Doctors used to think that there were two major types of chronic joint pains. In one type, called reactive or rheumatoid arthritis, there is an immune or infectious reaction that damages joints. The other type, called osteoarthritis or degenerative arthritis, there is a wearing away of cartilage, the white gristle that covers bones where they come together to form joints.

Often, but not always, osteoarthritis is characterized by swelling of the joints near the fingernails, while immune types of arthritis are characterized by swelling of the joints in the middle of the fingers and knuckles. People with degenerative arthritis usually have negative blood tests for arthritis which measure increased immunity against infections, while those with reactive or rheumatoid arthritis often have some positive blood tests.

Myriad bacteria and viruses can cause arthritis, and antibiotics are often effective in controlling symptoms. Retroviruses can be found in joint fluid of patients with rheumatoid arthritis. Venereal diseases, such as chlamydia, mycoplasma, ureaplasma, gonorrhea and Gardnerella cause arthritis, and the practicing physician has no available tests that are dependable in diagnosing these infections.

Even when doctors treat infectious arthritis with massive intravenous doses of antibiotics for 10 weeks, the germs can persist in the joint fluid. Patients with supposedly non-infectious osteoarthritis can have C-reactive protein in joint fluid, signifying an infection. Long-term antibiotics are often effective in controlling the symptoms of rheumatoid arthritis, while short-term antibiotics are usually ineffective. The antibiotic, doxycycline may prevent joint destruction by stabilizing cartilage in addition to clearing the germ from the body.