Glycan-specific IgM is critical for human immunity to Staphylococcus aureus.

Staphylococcus aureus is a major human pathogen, yet the immune factors that protect against infection remain elusive. High titers of opsonic IgG antibodies, achieved in preclinical animal immunization studies, have consistently failed to provide protection in humans. Here, we investigate antibody responses to the conserved S. aureus surface glycan wall teichoic acid (WTA) and detect the presence of WTA-specific IgM and IgG antibodies in the plasma of healthy individuals. Functionally, WTA-specific IgM outperforms IgG in opsonophagocytic killing of S. aureus and protects against disseminated S. aureus bacteremia through passive immunization. In a clinical setting, patients with S. aureus bacteremia have significantly lower WTA-specific IgM but similar IgG levels compared to healthy controls. Importantly, low WTA-IgM levels correlate with disease mortality and impaired bacterial opsonization. Our findings may guide risk stratification of hospitalized patients and inform future design of antibody-based therapies and vaccines against serious S. aureus infection.

Nationwide upsurge in invasive disease in the context of longitudinal surveillance of carriage and invasive Streptococcus pyogenes 2009-2023, the Netherlands: a molecular epidemiological study.

Since 2022, many countries have reported an upsurge in invasive group A streptococcal (iGAS) infections. We explored whether changes in Streptococcus pyogenes carriage rates or emergence of strains with potentially altered virulence, such as emm1 variants M1UK and M1DK, contributed to the 2022/2023 surge in the Netherlands. We determined emm (sub)type distribution for 2,698 invasive and 351 S. pyogenes carriage isolates collected between January 2009 and March 2023. Genetic evolution of emm1 was analyzed by whole-genome sequencing of 497 emm1 isolates. The nationwide iGAS upsurge coincided with a sharp increase of emm1.0 from 18% (18/100) of invasive isolates in Q1 2022 to 58% (388/670) in Q1 2023 (Fisher's exact test, P < 0.0001). M1UK became dominant among invasive emm1 isolates in 2016 and further expanded from 72% in Q1 2022 to 96% in Q1 2023. Phylogenetic comparison revealed evolution and clonal expansion of four new M1UK clades in 2022/2023. DNase Spd1 and superantigen SpeC were acquired in 9% (46/497) of emm1 isolates. S. pyogenes carriage rates and emm1 proportions in carriage isolates remained stable during this surge, and the expansion of M1UK in iGAS was not reflected in carriage isolates. During the 2022/2023 iGAS surge in the Netherlands, expansion of four new M1UK clades was observed among invasive isolates, but not carriage isolates, suggesting increased virulence and fitness of M1UK compared to contemporary M1 strains. The emergence of more virulent clades has important implications for public health strategies such as antibiotic prophylaxis for close contacts of iGAS patients.IMPORTANCEThis study describes the molecular epidemiology of invasive group A streptococcal (iGAS) infections in the Netherlands based on >3,000 Streptococcus pyogenes isolates from both asymptomatic carriers and iGAS patients collected before, during, and after the COVID-19 pandemic period (2009-2023) and is the first to assess whether changes in carriage rates or carried emm types contributed to the alarming post-COVID-19 upsurge in iGAS infections. We show that the 2022/2023 iGAS surge coincided with a sharp increase of emm1, particularly the toxicogenic M1UK variant, in invasive isolates, but not in carriage isolates. These findings suggest that increased virulence and fitness of M1UK likely contributes to an increased dissemination between hosts. The emergence of a more virulent and fit lineage has important implications for iGAS control interventions such as antibiotic prophylaxis for close contacts of iGAS patients and calls for a reappraisal of iGAS control interventions and guidelines.

Genetic markers associated with host status and clonal expansion of Group B Streptococcus in the Netherlands.

