Infectious arthritis

They produce an inflammatory reaction of the synovium with destruction and suppuration of the affected joint.

How is it produced?

The infectious agents that most frequently cause septic arthritis are:

• Gram-negative cocciGonococcal (gonococcal) arthritis should be suspected in sexually promiscuous patients with a history of sexually transmitted infection in the past 30 days and the appearance of migratory arthralgias, tenosynovitis, and characteristic skin lesions.
• Gram negative bacilli: E.coli, Pseudomonas and Proteus among the most frequent. Higher incidence in patients with chronic diseases, patients previously treated with antibiotics, corticosteroids and / or cytostatics and in ADVP (addicted to parenteral drugs).
• Mushrooms: in chronically ill and / or immunosuppressed by Candidas and Aspergillus
• Virus: by rubella virus and hepatitis B virus
• Mycobacteria: in 1% of those affected by tuberculosis (Mycobacterium tuberculosum). Increase in HIV patients.
• Lyme disease: for Borrelia Burgdorferi, transmitted by tick bite.

Depending on age, the germs involved in infectious arthritis also vary. Thus, during lactation, those caused by S. aureus and Enterobacteriaceae; in children under 5 years of age, infection by Haemophilus influenzae (in unvaccinated) is almost exclusive of this age, between 15 and 40 years the prevailing gonococcus and S. Aureus, the latter being the most frequent germ in adults> 40 years.

The most frequent route of infection in any of these age groups is hematogenous (through the blood) from an entrance door to the body such as the pharynx, paranasal sinuses, rectum, urethra and intestine.

Symptoms

The most common form (90%) is monoarticular and acute, with the knee being the most frequently affected joint, followed by the hip, shoulder, wrist, and ankle.

It manifests itself with pain, redness, local heat and limited mobility of the affected joint. In 10% more than one joint is affected. It can be accompanied by fever and chills (up to 50% of gonococcal arthritis have fever).

Subacute or chronic forms suggest a fungal, brucella, or microbacterial infection.

Diagnosis

The most important thing is the clinical suspicion of compatible symptoms in a patient with risk factors (chronic patients, ADVP, HIV, immunosuppression and previous antibiotic therapy among the most frequent).

Identification of the germ through arthrocentesis (puncture and aspiration of joint content) is the method of choice in peripheral arthritis. Serial cultures of blood samples (blood cultures) are of great diagnostic utility and are performed during feverish peaks of the disease.

The X-ray at the beginning of the disease does not show alterations, but rather at 2 or 3 weeks, in the form of narrowing of the joint interline and signs of osteoporosis until reaching more serious lesions from the 4th week in the form of joint erosions.

Viral arthritis does not produce radiological alterations and those caused by fungi and micro bacteria do so very slowly.

CT is of interest to more accurately assess the extent of joint destruction, as well as to reach joints that are difficult to explore with conventional radiography, such as the sternoclavicular, sacroiliac or vertebral joints.

Treatment

Prompt initiation of treatment is essential to avoid residual functional alterations of the affected joint, as well as to avoid mortality associated with infectious arthritis (up to 10% mortality in non-gonococcal arthritis).

Treatment with antibiotics should be started empirically due to clinical suspicion and after having extracted the synovial fluid samples for cultures, which will be kept parenterally for the first two weeks. Later, the treatment will be adjusted to the results of the cultures. Depending on the infectious agent, treatment has a variable duration, ranging from 6 weeks in non-gonococcal bacterial arthritis to 6-12 months in tuberculous arthritis.

During the first days, the joint must remain at rest, after 2 or 3 days if the evolution is correct, passive movements begin and later, active movements and against resistance.

Sometimes a joint drainage must be performed, which consists of evacuating it through arthrocentesis, on a daily basis. It is indicated in cases of poor evolution after starting treatment, in arthritis of long evolution without treatment, in persistence of positive cultures of the joint fluid and in the presence of intra-articular septa that make it difficult to empty it.