Infectious arthritis, also called septic arthritis, is an infection in the fluid and tissues of a joint. It is most commonly a bacterial infection, but can also be fungal or viral. Symptoms include joint pain, swelling, and fever and usually appear within a few days of infection.
Infectious arthritis is often caused by infection elsewhere in the body that spreads through the blood to invade the joint. The most commonly affected joints are the knee, hip, wrist, elbow, shoulder, and finger joints. People with weakened joints, such as those with a joint injury or chronic arthritis, are at the greatest risk of infectious arthritis. The condition is diagnosed by biopsy of the joint fluid, and in the case of bacterial infection, treated with a course of antibiotics.
Different types of bacteria are more likely to cause infectious arthritis in patients of different age groups. Gram-negative bacilli bacteria usually only causes infectious arthritis in infants and young children, while older children and adults are more susceptible to Gonococci, Streptococci, and spirochetes bacterial infection. Staphylococci infection can strike at any age. Viruses that can cause infectious arthritis include Human Immunodeficiency Virus (HIV), parvoviruses, and the viruses that cause mumps, rubella, and hepatitis B. Fungi and Mycobacterium tuberculosis can cause chronic infectious arthritis.
If you notice joint pain or swelling, you should consult a doctor immediately as you may have infectious arthritis. Those with chronic arthritis should consult a doctor if a particular joint suddenly becomes painful and swollen. Joints can be permanently damaged very quickly, sometimes in a manner of hours, if infectious arthritis is not treated.
If a doctor suspects infectious arthritis, he will perform a biopsy by drawing fluid from the affected joint with a syringe as early as possible and start the patient on antibiotics. Antibiotics will first be administered intravenously, followed by an oral antibiotics course. After laboratory analysis of the joint fluid, treatment may change depending upon the cause of the infection.
If a case of infectious arthritis is bacterial, antibiotics should begin clearing it up within 48 hours. Fungal infectious arthritis is treated with antifungal drugs, and a viral infection usually clears up on its own, so no medication is necessary except for painkillers. The affected joint may have to be drained with a needle, arthroscopy, or surgery, and physical therapy is sometimes required to prevent stiffness and maintain function and range of motion.