scholarly journals Pangenome analysis and virulence profiling of Streptococcus intermedius

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Dhiraj Sinha ◽  
Xifeng Sun ◽  
Mudra Khare ◽  
Michel Drancourt ◽  
Didier Raoult ◽  
...  
Keyword(s):  
Brain Abscess ◽  
Pulmonary Infection ◽  
Virulence Genes ◽  
Capsular Polysaccharide ◽  
Clinical Manifestations ◽  
Principal Component ◽  
Genomic Diversity ◽  
Abdominal Abscess ◽  
Streptococcus Intermedius ◽  
Polysaccharide Biosynthesis

Abstract Background Streptococcus intermedius, a member of the S. anginosus group, is a commensal bacterium present in the normal microbiota of human mucosal surfaces of the oral, gastrointestinal, and urogenital tracts. However, it has been associated with various infections such as liver and brain abscesses, bacteremia, osteo-articular infections, and endocarditis. Since 2005, high throughput genome sequencing methods enabled understanding the genetic landscape and diversity of bacteria as well as their pathogenic role. Here, in order to determine whether specific virulence genes could be related to specific clinical manifestations, we compared the genomes from 27 S. intermedius strains isolated from patients with various types of infections, including 13 that were sequenced in our institute and 14 available in GenBank. Results We estimated the theoretical pangenome size to be of 4,020 genes, including 1,355 core genes, 1,054 strain-specific genes and 1,611 accessory genes shared by 2 or more strains. The pangenome analysis demonstrated that the genomic diversity of S. intermedius represents an “open” pangenome model. We identified a core virulome of 70 genes and 78 unique virulence markers. The phylogenetic clusters based upon core-genome sequences and SNPs were independent from disease types and sample sources. However, using Principal Component analysis based on presence/ absence of virulence genes, we identified the sda histidine kinase, adhesion protein LAP and capsular polysaccharide biosynthesis protein cps4E as being associated to brain abscess or broncho-pulmonary infection. In contrast, liver and abdominal abscess were associated to presence of the fibronectin binding protein fbp54 and capsular polysaccharide biosynthesis protein cap8D and cpsB. Conclusions Based on the virulence gene content of 27 S. intermedius strains causing various diseases, we identified putative disease-specific genetic profiles discriminating those causing brain abscess or broncho-pulmonary infection from those causing liver and abdominal abscess. These results provide an insight into S. intermedius pathogenesis and highlights putative targets in a diagnostic perspective.

scholarly journals Mutational analysis of genes implicated in LPS and capsular polysaccharide biosynthesis in the opportunistic pathogen Bacteroides fragilis

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1039-1049 ◽  
Author(s):  
Sheila Patrick ◽  
Simon Houston ◽  
Zubin Thacker ◽  
Garry W. Blakely
Keyword(s):  
Capsular Polysaccharide ◽  
Mutational Analysis ◽  
Bacteroides Fragilis ◽  
Gene Clusters ◽  
Opportunistic Pathogen ◽  
Extracellular Polysaccharides ◽  
Phase Variable ◽  
Multiple Gene ◽  
Polysaccharide Biosynthesis ◽  
Group 1

The obligate anaerobe Bacteroides fragilis is a normal resident of the human gastrointestinal tract. The clinically derived B. fragilis strain NCTC 9343 produces an extensive array of extracellular polysaccharides (EPS), including antigenically distinct large, small and micro- capsules. The genome of NCTC 9343 encodes multiple gene clusters potentially involved in the biosynthesis of EPS, eight of which are implicated in production of the antigenically variable micro-capsule. We have developed a rapid and robust method for generating marked and markerless deletions, together with efficient electroporation using unmodified plasmid DNA to enable complementation of mutations. We show that deletion of a putative wzz homologue prevents production of high-molecular-mass polysaccharides (HMMPS), which form the micro-capsule. This observation suggests that micro-capsule HMMPS constitute the distal component of LPS in B. fragilis. The long chain length of this polysaccharide is strikingly different from classical enteric O-antigen, which consists of short-chain polysaccharides. We also demonstrate that deletion of a putative wbaP homologue prevents expression of the phase-variable large capsule and that expression can be restored by complementation. This suggests that synthesis of the large capsule is mechanistically equivalent to production of Escherichia coli group 1 and 4 capsules.

scholarly journals Non-tuberculous Mycobacterium Disease: Radiologic Manifestation in an Infant presenting with Respiratory Distress

2017 ◽  
Vol 5 (1-2) ◽  
pp. 13-20
Author(s):  
Rupesh Gautam ◽  
Maria Isabel Atienza ◽  
Maika Noda ◽  
Mariaem Andres
Keyword(s):  
Hypersensitivity Pneumonitis ◽  
Pulmonary Infection ◽  
Clinical Manifestations ◽  
Distinct Group ◽  
Middle Lobe ◽  
Air Trapping ◽  
Pulmonary Tb ◽  
Radiologic Findings ◽  
The Common ◽  
Common Manifestation

