What are the virulence factors of Streptococcus pneumoniae?
Important pneumococcal virulence factors include: the capsule; the cell wall; choline-binding proteins; pneumococcal surface proteins A and C (PspA and PspC); the LPXTG-anchored neuraminidase proteins; hyaluronate lyase (Hyl); pneumococcal adhesion and virulence A (PavA); enolase (Eno); pneumolysin; autolysin A (LytA); …
What is Streptococcus pneumoniae function?
Streptococcus pneumoniae is an infectious pathogen responsible for millions of deaths worldwide. Diseases caused by this bacterium are classified as pneumococcal diseases. This pathogen colonizes the nasopharynx of its host asymptomatically, but overtime can migrate to sterile tissues and organs and cause infections.
What virulence factor in Streptococcus pneumoniae makes the disease more severe in the host?
pneumoniae’s extracellular polysaccharide capsule, the most important virulence factor (55), helps to initiate infection by allowing the bacterium to adhere to host cells and cause inflammation, while also providing protection from the host’s immune system (54, 55).
What are the major virulence factors of Streptococcus pneumoniae and Streptococcus pyogenes?
Virulence factors include enzymes and exotoxins such as streptolysins (haemolysins), hyaluronidase, DNase, streptokinase and proteases. Polysaccharide capsules, which are major virulence factors of S. pyogenes, S. pneumoniae and most strains of S.
What are examples of virulence factors?
Factors that are produced by a microorganism and evoke disease are called virulence factors. Examples are toxins, surface coats that inhibit phagocytosis, and surface receptors that bind to host cells.
What are the characteristics of Streptococcus pneumoniae?
Streptococcus pneumoniae is a gram-positive, α-hemolytic, lancet-shaped diplococcus and is bile soluble and optochin sensitive. Streptococcus pneumoniae is catalase-negative but produces hydrogen peroxide.
Where does Streptococcus pneumoniae live in the body?
Streptococcus pneumoniae is a bacterium commonly found in the nose and throat. The bacterium can sometimes cause severe illness in children, the elderly and other people with weakened immune systems.
How does the body fight off Streptococcus pneumoniae?
Streptococcus pneumoniae has been shown to activate phagocytic cells and then be destroyed through different mechanisms involving TLRs, subsequently inducing B cells to produce cytokines including TNF-α, IL-6, and pro-IL-1β [30-35].
What antibiotic treats pneumococcal pneumonia?
Thus, based on current levels of resistance to penicillin and cephalosporin, most patients with mild/moderate pneumococcal pneumonia may respond to oral amoxicillin, and most with severe pneumonia may be successfully treated with intravenous ceftriaxone, cefotaxime, or amoxicillin-clavulanic acid.
How do you determine virulence factors?
Bacterial virulence factors in genomes may be identified by homology search with known virulence genes [17], by comparing strains with various levels of virulence [18], or by analysis of horizontally acquired genes [19].
What is the significance of virulence?
Virulence is defined by the ability of a microorganism to cause disease in the host. Food can carry microorganisms that are virulent and are able to cause disease in the individuals who consume the food.
Streptococcus pneumoniae is a major pathogen of humans, causing diseases such as pneumonia and meningitis. The organism produces several virulence factors that are involved in the disease process. The molecular basis of the action of some of these virulence factors is being elucidated.
What is the role of virulence factors in disease?
The role played by virulence factors in disease has been partly elucidated. It is clear from analysis of the increasing number of whole genome sequences that strains of pneumococci differ in their ability to produce virulence factors.
How does the capsule of Streptococcus pneumoniae protect the cell?
The presence of the capsule prevents iC3b and the Fc of immunoglobulins on the bacterial cell surface from interacting with their receptors on the surface of phagocytic cells, with the result that the organisms remain extracellular [ Infections caused by Streptococcus pneumoniae: clinical spectrum, pathogenesis, immunity, and treatment.
How many pneumococcal infections does S.pneumoniae cause?
S. pneumoniae causes about 40,000 fatal pneumococcal infections per year within the US ( 23, 32, 45, 46 ). S. pneumoniae colonizes the upper respiratory tract—specifically the nasopharynx ( 9, 47 ), and is able to asymptomatically reside in the upper respiratory tract—this is known as carriage ( 9 ).