Objectives: Certain Group B Streptococcus (GBS) genotypes are associated with invasive disease in neonates. We conducted a comparative genomic analysis of GBS isolates from neonatal disease and maternal carriage in the Netherlands to determine distribution of genetic markers between the two host groups. Methods: Whole genome sequencing was used to characterise 685 neonatal invasive isolates (2006-2021) and 733 maternal carriage isolates (2017-2021) collected in the Netherlands. Results: Clonal complex (CC) 17 and serotype III were significantly more common in disease while carriage isolates were associated with serotypes II, IV, V as well as CC1. Previously reported CC17-A1 sub-lineage was dominant among disease isolates and significantly less common in carriage. The phiStag1 phage, previously associated with expansion of invasive CC17 isolates in the Netherlands, was more common among disease isolates compared to carriage isolates overall, however it was equally distributed between CC17 isolates from carriage and disease. Prevalence of antimicrobial resistance genes was overall lower in disease compared to carriage isolates, but increased significantly over time, mediated by rise in prevalence of a multidrug resistance element ICESag37 among disease isolates. Conclusion: There is a stable association between certain GBS genotypes and invasive disease, which suggests opportunities for developing more precise disease prevention strategies based on GBS targeted screening. In contrast, GBS mobile genetic elements appear less likely to be correlated with carriage or disease, and instead are associated with clonal expansion events across the GBS population.

Cost of Illness Analysis of Invasive Meningococcal Disease Caused by Neisseria Meningitidis Serogroup B in the Netherlands-a Holistic Approach.

INTRODUCTION: Invasive meningococcal disease (IMD) caused by Neisseria meningitidis is a rapidly progressing, rare disease that often presents as meningitis or sepsis. It mostly affects infants and adolescents, with high fatality rates or long-term sequelae. In the Netherlands, serogroup B (MenB) is most prevalent. We aimed to estimate the economic burden of MenB-related IMD between 2015 and 2019, including direct and indirect medical costs from short- and long-term sequelae, from a societal perspective. METHODS: IMD incidence was based on laboratory-based case numbers from the Netherlands Reference Laboratory for Bacterial Meningitis (Amsterdam UMC, Amsterdam, the Netherlands); there were 74 MenB cases on average per year in the study period 2015-2019. Case-fatality rate (3.8%) and percentage of patients discharged with sequelae (46%) were derived from literature. Direct costs included treatment costs of the acute phase, long-term sequelae, and public health response. Indirect costs were calculated using the human capital (HCA) and friction costs (FCA) approaches, in which productivity losses were estimated for patients and parents during the acute and sequelae phases. Costs were discounted by 4% yearly. RESULTS: Estimated costs due to MenB IMD in an annual cohort were €3,094,199 with FCA and €9,480,764 with HCA. Direct costs amounted to €2,974,996, of which 75.2% were related to sequelae. Indirect costs related to sequelae were €52,532 with FCA and €5,220,398 with HCA. CONCLUSION: Our analysis reflects the high economic burden of MenB-related IMD in the Netherlands. Sequelae costs represent a high proportion of the total costs. Societal costs were dependent on the applied approach (FCA or HCA).

A multicenter evaluation of the QIAstat-Dx meningitis-encephalitis syndromic test kit as compared to the conventional diagnostic microbiology workflow.

