Use of Direct Amplification Techniques in HIV-infected Patients with Smear-negative Culture Proven Pulmonary Tuberculosis
C Defrance, S Dewit*, R Scheen, A Dediste, B Poll, and N Clumeck
St Pierre Univ Hosp, Brussels, Belgium
Background: The role of a direct
amplification test for the diagnosis of HIV-associated pulmonary tuberculosis
(TB) is currently not fully established. The use of this technique is
recommended for smear-positive respiratory samples (to distinguish TB from
infection with a non-tuberculous mycobacteria)
but not for smear-negative sputums. We evaluated this
technique in HIV+ patients with proven pulmonary TB who were
Methods: We included 73
HIV-infected patients with a first proven episode of pulmonary TB (clinical and
radiological suspicion of infection, positive culture for Mycobacterium tuberculosis) were evaluated between 1995 and 2004.
The mean CD4 level was 92/mm3. Direct amplification techniques were
performed in smear-negative patients (i.e. 3 negative samples).
Results: Of the 73 cases, 30 were
smear-negative TB (41%) (mean CD4 88/mm3).
Direct amplification test could be realized in 20 of 30 specimens (mean CD4
95/mm3) and was positive in 15 of 20 (75%) (9 on sputum and 6 on bronchoalveolar lavage) (mean CD4 66/mm3).Treatment against M. tuberculosis was initiated in all
patients as soon as amplification test results were made available.
Conclusions: Among HIV+ patients
with culture proven pulmonary TB who are smear-negative, direct amplification
techniques contributed to establish early diagnosis in 75% of the cases. This
is higher than published studies, where HIV and non-HIV patients where mixed.
Amplification technique costs US$20,
and can be performed in 1 day, allowing early initiation
of appropriate therapy and control of risk of transmission of M. tuberculosis. The clinical usefulness
and the cost benefit ratio of this approach should be further evaluated in