Acid-fast bacilli in airway specimens from HIV-infected patients: Tuberculosis or mycobacteriosis?

Objectives: The incidence of atypical mycobacterial infections has increased with the AIDS epidemic, To present, microscopic examinations of airway specimens positive for acid-fast bacteria were highly suggestive of tuberculosis, However, since the AIDS epidemic, certain authors have reported an increase in Mycobacterium avium intracellulare found in respiratory specimens, The aim of this work was to determine what factors might distinguish between these two infections revealed discovery of an acid-fact bacilli. Methods: Hospital files of all HIV seropositive patients seen between November 1992 and March 1995 and with at least one airway specimen positive for acid-fast bacilli were studied retrospectively. Results: Mycobacterium tuberculosis was isolated in 19 patients, Mycobacterium avium intracellulare in 8 and Mycobacterium kansasii in 2, One patient had both M. tuberculosis and M. avium intracellulare. There was no difference for age, sex, geographical origin, transmission mode, antigen positivity, radiologic findings or clinical signs between patients with the different types of mycobacterium. The CD4 count was however significantly lower in patients with an atypical mycobacteriosis (14.5/mm(3)) than in patients with tuberculosis (91.7 +/- 83.7) (p = 0.004). Conclusion: These findings show that in HIV-infected patients with a CD4 count under 100/mm(3), the presence of acid-fact bacilli can indicate either M. tuberculosis or M. avium intracellulare, Combined anti-tuberculosis and anti-mycobacteriosis therapy thus would appear to be justified until the germ can be identified.