PURPOSE: Rapid diagnosis and treatment of infectious meningitis and encephalitis (ME) is critical to minimize morbidity and mortality. Recently, Qiagen introduced the CE-IVD QIAstat-Dx ME panel (QS-ME) for syndromic diagnostic testing of meningitis and encephalitis. Some data on the performance of the QS-ME in comparison to the BioFire FilmArray ME panel are available. In this study, the performance of the QS-ME is compared to the current diagnostic workflow in two academic medical centers in the Netherlands. METHODS: A total of 110 cerebrospinal fluid samples were retrospectively tested with the QS-ME. The results obtained were compared to the results of laboratory-developed real-time PCR assays (LDTs), IS-pro, bacterial culture, and cryptococcal antigen (CrAg) testing. In addition, the accuracy of the QS-ME was also investigated using an external quality assessment (EQA) panel consisting of ten samples. RESULTS: Four of the 110 samples tested failed to produce a valid QS-ME result. In the remaining 106 samples, the QS-ME detected 53/53 viral targets, 38/40 bacterial targets, and 7/13 Cryptococcus neoformans targets. The discrepant bacterial results consisted of two samples that were previously tested positive for Listeria monocytogenes (CT 35.8) and Streptococcus pneumoniae (CT 40), respectively. The QS-ME detected one additional result, consisting of a varicella-zoster virus signal (CT 35.9), in a sample in which both techniques detected Streptococcus pyogenes. Finally, 100% concordance was achieved in testing a blinded bacterial ME EQA panel. CONCLUSION: The QS-ME is a relevant addition to the syndromic testing landscape to assist in diagnosing infectious ME.

The Group A Streptococcal Vaccine Candidate VAX-A1 Protects against Group B Streptococcus Infection via Cross-Reactive IgG Targeting Virulence Factor C5a Peptidase.

Group B Streptococcus (Streptococcus agalactiae or GBS) is the leading infectious cause of neonatal mortality, causing roughly 150,000 infant deaths and stillbirths annually across the globe. Approximately 20% of pregnant women are asymptomatically colonized by GBS, which is a major risk factor for severe fetal and neonatal infections as well as preterm birth, low birth weight, and neurodevelopmental abnormalities. Current clinical interventions for GBS infection are limited to antibiotics, and no vaccine is available. We previously described VAX-A1 as a highly effective conjugate vaccine against group A Streptococcus that is formulated with three antigens, SpyAD, streptolysin O, and C5a peptidase (ScpA). ScpA is a surface-expressed, well-characterized GAS virulence factor that shares nearly identical sequences with the lesser studied GBS homolog ScpB. Here, we show that GBS C5a peptidase ScpB cleaves human complement factor C5a and contributes to disease severity in the murine models of pneumonia and sepsis. Furthermore, antibodies elicited by GAS C5a peptidase bind to GBS in an ScpB-dependent manner, and VAX-A1 immunization protects mice against lethal GBS heterologous challenge. These findings support the contribution of ScpB to GBS virulence and underscore the importance of choosing vaccine antigens; a universal GAS vaccine such as VAX-A1 whose formulation includes GAS C5a peptidase may have additional benefits through some measure of cross-protection against GBS infections.

Recurrent bacterial meningitis in children in the Netherlands: a nationwide surveillance study.

OBJECTIVES: This study aimed to estimate the recurrence rate of culture-positive bacterial meningitis in children in the Netherlands. DESIGN: Nationwide surveillance study, using the database of the Netherlands Reference Laboratory for Bacterial Meningitis to identify patients with culture-positive bacterial meningitis during childhood. SETTING: The study was based in the Netherlands. PARTICIPANTS: A total of 9731 children with a first bacterial meningitis episode between 1 July 1987 and 30 June 2019 were identified. PRIMARY AND SECONDARY OUTCOME MEASURES: Recurrence was defined as a subsequent episode >28 days, or caused by a different pathogen. Annual incidence and incidence rate ratios (IRRs) comparing the periods 1988-2003 and 2004-2019 were calculated. Predictors of recurrent meningitis were assessed using Cox proportional hazards regression. RESULTS: Sixty-three (0.6%) of the 9731 children with a first bacterial meningitis episode contracted recurrent meningitis. Neisseria meningitidis was the leading pathogen for first meningitis episodes (52%) and Streptococcus pneumoniae for recurrent episodes (52%). The median annual incidence of first episodes per 100 000 children decreased from 11.81 (IQR 11.26-17.60) in 1988-2003 to 2.60 (IQR 2.37-4.07) in 2004-2019 (IRR 0.25, 95% CI 0.23 to 0.26). The incidence of recurrences did not change: 0.06 (IQR 0.02-0.11) in 1988-2003 to 0.03 (IQR 0.00-0.06) in 2004-2019 (IRR 0.65, 95% CI 0.39 to 1.1). Age above 5 years (OR 3.6 (95% CI 1.5 to 8.3)) and a first episode due to Escherichia coli (OR 25.7 (95% CI 7.2 to 92.0)) were associated with higher risks of recurrence. CONCLUSION: The recurrence rate of childhood bacterial meningitis in the Netherlands was 0.6%. While the incidence rate of first episodes decreased substantially, this was not the case for recurrent episodes. Older age and a first episode due to E. coli were associated with higher recurrence risks.

