Molecular epidemiology and mortality of group B streptococcal meningitis and infant sepsis in the Netherlands: a 30-year nationwide surveillance study

Specific interaction between Group B Streptococcus CC17 hypervirulent clone and phagocytes

Streptococcus agalactiae also named Group B Streptococcus (GBS) is the most significant pathogen causing invasive infections, such as bacteremia and meningitis, in neonates. Worldwide epidemiological studies have shown that a particular clonal complex (CC) of capsular serotype III, the CC17, is strongly associated with meningitis in neonates and is therefore, designated as the hypervirulent clone. Macrophages are a permissive niche for intracellular bacteria of all GBS clones. In this study, we deciphered the specific interaction of GBS CC17 strains with macrophages. Our study revealed that CC17 strains are phagocytosed at a higher rate than GBS non-CC17 strains by human monocytes and macrophages both in cellular models and in primary cells. CC17-enhanced phagocytosis is due to an initial enhanced-attachment step to macrophages mediated by the CC17-specific surface protein HvgA and the PI-2b pilus (Spb1). We showed that two different inhibitors of scavenger receptors (fucoidan and poly(I)) specifically inhibited CC17 adhesion and phagocytosis while not affecting those of non-CC17 strains. Once phagocytosed, both CC17 and non-CC17 strains remained in a LAMP-1 positive vacuole that ultimately fuses with lysosomes where they can survive at similar rates. Finally, both strains displayed a basal egress which occurs independently from actin and microtubule networks. Our findings provide new insights into the interplay between the hypervirulent GBS CC17 and major players of the host's innate immune response. This enhanced adhesion, leading to increased phagocytosis, could reflect a peculiar capacity of the CC17 lineage to subvert the host immune defenses, establish a niche for persistence or disseminate.

Mortality and neurodevelopmental outcome after invasive group B streptococcal infection in infants

AIM

To assess case fatality rate (CFR), infant mortality, and long-term neurodevelopmental disorders (NDDs) after invasive group B streptococcal (GBS; Streptococcus agalactiae) infection in infants.

METHOD

Children born in Norway between 1996 and 2019 were included. Data on pregnancies/deliveries, GBS infection, NDDs, and causes of death were retrieved from five national registries. The exposure was culture-confirmed invasive GBS infection during infancy. Outcomes were mortality and NDDs, the latter at a mean age of 12 years 10 months.

RESULTS

Among 1 415 625 live-born children, 866 (87%) of 1007 infants diagnosed with GBS infection (prevalence 0.71 per 1000) were included. The CFR was 5.0% (n = 43). GBS infection was associated with higher infant mortality (relative risk 19.41; 95% confidence interval [CI] 14.79-25.36) than the general population. Among survivors, 169 (20.7%) children were diagnosed with any NDD (relative risk 3.49; 95% CI 3.05-3.98). In particular, GBS meningitis was associated with high risks of attention-deficit/hyperactivity disorder, cerebral palsy, epilepsy, hearing impairment, and pervasive and specific developmental disorder.

INTERPRETATION

The burden of invasive GBS infection during infancy is considerable and continues to affect children beyond infancy. These findings emphasize the need for new preventive strategies for disease reduction, and the need for survivors to be directly included into early detection pathways to access early intervention if required.

WHAT THIS PAPER ADDS

The burden of invasive group B streptococcal (GBS) infection in Norway is considerable. Of GBS infection survivors, 20.7% were diagnosed with neurodevelopmental disorders (NDDs) at mean age 12 years 10 months. Infants with GBS meningitis were more often diagnosed with NDDs. Absolute risks associated with GBS infections were highest for pervasive and specific developmental disorder, cerebral palsy, and attention-deficit/hyperactivity disorder.

Molecular epidemiology of Streptococcus agalactiae in non-pregnant populations: a systematic review

Streptococcus agalactiae (group B Streptococcus, GBS) has recently emerged as an important pathogen among adults. However, it is overlooked in this population, with all global efforts being directed towards its containment among pregnant women and neonates. This systematic review assessed the molecular epidemiology and compared how the lineages circulating among non-pregnant populations relate to those of pregnant and neonatal populations worldwide. A systematic search was performed across nine databases from 1 January 2000 up to and including 20 September 2021, with no language restrictions. The Joanna Briggs Institute (JBI) Prevalence Critical Appraisal Tool (PCAT) was used to assess the quality of included studies. The global population structure of GBS from the non-pregnant population was analysed using in silico typing and phylogenetic reconstruction tools. Twenty-four articles out of 13 509 retrieved across 9 databases were eligible. Most studies were conducted in the World Health Organization European region (12/24, 50 %), followed by the Western Pacific region (6/24, 25 %) and the Americas region (6/24, 25 %). Serotype V (23%, 2310/10240) and clonal complex (CC) 1 (29 %, 2157/7470) were the most frequent serotype and CC, respectively. The pilus island PI1 : PI2A combination (29 %, 3931/13751) was the most prevalent surface protein gene, while the tetracycline resistance tetM (55 %, 5892/10624) was the leading antibiotic resistance gene. This study highlights that, given the common serotype distribution identified among non-pregnant populations (V, III, Ia, Ib, II and IV), vaccines including these six serotypes will provide broad coverage. The study indicates advanced molecular epidemiology studies, especially in resource-constrained settings for evidence-based decisions. Finally, the study shows that considering all at-risk populations in an inclusive approach is essential to ensure the sustainable containment of GBS.

