Blindness as an uncommon complication of Streptococcus pneumoniae systemic infection

ABSTRACT Bacteria frequently have multiple mechanisms for acquiring iron, an essential micronutrient, from the environment. We have identified a four-gene Streptococcus pneumoniae operon, named pit, encoding proteins with similarity to components of a putative Brachyspira hyodysenteriae iron uptake ABC transporter, Bit. An S. pneumoniae strain containing a defined mutation in pit has impaired growth in medium containing the iron chelator ethylenediamine di-o-hydroxyphenylacetic acid, reduced sensitivity to the iron-dependent antibiotic streptonigrin, and impaired virulence in a mouse model of S. pneumoniae systemic infection. Furthermore, addition of a mutation in pit to a strain containing mutations in the two previously described S. pneumoniae iron uptake ABC transporters, piu and pia, resulted in a strain with impaired growth in two types of iron-deficient medium, a high degree of resistance to streptonigrin, and a reduced rate of iron uptake. Comparison of the susceptibilities to streptonigrin of the individual pit, piu, and pia mutant strains and comparison of the growth in iron-deficient medium and virulence of single and double mutant strains suggest that pia is the dominant iron transporter during in vitro and in vivo growth.

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Infection with Conditionally Virulent Streptococcus pneumoniae ΔpabStrains Induces Antibody to Conserved Protein Antigens but Does Not Protect against Systemic Infection with Heterologous Strains

Infection and Immunity ◽

10.1128/iai.05923-11 ◽

2011 ◽

Vol 79 (12) ◽

pp. 4965-4976 ◽

Cited By ~ 22

Author(s):

Suneeta Chimalapati ◽

Jonathan Cohen ◽

Emilie Camberlein ◽

Claire Durmort ◽

Helen Baxendale ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Capsular Polysaccharide ◽

Bacterial Pathogen ◽

Systemic Infection ◽

Complete Medium ◽

Protein Antigens ◽

Live Attenuated Vaccine ◽

Content Type ◽

Immunological Responses ◽

Heterologous Challenge

ABSTRACTAvirulent strains of a bacterial pathogen could be useful tools for investigating immunological responses to infection and potentially effective vaccines. We have therefore constructed an auxotrophic TIGR4 Δpabstrain ofStreptococcus pneumoniaeby deleting thepabBgene Sp_0665. The TIGR4 Δpabstrain grew well in complete medium but was unable to grow in serum unless it was supplemented withpara-aminobenzoic acid (PABA). The TIGR4 Δpabstrain was markedly attenuated in virulence in mouse models ofS. pneumoniaenasopharyngeal colonization, pneumonia, and sepsis. Supplementing mouse drinking water with PABA largely restored the virulence of TIGR4 Δpab. An additional Δpabstrain constructed in the D39 capsular serotype 2 background was also avirulent in a sepsis model. Systemic inoculation of mice with TIGR4 Δpabinduced antibody responses toS. pneumoniaeprotein antigens, including PpmA, PsaA, pneumolysin, and CbpD, but not capsular polysaccharide. Flow cytometry demonstrated that IgG in sera from TIGR4 Δpab-vaccinated mice bound to the surface of TIGR4 and D39 bacteria but not to a capsular serotype 3 strain, strain 0100993. Mice vaccinated with the TIGR4 Δpabor D39 Δpabstrain by intraperitoneal inoculation were protected from developing septicemia when challenged with the homologousS. pneumoniaestrain. Vaccination with the TIGR4 Δpabstrain provided only weak or no protection against heterologous challenge with the D39 or 0100993 strain but did strongly protect against a TIGR4 capsular-switch strain expressing a serotype 2 capsule. The failure of cross-protection after systemic vaccination with Δpabbacteria suggests that parenteral administration of a live attenuated vaccine is not an attractive approach for preventingS. pneumoniaeinfection.

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Exploration of bacterial bottlenecks and Streptococcus pneumoniae pathogenesis by CRISPRi-seq

10.1101/2020.04.22.055319 ◽

2020 ◽

Cited By ~ 1

Author(s):

Xue Liu ◽

Jacqueline M. Kimmey ◽

Vincent de Bakker ◽

Victor Nizet ◽

Jan-Willem Veening

Keyword(s):

