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Related Concept Videos

Atypical Pneumonia01:14

Atypical Pneumonia

Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease include...
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Conjugated Proteins

Simple proteins and protein complexes contain only amino acids. In contrast, many other proteins, called conjugated proteins, covalently bond with non-protein moieties.
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Streptococcal Pharyngitis

Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
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Pneumonia I: Introduction

Pneumonia is an infection of the lower respiratory tract that leads to inflammation of the lung parenchyma, often resulting in the accumulation of inflammatory exudate in the alveoli and airways. Unlike the watery, low-protein fluid exudate in pulmonary edema, the exudate in this case is a thick fluid rich in immune cells, proteins, and debris produced during infection and inflammation.This impairs gas exchange and can lead to consolidation of lung tissue. The infection may be caused by a...
Bacterial Meningitis II: Pathophysiology01:26

Bacterial Meningitis II: Pathophysiology

Bacterial meningitis typically begins when pathogens such as Neisseria meningitidis and Streptococcus pneumoniae colonize the nasopharynx and invade the bloodstream. This process is facilitated by bacterial virulence factors, such as polysaccharide capsules, which resist phagocytosis and complement-mediated killing. Less commonly, bacteria reach the central nervous system via contiguous spread from infections like otitis media or sinusitis, through congenital or acquired dural defects, or...
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Formation of Lipopolysaccharides

Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin, triggering...

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Updated: Jun 22, 2026

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
09:11

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Published on: September 25, 2014

Pneumococcal capsular polysaccharide structure predicts serotype prevalence.

Daniel M Weinberger1, Krzysztof Trzciński, Ying-Jie Lu

  • 1Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA.

Plos Pathogens
|June 13, 2009
PubMed
Summary
This summary is machine-generated.

Capsular polysaccharide structure influences Streptococcus pneumoniae carriage. More prevalent serotypes are more encapsulated and resistant to neutrophil killing, linked to biochemical properties, potentially predicting serotype replacement.

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Last Updated: Jun 22, 2026

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
09:11

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Published on: September 25, 2014

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
04:25

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Published on: February 24, 2014

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
06:06

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43

Published on: September 11, 2020

Area of Science:

  • Microbiology
  • Immunology
  • Biochemistry

Background:

  • * Streptococcus pneumoniae has 91 known capsular serotypes.
  • * Factors influencing nasopharyngeal carriage prevalence and serotype stability are poorly understood.
  • * Understanding these factors is crucial for predicting serotype replacement post-vaccination.

Purpose of the Study:

  • * To investigate if capsular polysaccharide biochemical structure affects encapsulation, neutrophil killing resistance, and carriage success.
  • * To identify biological differences explaining epidemiological patterns of Streptococcus pneumoniae serotypes.
  • * To explore the relationship between polysaccharide structure and serotype replacement.

Main Methods:

  • * In vitro assays using isogenic capsule-switch variants and clinical carriage isolates.
  • * Measurement of encapsulation degree using FITC-dextran exclusion.
  • * Assessment of resistance to non-opsonic neutrophil-mediated killing.

Main Results:

  • * Increased carriage prevalence associated with resistance to neutrophil-mediated killing.
  • * Highly encapsulated serotypes showed greater resistance to neutrophil killing.
  • * Polysaccharide structure (fewer carbons/repeat unit, low energy/repeat unit) linked to increased prevalence of non-vaccine serotypes in vaccinated populations.

Conclusions:

  • * Capsular polysaccharide biochemistry directly impacts Streptococcus pneumoniae encapsulation and neutrophil resistance.
  • * These phenotypes correlate with nasopharyngeal carriage prevalence and serotype replacement patterns.
  • * Polysaccharide structure offers a potential method for predicting serotype replacement.