic component of novel vaccines designed to protect against meningococcal disease. Prediction of the potential coverage of these vaccines is difficult, as fHbp is antigenically variable and levels of expression differ among isolates. Transcriptional regulation of the fHbp gene is poorly understood, although evidence suggests that oxygen availability is involved. In this study iron accessibility was found to affect fHbp transcription. However, regulation differed among meningococcal clonal complexes (ccs). For the majority of isolates, increased iron concentrations upregulated transcription. This effect was enhanced by the presence of a 181 bp insertion element upstream of fHbp, associated with isolates belonging to cc4 and cc5. Conversely, meningococci belonging to cc32 showed iron-repressed control of fHbp, as regulation was dominated by cotranscription with the iron-repressed upstream gene cbbA. These results highlight the complexity of fHbp regulation and demonstrate that control of transcription can vary among genetic lineages.

No single genealogical reconstruction or typing method currently encompasses all levels of bacterial diversity, from domain to strain. We propose ribosomal multilocus sequence typing (rMLST), an approach which indexes variation of the 53 genes encoding the bacterial ribosome protein subunits (rps genes), as a means of integrating microbial genealogy and typing. As with multilocus sequence typing (MLST), rMLST employs curated reference sequences to identify gene variants efficiently and rapidly. The rps loci are ideal targets for a universal characterization scheme as they are: (i) present in all bacteria; (ii) distributed around the chromosome; and (iii) encode proteins which are under stabilizing selection for functional conservation. Collectively, the rps loci exhibit variation that resolves bacteria into groups at all taxonomic and most typing levels, providing significantly more resolution than 16S small subunit rRNA gene phylogenies. A web-accessible expandable database, comprising whole-genome data from more than 1900 bacterial isolates, including 28 draft genomes assembled de novo from the European Bioinformatics Institute (EBI) sequence read archive, has been assembled. The rps gene variation catalogued in this database permits rapid and computationally non-intensive identification of the phylogenetic position of any bacterial sequence at the domain, phylum, class, order, family, genus, species and strain levels. The groupings generated with rMLST data are consistent with current nomenclature schemes and independent of the clustering algorithm used. This approach is applicable to the other domains of life, potentially providing a rational and universal approach to the classification of life that is based on one of its fundamental features, the translation mechanism.

Multilocus sequence analysis of 417 strains of Yersinia pseudotuberculosis revealed that it is a complex of four populations, three of which have been previously assigned species status [Y. pseudotuberculosis sensu stricto (s.s.), Yersinia pestis and Yersinia similis] and a fourth population, which we refer to as the Korean group, which may be in the process of speciation. We detected clear signs of recombination within Y. pseudotuberculosis s.s. as well as imports from Y. similis and the Korean group. The sources of genetic diversification within Y. pseudotuberculosis s.s. were approximately equally divided between recombination and mutation, whereas recombination has not yet been demonstrated in Y. pestis, which is also much more genetically monomorphic than is Y. pseudotuberculosis s.s. Most Y. pseudotuberculosis s.s. belong to a diffuse group of sequence types lacking clear population structure, although this species contains a melibiose-negative clade that is present globally in domesticated animals. Yersinia  similis corresponds to the previously identified Y. pseudotuberculosis genetic type G4, which is probably not pathogenic because it lacks the virulence factors that are typical for Y. pseudotuberculosis s.s. In contrast, Y. pseudotuberculosis s.s., the Korean group and Y. pestis can all cause disease in humans., (© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.)

