Chromosome segregation drives division site selection in Streptococcus pneumoniae.

Proc Natl Acad Sci U S A. 2017 Jul 3. pii: 201620608. doi: 10.1073/pnas.1620608114. [Epub ahead of print]

Chromosome segregation drives division site selection in Streptococcus pneumoniae.

van Raaphorst R1,2, Kjos M1,3, Veening JW4,2.

Author information


Accurate spatial and temporal positioning of the tubulin-like protein FtsZ is key for proper bacterial cell division. Streptococcus pneumoniae(pneumococcus) is an oval-shaped, symmetrically dividing opportunistic human pathogen lacking the canonical systems for division site control (nucleoid occlusion and the Min-system). Recently, the early division protein MapZ was identified and implicated in pneumococcal division site selection. We show that MapZ is important for proper division plane selection; thus, the question remains as to what drives pneumococcal division site selection. By mapping the cell cycle in detail, we show that directly after replication both chromosomal origin regions localize to the future cell division sites, before FtsZ. Interestingly, Z-ring formation occurs coincidently with initiation of DNA replication. Perturbing the longitudinal chromosomal organization by mutating the condensin SMC, by CRISPR/Cas9-mediated chromosome cutting, or by poisoning DNA decatenation resulted in mistiming of MapZ and FtsZ positioning and subsequent cell elongation. Together, we demonstrate an intimate relationship between DNA replication, chromosome segregation, and division site selection in the pneumococcus, providing a simple way to ensure equally sized daughter cells.


FtsZ; SMC; Streptococcus pneumoniae; cell division; chromosome organization

PMID: 28674002 DOI: 10.1073/pnas.1620608114

Increasing incidence of penicillin- and cefotaxime-resistant Streptococcus pneumoniae causing meningitis in India: Time for revision of treatment guidelines?

Indian J Med Microbiol. 2017 Apr-Jun;35(2):228-236. doi: 10.4103/ijmm.IJMM_17_124.

Increasing incidence of penicillin- and cefotaxime-resistant Streptococcus pneumoniae causing meningitis in India: Time for revision of treatment guidelines?

Verghese VP1, Veeraraghavan B2, Jayaraman R2, Varghese R2, Neeravi A2, Jayaraman Y3, Thomas K4, Mehendale SM3.

Author information



Pneumococcal meningitis is a life-threatening infection, requiring prompt diagnosis and effective treatment. Penicillin resistance in pneumococcal infections is a concern. Here, we present the antibiotic susceptibility profile of pneumococcal meningeal isolates from January 2008 to August 2016 to elucidate treatment guidelines for pneumococcal meningitis.


Invasive pneumococcal isolates from all age groups, were included in this study. Minimum inhibitory concentrations for the isolates were identified by agar dilution technique and VITEK System 2. Serotyping of isolates was done by co-agglutination technique.


Out of 830 invasive pneumococcal isolates, 167 (20.1%) isolates were from meningeal infections. Cumulative penicillin resistance in pneumococcal meningitis was 43.7% and cefotaxime non-susceptibility was 14.9%. Penicillin resistance amongst meningeal isolates in those younger than 5 years, 5-16 years of age and those aged 16 years and older was 59.7%, 50% and 27.3%, respectively, with non-susceptibility to cefotaxime in the same age groups being 18%, 22.2% and 10.4%. Penicillin resistance amongst pneumococcal meningeal isolates increased from 9.5% in 2008 to 42.8% in 2016, whereas cefotaxime non-susceptibility increased from 4.7% in 2008 to 28.5% in 2016. Serotypes 14, 19F, 6B, 6A, 23F, 9V and 5 were the most common serotypes causing meningitis, with the first five accounting for over 75% of resistant isolates.


The present study reports increasing penicillin resistance and cefotaxime non-susceptibility to pneumococcal meningitis in our setting. This highlights the need for empiric therapy with third-generation cephalosporins and vancomycin for all patients with meningitis while awaiting results of culture and susceptibility testing.

PMID: 28681811 DOI: 10.4103/ijmm.IJMM_17_124

Mucin 1 protects against severe Streptococcus pneumoniae infection.

