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Importantly, Streptococcus agalactiae is the most common cause of meningitis in infants from one month to three months old. They can also colonize the intestines and the female reproductive tract, increasing the risk for premature rupture of membranes during pregnancy, and transmission of the organism to the infant.
However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen as well. Group A streptococci, when grown on blood agar, typically produce small (2–3 mm) zones of beta-hemolysis, a complete destruction of red blood cells. The name group A (beta-hemolytic) Streptococcus is thus also used. [1]
Group A β-hemolytic streptococcus can cause infections of the throat and skin. [6] These may vary from very mild conditions to severe, life-threatening diseases. Although it is not completely clear what causes different people to develop different diseases as a result of infection with the same pathogenic bacteria , it is suspected that host ...
Strep throat is caused by the bacteria Streptococcus pyogenes, or group A streptococcus. "These bacteria are contagious and can be spread through droplets when someone coughs or sneezes or through ...
Streptococcosis can start occurring due to a weak immune system, or by having bacteria enter wounds. [1] Spreading of Streptococcus is often sporadic, [4] and can be done through direct contact (may be done through materials that are likely to carry infection), air transport or (rarely) ingestion. [1]
Streptococcus salivarius is a species of spherical, gram-positive, facultative anaerobic lactic acid bacteria [1] that is both catalase and oxidase negative. S. salivarius colonizes (usually in chains) the oral cavity and upper respiratory tract of humans just a few hours after birth, making further exposure to the bacteria harmless in most circumstances.
Once pathogens attach to host cells, they can cause direct damage as the pathogens use the host cell for nutrients and produce waste products. [23] For example, Streptococcus mutans, a component of dental plaque, metabolizes dietary sugar and produces acid as a waste product. The acid decalcifies the tooth surface to cause dental caries. [24]
Some bacteria, such as Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa, produce a variety of enzymes which cause damage to host tissues.Enzymes include hyaluronidase, which breaks down the connective tissue component hyaluronic acid; a range of proteases and lipases; DNases, which break down DNA, and hemolysins which break down a variety of host cells, including red ...