Group B Streptococcus Early-Onset Disease: New Preventive and Diagnostic Tools to Decrease the Burden of Antibiotic Use

The difficulty in recognizing early-onset neonatal sepsis (EONS) in a timely manner due to non-specific symptoms and the limitations of diagnostic tests, combined with the risk of serious consequences if EONS is not treated in a timely manner, has resulted in a low threshold for starting empirical antibiotic treatment. New guideline strategies, such as the neonatal sepsis calculator, have been proven to reduce the antibiotic burden related to EONS, but lack sensitivity for detecting EONS. In this review, the potential of novel, targeted preventive and diagnostic methods for EONS is discussed from three different perspectives: maternal, umbilical cord and newborn perspectives. Promising strategies from the maternal perspective include Group B Streptococcus (GBS) prevention, exploring the virulence factors of GBS, maternal immunization and antepartum biomarkers. The diagnostic methods obtained from the umbilical cord are preliminary but promising. Finally, promising fields from the newborn perspective include biomarkers, new microbiological techniques and clinical prediction and monitoring strategies. Consensus on the definition of EONS and the standardization of research on novel diagnostic biomarkers are crucial for future implementation and to reduce current antibiotic overexposure in newborns.

Genomic Analysis of Group B Streptococcus from Neonatal Sepsis Reveals Clonal CC17 Expansion and Virulence- and Resistance-Associated Traits After Intrapartum Antibiotic Prophylaxis

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of invasive neonatal infections. This study aimed to investigate the trend of GBS serotype and genotype change and their correlation with antimicrobial resistance before and after implementation of intrapartum antibiotic prophylaxis (IAP).

METHODS

We performed serotyping, whole-genome sequencing, antimicrobial susceptibility testing, and single-nucleotide polymorphism (SNP)-based phylogenetic analysis on 238 invasive GBS isolates collected from October 1998 to February 2020 in Taiwan.

RESULTS

There were 7 serotypes and 6 clonal complexes (CCs) among the 238 GBS isolates, and more than half of the isolates carried multiple antimicrobial resistance genes. The expansion of CC17 strains and the increase in late-onset disease occurred synchronously after the implementation of IAP. Analysis of the carriage isolates from pregnant women showed diverse serotype distribution in the IAP era. The antimicrobial susceptibility testing showed that all 238 strains were susceptible to ampicillin and penicillin, while the number of various resistance genes in GBS genomes was found increased with the expansion of CC17. Compared with reference genomes, 697 nonsynonymous SNPs in 443 protein-coding genes were CC17 specific.

CONCLUSIONS

The study revealed the expansion of GBS CC17 and the increase of late-onset disease that occurred simultaneously with the implementation of IAP. Although the susceptibility of CC17 to antimicrobial agents is not different from that of other sequence types at present, GBS with phenotypic resistance to antimicrobials may emerge in the future, given the environmental selection pressure and the continued accumulation of SNP mutations.

Population genomics of Group B Streptococcus reveals the genetics of neonatal disease onset and meningeal invasion

Group B Streptococcus (GBS), or Streptococcus agalactiae, is a pathogen that causes preterm births, stillbirths, and acute invasive neonatal disease burden and mortality. Here, we investigate bacterial genetic signatures associated with disease onset time and meningeal tissue infection in acute invasive neonatal GBS disease. We carry out a genome-wide association study (GWAS) of 1,338 GBS isolates from newborns with acute invasive disease; the isolates had been collected annually, for 30 years, through a national bacterial surveillance program in the Netherlands. After controlling for the population structure, we identify genetic variation within noncoding and coding regions, particularly the capsule biosynthesis locus, statistically associated with neonatal GBS disease onset time and meningeal invasion. Our findings highlight the impact of integrating microbial population genomics and clinical pathogen surveillance, and demonstrate the effect of GBS genetics on disease pathogenesis in neonates and infants.

Group B Streptococcus (GBS) causes neonatal disease and mortality worldwide. Here, the authors use genome-wide association analyses to identify bacterial genetic signatures associated with disease onset time and meningeal tissue infection in acute invasive neonatal GBS disease.

Neonatal early-onset infections: Comparing the sensitivity of the neonatal early-onset sepsis calculator to the Dutch and the updated NICE guidelines in an observational cohort of culture-positive cases

BACKGROUND

The early-onset sepsis calculator (EOSC) reduces unnecessary antibiotic treatment in newborns. However, its performance in identifying cases with early-onset disease (EOD) is unclear. We compared the sensitivity of the EOSC to the current Dutch and National Institute for Health and Care Excellence (NICE) guidelines when applied to a cohort of newborns with culture-positive early-onset sepsis and meningitis.

