Osteomyelitis: Classification, Causes, Pathophysiology, Signs and Symptoms, Diagnosis and Treatment скачать в хорошем качестве

Osteomyelitis: Classification, Causes, Pathophysiology, Signs and Symptoms, Diagnosis and Treatment

osteomyelitis is an inflammation of the bone or bone marrow, and it typically results from an infection. Osteomyelitis is inflammation of the bone and the bone marrow caused by an infecting organism. Although bone is normally resistant to bacterial colonization, events such as trauma, surgery, the presence of foreign bodies, or the placement of prostheses may disrupt bony integrity and lead to the onset of bone infection. Osteomyelitis can also result from hematogenous spread after bacteremia. When prosthetic joints are associated with infection, microorganisms typically grow in biofilm, which protects bacteria from antimicrobial treatment and the host immune response. Early and specific treatment is important in osteomyelitis, and identification of the causative microorganisms is essential for antibiotic therapy. The major cause of bone infections is Staphylococcus aureus. Infections with an open fracture or associated with joint prostheses and trauma often must be treated with a combination of antimicrobial agents and surgery. When biofilm microorganisms are involved, as in joint prostheses, a combination of rifampin with other antibiotics might be necessary for treatment. In osteomyelitis, microorganisms, such as bacteria, reach the bone to cause an infection in a few different ways. Bacteria particularly affect certain high-risk individuals like those with a weak immune system, and those with poor blood circulation due to uncontrolled diabetes. In fact, a major way that bacteria reach the bone is through the bloodstream, and it's called hematogenous spread. For example, this might happen in a person who uses contaminated needles to inject drugs or in individuals undergoing hemodialysis that may be contaminated by a bacteria or even through the dental extraction of an infected tooth. Through the bloodstream, the microorganisms may reach specific places in the body, and this mostly depends on the age of the person. In older adults, for example, the microorganisms may reach the vertebrae and cause vertebral osteomyelitis. This usually affects two adjacent vertebrae and the interintervertebral disk between them. In children, the metaphysis of long bones like the femur is commonly affected. The second way that bacteria cause osteomyelitis is through trauma. For example, in an open fracture after an accident, the bone may get exposed to the outside environment and come into direct contact with bacteria. A third way is during surgery when there’s bacteria that’s introduced into the bone. A fourth way is when an infection spreads from one area, like cellulitis - which is an infection of the dermis layer of the skin - to an adjacent area like the bone, and this is known as contiguous spread. There can also be combinations of these. For example, when a prosthetic joint becomes contaminated with bacteria during surgery and then that bacteria contiguously spread to nearby bone. Another example, is when people with diabetes mellitus who develop a severe vascular compromise. A small trauma to the foot can lead to the formation of a foot ulcer, which then becomes infected and spreads to the nearby bone. Now, once the bacteria reach the bone by any of these routes, they start to proliferate. This alerts nearby immune cells - specifically dendritic cells and macrophages - that try to fight off the infection. This represents the acute phase of the disease and occurs over a course of weeks. The immune cells release chemicals and enzymes that break down bone and cause local destruction. Usually acute osteomyelitis comes to a resolution - meaning that the immune system eventually destroys all of the invading bacteria. If the lesion is not that extensive, and there’s viable bone the osteoblasts and the osteoclasts begin to repair the damage over a period of weeks. Join this our membership section to get access to perks:    / @medcrine   SUBSCRIBE, LIKE and SHARE Check our website for more medical lecture notes at https://medcrine.com Follow us on twitter @medcrine Facebook at www.fb.me/medcrine Pinterest at pinterest.com/medcrine Telegram at t.me/medcrine email us on [email protected]