Virulence. 2017 Jun 12:0. doi: 10.1080/21505594.2017.1341021. [Epub ahead of print]

Mucin 1 protects against severe Streptococcus pneumoniae infection.

Dhar P1,2, Ng GZ1,2, Dunne EM1, Sutton P1,2,3.

Author information


Streptococcus pneumoniae is a bacterial pathogen that commonly resides in the human nasopharynx, typically without causing any disease. However, in some cases these bacteria migrate from the nasopharynx to other sites of the body such as the lungs and bloodstream causing pneumonia and sepsis, respectively. This study used a mouse model of infection to investigate the potential role of Mucin 1 (MUC1), a cell membrane-associated glycoprotein known for playing a key barrier role at mucosal surfaces, in regulating this process. Wildtype (WT) and MUC1-deficient (Muc1-/-) mice were infected intranasally with an invasive strain of S. pneumoniae and bacterial loads in the nasopharynx, lungs, and blood were analyzed. Lungs were graded histologically for inflammation and cytokine profiles in the lungs analyzed by ELISA. While there was no difference in pneumococcal colonization of the nasopharynx between WT and Muc1-/- mice, infected Muc1-/- mice showed high pneumococcal loads in their lungs 16 hours post-infection, as well as bacteremia. In contrast, infected WT mice cleared the pneumococci from their lungs and remained asymptomatic. Infection in Muc1-/- mice was associated with an elevation in lung inflammation, with cellular recruitment especially of monocytes/macrophages. While MUC1-deficiency has been shown to increase phagocytosis of Pseudomonas aeruginosa, macrophages from Muc1-/- mice exhibited a reduced capacity to phagocytose S. pneumoniae indicating diverse and bacterial-specific effects. In conclusion, these findings indicate that MUC1 plays an important role in protection against severe pneumococcal disease, potentially mediated by facilitating macrophage phagocytosis.


Muc1; Streptococcus pneumoniae; bacteremia; inflammation; macrophages; phagocytosis

PMID: 28605238 DOI: 10.1080/21505594.2017.1341021

Conjugation of PspA4Pro with capsular Streptococcus pneumoniae polysaccharide serotype 14 does not reduce the induction of cross-reactive antibodies.

Clin Vaccine Immunol. 2017 Jun 21. pii: CVI.00118-17. doi: 10.1128/CVI.00118-17. [Epub ahead of print]

Conjugation of PspA4Pro with capsular Streptococcus pneumoniae polysaccharide serotype 14 does not reduce the induction of cross-reactive antibodies.

da Silva MA1, Converso TR1,2, Gonçalves VM1, Leite LCC1, Tanizaki MM1, Barazzone GC3.

Author information


Current pneumococcal vaccines are composed of bacterial polysaccharides as antigens plain or conjugated to carrier proteins. While efficacious against vaccine serotypes, epidemiologic data shows increasing incidence of infections caused by non-vaccine serotypes of Streptococcus pneumoniae. The use of Pneumococcal surface protein A (PspA) as a carrier protein in a conjugate vaccine could help preventing serotype replacement by increasing vaccine coverage and reducing selective pressure of S. pneumoniae serotypes. PspA is present in all pneumococcal strains, is highly immunogenic and is known to induce protective antibodies. Based on its sequence, PspA has been classified into 3 families and 6 clades. A PspA fragment derived from family 2 clade 4 (PspA4Pro) was shown to generate antibodies with a broad-range of cross-reactivity, across clades and families. Here, PspA4Pro was modified and conjugated to capsular polysaccharide serotype 14 (PS14). We investigated the impact of conjugation on the immune response induced to PspA4Pro and PS14. Mice immunized with the PS14-mPspA4Pro conjugate produced higher titers of anti-PS14 antibodies than the animals that received co-administered antigens. Both conjugated and co-administered PS14 and mPspA4Pro induced antibodies with opsonophagocytic activity against PS14-carrying strain as well as against a panel of strains bearing PspAs from five clades (encompassing families 1 and 2) bearing a non-PS14 serotype. Furthermore, mice immunized with PS14-mPspA4Pro were protected against nasal colonization with a non-related S. pneumoniae strain bearing PspA from clade 1, serotype 6B. These results demonstrate that the cross-reactivity mediated by PspA4Pro is retained following conjugation, supporting the use of PspA4 as a carrier protein in order to enhance pneumococcal vaccine coverage and encourage its further investigation as a candidate in future vaccine designs.

