Mycobacterium tuberculosis

Andrea Lawlor - 09016048

It is a gram-resistant rod shaped bacterium, thus you cannot perform a gram stain on it. Instead to stain this bacteria you must useexternal image MTBCDC.jpg

the acid fast stain.
M. tuberculosis is classified as an acid-fast gram-positive bacteria. This organism was originally known as Tubercule bacillus, discovered by Robert Koch in 1882.

It is thought to have affected over 1.8 billion people in the world, and it is approximated that over 50% of cases are fatal. This is due to these 50% being unable to seek and receive medical attention. (Textbook of Bacteriology, 2011)

It is estimated that in 2009 3.3% of new cases of TB are diagnosed as MDR-TB(Multiple Drug Resistant TB), this number is believed to have risen. (WHO, 2010)

Current Treatments

Commonly used antibiotics used to treat other pulmonary infections such as clarithromycin can not kill TB. Instead, a combination or several antibiotics taken over a period of 6-9 months must be taken.First stage of treatment involved four different antibiotics taken within the first two months in conjunction with each other. These antibiotics are isoniazid, rifampicin, pyrazinamide, and ethambutol. The second stage is taking a further two antibiotics for a following four months (on a six month treatment) using rifampicin and isoniazid. This treatment may vary depending on severity and availability of drugs dependent on region where the patient is.

Treatment failure is most commonly due to failure of taking the medication appropriately. It is important to complete the full course of antibiotics even if you are feeling better, this is what leads to the resistant strains of the bacteria which a resistant to the antibiotics taken during the course of treatment. (, 2008)

Infection Vs. Disease

Tuberculosis: Infection vs Disease
TB Infection
TB disease in lungs
M. tuberculosis present
M. tuberculosis present
Tuberculin skin test positive
Tuberculin skin test positive
Chest X-ray normal
Chest X-ray usually reveals lesion
Sputum smears and cultures negative
Sputum smears and cultures positive
No symptoms
Symptoms such as cough, fever, weight loss
Not infectious
Often infectious before treatment
Not defined as a case of TB
Defined as a case of TB
(Textbook of Bacteriology, 2011)

Image 1 -, [Last modified: 21/04/2008] [Accessed14/03/2011]
Textbook of Bacteriology,,,, [Last Modified 13/02/2011] [Accessed 14/03/2011], [Last Modified 20/11/2008] [Accessed 14/03/2011]
WHO, 2010/2011 Tuberculosis Global Facts, [Published: November 2010] [Accessed 04/02/2011]