Septic Arthritis

Septic arthritis is an infectious form of arthritis in which a joint becomes infected with bacteria or fungi. Typically, septic arthritis affects one large joint, such as the knee or hip, but less frequently may impact multiple joints at the same time. Septic arthritis occurs when germs travel through your bloodstream from another part of the body and settle in the joint, or when an open wound or surgery brings infection directly to the joint. The disease is extremely painful and debilitating due to swelling in the affected joint.

Infants and older adults are most likely to develop septic arthritis, which can cause rapid and severe damage to cartilage and bone. It can be fatal if not treated quickly.

What Causes Septic Arthritis?

Septic arthritis is caused by bacteria or fungi that are carried through the blood stream from another area of the body, usually settling in one large joint. A bacterial infection from an injury or opening from a surgical procedure can also cause septic arthritis by bringing germs directly to the joint. Normally, the joints of the body are lubricated with a fluid called synovial fluid, which is sterile. When a person has septic arthritis, microbes such as bacteria and fungi are present in the joint fluid, which cause infection. The infection then leads to swelling, pain and inflammation of the joint.

Haemophilus influenza, staphylococcus, and streptococcus are the most common bacteria that cause the disease, which normally live harmlessly on our skin and in the respiratory tract, are the most common bacteria that cause the disease, while histoplasma, coccidiomyces and blastomyces, which live in soil, are the fungi most commonly linked to septic arthritis.

Staphylococci or “staph” bacteria are normally found in the nose and on the skin, while streptococcus are typically found in the throat and on the skin, and are most commonly associated with strep throat and pink eye. Haemophilus influenza bacteria live in the nose and throat but despite the name, do not cause the flu. Most of the time, these bacteria are kept in check by the immune system and do not cause disease. However, damage to the skin or other injury may allow the bacteria to elude the body’s defense mechanisms, leading to infection.

According to the National Institute of Arthritis and Musculoskeletal Diseases, about eight out of 10 people with reactive arthritis have a gene called HLA-B27.