Copyright © 2017 American Society for Microbiology.

PMID: 28637805 DOI: 10.1128/CVI.00118-17

Increased Zinc Availability Enhances Initial Aggregation and Biofilm Formation of Streptococcus pneumoniae.

Front Cell Infect Microbiol. 2017 Jun 7;7:233. doi: 10.3389/fcimb.2017.00233. eCollection 2017.

Increased Zinc Availability Enhances Initial Aggregation and Biofilm Formation of Streptococcus pneumoniae.

Brown LR1, Caulkins RC1, Schartel TE1, Rosch JW2, Honsa ES2, Schultz-Cherry S2, Meliopoulos VA2, Cherry S2, Thornton JA1.

Author information


Bacteria growing within biofilms are protected from antibiotics and the immune system. Within these structures, horizontal transfer of genes encoding virulence factors, and promoting antibiotic resistance occurs, making biofilms an extremely important aspect of pneumococcal colonization and persistence. Identifying environmental cues that contribute to the formation of biofilms is critical to understanding pneumococcal colonization and infection. Iron has been shown to be essential for the formation of pneumococcal biofilms; however, the role of other physiologically important metals such as copper, zinc, and manganese has been largely neglected. In this study, we investigated the effect of metals on pneumococcal aggregation and early biofilm formation. Our results show that biofilms increase as zinc concentrations increase. The effect was found to be zinc-specific, as altering copper and manganese concentrations did not affect biofilm formation. Scanning electron microscopy analysis revealed structural differences between biofilms grown in varying concentrations of zinc. Analysis of biofilm formation in a mutant strain lacking the peroxide-generating enzyme pyruvate oxidase, SpxB, revealed that zinc does not protect against pneumococcal H2O2. Further, analysis of a mutant strain lacking the major autolysin, LytA, indicated the role of zinc as a negative regulator of LytA-dependent autolysis, which could affect biofilm formation. Additionally, analysis of cell-cell aggregation via plating and microscopy revealed that high concentrations of zinc contribute to intercellular interaction of pneumococci. The findings from this study demonstrate that metal availability contributes to the ability of pneumococci to form aggregates and subsequently, biofilms.


biofilms; cell-cell interactions; colonization; pneumococcus; zinc

PMID: 28638805 PMCID: PMC5461340 DOI: 10.3389/fcimb.2017.00233

Structure of the competence pilus major pilin ComGC in Streptococcus pneumoniae.

J Biol Chem. 2017 Jun 28. pii: jbc.M117.787671. doi: 10.1074/jbc.M117.787671. [Epub ahead of print]

Structure of the competence pilus major pilin ComGC in Streptococcus pneumoniae.

Muschiol S1, Erlendsson S2, Aschtgen MS1, Oliveira V1, Schmieder P3, de Lichtenberg C2, Teilum K2, Boesen T4, Akbey U4, Henriques-Normark B5.

Author information


Type IV pili are important virulence factors on the surface of many pathogenic bacteria and have been implicated in a wide range of diverse functions including attachment, twitching motility, biofilm formation and horizontal gene transfer. The respiratory pathogen Streptococcus pneumoniae deploys type IV pili to take up DNA during transformation. These "competence pili" are composed of the major pilin protein ComGC and exclusively assembled during bacterial competence, but their biogenesis remains unclear. Here, we report the high resolution NMR structure of N-terminal truncated ComGC revealing a highly flexible and structurally divergent type IV pilin. It consists of only three α-helical segments forming a well-defined electronegative cavity and confined electronegative and hydrophobic patches. The structure is particularly flexible between the first and second α-helix with the first helical part exhibiting slightly slower dynamics than the rest of the pilin, suggesting that the first helix is involved in forming the pilus structure core and that parts of helices two and three are primarily surface exposed. Taken together, our results provide the first structure of a type IV pilin protein involved in the formation of competence-induced pili in Gram-positive bacteria and corroborate the remarkable structural diversity among type IV pilin proteins.

Copyright © 2017, The American Society for Biochemistry and Molecular Biology.


