Invasion and trafficking of hypervirulent group B streptococci in polarized enterocytes

Streptococcus agalactiae (group B streptococcus or GBS) is a commensal bacterium that can frequently behave as a pathogen, particularly in the neonatal period and in the elderly. The gut is a primary site of GBS colonization and a potential port of entry during neonatal infections caused by hypervirulent clonal complex 17 (CC17) strains. Here we studied the interactions between the prototypical CC17 BM110 strain and polarized enterocytes using the Caco-2 cell line. GBS could adhere to and invade these cells through their apical or basolateral surfaces. Basolateral invasion was considerably more efficient than apical invasion and predominated under conditions resulting in weakening of cell-to-cell junctions. Bacterial internalization occurred by a mechanism involving caveolae- and lipid raft-dependent endocytosis and actin re-organization, but not clathrin-dependent endocytosis. In the first steps of Caco-2 invasion, GBS colocalized with the early endocytic marker EEA-1, to later reside in acidic vacuoles. Taken together, these data suggest that CC17 GBS selectively adheres to the lateral surface of enterocytes from which it enters through caveolar lipid rafts using a classical, actin-dependent endocytic pathway. These data may be useful to develop alternative preventive strategies aimed at blocking GBS invasion of the intestinal barrier.

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Capsular Sialic Acid Limits C5a Production on Type III Group B Streptococci

Infection and Immunity ◽

10.1128/iai.67.4.1866-1870.1999 ◽

1999 ◽

Vol 67 (4) ◽

pp. 1866-1870 ◽

Cited By ~ 28

Author(s):

Shinji Takahashi ◽

Youko Aoyagi ◽

Elisabeth E. Adderson ◽

Yoshiyuki Okuwaki ◽

John F. Bohnsack

Keyword(s):

Sialic Acid ◽

Specific Antibody ◽

Acid Content ◽

Alternative Pathway ◽

Group B Streptococcus ◽

Neonatal Infections ◽

Group B Streptococci ◽

Sialic Acid Content ◽

Type Iii ◽

Group B

ABSTRACT The majority of type III group B streptococcus (GBS) human neonatal infections are caused by a genetically related subgroup called III-3. We have proposed that a bacterial enzyme, C5a-ase, contributes to the pathogenesis of neonatal infections with GBS by rapidly inactivating C5a, a potent pro-inflammatory molecule, but many III-3 strains do not express C5a-ase. The amount of C5a produced in serum following incubation with representative type III strains was quantitated in order to better understand the relationship between C5a production and C5a-ase expression. C5a production following incubation of bacteria with serum depleted of antibody to the bacterial surface was inversely proportional to the sialic acid content of the bacterial capsule, with the more heavily sialylated III-3 strains generating less C5a than the less-virulent, less-sialylated III-2 strains. The amount of C5a produced correlated significantly with C3 deposition on each bacterial strain. Repletion with type-specific antibody caused increased C3b deposition and C5a production through alternative pathway activation, but C5a was functionally inactivated by strains that expressed C5a-ase. The increased virulence of III-3 strains compared to that of III-2 strains results at least partially from the higher sialic acid content of III-3 strains, which inhibits both opsonophagocytic killing and C5a production in the absence of type-specific antibody. We propose that C5a-ase is not necessary for III-3 strains to cause invasive disease because the high sialic acid content of III-3 strains inhibits C5a production.

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Hemolytic Membrane Vesicles of Group B Streptococcus Promote Infection

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa548 ◽

2020 ◽

Author(s):

Blair Armistead ◽

Phoenicia Quach ◽

Jessica M Snyder ◽

Verónica Santana-Ufret ◽

Anna Furuta ◽

...

Keyword(s):

