Case 23-2000: osteomyelitis in HIV-infected patients

Nontuberculous mycobacterial osteomyelitis

Osteomyelitis caused by nontuberculous mycobacteria (NTM) can have severe consequences and a poor prognosis. Physicians therefore need to be alert to this condition, especially in immunocompromised patients. Although the pathogenesis of NTM osteomyelitis is still unclear, studies in immunodeficient individuals have revealed close relationships between NTM osteomyelitis and defects associated with the interleukin-12-interferon-γ-tumor necrosis factor-α axis, as well as human immunodeficiency virus infection, various immunosuppressive conditions, and diabetes mellitus. Culture and species identification from tissue biopsies or surgical debridement tissue play crucial roles in diagnosing NTM osteomyelitis. Suitable imaging examinations are also important. Adequate surgical debridement and the choice of appropriate, combined antibiotics for long-term anti-mycobacterial chemotherapy, based on in vitro drug susceptibility tests, are the main therapies for these bone infections. Bacillus Calmette-Guerin vaccination might have limited prophylactic value. The use of multiple drugs and long duration of treatment mean that the therapeutic process needs to be monitored closely to detect potential side effects. Adequate duration of anti-mycobacterial chemotherapy together with regular monitoring with blood and imaging tests are key factors determining the recovery outcome in patients with NTM osteomyelitis.

Microbiology of osteomyelitis in patients infected with the human immunodeficiency virus

Osteomyelitis rarely develops in patients infected with the human immunodeficiency virus despite their immunosuppressed state. In the limited literature available on this subset of patients, the role of opportunistic micro-organisms is controversial. Our purpose is to describe the microbiologic features of osteomyelitis. This is a retrospective review of 20 patients infected with the human immunodeficiency virus who were admitted to our musculoskeletal infection ward with the diagnosis of osteomyelitis. Eleven patients (55%) were intravenous drug users. Medical comorbidities were present in 14 of 20 patients (70%), including tuberculosis in five patients and hepatitis C in three patients. The mean CD4 count was 269/mm (range, 20-539/mm). Osteomyelitis was monomicrobial in 10 patients (50%) and polymicrobial in seven patients (35%) whereas in three patients no organism was cultured. The most common pathogen was Staphylococcus aureus, present in 10 patients (50%). No mycobacterial or fungal pathogens were identified. Infection recurred in 3 of 14 patients (21%) that were available for followup. Despite their immunocompromised status, patients infected with the human immunodeficiency virus did not develop osseous infections with opportunistic pathogens. Staphylococcus aureus was the most common pathogen found; however, a considerable proportion of infections were polymicrobial.

Mycobacterium kansasii osteomyelitis in a patient with AIDS on highly active antiretroviral therapy

Skeletal infections with atypical mycobacteria are usually a manifestation of advanced HIV disease with most patients having CD4 counts of less than 100 cells/mm3. We report a case of Mycobacterium kansasii vertebral osteomyelitis on highly active antiretroviral therapy with a CD4 count of 320 cells/mm3 and viral load below the level of detection at the onset.

[Bacterial osteitis. Special considerations in immunocompromised patients]

With increasing life expectancy and better medical competence, the number of older patients with multimorbidity is growing. Patients with a deficient immune system need more attention during diagnosis and treatment of osteomyelitis.