There is currently no comprehensive meningococcal vaccine, due to difficulties in immunizing against organisms expressing serogroup B capsules. To address this problem, subcapsular antigens, particularly the outer-membrane proteins (OMPs), are being investigated as candidate vaccine components. If immunogenic, however, such antigens are often antigenically variable, and knowledge of the extent and structuring of this diversity is an essential part of vaccine formulation. Factor H-binding protein (fHbp) is one such protein and is included in two vaccines under development. A survey of the diversity of the fHbp gene and the encoded protein in a representative sample of meningococcal isolates confirmed that variability in this protein is structured into two or three major groups, each with a substantial number of alleles that have some association with meningococcal clonal complexes and serogroups. A unified nomenclature scheme was devised to catalogue this diversity. Analysis of recombination and selection on the allele sequences demonstrated that parts of the gene are subject to positive selection, consistent with immune selection on the protein generating antigenic variation, particularly in the C-terminal region of the peptide sequence. The highest levels of selection were observed in regions corresponding to epitopes recognized by previously described bactericidal monoclonal antibodies.

The global surveillance of bacterial pathogens is particularly important for bacteria with diverse and dynamic populations that cause periodic epidemics or pandemics. The isolate characterization methods employed for surveillance should: (1) generate unambiguous data; (2) be readily implemented in a variety of scenarios and be reproducible among laboratories; (3) be scalable and preferably available in a high throughput format; and (4) be cost effective. Multilocus sequence typing (MLST) was designed to meet these criteria and has been implemented effectively for a wide range of microorganisms. The 'Impact of meningococcal epidemiology and population biology on public health in Europe (EU-MenNet)' project had amongst its objectives: (1) to disseminate meningococcal MLST and sequence-based typing throughout Europe by establishing a centre for training and data generation, and (2) to produce a comprehensive Europe-wide picture of meningococcal disease epidemiology for the first time. Data produced from the project have shown the distribution of a relatively small number of STs, clonal complexes and PorA types that account for a large proportion of the disease-associated isolates in Europe. The project demonstrates how molecular typing can be combined with epidemiological data via the Internet for global disease surveillance.

The diversity and dynamics of Neisseria meningitidis populations generate a requirement for high resolution, comprehensive, and portable typing schemes for meningococcal disease surveillance. Molecular approaches, specifically DNA amplification and sequencing, are the methods of choice for various reasons, including: their generic nature and portability, comprehensive coverage, and ready implementation to culture negative clinical specimens. The following target genes are recommended: (1) the variable regions of the antigen-encoding genes porA and fetA and, if additional resolution is required, the porB gene for rapid investigation of disease outbreaks and investigating the distribution of antigenic variants; (2) the seven multilocus sequence typing loci-these data are essential for the most effective national, and international management of meningococcal disease, as well as being invaluable in studies of meningococcal population biology and evolution. These targets have been employed extensively in reference laboratories throughout the world and validated protocols have been published. It is further recommended that a modified nomenclature be adopted of the form: serogroup: PorA type: FetA type: sequence type (clonal complex), thus: B: P1.19,15: F5-1: ST-33 (cc32).

Between 1999 and 2004, the European Union Invasive Bacterial Infections Surveillance Network (EU-IBIS) received c. 50,000 reports of meningococcal disease from 27 participating countries. Analysis has demonstrated a major decline in the incidence of invasive disease in those countries that have introduced routine vaccination against serogroup C infection. The establishment of rapid reporting of W135 and B2a/B2b strains has been able to provide early reassurance that these strains are not emerging as major public health problems in Europe. Between September 2001 and February 2005, the EU-MenNet project offered further opportunities for enhancing this data resource. Collaborative projects included: improving the EU-IBIS website; reviewing case ascertainment in Europe; reviewing cost-effectiveness studies for meningococcal serogroup C conjugate (MCC) vaccination; international comparisons of MCC vaccine efficacy; and mathematical modelling studies. In addition, linking of data from the European Meningococcal Multi-locus Sequence Type Centre to epidemiological data was performed. Particular clonal complexes were found to be preferentially associated with certain serogroups. Case fatality was also found to vary with clonal complex, suggesting that genotype can be a marker for hypervirulence. The importance of close collaboration between networks of epidemiologists, microbiologists, and the wider scientific and public health community is demonstrated.