Tuberculosis (MTBC)

Causative agents

Mycobacterium tuberculosis is a 4μm long, 0.3-0.6μm wide, thin and sometimes slightly curved, non-encapsulated bacilli (bacillus) shaped bacteria. It is the main cause of the most cases of tuberculosis. [1]

Epidemiology

Tuberculosis is the most common second infection worldwide causing the death of young and older people. One-third of the world population is infected with tuberculosis. Each year 9 million people worldwide have been infected with tuberculosis and nearly 2 million of this has resulted in death. In Turkey between 10 million and 20 million people are infected with tuberculosis and carry infectious agent of tuberculosis (mycobacterium tuberculosis). The prevalence of TB is approximately 27 in one hundred thousand. [2], [3]

Modes of transmission

Even though it can affect all organs of the body, the main entry of the infection is respiratory system through lung. It is transmitted through air droplets which are generated when TB infected persons cough, sneeze, speak, etc. Also being in close contact with a person that has active TB disease with TB germs present in the sputum and consumption of unpasteurized infected cow's milk that has Mycobacterium bovis are the other causes of the human tuberculosis. [4]

Diagnosis

Diagnosis of tuberculosis can definitely be made by examining (culturing) the infectious agent (Mycobacterium tuberculosis) from clinical specimens (blood, sputum, or etc.). Radiography (chest X-rays, Abreugraphy, etc.), skin tests, direct microscopy and staining can also be applied for the diagnosis, but results of these methods are without high sensitivity, specificity and not sufficient for the precise diagnosis. [5]

Advances in molecular techniques may overcome these obstacles. Real-time PCR system is used to rapidly diagnose TB with high sensitivity and high specificity when compared to the conventional methods. [6]

Annotated Bibliography

1. 1-K. E. Nelson, C. Williams, and N. Graham., Infectious Disease Epidemiology: Theory and Practice, July 15, 2000 , p :653-655
2. 2-Anonymous, Tuberculosis Fact Sheet, 2009 Update, World Health Organization.
3. 3-Thierry Zozio, Caroline Allix, Selami Gunal, Genotyping of Mycobacterium tuberculosis clinical isolates in two cities of Turkey: Description of a new family of genotypes that is phylogeographically specific for Asia Minor, BMC Microbiol. 2005; 5: 44
4. 4-Barry R. Bloom ,William N. Rom ,Stuart M. Garay , Tuberculosis: Pathogenesis, Protection, and Control ,Oct 1, 1994, p:47-49
5. 5-Anonymous ,Tuberculosis, NIAID Fact Sheet: NIAID, July 1999
6. 6-Benjamin A. Pinsky and Niaz Banaei, Multiplex Real-Time PCR Assay for Rapid Identification of Mycobacterium tuberculosis Complex Members to the Species Level, Journal of Clinical Microbiology, July 2008, p. 2241-2246, Vol. 46, No. 7