Infectious arthritis or septic arthritis is infection in a joint that is caused due to bacteria, virus, or fungus responsible for an infection in another part of the body but travels through the bloodstream.
For example, the patient might be having urinary tract infection but the bacteria might enter the bloodstream, then travel and attack a joint resulting in septic arthritis. Septic arthritis is a medical emergency and prompt diagnosis and treatment is essential.
Older adults are more prone to develop septic arthritis and its diagnosis is challenging due to the lack of consistent signs and symptoms with sepsis in many cases. The right diagnosis and the subsequent treatment is largely dependent on the physician’s experience.
The temperature spike is very less and even minor elevations may indicate significant bacteremia, and the changes caused by the septic arthritis are very subtle and nonspecific. There are a number of conditions that mimic septic arthritis. Hence arriving at the diagnosis of septic arthritis is very difficult. Systemic changes like anorexia, falls, and weight losscan be notedcan also be noted.
It is also quite common to witness conditions like osteoarthritis in the older adult population that carry symptoms of pain and swelling in multiple joints. In case of an infected joint, the symptoms displayed may be out of proportion to the background disease activity, making it difficult to arrive at the diagnosis of septic arthritis.
A few studies conducted also show that septic arthritis can affect multiple joints in the older adults, around 22%, contradicting the belief that septic arthritis affects a single joint only. Studies also show that the prognosis is not great and there is development of septic arthritis in structurally abnormal joints.
The other risk factors for the development of septic arthritis include rheumatoid arthritis, prosthetic joints, diabetes, intravenous drug abuse, cutaneous ulcers, alcoholism, and osteoarthritis. If the patient has any of these pre-existent conditions, then the suspicion of septic arthritis should ideally increase. Since the older adults are more likely to have a pre-existing joint disease, this section of the population is also more likely to develop septic arthritis.Conditions such as diabetes and skin ulcerations can be seen more commonly in this section of the population, increasing the risk of septic arthritis further.
Although the most common reason for septic arthritis is Staphylococcus and Streptococcus,it is Gram-negative bacillus that is more common in the older patients. Additional risk factors for Gram-negative bacillus include UTI recently, urinary catheterization, or immunosuppression.
Due to the fact that the etiology of septic arthritis is evolving and the germs are becoming more resistant, it is becoming a bigger challenge to treat septic arthritis and this is a major concern.
In case septic arthritis is suspected, a joint aspiration needs to be performed and the synovial fluid sent to the lab for culture and microscopic analysis even before commencing antibiotic therapy. Microscopic analysis and Gram stain may not give accurate results and reveal germs in only 50% of cases. Culture of the fluid and other blood tests will help in proper diagnosis, but it must be noted that there can still be cases with no positive microbiological proof.
The removal of purulent material along with appropriate antibiotic therapy is the treatment for suspected or proven septic arthritis, but the commencement of antibiotic therapy must be exercised with caution taking into account the various side effects and the older patient’s condition.