Novel emm4 lineage associated with an upsurge in invasive group A streptococcal disease in the Netherlands, 2022.

Invasive group A streptococcal (iGAS) disease cases increased in the first half of 2022 in the Netherlands, with a remarkably high proportion of emm4 isolates. Whole-genome sequence analysis of 66 emm4 isolates, 40 isolates from the pre-coronavirus disease 2019 (COVID-19) pandemic period 2009-2019 and 26 contemporary isolates from 2022, identified a novel Streptococcus pyogenes lineage (M4NL22), which accounted for 85 % of emm4 iGAS cases in 2022. Surprisingly, we detected few isolates of the emm4 hypervirulent clone, which has replaced nearly all other emm4 in the USA and the UK. M4NL22 displayed genetic differences compared to other emm4 strains, although these were of unclear biological significance. In publicly available data, we identified a single Norwegian isolate belonging to M4NL22, which was sampled after the isolates from this study, possibly suggesting export of M4NL22 to Norway. In conclusion, our study identified a novel S. pyogenes emm4 lineage underlying an increase of iGAS disease in early 2022 in the Netherlands and the results have been promptly communicated to public health officials.

Epidemiology, clinical features and outcome of adults with meningococcal meningitis: a 15-year prospective nationwide cohort study.

Background: We describe the epidemiology, clinical features and outcome of adult meningococcal meningitis in the Netherlands over a 15-year period. Methods: We studied adults (age ≥ 16 years) who were listed by the Netherlands Reference Laboratory for Bacterial Meningitis and/or included in the prospective nationwide cohort study (MeninGene) between January 2006 and July 2021. Incidences were calculated per epidemiological year (July-June). Findings: We identified 442 episodes of adult meningococcal meningitis. The median patient age was 32 years (IQR 18-55) and 226 episodes (51%) occurred in female patients. The annual incidence per 100,000 adults fluctuated, from 0.33 in 2006-2007 to 0.05 in 2020-2021, with a temporal increase up to 0.30 from 2016 to 2018, driven by an outbreak of serogroup W (MenW). Of 442 episodes, 274 episodes (62%) in 273 patients were included in the clinical cohort study. The overall case fatality rate was 4% (10 of 274) and 16% (43 of 274) had an unfavourable outcome (Glasgow Outcome Scale score 1-4). Compared to other serogroups, MenW was associated with higher rates of unfavourable outcome (6 of 16 [38%] vs. 37 of 251 [15%], P = 0.03) and death (4 of 16 [25%] vs. 6 of 251 [2%], P = 0.001). Interpretation: The overall incidence of adult meningococcal meningitis in the Netherlands is low and outcome is generally favourable. An increase of MenW meningitis occurred from 2016 to 2018, which was associated with more unfavourable outcome and death. Funding: Netherlands Organisation for Health Research and Development, European Research Council, National Institute of Public Health and Environmental protection.

Group A Streptococcal Meningitis With the M1UK Variant in the Netherlands.

This study reports an epidemiological assessment of laboratory-confirmed group A streptococcal meningitis cases in the Netherlands using more than 40 years of national bacteriological surveillance data.

Human CEACAM1 is targeted by a Streptococcus pyogenes adhesin implicated in puerperal sepsis pathogenesis.

