Diversity of meningococci associated with invasive meningococcal disease in the Republic of Ireland over a 19 year period, 1996-2015.

This study examined the capsular phenotype and genotype of invasive meningococcal disease (IMD)-associated Neisseria meningitidis recovered in the Republic of Ireland (RoI) between 1996 and 2015. This time period encompasses both pre- (when IMD was hyperendemic in the RoI) and post- meningococcal serogroup C conjugate (MCC) vaccine introduction. In total, 1327 isolates representing over one-third of all laboratory-confirmed cases of IMD diagnosed each epidemiological year (EY), were characterised. Serogroups B (menB) and C (menC) predominated throughout, although their relative abundance changed; with an initial increase in the proportion of menC in the late 1990s followed by their dramatic reduction post-MCC vaccine implementation and a concomitant dominance of menB, despite an overall decline in IMD incidence. While the increase in menC was associated with expansion of specific clonal-complexes (cc), cc11 and cc8; the dominance of menB was not. There was considerable variation in menB-associated cc with declines in cc41/44 and cc32, and increases in cc269 and cc461, contributing to a significant increase in the clonal diversity of menB isolates over the study. This increase in diversity was also displayed among the serosubtyping data, with significant declines in proportions of menB isolates expressing p1.4 and p1.15 antigens. These data highlight the changing diversity of IMD-associated meningococci since 1996 in the RoI and emphasise the need for on-going surveillance particularly in view of the recent introduction of a menB vaccine.

Influence of serogroup on the presentation, course, and outcome of invasive meningococcal disease in children in the Republic of Ireland, 1995-2000.

To test the hypothesis that the infecting meningococcal serogroup modulates the presentation, course, and outcome of invasive meningococcal disease (IMD), we performed a retrospective review of cases of IMD in 407 children from 2 tertiary referral centers and 2 regional centers in Ireland. Patients infected with serogroup C meningococci (n=104) were older than those infected with serogroup B (n=303; median, 2.5 vs. 1.5 years; P=.04); all other demographic and clinical parameters were similar for the 2 groups. Among serogroup B patients, mortality was 3.6% and morbidity was 10%; for serogroup C patients, mortality was 4.8% and morbidity was 12.5% (P=.81 and P=.76, respectively). Serogroup C-associated sequelae more often were multiple (P=.003). Despite the introduction of serogroup C conjugate vaccine into the routine immunization schedule of some countries, ongoing morbidity from IMD is anticipated, because group B disease was very similar to group C disease in this pediatric population.

Measles outbreak in Dublin, 2000.

BACKGROUND: An outbreak of measles occurred in Ireland between December 1999 and July 2000. The majority of cases were in north Dublin, the catchment area of The Children's University Hospital (TCUH). METHODS: Details of all of the 111 children attending the hospital with a diagnosis of measles between December 1999 and July 2000 were prospectively entered into a database. Charts were subsequently reviewed to extract epidemiologic and clinical details. National figures were obtained from the National Disease Surveillance Centre. RESULTS: In the study period 355 attended TCUH with a serologic or clinical diagnosis of measles, and 111 were admitted (47% female, 53% male). The main indications for admission were dehydration in 79%, pneumonia or pneumonitis in 47% and tracheitis in 32%. Thirteen children (11.7% of those admitted) required treatment in the intensive care unit, and in 7 of these mechanical ventilation was necessary. There were 3 deaths as a result of measles. Public health measures to curb spread of the disease included promotion of immunization for susceptible children nationally and recommending administration of measles-mumps-rubella vaccine (MMR) from the age of 6 months, in North Dublin. CONCLUSION: This outbreak of measles posed a major challenge to the hospital and the community for the first half of 2000. The national MMR immunization rate before the outbreak was gravely suboptimal at 79%, whereas the rate in North Dublin, the catchment area of TCUH, was <70%. Three children died as a result of a vaccine-preventable illness.

Multilocus restriction typing: a tool for Neisseria meningitidis strain discrimination.

