Publications by authors named "Nadav Topaz"

Predictions of vaccine efficacy against Neisseria meningitidis serogroup B (NmB) disease are hindered by antigenic variability, limiting the representativeness of individual NmB isolates. A qualitative human serum bactericidal assay using endogenous complements of individual subjects (enc-hSBA) enables large panels of NmB isolates to be tested. A 110-isolate panel was randomly selected from 442 invasive NmB isolates from United States cases reported to the Centers for Disease Control (CDC) from 2000 to 2008.

View Article and Find Full Text PDF

Recent reports have indicated a rise of invasive disease caused by serotype a (Hia) in North America and some European countries. The whole-genome sequences for a total of 410 invasive Hia isolates were obtained from 12 countries spanning the years of 1998 to 2019 and underwent phylogenetic and comparative genomic analysis in order to characterize the major strains causing disease and the genetic variation present among factors contributing to virulence and antimicrobial resistance. Among 410 isolate sequences received, 408 passed our quality control and underwent genomic analysis.

View Article and Find Full Text PDF

Rollout of meningococcal serogroup A conjugate vaccine in Africa started in 2010, aiming to eliminate meningitis outbreaks, in meningitis belt countries. Since then, studies have been conducted, primarily using isolates, to assess the vaccine impact on the distribution of meningococcal strains in the region. Here, we implemented an innovative, culture-free whole-genome sequencing approach on almost 400 clinical specimens collected between 2017 and 2019 from meningococcal meningitis cases in 6 African countries.

View Article and Find Full Text PDF

To monitor the burden and changes in Haemophilus influenzae (Hi) disease, direct real-time PCR (drt-PCR) assays have been developed for Hi detection in monoplex form and its six serotypes in triplex form, directly from cerebrospinal fluid (CSF) specimens. These assays target the gene for the species detection (Hi-) and serotype-specific genes in region II of the capsule biosynthesis locus (Hi-abf and Hi-cde), identified through comparative analysis of Hi and non-Hi whole-genome sequences. The lower limit of detection (LLD) is 293 CFU/mL for the Hi- assay and ranged from 11 to 130 CFU/mL for the triplex serotyping assays.

View Article and Find Full Text PDF

In January and February 2015, serogroup B (NmB) outbreaks occurred at two universities in the United States, and mass vaccination campaigns using MenB vaccines were initiated as part of a public health response. Meningococcal carriage evaluations were conducted concurrently with vaccination campaigns at these two universities and at a third university, where no NmB outbreak occurred. Meningococcal isolates ( = 1,514) obtained from these evaluations were characterized for capsule biosynthesis by whole-genome sequencing (WGS).

View Article and Find Full Text PDF

Togo has reported seasonal meningitis outbreaks caused by non-Neisseria meningitidis serogroup A (NmA) pathogens since the introduction of meningococcal serogroup A conjugate vaccine (MACV, MenAfriVac) in 2014. From 2016 to 2017, NmW caused several outbreaks. In early 2019, a NmC outbreak was detected in the Savanes region of Togo and its investigation is described here.

View Article and Find Full Text PDF

Background: In 2019, 5 cases of invasive Haemophilus influenzae serotype b (Hib) occurred in the Anchorage region of Alaska over a period of 16 days. No cases had occurred in Alaska in the preceding 26 months.

Methods: Alaska Hib isolates from 2005 through 2019 were analyzed using whole-genome sequencing (WGS).

View Article and Find Full Text PDF

Background: The Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination with a quadrivalent meningococcal conjugate serogroup A,C,W,Y (MenACWY) vaccine at 11-12 years of age, with a booster dose at 16 years. ACIP also recommends meningococcal vaccination for persons at increased risk of meningococcal disease, including a 2-dose primary series and regular booster doses for persons at increased risk because of underlying medical conditions. U.

View Article and Find Full Text PDF
Article Synopsis
  • Six cases of serogroup B meningococcal disease were reported among individuals who had received either the MenB-4C or MenB-FHbp vaccines in the U.S. since their availability.
  • All cases were investigated through health records and whole genome sequencing, revealing that most patients were at higher risk due to either outbreaks or pre-existing medical conditions.
  • Factors such as incomplete vaccination, waning immunity, and strain resistance to vaccine-induced serum bactericidal activity (SBA) played significant roles in the occurrence of these cases.
View Article and Find Full Text PDF

Background: Haemophilus influenzae serotype a (Hia) can cause severe invasive disease, especially in young children. In 2018, 4 invasive Hia cases occurred in an Alaska community. We used whole-genome sequencing (WGS) to evaluate the relationship of the bacteria from this community and other Alaska patients with invasive Hia.

View Article and Find Full Text PDF

Carriage evaluations were conducted during 2015 to 2016 at two U.S. universities in conjunction with the response to disease outbreaks caused by serogroup B and at a university where outbreak and response activities had not occurred.

