Caused by Mycobacterium tuberculosis , a bacterium.
The bacteria are prokaryotic cells
Every year 1.6 million people die from this disease.
Prokaryotic Cell Structure As you can see, the structure is very different from plant and animal cells that we have already learnt about. Capsule is a layer of mucilage which may unite bacteria into colonies. Pili are protein rods concerned with cell-cell attachment. The sex pilus is involved in DNA transfer Plasma membrane is a typical phospholipid bilayer. Plasmids are small pieces of circular DNA which replicate independently of the main genome. Cell wall has a rigid framework of murein , a polysaccharide cross-linked by peptide chains. Genetic material is composed of a circle of double-stranded DNA which is not enclosed within a nucleus. Ribosomes smaller than those in eukaryotes and not supported by an endoplasmic reticulum. Food stores are typically lipid droplets glycogen granules. Flagellum is responsible for motility of many bacteria.
Like all bacterial infections TB can be treated successfully using antibiotics. Isoniazid is the drug of choice.
The drugs need to be taken over six to nine months to be effective. Initially the patient feels ill so takes the medication and the most susceptible strains of Mycobacterium are destroyed. As the patient feels better they stop taking the medication, however the more resistant Mycobacterium strains are still present in the body ; these multiply and spread to others. These bacteria are likely to be the resistant ones.
To try to stop resistance developing, TB patients are usually given a cocktail of three or four different drugs – hopefully at least one of these will be effective.
A scheme called DOTS (Direct Observation Therapy) has been developed. Here patients are watched while they take their medication, this ensures they complete the course of treatment. DOTS also enable the patients health to be monitored.
Vaccination – BCG (Bacille-Calmet-Guerin) vaccine, This is an attenuated vaccine – it contains a live but weakened strain of Mycobacterium bovis .