Life-threatening bacterial infections in women after childbirth, known as puerperal sepsis, resulted in classical epidemics and remain a global health problem. While outbreaks of puerperal sepsis have been ascribed to Streptococcus pyogenes, little is known about disease mechanisms. Here, we show that the bacterial R28 protein, which is epidemiologically associated with outbreaks of puerperal sepsis, specifically targets the human receptor CEACAM1. This interaction triggers events that would favor the development of puerperal sepsis, including adhesion to cervical cells, suppression of epithelial wound repair and subversion of innate immune responses. High-resolution structural analysis showed that an R28 domain with IgI3-like fold binds to the N-terminal domain of CEACAM1. Together, these findings demonstrate that a single adhesin-receptor interaction can drive the pathogenesis of bacterial sepsis and provide molecular insights into the pathogenesis of one of the most important infectious diseases in medical history.

The burden of invasive meningococcal disease in the Netherlands, 2011-2020.

INTRODUCTION: Representative information on disease course and outcome of invasive meningococcal disease (IMD) is important because of the shift in meningococcal epidemiology that recently occurred in the Netherlands. With this study, we update earlier research on the burden of IMD in the Netherlands. MATERIAL AND METHODS: We performed a retrospective study using Dutch surveillance data on IMD from July 2011 to May 2020. Clinical information was collected from hospital records. The effect of age, serogroup, and clinical manifestation on disease course and outcome was assessed in multivariable logistic regression analyses. Grouping of infecting isolates was performed by Ouchterlony gel diffusion or by PCR. RESULTS: Clinical information was collected for 278 IMD cases of which the majority had IMD-B (55%), followed by IMD-W (27%), IMD-Y (13%), and IMD-C (5%). Most patients presented with meningitis (32%) or sepsis (30%). Hospitalisation for ≥ 10 days was most frequent among 24-64 year olds (67%). ICU admission was highest among 24-64 year olds (60%), and in case of sepsis (70%), or sepsis plus meningitis (61%). Sequelae at discharge was lower for patients with mild meningococcaemia compared to patients with sepsis plus meningitis (OR: 0.19, 95% CI: 0.07-0.51). The overall case fatality rate was 7%, and was highest for IMD-Y (14%) and IMD-W (13%) patients. CONCLUSIONS: IMD remains a disease with high morbidity and mortality. Sepsis (with or without meningitis) is associated with a more severe disease course and outcome compared to other clinical manifestations. The high disease burden can be partly prevented by meningococcal vaccination.

Neisseria meningitidis Sibling Small Regulatory RNAs Connect Metabolism with Colonization by Controlling Propionate Use.

Neisseria meningitidis (meningococcus) colonizes the human nasopharynx, primarily as a commensal, but sporadically causing septicemia and meningitis. During colonization and invasion, it encounters different niches with specific nutrient compositions. Small noncoding RNAs (sRNAs) are used to fine-tune expression of genes, allowing adaptation to their physiological differences. We have previously characterized sRNAs (Neisseria metabolic switch regulators [NmsRs]) controlling switches between cataplerotic and anaplerotic metabolism. Here, we extend the NmsR regulon by studying methylcitrate lyase (PrpF) and propionate kinase (AckA-1) involved in the methylcitrate cycle and serine hydroxymethyltransferase (GlyA) and 3-hydroxyacid dehydrogenase (MmsB) involved in protein degradation. These proteins were previously shown to be dysregulated in a ΔnmsRs strain. Levels of transcription of target genes and NmsRs were assessed by reverse transcriptase quantitative PCR (RT-qPCR). We also used a novel gene reporter system in which the 5' untranslated region (5' UTR) of the target gene is fused to mcherry to study NmsRs-target gene interaction in the meningococcus. Under nutrient-rich conditions, NmsRs downregulate expression of PrpF and AckA-1 by direct interaction with the 5' UTR of their mRNA. Overexpression of NmsRs impaired growth under nutrient-limiting growth conditions with pyruvate and propionic acid as the only carbon sources. Our data strongly suggest that NmsRs downregulate propionate metabolism by lowering methylcitrate enzyme activity under nutrient-rich conditions. Under nutrient-poor conditions, NmsRs are downregulated, increasing propionate metabolism, resulting in higher tricarboxylic acid (TCA) activities. IMPORTANCE Neisseria meningitidis colonizes the human nasopharynx, forming a reservoir for the sporadic occurrence of epidemic invasive meningococcal disease like septicemia and meningitis. Propionic acid generated by other bacteria that coinhabit the human nasopharynx can be utilized by meningococci for replication in this environment. Here, we showed that sibling small RNAs, designated NmsRs, riboregulate propionic acid utilization by meningococci and, thus, colonization. Under conditions mimicking the nasopharyngeal environment, NmsRs are downregulated. This leads to the conversion of propionic acid to pyruvate and succinate, resulting in higher tricarboxylic acid cycle activity, allowing colonization of the nasopharynx. NmsRs link metabolic state with colonization, which is a crucial step on the trajectory to invasive meningococcal disease.

