Tuberculosis Flashcards
What is granuloma
Granuloma is a collection of macrophages formed during inflammation, frequently occur in lungs
What is an obligate aerobe
Obligate aerobes are organisms that need 02 to grow because they can’t ferment or respire anaerobically.
What is a tubercule
Tubercule is a type of granuloma produced in tuberculosis, they are anaerobic and have dead bacteria and macrophages in the middle.
How does mycobacterium tuberculosis cause tuberculosis
TB is transmitted when mycobacterium tuberculosis is carried in droplets of mucus and saliva when an infected person talks, coughs or sneezes. Others then inhale the droplets (this is droplet infection). In lungs, bacteria are taken up by phagocytes. The bacteria survive and replicate inside phagocytes. Immune system seals off infected phagocytes in tubercules. When this happens, bacteria become dormant and infected person shows no symptoms. Dormant bacteria may become deactivated and overcome immune system, causing TB. This is more likely in people with weaker immune systems e,g AIDS.
How does TB spread
TB spreads by droplet infection, it is carried in droplets of mucus and saliva released into air when infected person talks, coughs or sneezes. Others then inhale droplets. Droplets can stay suspended for several hours in air and can survive as dust as dried droplets for weeks as M.tuberculosis is a very tough bacterium.
What is the 1st phase (primary infection) of TB
1st phase of TB is when infection occurs, M.tuberculosis bacteria are inhaled and lodged in lungs where they multiply. Inflammatory response by host’s immune system occurs and macrophages engulf bacteria. Tubercules form in response to infection and contain dead bacteria and macrophages in centre. After 3-8weeks infection is controlled and infected region of lungs heals.
Why is M.tuberculosis a tough bacterium and what may happen overtime
M.tuberculosis has very thick, waxy cell walls which makes destruction in macrophages very difficult so some M.tuberculosis bacterium survive in macrophages (tubercules, which are dormant).
Overtime, mutations may occur to evade immune system e.g change in shape of receptor (evolution by natural selection), ability to use different food sources, ability to infect cells more easily
What is the 2nd phase (active tuberculosis)
2nd phase occurs if there are too many bacteria for immune response to deal with or if an old infection breaks out because immune system isn’t functioning properly. Bacteria multiply rapidly and destroy lung tissues, creating cavities. Lung damage will eventually kill sufferer if they’re not treated with appropriate antibiotic.
What happens when an individual is infected with TB and left untreated
When an individual is infected with TB and left untreated, it leads to initial symptoms including fever, weakness and severe coughing caused by inflammation of lungs. As TB progressed it damages lungs and can cause respiratory failure. TB can spread to other parts of body leg brain and kidneys.
How can TB reduce antibody production
TB can suppress T cells which reduces antibody production and attack by T killer cells.
