Microbiología de la tuberculosis

Tuberculosis (TB) is one of the infectious diseases with a larger number of cases, especially in low-income countries. Despite having an effective treatment, its control is difficult due to the characteristics of the bacterium and the transmission mechanism of the disease. The microbiological diagnosis establishes the etiology and confirms the disease. It is based on specific staining microscopy, mycobacterial culture, especially liquid media, and gene amplification, when the suspicion is moderate to high. It is always necessary to identify positive cultures, since in the recent years an increase in non-tuberculous Mycobacteria (NMT), with different TB treatment, has been observed. The treatment of resistant cases is complicated and also limited due to the lack of alternative drugs. Therefore, systematic susceptibility testing should be performed on all patients with positive isolates. The screening of the mutations associated with resistance provides information in 2-3 days instead of 3-4 weeks. It is indicated in previously treated patients, contacts with resistant cases, in clinical failures or recurrences, and in patients originating from countries with a high incidence of TB.

New diagnostic tests are needed to improve the current limitations of these tests, such as the sensitivity and slow growth rate of Mycobacterium tuberculosis.