Xpert MTB/RIF for Diagnosing TB in HIV-Infected Individuals

In a cross-sectional study, Xpert cycle times were correlated with time to culture positivity and with smear positivity, regardless of HIV status.

Although smear positivity is commonly used to determine the infectiousness of a patient with pulmonary tuberculosis (TB), it may be less sensitive than other measures, such as time to culture positivity (TTCP). A new measure, the Xpert MTB/RIF assay, employs real-time polymerase chain reaction to amplify mycobacterial DNA. The cycle threshold value (C_T), or the number of reaction cycles to obtain a positive result, is a semiquantitative measure of bacillary burden, with a lower C_T indicating a higher burden. However, the bacillary burden is decreased in HIV-infected individuals, and little information is available about how such infection and immunosuppression affect the assay's results.

To explore this issue, researchers analyzed data from …

Reviewing Author

Neil M. Ampel, MD

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Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Neil M. Ampel, MD

Disclosures

Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Xpert MTB/RIF for Diagnosing TB in HIV-Infected Individuals

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Reviewing Author