[Comparison of the mycobacteria growth indicator tube with solid culture for the detection of tuberculosis complex mycobacteria from blood]

Abstract

Aim of this study: The aim of this study was to compare the mycobacteria growth indicator tube and solid culture for recovery of complex tuberculosis mycobacteria from blood.

Patients and methods: One hundred and twenty-five specimens from 67 Djiboutian patients with a positive serologic diagnosis of HIV and fever were collected in an Isolator tube. After centrifugation and washing with phosphate-buffer, smears were prepared from the pellet for auramin staining. The remaining sediment was suspended in 1 ml of buffer. One half was inoculated into two MGIT (incubation at 30 and 37 degrees C into Bactec 960) and the other onto two Loewenstein-Jensen and two Coletsos medium (incubation at 30 and 37 degrees C).

Results: Eight cultures were contaminated: three on solid medium and MGIT simultaneously, five in MGIT only (three coagulase negative staphylococci, five enterobacteria). Fourteen strains of M. tuberculosis (six patients) and three M. canettii (two patients) (12 on solid media and MGIT, five in MGIT only) were recovered. The mean time to detection was 32.8 days for solid medium and 20.4 days for MGIT. Of a total of 25 patients with culture-proven tuberculosis, two patients had a positive blood culture only, six had blood and other specimens positive culture, 17 had a non blood specimens positive culture only.

Conclusion: MGIT processed into Bactec 960 is a viable tool for the detection of complexe tuberculosis mycobacteria from blood and the high-frequency of these mycobacteremia in HIV infected patients from country where the prevalence of tuberculosis is high is confirmed. However, the cost/benefit ratio of this bacteriologic diagnosis had to be evaluated in developping country.