Group B Streptococcus ◽

Membrane Vesicles ◽

Neonatal Infections ◽

Group B Streptococci ◽

Bacterial Surface ◽

Gram Positive Bacteria ◽

Bacterial Dissemination ◽

Key Factor ◽

Associated Proteins ◽

Group B

Abstract Background Group B streptococci (GBS) are β-hemolytic, Gram-positive bacteria associated with fetal injury, preterm birth, spontaneous abortion, and neonatal infections. A key factor promoting GBS virulence is the β-hemolysin/cytolysin, a pigmented ornithine rhamnolipid (also known as granadaene) associated with the bacterial surface. Methods A previous study indicated that GBS produce small structures known as membrane vesicles (MVs), which contain virulence-associated proteins. In this study, we show that GBS MVs are pigmented and hemolytic, indicating that granadaene is functionally active in MVs. Results In addition, MVs from hyperhemolytic GBS induced greater cell death of neutrophils, T cells, and B cells compared with MVs from isogenic nonhemolytic GBS, implicating MVs as a potential mechanism for granadaene-mediated virulence. Finally, hemolytic MVs reduced oxidative killing of GBS and aggravated morbidity and mortality of neonatal mice infected with GBS. Conclusions These studies, taken together, reveal a novel mechanism by which GBS deploy a crucial virulence factor to promote bacterial dissemination and pathogenesis.

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Trends in molecular characteristics and antimicrobial resistance of group B streptococci: a multicenter study in Serbia, 2015–2020

Scientific Reports ◽

10.1038/s41598-020-79354-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Dusan Kekic ◽

Ina Gajic ◽

Natasa Opavski ◽

Milan Kojic ◽

Goran Vukotic ◽

...

Keyword(s):

Antimicrobial Resistance ◽

Late Onset ◽

Group B Streptococcus ◽

Neonatal Morbidity ◽

Disease Rate ◽

Molecular Characteristics ◽

Group B Streptococci ◽

Live Births ◽

Invasive Infections ◽

Group B

AbstractGroup B Streptococcus (GBS) is a major cause of neonatal morbidity and mortality. Serbia has not fully implemented preventive measures against GBS neonatal diseases. Therefore, we aimed to assess the maternal GBS colonisation and invasive neonatal disease rate, to reveal the trends of antimicrobial resistance and serotype distribution of GBS from various patient groups. Randomly selected non-invasive (n = 991) and all invasive GBS (n = 80) collected throughout Serbia from 2015 to 2020 were tested for antimicrobial susceptibility, capsular typing, and hvgA detection. Overall, 877/5621 (15.6%) pregnant women were colonised with GBS. Invasive GBS infections incidence in infants (0.18/1000 live births) showed a decreasing trend (0.3 to 0.1/1000 live births). Type III was overrepresented in infants with invasive infections (n = 35, 58.3%), whereas type V predominated among colonised adults (n = 224, 25.5%) and those with noninvasive (n = 37, 32.5%) and invasive infections (n = 8, 40%). The hypervirulent clone III/ST17 was highly associated with invasive infections (n = 28, 35%), particularly late-onset disease (n = 9, 47.4%), showing an increase from 12.3 to 14.8%. The GBS resistance to erythromycin and clindamycin was 26.7% and 22.1%, respectively, with an upward trend. The emergence of the hypervirulent clone III/ST17 and the escalation in GBS resistance highlight an urgent need for continuous monitoring of GBS infections.

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Colonization With Group B Streptococci in Girls Under 16 Years of Age

PEDIATRICS ◽

10.1542/peds.60.4.473 ◽

1977 ◽

Vol 60 (4) ◽

pp. 473-476 ◽

Cited By ~ 1

Author(s):

Margaret R. Hammerschlag ◽

Carol J. Baker ◽

Susan Alpert ◽

Dennis L. Kasper ◽

Ingrid Rosner ◽

...

Keyword(s):

Anal Canal ◽

Serum Antibody ◽

Group B Streptococcus ◽

Group B Streptococci ◽

Capsular Antigen ◽

Type Iii ◽

Group B

Cultures from the vagina, pharynx, and anal canal of 100 healthy girls, 2 months through 15 years of age, were examined for the presence of group B streptococci. Of the 100 participants, 20% were colonized at one or more of these three sites. Pharyngeal colonization was detected in 15% of the girls under 11 years of age and in 5% of those over 11 years of age. Colonization at anogenital sites was observed in 19% of participants under 3 years of age, in 25% of those 11 years of age and older, and in only 4% of those between the ages of 3 and 10 years (P < .025). The concentration of serum antibody directed against the polysaccharide capsular antigen isolated from type III, group B Streptococcus appeared, in part, to be related to increasing age.

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Changes in incidence and etiology of early-onset neonatal infections 1997–2017 – a retrospective cohort study in western Sweden

BMC Pediatrics ◽

10.1186/s12887-019-1866-z ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Margrét Johansson Gudjónsdóttir ◽

Anders Elfvin ◽

Elisabet Hentz ◽

Ingegerd Adlerberth ◽

Ingemar Tessin ◽

...

