How does reactive arthritis occur?
After contact with certain bacteria, the immune system produces antibodies against them and activates T lymphocytes. Some bacterial structures are similar to proteins in the body's own tissues, and the immune response is mistakenly transferred to joints, tendons, eyes and mucous membranes. That is why arthritis does not develop at the height of the infection, but after two to four weeks, when the infection itself has already passed or is almost no longer bothersome. Predisposition is largely determined genetically: in carriers of the HLA-B27 antigen, the disease is more common and more severe.
- Infection triggers an immune response
- Similarity between bacterial and self proteins
- The interval between infection and arthritis is 2–4 weeks.
- There is no living pathogen in the joint
- The role of genetic predisposition HLA-B27
What infections cause it?
The two main groups are intestinal and urogenital. The most common intestinal culprits are Salmonella, Shigella, Yersinia and Campylobacter: a person suffers from food poisoning or an intestinal infection, recovers, and after a few weeks his knee swells. Among sexually transmitted infections, chlamydia trachomatis plays the main role; mycoplasma genitalium is less often mentioned. The urogenital form is more common in young men. Sometimes the connection with the infection cannot be established because it was asymptomatic - this is especially typical for chlamydia.
- Salmonellosis
- Shigellosis (dysentery)
- Yersiniosis
- Campylobacteriosis
- Chlamydial urogenital infection
- Sometimes - an asymptomatic infection
Symptoms
Usually one to four joints are affected, most often on the legs and asymmetrically: knee, ankle, foot joints. Characterized by dactylitis - inflammation of the entire finger, which is why it looks like a sausage. Heels often hurt at the site of attachment of the Achilles tendon and plantar fascia - this is enthesitis, a typical symptom of this group of diseases. Extra-articular manifestations include conjunctivitis or more severe inflammation of the choroid, urethritis with pain when urinating, painless mouth ulcers, and skin rashes on the palms and soles. The general condition may suffer: fatigue, low-grade fever.
- Asymmetrical damage to 1–4 leg joints
- Pain and swelling of the knee or ankle
- Dactylitis - the entire finger swells
- Heel pain when standing
- Conjunctivitis or pain and redness of the eye
- Pain when urinating, discharge
- Pain in the lower back and buttocks
- Mouth sores, rashes on palms and soles
Diagnostics
There is no specific analysis to confirm the diagnosis - it is made based on the totality of the picture, the connection with a previous infection and after excluding other causes. Inflammation levels are usually elevated. The rheumatoid factor in this form is negative, which helps distinguish it from rheumatoid arthritis. Be sure to look for the causative infection: PCR smear for chlamydia in both partners and stool culture for a recent intestinal infection. Determination of HLA-B27 does not confirm the diagnosis, but helps assess the prognosis. In case of acute inflammation of one joint, purulent arthritis must be excluded using a puncture.
- Complete blood count with ESR and C-reactive protein
- PCR swab for chlamydia
- Culture of stool for intestinal group
- Rheumatoid factor for differential diagnosis
- HLA-B27 for prognosis assessment
- Ultrasound of joints and entheses assessment
- Joint puncture for suspected infectious arthritis
- Examination by an ophthalmologist for eye complaints
Treatment
The basis is non-steroidal anti-inflammatory drugs, which reduce pain and inflammation; They are prescribed by a doctor taking into account the condition of the stomach and kidneys. In case of severe inflammation of one or two joints, the introduction of a glucocorticosteroid into the joint is effective after ruling out infection. Antibiotics are justified only for confirmed chlamydial infection, and both partners should be treated; in the intestinal form, when the infection has already passed, antibiotics do not affect the course of arthritis. If the course is prolonged, the rheumatologist initiates basic therapy. Physical therapy plays an important role: movement preserves mobility, but complete immobility is harmful.
- Nonsteroidal anti-inflammatory drugs
- Intra-articular administration of glucocorticosteroid according to indications
- Antibiotics for confirmed chlamydial infection, with a partner
- Basic therapy for prolonged course
- Physical therapy and maintaining mobility
- Treatment of conjunctivitis and uveitis by an ophthalmologist
- Observation by a rheumatologist until complete recovery