Introduction: The bacteriological diagnosis of tuberculosis is mainly based on the isolation and identification of the responsible mycobacteria. However, the slow growth of mycobacteria remains a real obstacle for studies interested in this disease. Microscopic examination is the initial step and often the only possibility in many developing countries to make the diagnosis. Faced with this problematic, this work focused on evaluating the contribution of centrifugation of the pathological product on the positivity of the microscopic examination and to make a comparison of the cultures of mycobacteria in Löwenstein Jensen (LJ) and in Middlebrook 7H9 (MB7H9) for the bacteriological diagnosis of tuberculosis.
Methods: Over a period of 6 months, all samples for diagnosis of tuberculosis, received at the Bacteriology-Virology-Hygiene laboratory of the IBN ROCHD University Hospital center in Casablanca were included in our work. Middlebrook 7H9 was prepared at our laboratory.
Results: On 613 clinical samples analyzed. The study showed that smear microscopy after centrifugation showed a better yield with a specificity of 100%; it increased the sensitivity of direct examination, allowing a gain of 50%, with a VPP of 100% and a VPN of 97, 56%. The MB7H9 liquid also gave a better yield with a very short growth time compared to the solid LJ.
Conclusion: The implementation of MB7H9 culture technique requires well-adapted structures and its systematic use in bacteriological diagnosis remains dependent on financial resources.