Keyword(s):

Early Onset ◽

Antimicrobial Prophylaxis ◽

List Type ◽

Neonatal Infections ◽

Group B Streptococci ◽

Gram Negative ◽

Live Births ◽

Extremely Preterm ◽

Extremely Preterm Infants ◽

Group B

Abstract Background The objective of the study was to evaluate data on early-onset neonatal invasive infections in western Sweden for the period 1997–2017. To identify changes in incidence, etiology and mortality and compare to previous studies from the same area starting from 1975. Methods Observational epidemiological, retrospective study on infants 0–6 days of age with a positive culture in blood and/or cerebrospinal fluid between 1997 and 2017. A comparison was made of the incidence between 2008 and 2017 compared to 1997–2007. Changes in the incidence of infections due to Group B streptococci, Staphylococcus aureus and aerobic Gram-negative rods were assessed from 1975. Results The total incidence, including both recognized pathogens and commensals as causative agents, was 1.1/1000 live births. The incidence declined from 1.4/1000 LB in 1997–2007 to 0.9/1000 LB in 2008–2017 but the case-fatality rate remained unchanged, (8/119 vs 7/90), at 7%. Among the 209 patients identified during 1997–2017 with sepsis or meningitis the most common organisms were Group B streptococci (40%, 84/209), S. aureus (16%, 33/209) and E. coli (9%, 18/209). The incidence of Group B streptococci infections went from 0.9/1000 live births 1987–1996 to 0.45/1000 live births 1997–2017 and all cases were within 72 h. The proportion of extremely preterm infants (< 28 weeks gestation) rose steadily during the study period but there was no rise in infections due to Gram-negative organisms. The spectrum of cultured organisms changed after 72 h as commensal organisms started to emerge. Conclusion There has been a decrease in the incidence of neonatal early-onset infections compared to previous studies in western Sweden. The incidence of GBS infections was not as low as in other reports. Further studies are needed to assess if screening-based intra partum antimicrobial prophylaxis instead of a risk factor-based approach for identifying candidates for intrapartum antimicrobial prophylaxis would be a better option for this study area. Key notes This study is one of the longest running follow-ups in the world, a follow-up of 43 years of early-onset neonatal infections.The incidence of early-onset GBS infections is higher in Western Sweden compared to other local reports.No difference in the incidence of early-onset GBS depending on the definition of early-onset being within 72 h or 7 days of life.

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Increasing incidence of group B streptococcus neonatal infections in the Netherlands is associated with clonal expansion of CC17 and CC23

Scientific Reports ◽

10.1038/s41598-020-66214-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Dorota Jamrozy ◽

Merijn W. Bijlsma ◽

Marcus C. de Goffau ◽

Diederik van de Beek ◽

Taco W. Kuijpers ◽

...

Keyword(s):

The Netherlands ◽

Group B Streptococcus ◽

Clonal Expansion ◽

Neonatal Infections ◽

Group B

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Whole-Genome Sequencing Confirms the Coexistence of Different Colonizing Group B Streptococcus Isolates Underscored by CRISPR Typing

Microbiology Resource Announcements ◽

10.1128/mra.01359-19 ◽

2020 ◽

Vol 9 (5) ◽

Author(s):

Clémence Beauruelle ◽

Maxime Branger ◽

Thierry Cochard ◽

Adeline Pastuszka ◽

Franck Biet ◽

...

Keyword(s):

Genome Sequencing ◽

Draft Genome ◽

Group B Streptococcus ◽

Whole Genome ◽

Industrialized Countries ◽

Genome Sequences ◽

Neonatal Infections ◽

Content Type ◽

Phylogenetic Affiliation ◽

Group B

Streptococcus agalactiae is a major pathogen and is the leading cause of neonatal infections in industrialized countries. The diversity of strains isolated from two pregnant women was investigated. Here, we present the draft genome sequences of strains W8A2, W8A6, W10E2, and W10F3, obtained in order to ascertain their phylogenetic affiliation.

