Tb in the immunosuppressed
This document discusses tuberculosis (TB) in immunosuppressed individuals, particularly those with HIV. It notes that TB is a common opportunistic infection in HIV patients, as HIV impairs cell-mediated immunity and increases the risk of developing active TB from latent TB infection. In HIV patients, active TB often presents atypically with extra-pulmonary involvement, nonspecific chest x-ray findings, or even a normal chest x-ray. The degree of immunosuppression also affects clinical presentation and radiographic patterns of TB. Advanced immunosuppression is associated with less typical radiographic presentations and increased risk of extra-pulmonary and disseminated disease. A CD4 count can provide guidance on the likelihood of TB versus other
Tb in the immunosuppressed
- 1. TB In The Immunosuppressed Slam 201002414
- 3. Introduction TB is the most common opportunistic infection By producing a progressive decline in cell-mediated immunity, HIV alters the pathogenesis of TB, greatly increasing the risk of disease from TB in HIV-co-infected individuals and leading to more frequent extra-pulmonary involvement, atypical radiographic manifestations, and paucibacillary disease, which can impede timely diagnosis
- 4. In HIV-infected patients with LTBI, active TB develops in about 5 to 10%/yr, whereas in people who are not immunocompromised, it develops in about the same percentage over a lifetime a chest x-ray may show a nonspecific pneumonia or even be normal. Smear-negative TB is more common when HIV coinfection is present. Because smear-negative TB is common, HIV-TB coinfection is often considered a paucibacillary disease state.
- 5. Immunity
- 6. Impact of HIV Infection on the Pathogenesis of Tuberculosis Defective macrophages function in response to TB infection HIV impairs the host's ability to contain new TB infection etc
- 8. The presentation of TB also is affected by the extent of HIV-related immunosuppression. In patients with CD4 counts of >350 cells/袖L, the clinical and radiographic presentation is similar to that of patients without HIV infection. However, as immunosuppression advances, the radiographic presentation becomes less typical and extra-pulmonary and disseminated disease become more common
- 9. Radiographic Findings Upper-lobe infiltrates and cavities are the typical findings in reactivation TB, whereas intra-thoracic lymphadenopathy and lower-lobe disease are seen in primary TB. In HIV-infected persons with higher CD4 counts (ie, >200 cells/袖L), the radiographic pattern tends to be one of reactivation disease with upper-lobe infiltrates with or without cavities. In HIV-infected persons who have a greater degree of immunosuppression (ie, CD4 count <200 cells/袖L), a pattern of primary disease with intra-thoracic lymphadenopathy and lower-lobe infiltrates is seen. As chest radiographs may appear normal in up to 21% of those with culture- positive TB and CD4 counts of <50 cells/袖L,(51) a high index of suspicion must be maintained in evaluating an HIV-infected patient with symptoms suggestive of TB
- 12. CD4 Count Significance In AIDS patients, a mycobacterial illness that develops while the CD4 count is 200/亮L is almost always TB. By contrast, depending on the probability of TB exposure, a mycobacterial infection that develops while the CD4 count is < 50/亮L is usually due to M. avium complex
- 13. MAC