How does staphylococcus aureus cause disease

Abscess Pocket of infection that forms at the site of injury. Usually filled with pus. Area surrounding the abscess is usually red, painful and swollen and the skin surrounding the abscess can feel warm to the touch.

Cellulitis An infection of the underlying layers of the skin. Usually results from a scrape or cut in the skin which allows bacteria to enter, although no injury may be apparent.

Cellulitis can occur anywhere in the body, but most often occurs on the legs or arms. Symptoms include redness, swelling, and pain at the site of infection. Most of the time, these bacteria cause no problems or result in relatively minor skin infections.

But staph infections can turn deadly if the bacteria invade deeper into your body, entering your bloodstream, joints, bones, lungs or heart. A growing number of otherwise healthy people are developing life-threatening staph infections.

Treatment usually involves antibiotics and drainage of the infected area. However, some staph infections no longer respond to common antibiotics. MRSA infections start out as small red bumps that can quickly turn into deep, painful abscesses. Staph infections can range from minor skin problems to endocarditis, a life-threatening infection of the inner lining of your heart endocardium.

Because of this, signs and symptoms of staph infections vary widely, depending on the location and severity of the infection. The most common type of staph infection is the boil, a pocket of pus that develops in a hair follicle or oil gland. The skin over the infected area usually becomes red and swollen. If a boil breaks open, it will probably drain pus.

Boils occur most often under the arms or around the groin or buttocks. Staph bacteria are one of the most common causes of food poisoning. Symptoms come on quickly, usually within hours of eating a contaminated food. Symptoms usually disappear quickly, too, often lasting just half a day.

A staph infection in food usually doesn't cause a fever. Signs and symptoms you can expect with this type of staph infection include:. Also known as a bloodstream infection, bacteremia occurs when staph bacteria enter a person's bloodstream. A fever and low blood pressure are signs of bacteremia.

Some strains elaborate toxins that cause gastroenteritis, scalded skin syndrome, and toxic shock syndrome. Diagnosis is by Gram stain and culture. Treatment is usually with penicillinase-resistant beta-lactams, but because antibiotic resistance is common, vancomycin or other newer antibiotics may be required. The ability to clot blood by producing coagulase distinguishes the virulent pathogen, Staphylococcus aureus , from the less virulent coagulase-negative staphylococcal species.

Coagulase-positive S. Coagulase-negative species such as S. Unlike most coagulase-negative staphylococcal species, S. A carrier state is common. Pathogenic staphylococci are ubiquitous. Carriage rates are higher in hospital patients and personnel. Patients with influenza, chronic bronchopulmonary disorders eg, cystic fibrosis, emphysema , leukemia, tumors, chronic skin disorders, or diabetes mellitus. Patients with a transplant, an implanted prosthesis, other foreign bodies, or an indwelling intravascular plastic catheter.

Predisposed patients may acquire antibiotic-resistant staphylococci from other patients, health care personnel, or inanimate objects in health care settings. Transmission via the hands of personnel is the most common means of spread, but airborne spread can also occur.

Direct tissue invasion is the most common mechanism for staphylococcal disease, including the following:.

Skin infections Staphylococcal skin infections Staphylococci are gram-positive aerobic organisms. Staphylococcus aureus is the most pathogenic; it typically causes skin infections and sometimes pneumonia, endocarditis, and osteomyelitis Pneumonia Staphylococcal pneumonia Staphylococci are gram-positive aerobic organisms. Endocarditis Staphylococcal endocarditis Staphylococci are gram-positive aerobic organisms.

Osteomyelitis Staphylococcal osteomyelitis Staphylococci are gram-positive aerobic organisms. Infectious septic arthritis Acute Infectious Arthritis Acute infectious arthritis is a joint infection that evolves over hours or days. The infection resides in synovial or periarticular tissues and is usually bacterial—in younger adults, frequently Multiple exotoxins are sometimes produced by staphylococci.

Some have local effects; others trigger cytokine release from certain T cells, causing serious systemic effects eg, skin lesions, shock, organ failure, death. Panton-Valentine leukocidin PVL is a toxin produced by strains infected with a certain bacteriophage. PVL is typically present in strains of community-associated methicillin-resistant S. Toxic shock syndrome Staphylococcal toxic shock syndrome Staphylococci are gram-positive aerobic organisms.

Staphylococcal scalded skin syndrome Staphylococcal scalded skin syndrome Staphylococci are gram-positive aerobic organisms. Staphylococcal food poisoning Staphylococcal food poisoning Staphylococci are gram-positive aerobic organisms. It can occur spontaneously, during certain tissue infections, with use of indwelling genitourinary or IV catheters, or after dental It may also occur without any obvious primary site.

Staphylococcal bacteremia is an important cause of morbidity especially prolongation of hospitalization and mortality in debilitated patients. Skin infections are the most common form of staphylococcal disease. Superficial infections may be diffuse, with vesicular pustules and crusting impetigo Impetigo and Ecthyma Impetigo is a superficial skin infection with crusting or bullae caused by streptococci, staphylococci, or both.

Ecthyma is an ulcerative form of impetigo. Diagnosis is clinical. Treatment is Symptoms and signs are pain, warmth, rapidly spreading erythema Carbuncles are clusters of furuncles connected subcutaneously, Deeper cutaneous abscesses are common. Severe necrotizing skin infections Necrotizing Soft Tissue Infection Necrotizing soft tissue infection is typically caused by a mixture of aerobic and anaerobic organisms that cause necrosis of subcutaneous tissue, usually including the fascia.

This infection In impetigo, clusters of vesicopustular or bullous lesions form, rupture, and develop a honey-colored crust. This photo shows clusters of vesicles and pustules with developing honey-colored crust on the nose. Furuncles boils are tender nodules or pustules that involve a hair follicle and are caused by staphylococcal infection.

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