Staph Aureus

Student Name: Hassan Mohammad Al-Shehri

ID#2051040006

Staphylococcus Aureus Staphylococcus aureus is a spherical bacterium. It is a Gram-positive coccus, which appears as grape-like clusters when viewed through a microscope and has largened, round, golden-yellow colonies, often with β-hemolysis, when grown on blood agar plates. Frequently living on the skin or in the nose of a healthy person, that can cause a range of illnesses from minor skin infections and abscesses, to life-threatening diseases such as pneumonia, meningitis, endocarditis, Toxic shock syndrome (TSS), and septicemia. S. aureus is catalase & coagulase positive Penicillin resistance Staphylococcal resistance to penicillin is mediated by penicillinase (a form of βlactamase). Today, S. aureus has become resistant to many commonly used antibiotics. In the UK, only 2% of all S. aureus isolates are sensitive to penicillin with a similar picture in the rest of the world. The Methicillin was the first antibiotic in this class to be used (it was introduced in 1959), but only two years later, the first case of Methicillin-resistant S. aureus (MRSA) was reported in England Treatment of penicillin resistance S.aureus MRSA are commonly treated with non-β-lactam antibiotics such as clindamycin trimethoprim/sulfamethoxazole. Resistance to these antibiotics has also lead to the use of new, broad-spectrum anti-Gram positive antibiotics such as linezolid. First-line treatment for serious invasive infections due to MRSA is currently glycopeptide antibiotics (vancomycin and teicoplanin). Vancomycin-resistant S. aureus (VRSA) is a strain of S. aureus that has become resistant to the glycopeptides. Role in disease S. aureus may occur as a commensal on human skin (particularly the scalp, armpits and groins); it also occurs in the nose (in about 25% of the population). The finding of Staph. aureus under these circumstances does not always indicate infection and therefore does not always require treatment. S. aureus can infect other tissues when normal barriers have been breached (e.g. skin or mucosal lining). This leads to furuncles (boils) and carbuncles (a collection of furuncles). In infants S. aureus infection can cause a severe disease Staphylococcal scalded skin syndrome (SSSS). Transmission S. aureus infections can be spread through contact with pus from an infected wound, skin-to-skin contact with an infected person, and contact with objects such as towels, sheets, clothing, or athletic equipment used by an infected person.