Invasive disease-associated strains of Neisseria meningitidis were analysed by multilocus restriction typing (MLRT), which involves the restriction fragment-length polymorphism analysis of PCR products generated from the seven loci of housekeeping genes used in MLST. Several different restriction patterns (alleles) were observed for each of the seven loci examined. Greater allelic variation was observed with the fumC and pgm loci than with the abcZ and adk loci, suggesting that the latter were more conserved. The alleles at each of the seven loci were combined to give an allelic profile or restriction type (RT). A good correlation between RT and serogroup, serotype and serosubtype was observed, as all C 2ap1.2,5 strains were contained in a single RT, as were all but one strain of B 4p1.4. In this study, MLRT proved to be an efficient, effective and relatively inexpensive method for N. meningitidis strain characterization.

Target gene sequencing to characterize the penicillin G susceptibility of Neisseria meningitidis.

Clinical isolates of Neisseria meningitidis with reduced susceptibility to penicillin G (intermediate isolates, Pen(I)) harbor alterations in the penA gene encoding the penicillin binding protein 2 (PBP2). A 402-bp DNA fragment in the 3' half of penA was sequenced from a collection of 1,670 meningococcal clinical isolates from 22 countries that spanned 60 years. Phenotyping, genotyping, and the determination of MICs of penicillin G were also performed. A total of 139 different penA alleles were detected with 38 alleles that were highly related, clustered together in maximum-likelihood analysis and corresponded to the penicillin G-susceptible isolates. The remaining 101 penA alleles were highly diverse, corresponded to different genotypes or phenotypes, and accounted for 38% of isolates, but no clonal expansion was detected. Analysis of the altered alleles that were represented by at least five isolates showed high correlation with the Pen(I) phenotype. The deduced amino acid sequence of the corresponding PBP2 comprised five amino acid residues that were always altered. This correlation was not complete for rare alleles, suggesting that other mechanisms may also be involved in conferring reduced susceptibility to penicillin. Evidence of mosaic structures through events of interspecies recombination was also detected in altered alleles. A new website was created based on the data from this work (http://neisseria.org/nm/typing/penA). These data argue for the use of penA sequencing to identify isolates with reduced susceptibility to penicillin G and as a tool to improve typing of meningococcal isolates, as well as to analyze DNA exchange among Neisseria species.

Consecutive use of two multiplex PCR-based assays for simultaneous identification and determination of capsular status of nine common Neisseria meningitidis serogroups associated with invasive disease.

We developed two Neisseria meningitidis multiplex PCR assays to be used consecutively that allow determination of the serogroup and capsular status of serogroup A, B, C, 29E, W135, X, and Y cnl-3/cnl-1-like-containing N. meningitidis isolates by direct analysis of the amplicon size. These assays offer a rapid and simple method of serogrouping N. meningitidis.

Multiplex PCR for identification of seven Streptococcus pneumoniae serotypes targeted by a 7-valent conjugate vaccine.

Here we describe a Streptococcus pneumoniae one-step multiplex PCR assay which identifies by amplicon size the seven capsular polysaccharide serotypes targeted by the 7-valent conjugate vaccine. The multiplex PCR assay was used to blindly assay clinical isolates recovered during 1999 in the Republic of Ireland from cases of invasive disease whose serotypes were previously determined by classical methods.

PCR and restriction endonuclease assay for detection of a novel mutation associated with sulfonamide resistance in Neisseria meningitidis.

We identified a previously undocumented mutation in the dihydropteroate synthase (folP) gene associated with Neisseria meningitidis sulfonamide resistance. A PCR-based assay to detect this mutation, which is 100% predictive of sulfonamide resistance, was developed.

PCR-based assay for detection of Neisseria meningitidis capsular serogroups 29E, X, and Z.

PCR-based assays for the identification of Neisseria meningitidis serogroups 29E, X, and Z by detection of specific regions of the ctrA gene are described. The specificities of these assays were confirmed using serogroups A, B, C, 29E, H, W135, X, Y, and Z and nongroupable meningococcal isolates.