Search results
8 sie 2023 · Streptococcus pneumoniae is a gram-positive, lancet-shaped bacterium and a cause of community-acquired pneumonia. Pneumococcal infections are present throughout the world and are most prevalent during the winter and early spring months.
The encapsulated, Gram-positive, coccoid bacteria have a distinctive morphology on Gram stain, lancet -shaped diplococci. They have a polysaccharide capsule that acts as a virulence factor for the organism; more than 100 different serotypes are known, and these types differ in virulence, prevalence, and extent of drug resistance.
Streptococcus pneumoniae in clinical material occurs in two distinctive forms. Encapsulated, virulent strains isolated e.g., from sputum in patients with acute pneumonia, often forming highly mucoid, glistening colonies (production of capsular polysaccharide) surrounded by a zone of alpha-hemolysis. After prolonged cultivation (48 hours in an ...
Inactivation of the pce gene in S. pneumoniae strains by insertion-duplication mutagenesis caused a unique change in colony morphology and a striking increase in the virulence of a capsular type III strain in the intraperitoneal mouse model.
Streptococci often have a mucoid or smooth colonial morphology, and S pneumoniae colonies exhibit a central depression caused by rapid partial autolysis. As S pneumoniae colonies age, viability is lost during fermentative growth in the absence of catalase and peroxidase because of the accumulation of peroxide.
29 mar 2018 · Streptococcus pneumoniae (also known as pneumococcus) is a Gram-positive, extracellular, opportunistic pathogen that colonizes the mucosal surfaces of the human upper respiratory tract (URT).
13 maj 2016 · Streptococcus pneumoniae is characterized by a polysaccharide capsule that completely encloses the cell, and plays a key role in its virulence. The cell wall of S. pneumoniae is composed of peptidoglycan, with teichoic acid attached to every third N-acetylmuramic acid, and is about 6 layers thick.
