TB treatment should only be modified when drug interactions with these antiretrovirals do not allow the
optimal TB regimen. In some of these cases a longer duration of TB treatment may be necessary. The gold standard for diagnosing TB is microscopy followed by culture and drug sensitivity testing. Molecular diagnostics may be valuable when acid-fast bacilli are seen on smears. Rapid confirmation, by molecular diagnostics, that acid-fast bacilli are not Mycobacterium tuberculosis may avoid unnecessary treatment and infection-control measures. We recommend rapid detection of rifampicin resistance using molecular techniques in patients whose initial assessment (e.g. recent immigrant from an area with a high prevalence of rifampicin-resistant disease) find more or clinical course suggests multi-drug-resistant
TB (MDR-TB). These molecular tests should be used as an adjunct to standard laboratory techniques. HIV-infected individuals with latent TB infection are much more likely to progress to active TB than HIV-uninfected people. Detection and treatment of latent TB infection is therefore important, although diagnosis can be difficult. TSTs/interferon-γ release assays (IGRAs) are used to detect latent infection. They are not recommended as a diagnostic tool in suspected active TB as they only reflect previous mycobacterial exposure. Tuberculin skin testing is less useful in patients with HIV infection compared with HIV-uninfected patients, especially at low CD4 cell counts. IGRAs are newer blood assays derived from essentially selleckchem M. tuberculosis-specific T cells, which are generally more sensitive than tuberculin tests for detecting both active and latent disease in HIV-negative subjects. They are also more specific in Bacillus Calmette–Guérin (BCG)-vaccinated individuals. Although there are few data regarding their performance in HIV-infected patients, especially at low blood CD4 cell counts, we believe that IGRAs RANTES may have value in detecting latent TB infection and we recommend the use of IGRAs rather than TSTs as a screening tool for latent TB. However, their precise role remains
unclear and draft National Institute for Health and Clinical Excellence (NICE) guidance suggests using IGRA testing in those patients with a CD4 count >200 cells/μL, and both an IGRA and a tuberculin test in those with CD4 counts below this threshold. Although physicians can perform both tests in severely immunosuppressed patients, we believe that there are few data to support this strategy and doing this would add complexity, cost and difficulties in interpretation. The majority of the Committee believe that an IGRA test alone would be sufficient. New data would be welcome in guiding physicians in this difficult area. We recommend screening for latent infection in HIV-infected patients dependent on a risk assessment based on country of origin, blood CD4 cell count and length of time on antiretroviral therapy.