ABSTRACT
Atypical mycobacterial infections of the musculoskeletal system are very rare and are generally associated with predisposing factors, such as trauma, use of corticosteroids, or an immunocompromised state. There have only been three reports of Mycobacterium chelonae prosthetic infection of which two cases were associated with total hip arthroplasty and one with total knee arthroplasty and no reports of both Mycobacterium tuberculosis and M. chelonae occurring in the same joint. We report a case of a patient with rheumatoid arthritis treated with low-dose methotrexate (15 mg/week) who developed infection with both M. tuberculosis and M. chelonae after the revision of a prosthetic hip. Joint infections by mycobacteria are clinically indistinguishable from those caused by more common bacterial pathogens and, therefore, diagnosis is often delayed. Recurrent prosthetic hip infections, particularly in immunosuppressive patients, should alert the physician to consider the possibility of both tuberculous and atypical mycobacterial infections. Obtaining appropriate cultures can be critical in making the diagnosis and directing treatment. With the increasing use of immunosuppressive agents, including TNF alpha inhibitors, it is likely that there will be an increase in the number of mycobacterial infections complicating arthroplasties.
Subject(s)
Arthritis, Rheumatoid/drug therapy , Hip Prosthesis/microbiology , Mycobacterium Infections, Nontuberculous/diagnosis , Mycobacterium chelonae/pathogenicity , Mycobacterium tuberculosis/pathogenicity , Opportunistic Infections/diagnosis , Tuberculosis/diagnosis , Aged , Antirheumatic Agents/adverse effects , Antirheumatic Agents/therapeutic use , Arthritis, Rheumatoid/complications , Arthritis, Rheumatoid/surgery , Humans , Immunosuppressive Agents/adverse effects , Immunosuppressive Agents/therapeutic use , Male , Methotrexate/adverse effects , Methotrexate/therapeutic use , Mycobacterium Infections, Nontuberculous/etiology , Opportunistic Infections/etiology , Tuberculosis/etiology , Tumor Necrosis Factor-alpha/antagonists & inhibitorsABSTRACT
The pathogenesis of immunodeficiency associated with human immunodeficiency virus (HIV) infection remains incompletely understood. CD154, a molecule that is expressed primarily on activated CD4(+) T cells, is pivotal for regulation of cell-mediated and humoral immunity and is crucial for control of many opportunistic infections. We investigated whether CD4(+) T cells from HIV-infected patients exhibit defective induction of CD154 in response to opportunistic pathogens. Incubation of purified human CD4(+) T cells with monocytes plus antigenic preparations of either Candida albicans, cytomegalovirus, or Toxoplasma gondii resulted in induction of CD154. Expression of CD154 in response to these pathogens was impaired in CD4(+) T cells from HIV-infected patients. This defect correlated with decreased production of interleukin (IL)-12 and interferon (IFN)-gamma in response to T. gondii. Recombinant CD154 partially restored secretion of IL-12 and IFN-gamma in response to T. gondii in cells from HIV-infected patients. Together, defective induction of CD154 is likely to contribute to impaired cell-mediated immunity against opportunistic pathogens in HIV-infected patients.