View Article and Find Full Text PDF
Article Synopsis
  • * A study conducted in 2016-2017 involved oropharyngeal swabs from 13,758 participants to identify circulating meningococcal strains, revealing that 90.2% of the isolates were non-groupable, mainly from clonal complex 192 (CC192).
  • * The study found groupable isolates from recent outbreak-associated clonal complexes (CC11 and CC10217) and highlights the necessity of carriage studies for understanding and managing meningococcal
View Article and Find Full Text PDF

Effective laboratory-based surveillance and public health response to bacterial meningitis depends on timely characterization of bacterial meningitis pathogens. Traditionally, characterizing bacterial meningitis pathogens such as (Nm) and (Hi) required several biochemical and molecular tests. Whole genome sequencing (WGS) has enabled the development of pipelines capable of characterizing the given pathogen with equivalent results to many of the traditional tests.

View Article and Find Full Text PDF
Article Synopsis
  • A nationwide vaccination campaign with the MenAfriVac meningococcal serogroup A vaccine in Burkina Faso significantly reduced the carriage and disease of serogroup A Neisseria meningitidis in the first two years and is assessed for its long-term impact.
  • Cross-sectional studies conducted from May 2016 to November 2017 included nearly 14,300 participants aged 9 months to 36 years, revealing a 7.60% prevalence of meningococcal carriage without any cases of serogroup A.
  • The study indicates that the MenAfriVac vaccine continues to effectively reduce serogroup A carriage for at least 7 years, while carriage of other serogroups remains low, highlighting the
View Article and Find Full Text PDF
Article Synopsis
  • The study evaluated meningococcal carriage among university students in the U.S. after vaccination campaigns for serogroup B disease outbreaks, with a total of 10 rounds and 1,514 isolates from 7,001 participants.
  • It identified that the most common clonal complexes were CC198 and CC1157, and genetic analysis revealed similarities between carriage isolates and outbreak strains, highlighting genetic changes in virulence.
  • The research showed that over 50% of repeat participants carried the same strain over time, with genetic mechanisms such as recombination and mutations contributing to strain variation, emphasizing the increased risk of invasive meningococcal disease in this population.
View Article and Find Full Text PDF

Meningococcal carriage studies are important to improve the knowledge of disease epidemiology as well as to support appropriate vaccination strategies. We conducted a cross-sectional study to determine the prevalence and genotypic characteristics of meningococci collected from young adults in Salvador, Brazil six years after a meningococcal C conjugate vaccine catch-up campaign. From August through November 2016, oropharyngeal swabs were collected from 407 students aged 1824 years attending a private college in Salvador, Brazil.

View Article and Find Full Text PDF

Background: Haemophilus influenzae (Hi) can cause invasive diseases such as meningitis, pneumonia, or sepsis. Typeable Hi includes six serotypes (a through f), each expressing a unique capsular polysaccharide. The capsule, encoded by the genes within the capsule locus, is a major virulence factor of typeable Hi.

View Article and Find Full Text PDF

The human pathogens and share high genome identity. Retrospective analysis of surveillance data from New Zealand indicates the potential cross-protective effect of outer membrane vesicle (OMV) meningococcal serogroup B vaccine (MeNZB) against A licensed OMV-based MenB vaccine, MenB-4C, consists of a recombinant FHbp, NhbA, NadA, and the MeNZB OMV. Previous work has identified several abundantly expressed outer membrane proteins (OMPs) as major components of the MenB-4C OMV with high sequence similarity between and , suggesting a mechanism for cross-protection.

View Article and Find Full Text PDF

We characterized 22 meningococcal disease cases due to nongroupable , a rare cause of invasive disease. Disease presentation and severity were similar to those for serogroupable meningococcal disease. However, 7 (32%) patients had complement deficiency or abnormal complement testing results, highlighting the importance of complement testing for nongroupable cases.

View Article and Find Full Text PDF

Background: Historically, the major cause of meningococcal epidemics in the meningitis belt of sub-Saharan Africa has been Neisseria meningitidis serogroup A (NmA), but the incidence has been substantially reduced since the introduction of a serogroup A conjugate vaccine starting in 2010. We performed whole-genome sequencing on isolates collected post-2010 to assess their phylogenetic relationships and inter-country transmission.

Methods: A total of 716 invasive meningococcal isolates collected between 2011 and 2016 from 11 meningitis belt countries were whole-genome sequenced for molecular characterization by the three WHO Collaborating Centers for Meningitis.

View Article and Find Full Text PDF
Article Synopsis
  • * A new whole-genome sequencing (WGS) approach has been developed to accurately characterize capsule polysaccharide synthesis and identify novel genomic features associated with serogroup identification, including genetic mutations leading to nongroupability.
  • * The WGS method shows a high level of agreement (91%-100%) with traditional serogrouping techniques, highlighting its effectiveness for meningococcal surveillance and the importance of understanding genetic variations in isolates.
View Article and Find Full Text PDF

is a complex genus that includes commensal and pathogenic species that pose a public health threat to humans. While the pathogenic species have been studied extensively, many commensals have limited genomic information available. Here, we present 24 draft genomes for a diverse set of 7 and species.

View Article and Find Full Text PDF

Background: Bacterial meningitis is a life-threatening infection that remains a public health concern. Bacterial meningitis is commonly caused by the following species: Neisseria meningitidis, Streptococcus pneumoniae, Listeria monocytogenes, Haemophilus influenzae and Escherichia coli. Here, we describe BMScan (Bacterial Meningitis Scan), a whole-genome analysis tool for the species identification of bacterial meningitis-causing and closely-related pathogens, an essential step for case management and disease surveillance.

View Article and Find Full Text PDF