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Subtractive Hybridization Identifies a Novel Predicted Protein Mediating Epithelial Cell Invasion by Virulent Serotype III Group B Streptococcus agalactiae

Infection and Immunity ◽

10.1128/iai.71.12.6857-6863.2003 ◽

2003 ◽

Vol 71 (12) ◽

pp. 6857-6863 ◽

Cited By ~ 37

Author(s):

Elisabeth E. Adderson ◽

Shinji Takahashi ◽

Yan Wang ◽

Jianling Armstrong ◽

Dylan V. Miller ◽

...

Keyword(s):

Epithelial Cells ◽

Streptococcus Agalactiae ◽

Group B Streptococcus ◽

Newborn Infants ◽

Subtractive Hybridization ◽

Group B Streptococci ◽

Mutant Type ◽

Isogenic Mutant ◽

Type Iii ◽

Group B

ABSTRACT Group B Streptococcus agalactiae bacteria (group B streptococci [GBS]) are the most common cause of serious bacterial infection in newborn infants. The majority of serotype III-related cases of neonatal disease are caused by a genetically related subgroup of bacteria, restriction fragment digest pattern (RDP) type III-3, suggesting that these strains possess unique genes contributing to virulence. We used genomic subtractive hybridization to identify regions of genomic DNA unique to virulent RDP type III-3 GBS strains. Within one of these III-3-specific regions is a 1,506-bp open reading frame, spb1 (surface protein of group B streptococcus 1). A mutant type III GBS strain lacking Spb1 was constructed in virulent RDP type III-3 strain 874391, and the interactions of the wild-type and spb1 isogenic mutant with a variety of epithelial cells important to GBS colonization and infection were compared. While adherence of the spb1 isogenic mutant to A549 respiratory, C2Bbe1 colonic, and HeLa cervical epithelial cells was slightly lower than that of the 874391 strain, invasion of the Spb1− mutant was significantly reduced with these cell lines compared to what was seen with 874391. The defect in epithelial invasion was corrected by supplying spb1 in trans. These observations suggest that Spb1 contributes to the pathogenesis of neonatal GBS infection by mediating internalization of virulent serotype III GBS and confirm that understanding of the population structure of bacteria may lead to insights into the pathogenesis of human infections.

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Mutually Exclusive Distribution of IS1548 and GBSi1, an Active Group II Intron Identified in Human Isolates of Group B Streptococci

Journal of Bacteriology ◽

10.1128/jb.183.8.2560-2569.2001 ◽

2001 ◽

Vol 183 (8) ◽

pp. 2560-2569 ◽

Cited By ~ 62

Author(s):

Margareta Granlund ◽

François Michel ◽

Mari Norgren

Keyword(s):

Insertion Site ◽

Group B Streptococcus ◽

Group Ii Intron ◽

Major Product ◽

Repeat Sequence ◽

Bacillus Halodurans ◽

Group B Streptococci ◽

Genetic Lineages ◽

Group Ii ◽

Group B

ABSTRACT The present study shows that active, self-splicing group II intron GBSi1 is located downstream of the C5a-peptidase gene,scpB, in some group B streptococcus (GBS) isolates that lack insertion sequence IS1548. IS1548 was previously reported to be often present at the scpB locus in GBS isolated in association with endocarditis. Since none of 67 GBS isolates examined, 40 of which were of serotype III, harbored both IS1548 and GBSi1, these two elements are suggested to be markers for different genetic lineages in GBS serotype III. The DNA region downstream of scpB in GBS isolates harboring either GBSi1, IS1548, or none of these mobile elements was found to encode the laminin binding protein, Lmb, which shows sequence similarities to a family of streptococcal adhesins. IS1548 is inserted 9 bp upstream of the putative promoter for lmb, while the insertion site for GBSi1 is located 88 bp further upstream. Sequences highly similar to GBSi1 exist also in Streptococcus pneumoniae. An inverted repeat sequence, with features typical of transcription terminators, was identified immediately upstream of the insertion site for the group II intron both in the GBS and S. pneumoniae sequences. This motif is suggested to constitute a target for the GBS intron as well as for rather closely related introns in Bacillus halodurans, Pseudomonas alcaligenes, andPseudomonas putida. When transcripts containing the GBSi1 intron were incubated at high concentrations of ammonium and magnesium, a major product with the expected length and sequence for the ligated exons was generated. Unlike, however, all members of group II investigated so far, the excised intron was in linear, rather than in a branched (lariat), form.

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