Non-tuberculous mycobacterium (NTM) comprises distinct group of organisms with lymphadenitis and pulmonary infection as the common manifestation. The diagnosis of pulmonary disease is based on clinical manifestations, radiologic findings and microbiologic culture. The classic NTM infection may be indistinguishable from pulmonary TB. Non-classic infection has predilection to the middle lobe and lingula unlike tuberculosis which is commonly seen in the upper lobes. The disease may also present as hypersensitivity pneumonitis with ground glass like opacities, centrilobular nodules and air trapping on imaging. The knowledge of imaging manifestations of NTM will aid in timely diagnosis and treatment of the disease.Nepal Journal of Radiology Vol.5(1-2) 2015: 13-20

scholarly journals Identification and Characterization of thecps Locus of Streptococcus suis Serotype 2: the Capsule Protects against Phagocytosis and Is an Important Virulence Factor

1999 ◽  
Vol 67 (4) ◽  
pp. 1750-1756 ◽  
Author(s):  
Hilde E. Smith ◽  
Marloes Damman ◽  
Joeke van der Velde ◽  
Frans Wagenaar ◽  
Henk J. Wisselink ◽  
...  
Keyword(s):  
Insertional Mutagenesis ◽  
Capsular Polysaccharide ◽  
Streptococcus Suis ◽  
Open Reading Frames ◽  
Transcriptional Unit ◽  
Polysaccharide Biosynthesis ◽  
Capsule Production ◽  
Important Virulence Factor ◽  
Isogenic Mutants

ABSTRACT To study the role of the capsule of Streptococcus suisserotype 2 in virulence, we generated two isogenic mutants disturbed in capsule production. For that purpose, we first cloned and characterized a major part of the capsular polysaccharide biosynthesis (cps) locus of S. suis serotype 2. Based on the established sequence, 14 open reading frames (ORFs), designated Orf2Z, Orf2Y, Orf2X, and Cps2A to Cps2K, were identified. Twelve ORFs belonged to a single transcriptional unit. The gene products of 11 of these ORFs showed similarity to proteins involved in polysaccharide biosynthesis of other gram-positive microorganisms. Nonencapsulated isogenic mutants were generated in the cps2B and cps2EF genes by insertional mutagenesis. In contrast to the wild-type S. suis serotype 2 strain, the nonencapsulated strains were highly sensitive to ingestion by porcine alveolar lung macrophages in vitro. More importantly, the nonencapsulated mutant strains were completely avirulent in young germfree pigs after intranasal inoculation. These observations indicate that the capsule of S. suis serotype 2 plays an essential role in the pathogenesis of S. suisserotype 2 infections.

scholarly journals An uncommon brain abscess caused by Streptococcus intermedius due to periodontal inflammation

2017 ◽  
Vol 18 (4) ◽  
pp. 254-257
Author(s):  
Vladimír Mihál ◽  
Marta Neklanová ◽  
Eva Klásková ◽  
David Krahulík ◽  
Kamila Michálková
Keyword(s):  
Brain Abscess ◽  
Streptococcus Intermedius ◽  
Periodontal Inflammation

Brain and Spinal Abscesses

2017 ◽  
Author(s):  
Allan R Tunkel ◽  
W Michael Scheld
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Brain Abscess ◽  
Antimicrobial Therapy ◽  
Epidural Abscess ◽  
Clinical Manifestations ◽  
Spinal Epidural Abscess ◽  
Diffusion Weighted Images ◽  
Optimal Approach ◽  
Spinal Cord Dysfunction

Brain and spinal abscesses are focal infections of the central nervous system that are often associated with significant morbidity and mortality if not recognized early and managed in a timely manner. In patients with brain abscess, the clinical manifestations run the gamut from indolent to fulminant; most are related to the size and location of the space-occupying lesion within the brain and the virulence of the infecting organism. Untreated spinal epidural abscess usually progresses through four stages: backache and focal vertebral pain, nerve root pain, spinal cord dysfunction, and complete paralysis. Magnetic resonance imaging is the diagnostic neuroimaging procedure of choice in patients with brain and spinal abscesses; on diffusion-weighted images, restricted diffusion may be seen and may help distinguish abscesses from necrotic neoplasms. Aspiration of the abscess is important to facilitate microbiologic diagnosis; after aspiration and submission of specimens for special stains, histopathologic examination, and culture, empirical antimicrobial therapy should be initiated based on stains of the aspirated specimen and the probable pathogenesis of infection. Once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Surgical therapy is often required for the optimal approach to patients with brain and spinal abscesses. This review contains 6 figures, 5 tables, and 72 references. Key words: antimicrobial therapy for central nervous system infections, brain abscess, epidural abscess, focal intracranial infections, head trauma, infections in immunocompromised hosts, spine infections, subdural empyema, toxoplasmosis 

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