Tuesday, December 2, 2014

Arthritis and HIV-infected patients

Musculoskeletal syndromes that occur in HIV-infected patients include manifestations of drug toxicity, reactive arthritis, Reiter's syndrome, infectious arthritis, and myositis. Principles to keep in mind when evaluating an HIV-infected patient with a musculoskeletal syndrome include the following:

Any musculoskeletal syndrome in non-HIV infected patients can occur in HIV-infected patients, such syndromes may not be related to the HIV infection.
HIV infection can alter clinical presentation and course. Reactive arthritis, inflammatory arthritis, or musculoskeletal infections may be more severe in presentation and course in HIV-infected persons. In some cases, musculoskeletal infections may be more insidious and subtle in onset.
Ruling out or correctly diagnosing infections is especially important to prevent the spread of infection in an immunocompromised patient.
The probability of an opportunistic infection as a cause for a musculoskeletal complaint depends on the stage of the patient's HIV disease. At early stages (CD4 count above 300), opportunistic infections are unlikely, although resistance to common bacterial pathogens may be reduced.
Generally, diagnostic tests and treatment regimens for musculoskeletal syndromes are the same as when the syndromes occur in non-HIV infected patients, except that the patient's HIV-related medications may cause side effects and interactions that impact differential diagnosis and limit therapeutic options, and there should be a very high threshold to using immunosuppressive drugs.

Some risk factors for HIV infection are also risk factors for other conditions that may present as musculoskeletal syndromes. Examples include injection drug use and arthritis associated with hepatitis B virus infection or endocarditis, sexual promiscuity and the arthritis syndromes associated with sexually transmitted infections such as gonorrhea and chlamydia, and hemophilia and hemarthrosis. Clinicians need to examine HIV-infected patients who present with acute or subacute musculoskeletal pains for evidence of infection in the joints and muscles. Careful examination of the skin may reveal a fungal infection that has spread to the joints. Septic arthritis may be difficult to differentiate from reactive arthritis, but cultures of the synovial fluid and blood will be sterile in cases of reactive arthritis. Septic arthritis in HIV-infected injection drug users (IDUs) is most commonly due to Staphylococcus aureus and usually responds well to treatment. In patients with advanced HIV disease who are not IDUs, clinicians must always consider opportunistic infections in joints, bones, and muscles. HIV-infected patients with muscle pain and weakness must be evaluated for idiopathic polymyositis, myositis secondary to zidovudine (AZT) toxicity, and infectious pyomyositis. Although many clinicians believe that HIV infection predisposes patients to musculoskeletal infections and has a negative impact on the outcome of the therapy, this hypothesis is not yet proved.
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Both Reiter's syndrome and septic bursitis can cause a monarticular arthritis in an HIV-infected patient. Evaluation of synovial fluid is necessary to rule out infection and make a diagnosis. Clues to help the clinician differentiate between infectious and reactive arthritis in patients with HIV disease include a history of urethritis, cervicitis, diarrhea, or conjunctivitis, and findings of psoriasiform lesions, nail changes and enthesopathy (inflammation of tendinous insertions), as these may accompany a reactive arthritis.

The onset of reactive arthritis in HIV-positive patients usually occurs in the foot and ankle, and the common types of inflammation are enthesopathy (involving the Achilles tendon, plantar fascia, or anterior and posterior tibial tendons) and multidigit dactylitis. Synovitis is rare but may occur in joints of the lower extremities. In the upper extremities, dactylitis and enthesopathy occur in the tendinous insertions in the lower part of the arms. Cutaneous symptoms include psoriasiform rashes, keratoderma blennorrhagicum, and onychodystrophy.

In reactive arthritis, the synovial fluid is usually inflammatory, with a few thousand white blood cells and a synovial glucose level that is at least two thirds the serum glucose level. Gram stain or culture of synovial fluid is the only reliable way to make the diagnosis of a septic arthritis or bursitis. If the diagnosis is entertained, aspiration and culture should be performed immediately. If the synovial fluid is purulent, it may be prudent to initiate broad antibiotic coverage while waiting for the results of definitive synovial fluid cultures. Also, if the synovial fluid is initially unobtainable (as in axial joint infection), it is prudent to initiate antibiotic coverage. Blood cultures should be obtained during the work-up of the arthritis, as they may become positive before the synovial fluid cultures. HIV-infected patients who are at high risk for septic arthritis include IDUs and hemophiliacs. Clinicians must always consider and rule out acute infectious synovitis in these patients.

Gram-positive bacteria, such as S. aureus and Streptococcus pneumoniae, commonly found in non-HIV infected patients with septic arthritis and bursitis, are causative factors in most reported cases of septic arthritis and bursitis in HIV-infected persons. Infections with organisms not common to the skin have also been reported. One report described osteomyelitis in HIV-infected patients, but usually it results from direct extension from a septic joint. Clinicians must frequently re-examine HIV-infected patients treated for septic arthritis for evidence of worsening or unchanging symptoms and signs. If bone pain and fever continue despite antibiotic coverage, extension of the infection to the surrounding bone should be considered, surgical debridement may be necessary.

In most HIV-infected patients with acute joint or bursa infections, broad antibacterial coverage to cover common skin organisms (including staphylococcal and streptococcal infections) should be initiated. Patients with advanced HIV disease occasionally have opportunistic joint infections, such as sporotrichosis, cryptococcosis and Mycobacterium avium intracellulare. Often these patients have extraarticular features suggestive of such infections, including typical skin lesions. These opportunistic infections often present with a more indolent course than that of a bacterial septic arthritis. If extra articular features of fungal infection are present or hyphae or budding yeasts are seen on direct synovial fluid examination, the patient should receive standard doses of intravenous amphotericin B.

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