Streptococcus Pneumoniae ◽

Post Infection ◽

Systemic Infection ◽

The Body ◽

Genetic Screens ◽

Animal Pathogens ◽

Genes Encoding ◽

One Step

AbstractStreptococcus pneumoniae is a commensal bacterium of the human nasopharynx, but can cause harmful infections if it spreads to other parts of the body, such as pneumonia, sepsis or meningitis. To facilitate pathogenesis studies, we constructed a doxycycline-inducible pooled CRISPR interference (CRISPRi) library targeting all operons in protypical S. pneumoniae strain D39V. Our library design allows fitness within the pool to be assessed by a one-step PCR reaction directly followed by Illumina sequencing (CRISPRi-seq). The doxycycline-inducible CRISPRi system is tightly controllable and suitable for both bottleneck exploration and evaluation of gene fitness in vitro and in vivo. Here, we applied CRISPRi-seq to identify genetic factors important for causing pneumococcal pneumonia. Mice were infected intratracheally with our CRISPRi library and bacteria collected at 24 h (from lung) and 48 h (from both lung and blood) post-infection. CRISPRi-seq showed a critical bottleneck at 48 h after intratracheal infection, with only a few bacteria surviving the brunt of the innate immune response to cause systemic infection. However, earlier at 24 h post-infection, many significant differences in gene fitness cost between in vitro and in vivo conditions were identified, including genes encoding known and putative novel virulence factors, genes essential only in vivo, and genes essential only in vitro. A key advantage of CRISPRi-seq over traditional transposon-based genetic screens is that all genes, including essential genes, can be tested for their role in virulence and pathogenicity. The approaches developed here should be generally applicable to study infection bottlenecks and in vivo fitness for other important human and animal pathogens.

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Immunization with Components of Two Iron Uptake ABC Transporters Protects Mice against Systemic Streptococcus pneumoniae Infection

Infection and Immunity ◽

10.1128/iai.69.11.6702-6706.2001 ◽

2001 ◽

Vol 69 (11) ◽

pp. 6702-6706 ◽

Cited By ~ 119

Author(s):

Jeremy S. Brown ◽

A. David Ogunniyi ◽

Matthew C. Woodrow ◽

David W. Holden ◽

James C. Paton

Keyword(s):

Streptococcus Pneumoniae ◽

Abc Transporters ◽

Iron Uptake ◽

Protective Immunity ◽

Vaccine Candidate ◽

Systemic Infection ◽

Antibody Responses ◽

Protein Vaccine ◽

Protein Antigens ◽

Bacterial Cell Membrane

ABSTRACT There has been considerable recent research into protein basedStreptococcus pneumoniae vaccines as alternatives to the existing capsular antigen vaccines. PiuA and PiaA (formerly Pit1A and Pit2A) are recently identified lipoprotein components of S. pneumoniae iron uptake ABC transporters which are required for full virulence and are likely to be expressed on the surface of the bacterial cell membrane. We investigated the efficacy of recombinant PiuA and PiaA proteins at eliciting protective immunity in mice against systemic infection with S. pneumoniae. Both recombinant PiuA and PiaA generated antibody responses that cross-reacted with each other but not with pneumolysin and reacted with identical proteins from nine different S. pneumoniae serotypes. Mice immunized with recombinant PiuA and PiaA were protected against systemic challenge to a degree similar to those immunized with an existing protein vaccine candidate, PdB (a genetically modified pneumolysin toxoid). Immunization with a combination of both PiuA and PiaA resulted in additive protection and was highly protective against systemic infection with S. pneumoniae. PiuA and PiaA are therefore promising additional candidates for a novel S. pneumoniae vaccine using protein antigens.

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Transformation of nonencapsulated Streptococcus pneumoniae during systemic infection

Scientific Reports ◽

10.1038/s41598-020-75988-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jessica L. Bradshaw ◽

Iftekhar M. Rafiqullah ◽

D. Ashley Robinson ◽

Larry S. McDaniel

Keyword(s):

Streptococcus Pneumoniae ◽

Systemic Infection ◽

Dna Uptake ◽

Pathogenic Potential ◽

Bacterial Surface ◽

Capsule Production ◽

Virulent Strains ◽

Capsule Locus ◽

Ear Infections ◽

Complement Deposition

Abstract Streptococcus pneumoniae (pneumococcus) is a principal cause of bacterial middle ear infections, pneumonia, and meningitis. Capsule-targeted pneumococcal vaccines have likely contributed to increased carriage of nonencapsulated S. pneumoniae (NESp). Some NESp lineages are associated with highly efficient DNA uptake and transformation frequencies. However, NESp strains lack capsule that may increase disease severity. We tested the hypothesis that NESp could acquire capsule during systemic infection and transform into more virulent pneumococci. We reveal that NESp strains MNZ67 and MNZ41 are highly transformable and resistant to multiple antibiotics. Natural transformation of NESp when co-administered with heat-killed encapsulated strain WU2 in a murine model of systemic infection resulted in encapsulation of NESp and increased virulence during bacteremia. Functional capsule production increased the pathogenic potential of MNZ67 by significantly decreasing complement deposition on the bacterial surface. However, capsule acquisition did not further decrease complement deposition on the relatively highly pathogenic strain MNZ41. Whole genome sequencing of select transformants demonstrated that recombination of up to 56.7 kbp length occurred at the capsule locus, along with additional recombination occurring at distal sites harboring virulence-associated genes. These findings indicate NESp can compensate for lack of capsule production and rapidly evolve into more virulent strains.

