TUBERCULOSISMYCOBACTERIUM TUBERCULOSIS

Stavros GiannoukosBen Altland

TaxonomyKingdom: Bacteria

Phylum: Actinobacteria

Order: Actinobacteridae

Family: Actinomycetales

Genus: Mycobacterium

Species: tuberculosis

General Information about M.TB.

Aerobic Rod shaped Non-motile Neither Gram-negative nor

Gram-positive. Stains weakly Gram-positive.

Genome was mapped in its entirety in 1998.

The main cause of Tuberculosis, however other species of mycobacterium can also cause the disease.

PathogenicityHighly pathogenicLong generation time (15-20 hours) prevents recognition of the immune system.Low permeability membrane allows survival inside macrophages.Only susceptible to a select few antibiotics.Over 20% are resistant to primary treatment. And 2% are resistant to secondary treatment.Byproducts of the infection inhibit oxygen transfer from Causes extreme necrosis of Lung tissue, leading to emphysema and eventual death by asphyxiation.

Ecology M.TB. is found exclusively in the human

body. Complexes primarily form in the lungs. If infection is not contained by granuloma

formation, infection can spread to other tissues of the body.

No other reservoirs for the bacteria exist in the world.

Believed to have been created from the mutation of Mycobacterium leprosy within the human body.

Target Tissues

Cross sections of an alveoli infected with M.TB. The blue spheres are granulomas, the immune response to contain the infection.

Photo of the rare event of an M.TB infection of the skin.

Lungs (Pulmonary alveoli)

Ghon focus

Central Nervous System

Circulatory System

Lymphatic System

Joints

Skin

SymptomsOnly 10% of infected patients are symptomatic.Active symptoms include chest pain, coughing up blood, or white mucosa and necrotic tissue, and a productive, persistent cough for more than three weeks.Systemic symptoms of wide spread infection are, weight loss, loss of apatite, fever, chills, night sweats, paling (loss of skin color) and rapid fatigue.

Diagnostic TestingComprehensive review of medical history.Chest X-rayPhysical examSkin test of an active TB skin infection site.

Treatment Complete treatment takes 6-9

months. Multiple drugs are used in

combination. Isoniazid– Inhibits cells wall

synthesis. Ethambutol- Inhibits cell wall

synthesis. Pyrazinaide- Destroys plasma

membrane and inhibits metabolic processes. Exact mechanism unknown.

Rifampin- Inhibits RNA synthesis.

Prevention

A child receiving a tuberculosis vaccine at school in Bulacan province, Philippines, c. 1952.UNICEF/ICEF-2539

Prevention almost entirely consists of avoiding contact with great numbers of people potentially infected with M.TB.M.TB is spread by the transmission of sneeze droplets from person to person, with only one droplet between .5 and 5 micro liters required to transmit an infections amount of bacteria.40,000 of these drops are released with every sneeze.Infected persons are usually required to wear masks to prevent transmission through sneezing.The vaccine BCG exists derived from attenuated M. bovine virus, but is not approved for use in the US.

Epidemiology

World TB incidence. Cases per 100,000; Red > 300, orange = 200–300; yellow = 100–200; green 50–100 and grey <50. Data from WHO, 2006.

Is the most prevalent pathogen infection in the world, with an estimated 2,000,000,000 of the worlds population infected on some level.Also referred to as the “White plague.”Highest concentrations of infections occur in areas with higher HIV prevalence. (South Africa has 718/100,000 population infected.)India has the single largest number of infections with over 1,800,000 cases.Occurs less frequently (between 5<50/100,000 population) in more developed countries.

Morbidity and Mortality Over 8,000,000 people become infected with

tuberculosis annually. 2,000,000 people die annually from tuberculosis. In 2004, worldwide there were 14.6 million people

with active TB disease, with 9 million new cases being presented that year.

The world’s greatest infectious killer of women of reproductive age, and the leading cause of death among people with HIV.

In 2006, there was a total of 13,767 deaths in the U.S. from TB (4.6/100,000 population) reported. This is a 3.2% decrease from 2005, and the lowest in U.S. history since tracking began in 1953.

Refrences

www.CDC.gov http://library.med.utah.edu http://www.textbookofbacteriology.net http://www.microbiologybytes.com National Institute of Allergy and Infectious Diseases (NIAID).

Microbes in Sickness and in Health. 26 October 2005. Retrieved on 3 October 2006.

(1997) "Diagnosis and treatment of disease caused by nontuberculous mycobacterium. This official statement of the American Thoracic Society was approved by the Board of Directors, March 1997. Medical Section of the American Lung Association". Am J Respir Crit Care Med 156 (2 Pt 2): S1–25. PMID 9279284. 

Nahid P, Pai M, Hopewell P (2006). "Advances in the diagnosis and treatment of tuberculosis". Proc Am Thorac Soc 3 (1): 103-10. PMID 16493157.