Streptococcus pneumoniae; horizontal gene transfer; major pilin; microbiology; nuclear magnetic resonance (NMR); pneumococci; protein structure; transformation; type IV pili

PMID: 28659339 DOI: 10.1074/jbc.M117.787671

10-valent pneumococcal conjugate vaccine (PCV10) decreases metabolic activity but not nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae.

Vaccine. 2017 Jun 28. pii: S0264-410X(17)30841-1. doi: 10.1016/j.vaccine.2017.06.048. [Epub ahead of print]

10-valent pneumococcal conjugate vaccine (PCV10) decreases metabolic activity but not nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae.

Andrade DC1, Borges IC2, Bouzas ML2, Oliveira JR2, Fukutani KF3, Queiroz AT3, de Oliveira CI4, Barral A4, Van Weyenbergh J5, Nascimento-Carvalho C6.

Author information



The effect of pneumococcal vaccination is widely variable when measured by nasopharyngeal carriage of vaccine and non-vaccine targets. The aim of this study was to compare the carriage rates and metabolic activity of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae and Moraxella catarrhalis among children who were or were not vaccinated with PCV10.


We included children with acute respiratory infection aged 6-23months from a cross-sectional study (CHIADO-IVAS). Nasopharyngeal aspirates were collected and respiratory pathogens were quantified by nCounter digital transcriptomics (Nanostring) and metagenomic sequencing of 16S ribosomal RNA (Illumina). The metabolic rate was calculated by the ratio between RNA transcripts and 16S DNA reads.


Out of the 80 patients in this study, 53 were vaccinated with PCV10 and 27 were unvaccinated. There was no difference in nasopharyngeal carriage rates of S. pneumoniae, S. aureus, H. influenzae or M. catarrhalis by either transcriptomic analysis or 16S metagenomics. However, unvaccinated children presented a higher metabolic rate for S. pneumoniae compared to PCV10-vaccinated children (Median [25-75th percentiles]: 126 [22.75-218.41] vs. 0[0-47.83], p=0.004). Furthermore, unvaccinated children presented a positive correlation between mRNA counts and 16S DNA reads for S. pneumoniae (r=0.707; p<0.001) and H. influenzae (r=0.525; p=0.005), in contrast to vaccinated children. No such effect was observed for S. aureus and M. catarrhalis.


Vaccination by PCV10 exerts a pathogen-specific effect on pneumococcal metabolic rate. Pathogen RNA/DNA ratio might represent a more sensitive readout for vaccine follow-up, as compared to nasopharyngeal carriage.

Copyright © 2017 Elsevier Ltd. All rights reserved.


Capsular polysaccharides; Metabolism; Nasopharyngeal colonization; Protein D

PMID: 28668567 DOI: 10.1016/j.vaccine.2017.06.048

Phylogenetic analysis of emergent Streptococcus pneumoniae serotype 22F causing invasive pneumococcal disease using whole genome sequencing.

PLoS One. 2017 May 22;12(5):e0178040. doi: 10.1371/journal.pone.0178040. eCollection 2017.

Phylogenetic analysis of emergent Streptococcus pneumoniae serotype 22F causing invasive pneumococcal disease using whole genome sequencing.

Demczuk WHB1, Martin I1, Hoang L2, Van Caeseele P3, Lefebvre B4, Horsman G5, Haldane D6, Gubbay J7, Ratnam S8, German G9, Daley Bernier J10, Strudwick L11, McGeer A12, Zhanel GG13, Van Domselaar G1,14, Graham M1,14, Mulvey MR1.