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Overwhelming post-splenectomy sepsis in patients with asplenia and hyposplenia: a retrospective cohort study

Epidemiology and Infection ◽

10.1017/s0950268816002405 ◽

2016 ◽

Vol 145 (2) ◽

pp. 397-400 ◽

Cited By ~ 15

Author(s):

J. CHONG ◽

P. JONES ◽

D. SPELMAN ◽

K. LEDER ◽

A. C. CHENG

Keyword(s):

Cohort Study ◽

Intensive Care ◽

Streptococcus Pneumoniae ◽

Retrospective Cohort Study ◽

Older Patients ◽

Retrospective Cohort ◽

Risk Of Infection ◽

Intravenous Antibiotics ◽

Clinically Significant ◽

Uncommon Complication

SUMMARYOverwhelming post-splenectomy infection (OPSI) is a serious complication of asplenia and is associated with encapsulated organisms, most commonly Streptococcus pneumoniae, but also Haemophilus influenzae and Neisseria meningitidis. We aimed to estimate the risk of infection in this patient group. We reviewed data collected by the Victorian Spleen Registry in Australia. On registration, all patients are asked about significant infections requiring admission to hospital for intravenous antibiotics; those requiring admission to ICU were defined as OPSI. In the 3274 asplenic patients registered 492 patients reported at least one episode of infection. There were 47 episodes of OPSI requiring intensive care (incidence rate 1·11/1000 patient-years). The risk of OPSI was highest in older patients, and there were no statistically significant differences in incidence by reason for splenectomy except for a higher rate in patients with medical hyposplenia. This study reinforces that post-splenectomy infection is a clinically significant but uncommon complication, and that fulminant infection requiring intensive care is a minority of all infections.

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Immunization with Recombinant Pneumolysin Induces the Production of Antibodies and Protects Mice in a Model of Systemic Infection Caused by Streptococcus pneumoniae

Bulletin of Experimental Biology and Medicine ◽

10.1007/s10517-020-04736-6 ◽

2020 ◽

Vol 168 (4) ◽

pp. 485-487

Author(s):

E. S. Petukhova ◽

D. S. Vorobyev ◽

A. V. Sidorov ◽

I. B. Semenova ◽

Y. V. Volokh ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Systemic Infection

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Transcriptional Regulation in the Streptococcus pneumoniae rlrA Pathogenicity Islet by RlrA

Journal of Bacteriology ◽

10.1128/jb.185.2.413-421.2003 ◽

2003 ◽

Vol 185 (2) ◽

pp. 413-421 ◽

Cited By ~ 84

Author(s):

David L. Hava ◽

Carolyn J. Hemsley ◽

Andrew Camilli

Keyword(s):

Streptococcus Pneumoniae ◽

Transcriptional Activation ◽

Virulence Genes ◽

Systemic Infection ◽

Transcriptional Regulators ◽

Lung Infection ◽

Surface Proteins ◽

Microbial Pathogens ◽

Temporal Expression ◽

Bacterial Surface

ABSTRACT The proper temporal expression of virulence genes during infection is crucial to the infectious life cycle of microbial pathogens, particularly in pathogens that encounter a multitude of environments in eukaryotic hosts. Streptococcus pneumoniae normally colonizes the nasopharynges of healthy adults but can cause a range of diseases at a variety of host sites. Transcriptional regulators that are essential for full virulence of S. pneumoniae in different animal models have been identified. One such regulator, rlrA, is required for colonization of the nasopharynx and lung infection but is dispensable for systemic infection. Previous work has shown that rlrA lies in a 12-kb pathogenicity islet, divergently opposed to three putative sortase-anchored surface proteins and three sortase enzymes. In addition to rlrA, one of the putative surface proteins and one of the sortases have also been shown to be essential for lung infection. In this work, we demonstrate that RlrA is a positive regulator of all seven genes in the rlrA pathogenicity islet, with transcriptional activation occurring at four different promoters in the islet with AT-rich sequences. These promoters direct the expression of rlrA itself, the three sortases, rrgA, and rrgBC. These data are consistent with the model whereby the rlrA pathogenicity islet acts in an autonomous manner to alter the bacterial surface components that interact with the pulmonary and nasopharyngeal environments.

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