4.3 Tuberculosis Flashcards
Tuberculosis is cause by the bacterium…
MYCOBACTERIUM TUBERCULOSIS
TB is spread by…
Droplet infection - spread through the air, infected person coughs or sneezes they release tiny droplets of mucus that contain the bacteria, another person breathes in these droplets the bacteria enter their lungs (have to usually be in close contact for long period of time to be infected)
Where is the disease most likely to spread?
When people live in overcrowded, poorly ventilated homes
MYCOBACTERIUM BOVIS infects
Cattle
The infection mainly lies…
Dormant - can become active later on especially if the person is infected with HIV
Most cases of TB affect the…
Lungs - droplets are inhaled and enter the lungs.
After entering the lungs the next stage is…
Development of tubercles - consist of a mass of dead lung tissue surrounding the MYCOBACTERIUM bacteria. The bacteria cannot multiply inside the tubercles due to a low pH and lack of oxygen.
The tubercles are surrounded by many…
Macrophages.
MYCOBACTERIUM is able to multiply inside some of the macrophages which causes the tubercles to grow.
The tubercles may…
Invade the bronchioles and spread to other parts of the lung or the bacteria may enter a blood vessel and cause an infection in another part of the body.
The secondary infection can occur anywhere in the body but usually occurs in the…
Reproductive system Urinary system Bones Joints Lymph nodes Peritoneum (membrane surrounding the body cavity)
Final stages of TB…
Centres of the tubercles begin to liquefy, causes the MYCOBACTERIUM to multiply very quickly. The tissue of the bronchioles die and break open, leaving cavities in the lungs - causes the MYCOBACTERIUM to spread quickly to other parts of the lungs.
Humans can develop TB (mycobacterium bovis) by…
Consuming unpasteurised milk from TB-infected cattle (these cases bacteria usually infect the bones rather than the lungs)
Early symptoms of TB in the lungs…
Develop a mild cough
May feel slightly sick
(Symptoms similar to many other infections of the respiratory system)
Progressed symptoms of TB in lungs…
May cough up small amounts of greenish or yellow sputum, may contain blood
Later symptoms of TB in the lungs…
Slight fever Loss of appetite Mild chest pain Difficulty in breathing Night sweats
If TB spreads to other parts of the body other symptoms may develop such as…
Skin infections
Severe weight loss
What can treat TB?
Modern antibiotic treatment before these severe symptoms develop
How to diagnose TB?
Chest X-ray - shows any infections in the lungs as tubercles show up as shadowy areas
Skin test must be carried out to show the lung infection caused by MYCOBACTERIUM
TB can be detected by?
Administering the MANTOUX or TUBERCULIN test - a protein from mycobacterium (antigen) is injected into the skin, the tissue surrounding the infection site becomes red and swollen, if this areas is greater than 15mm in diameter the person is infected with mycobacterium or has previously been infected.
TB can be treated successfully with…
Antibiotics
If just one drug is given the bacterium is likely to develop resistance so a mixture of 4 different antibiotics is usually given.
However, it is very difficult for the antibiotics to penetrate the tubercles and kill the bacteria - the drugs must be taken regularly for a period of 6 months.
TB can be prevents by a vaccination called the…
BCG vaccination
Risk factors for TB are…
People who are infected with HIV are more likely to develop TB
More people travel internationally , this has spread the disease worldwide
Drug-resistant forms of TB have developed, difficult to treat
More people are homeless and living on the streets or in overcrowded accommodation
Koch showed that Mycobacterium caused TB by using the following set of rules, known as Koch’s Postulates:
1) the microorganism must be found in all organisms suffering from the disease, but not in healthy organisms
2) the microorganism must be isolated from a diseased organism and grown in pure culture
3) when the cultured microorganism is introduced into a healthy organism, it should cause the disease
4) the microorganism must be reisolated from the inoculated diseased organism from stage 3 and be identical to the original microorganism from stage 2
Phagocytic white blood cells called MACROPHAGES…
engulf the MYCOBACTERIUM cells. They act like a ‘shell’ that surrounds the bacteria and keeps them under control.