Author information


Since implementation of the 13-valent polyvalent conjugate vaccine (PCV13) in Canada during 2010, the proportion of PCV13 serotypes causing invasive pneumococcal disease (IPD) has declined from 55% (n = 1492) in 2010 to 31% (n = 764) in 2014. A concurrent increase of non-PCV13 serotypes has occurred and 22F has become the most prevalent serotype in Canada increasing from 7% (n = 183) to 11% (n = 283). Core single nucleotide variant phylogenetic analysis was performed on 137 Streptococcus pneumoniae serotype 22F isolates collected across Canada from 2005-2015. Six phylogenetic lineages (n = 117) were identified among a serotype 22F/ST433 clonal complex (CC), including a recently expanding erythromycin-resistant clone. Erythromycin-resistance was observed in 25 isolates possessing ermB, mef or a 23S rRNA A2061G point mutation; 2 penicillin-resistant isolates had recombinant pbp1a, pbp2a and/or pbp2x; 3 tetracycline-resistant isolates contained tetM; and 1 isolate was multidrug-resistant. Virulence factor analysis indicated a high level of homogeneity among the 22F/ST433 clonal complex strains. A group of 6 phylogenetic outlier strains had differing MLST, antimicrobial resistance and molecular profiles suggestive of capsule switching events. While capsule switch events among S. pneumoniae serotype 22F has been observed, increasing prevalence of S. pneumoniae serotype 22F can be attributed to an evolving homogenous clone expanding nationally through local transmission events.

PMID: 28531208 PMCID: PMC5439729 DOI: 10.1371/journal.pone.0178040

Clinically Relevant Detection of Streptococcus pneumoniae with DNA-Antibody Nanostructures.

Anal Chem. 2017 Jun 20;89(12):6900-6906. doi: 10.1021/acs.analchem.7b01508. Epub 2017 Jun 8.

Clinically Relevant Detection of Streptococcus pneumoniae with DNA-Antibody Nanostructures.

Wang J1, Leong MC1, Leong EZW1, Kuan WS2,3, Leong DT1.

Author information


Streptococcus pneumoniae (SP) is a pathogenic bacterium and a major cause of community-acquired pneumonia that could be fatal if left untreated. Therefore, rapid and sensitive detection of SP is crucial to enable targeted treatment during SP infections. In this study, DNA tetrahedron (DNA TH) with a hollow structure is anchored on gold electrodes to construct an electrochemical immunosensor for rapid detection of pneumococcal surface protein A (PspA) peptide and SP lysate from synthetic and actual human samples. This DNA nanostructure-based immunosensor displays excellent electrochemical activity toward PspA with a sensitive linear region from 0 to 8 ng/mL of PspA peptide and a low limit of detection (LOD) of 0.218 ng/mL. In addition, this DNA-TH-based immunosensor exhibits good sensing performance toward SP lysate in a clinically relevant linear range from 5 to 100 CFU/mL with a LOD of 0.093 CFU/mL. Along with these attractive features, this electrochemical immunosensor is able to specifically recognize and detect the PspA peptide mixed with other physiologically relevant components like bovine serum albumin (BSA) and lipopolysaccharide. In addition, our sensor could detect SP lysate even when dispersed in BSA or Escherichia coli lysate. Lastly, uncultured samples from the nasal cavity, mouth, and axilla of a human subject could be successfully determined by this well-designed electrochemical immunosensor.

PMID: 28548485 DOI: 10.1021/acs.analchem.7b01508

Proteomic comparisons of opaque and transparent variants of Streptococcus pneumoniae by two dimensional-differential gel electrophoresis.

Sci Rep. 2017 May 26;7(1):2453. doi: 10.1038/s41598-017-02465-x.

Proteomic comparisons of opaque and transparent variants of Streptococcus pneumoniae by two dimensional-differential gel electrophoresis.

Chai MH1, Weiland F2,3,4, Harvey RM1, Hoffmann P2,3, Ogunniyi AD5,6, Paton JC1.

Author information


Streptococcus pneumoniae (the pneumococcus) is a human pathogen, accounting for massive global morbidity and mortality. Although asymptomatic colonization of the nasopharynx almost invariably precedes disease, the critical determinants enabling pneumococcal progression from this niche to cause invasive disease are poorly understood. One mechanism proposed to be central to this transition involves opacity phase variation, whereby pneumococci harvested from the nasopharynx are typically transparent, while those simultaneously harvested from the blood are opaque. Here, we used two dimensional-differential gel electrophoresis (2D-DIGE) to compare protein expression profiles of transparent and opaque variants of 3 pneumococcal strains, D39 (serotype 2), WCH43 (serotype 4) and WCH16 (serotype 6A) in vitro. One spot comprising a mixture of capsular polysaccharide biosynthesis protein and other proteins was significantly up-regulated in the opaque phenotype in all 3 strains; other proteins were differentially regulated in a strain-specific manner. We conclude that pneumococcal phase variation is a complex and multifactorial process leading to strain-specific pathogenicity.

