What is the cell arrangement of Streptococcus pneumoniae?
What is the cell arrangement of Streptococcus pneumoniae?
Streptococcus pneumoniae bacteria are gram-positive cocci arranged in chains and pairs (diplococci) on microscopic examination. A green, α-hemolytic, zone surrounds S. pneumoniae colonies on blood-agar plates.
What is unique about Streptococcus pneumoniae?
Streptococcus pneumoniae are lancet-shaped, gram-positive, facultative anaerobic bacteria with more than 100 known serotypes. Most S. pneumoniae serotypes can cause disease, but only a minority of serotypes produce the majority of pneumococcal infections.
What causes pathogenesis in Streptococcus pneumoniae?
5. Pneumococcal surface proteins: S. pneumoniae has a large variety of surface-exposed proteins (17, 72) that aid in its pathogenesis by acting as adhesins to host cells and hindering the host’s immune system, specifically the complement system (22, 27, 51, 145, 146).
What is Streptococcus pneumoniae cell wall made of?
The complex and heterogeneous cell wall of the pathogenic bacterium Streptococcus pneumoniae is composed of peptidoglycan and a covalently attached wall teichoic acid. The net-like peptidoglycan is formed by glycan chains that are crosslinked by short peptides.
What is the morphology of Streptococcus?
Morphology: Spherical, ovoid, or cocci shaped. Often occur in pairs or chains when grown in liquid media.
Is Streptococcus pneumoniae Group A or B?
Group B (GBS) streptococcal pneumonia is the most common type of pneumonia in neonates. The infection is acquired during birth, and at least 25% of women in labor are colonized by the organism.
What is the morphology of Streptococcus pneumoniae?
Streptococcus pneumoniae cells are Gram-positive, lancet-shaped cocci (elongated cocci with a slightly pointed outer curvature). Usually, they are seen as pairs of cocci (diplococci), but they may also occur singly and in short chains.
What is the major virulence factor of Streptococcus pneumoniae?
Capsule The polysaccharide capsule
Capsule. The polysaccharide capsule is probably the most important virulence factor of the pneumococcus.
How does Streptococcus pneumoniae damage host cells?
Streptococcus pneumoniae produces pneumolysin toxin as a key virulence factor against host cells. Pneumolysin is a cholesterol-dependent cytolysin (CDC) toxin that forms lytic pores in host membranes and mediates pneumococcal disease pathogenesis by modulating inflammatory responses.
What is pathogenesis of pneumonia?
PATHOGENESIS. Pneumonia indicates an inflammatory process of the lung parenchyma caused by a microbial agent. The most common pathway for the microbial agent to reach the alveoli is by microaspiration of oropharyngeal secretions.
What is the cellular structure of pneumonia?
CDC. The cell wall of S. pneumoniae is roughly six layers thick and is composed of peptidoglycan with teichoic acid attached to approximately every third N-acetylmuramic acid. Lipoteichoic acid is chemically identical to the teichoic acid but is attached to the cell membrane by a lipid moiety.
What is the cell structure of strep bacteria?
Structure. Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains. Older cultures may lose their Gram-positive character. Most streptococci are facultative anaerobes, and some are obligate (strict) anaerobes.
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