METHODS

Culture-positive Streptococcus agalactiae (GBS) and Escherichia coli (E. coli) sepsis and meningitis patients ≤3 days old with a gestational age ≥34 weeks, identified between 1/1/2018 and 31/1/2021 in a Dutch prospective nationwide cohort study were included. Cases were identified by treating physicians and microbiological surveillance. Primary outcome was the proportion of patients that would have been treated according to the EOSC, the Dutch, and the NICE EOD prevention guidelines. Differences between proportions were analysed using McNemar's test.

FINDINGS

We included 81 GBS and 7 E. coli EOD cases. At 4 h after birth, the EOSC would have recommended antibiotic treatment in 32 (36%) patients, compared to 44 (50%) by the Dutch (p<0·01) and 48 (55%) by the NICE guideline (p<0·01). The EOSC would have initially recommended routine care for 52% of patients compared to 31% and 30% for the Dutch and NICE guidelines (p<0·01). At 24 h after birth, the EOSC would have recommended antibiotic treatment in 54 (61%) infants compared to 64 (73%) by the Dutch (p = 0·02) and 63 (72%) by the NICE guidelines (p = 0·06).

INTERPRETATION

The sensitivity of the EOSC in identifying cases of EOD is lower compared to both Dutch and NICE guidelines, especially directly after birth. The EOSC relies more on clinical symptoms and results in less overtreatment of healthy newborns at the cost of later antibiotic treatment in initially well-appearing EOD patients.

FUNDING

This work was supported by grants received from Netherlands Organization for Health Research and Development (ZonMw; NWO-Vidi-Grant (grant number 917·17·308); NWO-Vici-Grant (grant number 918·19·627)), the Academic Medical Centre (AMC Innovative Impulse Grant) and Steun Emma Foundation Grant.

Sex Differences in Long-term Outcomes After Group B Streptococcal Infections During Infancy in Denmark and the Netherlands: National Cohort Studies of Neurodevelopmental Impairments and Mortality

BACKGROUND

Male infants have a higher incidence of invasive group B Streptococcus disease (iGBS) compared with female infants; however, data on sex differences in mortality and long-term outcomes after iGBS are lacking. We assessed whether a child's sex influences the effects of iGBS on mortality and risk of neurodevelopmental impairments (NDIs).

METHODS

We used Danish and Dutch registry data to conduct a nationwide cohort study of infants with a history of iGBS. A comparison cohort, children without a history of iGBS, was randomly selected and matched on relevant factors. Effect modification by sex was assessed on additive and multiplicative scales.

RESULTS

Our analyses included data from children with a history of iGBS in Denmark (period 1997 -2017; n = 1432) and the Netherlands (2000 -2017; n = 697) and from 21 172 children without iGBS. There was no clear evidence of between-sex heterogeneity in iGBS-associated mortality. Boys had a higher risk of NDI, with evidence for effect modification on additive scale at the age of 5 years for any NDI (relative excess risk due to interaction = 1.28; 95% confidence interval [CI], -0.53 to 3.09 in Denmark and 1.14; 95% CI, -5.13 to 7.41 in the Netherlands). A similar pattern was observed for moderate/severe NDI at age 5 years in Denmark and age 10 years in the Netherlands.

CONCLUSION

Boys are at higher risk of NDI ; our results suggest this is disproportionally increased in those who develop iGBS. Future studies should investigate mechanisms of this effect modification by sex.

Community-acquired bacterial meningitis

Progress has been made in the prevention and treatment of community-acquired bacterial meningitis during the past three decades but the burden of the disease remains high globally. Conjugate vaccines against the three most common causative pathogens (Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae) have reduced the incidence of disease, but with the replacement by non-vaccine pneumococcal serotypes and the emergence of bacterial strains with reduced susceptibility to antimicrobial treatment, meningitis continues to pose a major health challenge worldwide. In patients presenting with bacterial meningitis, typical clinical characteristics (such as the classic triad of neck stiffness, fever, and an altered mental status) might be absent and cerebrospinal fluid examination for biochemistry, microscopy, culture, and PCR to identify bacterial DNA are essential for the diagnosis. Multiplex PCR point-of-care panels in cerebrospinal fluid show promise in accelerating the diagnosis, but diagnostic accuracy studies to justify routine implementation are scarce and randomised, controlled studies are absent. Early administration of antimicrobial treatment (within 1 hour of presentation) improves outcomes and needs to be adjusted according to local emergence of drug resistance. Adjunctive dexamethasone treatment has proven efficacy beyond the neonatal age but only in patients from high-income countries. Further progress can be expected from implementing preventive measures, especially the development of new vaccines, implementation of hospital protocols aimed at early treatment, and new treatments targeting checkpoints of the inflammatory cascade.