PMID: 28550292 PMCID: PMC5446427 DOI: 10.1038/s41598-017-02465-x

T Cell-Mediated Humoral Immune Responses to Type 3 Capsular Polysaccharide of Streptococcus pneumoniae.

J Immunol. 2017 May 31. pii: 1700026. doi: 10.4049/jimmunol.1700026. [Epub ahead of print]

T Cell-Mediated Humoral Immune Responses to Type 3 Capsular Polysaccharide of Streptococcus pneumoniae.

Middleton DR1, Sun L1, Paschall AV1, Avci FY2.

Author information


Most pathogenic bacteria express surface carbohydrates called capsular polysaccharides (CPSs). CPSs are important vaccine targets because they are easily accessible and recognizable by the immune system. However, CPS-specific adaptive humoral immune responses can only be achieved by the covalent conjugation of CPSs with carrier proteins to produce glycoconjugate vaccines. We previously described a mechanism by which a model glycoconjugate vaccine can activate the adaptive immune system and demonstrated that the mammalian CD4+ T cell repertoire contains a population of carbohydrate-specific T cells. In this study, we use glycoconjugates of type 3 Streptococcus pneumoniae CPS (Pn3P) to assess whether the carbohydrate-specific adaptive immune response exemplified in our previous study can be applied to the conjugates of this lethal pathogen. In this article, we provide evidence for the functional roles of Pn3P-specific CD4+ T cells utilizing mouse immunization schemes that induce Pn3P-specific IgG responses in a carbohydrate-specific T cell-dependent manner.

Copyright © 2017 by The American Association of Immunologists, Inc.

PMID: 28566369 DOI: 10.4049/jimmunol.1700026

An evolutionary model to predict the frequency of antibiotic resistance under seasonal antibiotic use, and an application to Streptococcus pneumoniae.

Proc Biol Sci. 2017 May 31;284(1855). pii: 20170679. doi: 10.1098/rspb.2017.0679.

An evolutionary model to predict the frequency of antibiotic resistance under seasonal antibiotic use, and an application to Streptococcus pneumoniae.

Blanquart F1, Lehtinen S2,3, Fraser C2,3.

Author information


The frequency of resistance to antibiotics in Streptococcus pneumoniae has been stable over recent decades. For example, penicillin non-susceptibility in Europe has fluctuated between 12% and 16% without any major time trend. In spite of long-term stability, resistance fluctuates over short time scales, presumably in part due to seasonal fluctuations in antibiotic prescriptions. Here, we develop a model that describes the evolution of antibiotic resistance under selection by multiple antibiotics prescribed at seasonally changing rates. This model was inspired by, and fitted to, published data on monthly antibiotics prescriptions and frequency of resistance in two communities in Israel over 5 years. Seasonal fluctuations in antibiotic usage translate into small fluctuations of the frequency of resistance around the average value. We describe these dynamics using a perturbation approach that encapsulates all ecological and evolutionary forces into a generic model, whose parameters quantify a force stabilizing the frequency of resistance around the equilibrium and the sensitivity of the population to antibiotic selection. Fitting the model to the data revealed a strong stabilizing force, typically two to five times stronger than direct selection due to antibiotics. The strong stabilizing force explains that resistance fluctuates in phase with usage, as antibiotic selection alone would result in resistance fluctuating behind usage with a lag of three months when antibiotic use is seasonal. While most antibiotics selected for increased resistance, intriguingly, cephalosporins selected for decreased resistance to penicillins and macrolides, an effect consistent in the two communities. One extra monthly prescription of cephalosporins per 1000 children decreased the frequency of penicillin-resistant strains by 1.7%. This model emerges under minimal assumptions, quantifies the forces acting on resistance and explains up to 43% of the temporal variation in resistance.

© 2017 The Authors.


adaptation; antimicrobial resistance; balancing selection; drug resistance; fluctuating selection; microbiology

PMID: 28566489 PMCID: PMC5454275 DOI: 10.1098/rspb.2017.0679