Increase in Invasive Group a Streptococcal Infections in Children in the Netherlands, A Survey Among 7 Hospitals in 2022.

Following an increase in notifiable invasive group A streptococcal (iGAS) infections in the Netherlands, we conducted a survey among 7 hospitals. Pediatric iGAS case numbers were 2-fold higher between July 2021 and June 2022 versus pre-COVID-19. A sharp increase occurred early 2022, most pronounced in <5 years old and for diagnoses empyema and necrotizing fasciitis. This recent pediatric iGAS surge warrants investigation and vigilance.

Increase in invasive group A streptococcal (Streptococcus pyogenes) infections (iGAS) in young children in the Netherlands, 2022.

In 2022, a sevenfold increase in the number of notifiable invasive Streptococcus pyogenes (iGAS) infections among children aged 0-5 years was observed in the Netherlands compared with pre-COVID-19 pandemic years. Of 42 cases in this age group, seven had preceding or coinciding varicella zoster infections, nine were fatal. This increase is not attributable to a specific emm type. Vigilance for clinical deterioration as iGAS sign is warranted in young children, especially those with varicella zoster infection.

Community-acquired Staphylococcus aureus meningitis in adults.

BACKGROUND: Staphylococcus aureus is an uncommon cause of community-acquired bacterial meningitis. We aimed to describe patients with this disease. METHODS: We evaluated clinical characteristics and outcome of adults with community-acquired S. aureus meningitis from prospective nationwide cohort studies from Denmark (2015-2020) and the Netherlands (2006-2021). Whole genome sequencing of S. aureus isolates was performed to evaluate the potential association between clonal complex and clinical characteristics. RESULTS: We evaluated 111 episodes of community-acquired S. aureus meningitis: 65 from Denmark and 46 from the Netherlands. The median age was 66 years (interquartile range [IQR] 50-74) and 43 of 111 patients were female (39%). Concomitant infectious foci were found in 95 of 107 patients (89%), most commonly endocarditis (53 of 109 [49%]) and spondylodiscitis (43 of 109 [39%]). The triad of neck stiffness, altered mental status (Glasgow Coma Scale score <14), and fever was present in only 18 of 108 patients (17%). Surgery was performed in 14 of 33 patients (42%) with spondylodiscitis and 26 of 52 (50%) with endocarditis. A favorable outcome (Glasgow Outcome Scale score 5) occurred in 26 of 111 patients (23%), while 39 (35%) died. The most common bacterial clonal complexes (CC) were CC30 (16 [17%]), CC45 (16 [17%]), CC5 (12 [13%], and CC15 (10 [11%]); no associations between CCs and concomitant foci or outcome were found. CONCLUSIONS: Community-acquired S. aureus meningitis is a severe disease with a high case fatality rate, occurring mainly in patients with concomitant endocarditis or spondylodiscitis.