|
''Staphylococcus aureus'' is a gram-positive coccal bacterium that is a member of the Firmicutes, and is frequently found in the respiratory tract and on the skin forms where perspiration is present. It is often positive for catalase and nitrate reduction. Although ''S. aureus'' is not always pathogenic, it is a common cause of skin infections such as abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing potent protein toxins, and expressing cell-surface proteins that bind and inactivate antibodies. The emergence of antibiotic-resistant forms of ''S. aureus'' such as MRSA is a worldwide problem in clinical medicine. ''Staphylococcus'' was first identified in 1880 in Aberdeen, Scotland, by the surgeon Sir Alexander Ogston in pus from a surgical abscess in a knee joint. This name was later appended to ''Staphylococcus aureus'' by Friedrich Julius Rosenbach, who was credited by the official system of nomenclature at the time. An estimated 20% of the human population are long-term carriers of ''S. aureus'' which can be found as part of the normal skin flora and in the nostrils.〔 ''S. aureus'' is the most common species of ''Staphylococcus'' to cause ''Staph'' infections and is a successful pathogen due to a combination of nasal carriage and bacterial immunoevasive strategies.〔〔 ''S. aureus'' can cause a range of illnesses, from minor skin infections, such as pimples, impetigo, boils, cellulitis, folliculitis, carbuncles, scalded skin syndrome, and abscesses, to life-threatening diseases such as pneumonia, meningitis, osteomyelitis, endocarditis, toxic shock syndrome, bacteremia, and sepsis. Its incidence ranges from skin, soft tissue, respiratory, bone, joint, endovascular to wound infections. It is still one of the five most common causes of hospital-acquired infections and is often the cause of postsurgical wound infections. Each year, around 500,000 patients in United States' hospitals contract a staphylococcal infection like S. aureus. == Microbiology == ''S. aureus'' (, Greek σταφυλόκοκκος, "grape-cluster berry", Latin ''aureus'', "golden") is a facultative anaerobic, gram-positive coccal bacterium also known as "golden staph" and Oro staphira. In medical literature, the bacterium is often referred to as ''S. aureus'' or ''Staph aureus''. ''Staphylococcus'' should not be confused with the similarly named and medically relevant genus ''Streptococcus''. ''S. aureus'' appears as grape-like clusters when viewed through a microscope, and has large, round, golden-yellow colonies, often with hemolysis, when grown on blood agar plates. ''S. aureus'' reproduces asexually by binary fission. The two daughter cells do not fully separate and remain attached to one another, so the cells are observed in clusters.〔"(''Staphylococcus aureus'': Reproduction )". palexander13.webs.com.〕 ''S. aureus'' is catalase-positive (meaning it can produce the enzyme catalase). Catalase converts hydrogen peroxide () to water and oxygen. Catalase-activity tests are sometimes used to distinguish staphylococci from enterococci and streptococci. Previously, ''S. aureus'' was differentiated from other staphylococci by the coagulase test. However, not all ''S. aureus'' strains are coagulase-positive〔〔PreTest, Surgery, 12th ed., p.88〕 and incorrect species identification can impact effective treatment and control measures. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「staphylococcus aureus」の詳細全文を読む スポンサード リンク
|