Tuberculosis 2 Flashcards
How may TB be diagnosed
TB may be diagnosed by
History taken from patient (describe symptoms to doctor) then a range of tests may be used including skin and blood tests.
How do skin and blood tests work
Skin and blood tests work by
Small amount of tuberculin is injected under skin of forearm.
Positive result shows as an inflamed area of skin around site of test injection. Antibodies in blood cause this inflammation indicating TB antigens are already present. However can give negative result if person has latent TB (disease is not active) and can give false positive if person has BCG vaccine. To overcome this, blood tests have been developed that analyse blood samples for T ells specific to antigens only occurring on M.tuberculosis
What is tuberculin
Tuberculin is name given to extracts from several species of mycobacteria and is usually composed of purified proteins.
How can skin test be confirmed
Skin test can be confirmed by a sample of sputum coughed up by patient is taken and cultured to see what bacteria are present. These bacteria can be identified by staining techniques - depending on make up of cell wall, only some types of bacteria take up particular stains.
How can TB be treated
TB can be treated with antibiotics because active TB bacteria can be killed with antibiotics. Usually a com nation of 4 antibiotic drugs are given for 2 months, with 2 continued for a further 4 months ensure any dormant bacteria are destroyed.
Why may someone’s immune system be reduced
Someone’s immune system may be reduced due to 0-5 years old/old age Malnutrition Poor living conditions AIDS
Why does fever occur in TB patients
Fever occurs because as part of the inflammatory response, fever causing substances are released from phagocytes. These chemicals affect hypothalamus and alter set pint for core body temp to be higher. The raised temperatures enhance immune function and phagocytosis. Furthermore, bacteria and viruses reproduce slower. TB is temperature sensitive and will stop reproducing above 42degrees.
Why can fever be dangerous
Fever can be dangerous because if it is above 42 degrees, enzymes involved in metabolism will denature and cause death.
Why may treatment with antibiotics be ineffective against dormant bacteria in tubercules
Treatment with antibiotics against dormant bacteria in tubercules may be ineffective because Tb bacteria can stay alive within macrophages inside tubercules, so antibiotic treatment may not be able to reach them in tubercules, which are closed off.
