PBL 8 Flashcards
What is the definition fo sputum test
a sputum culture is a sample of substance that comes up form the chest when you have an infection in your lungs or airways
what does CCDC stand for
- Consultant in Communicable Disease Control
what are the risk factors of TB
- Infection with HIV
- Diabetes mellitus
- Low body weight
- Head or neck cancer leukemia
- Some medicial treatments including corticosteroids or certain medianction
- Silicosis
- Country or area with high levels of TB
- Prolonged close contact with someones who is infected
- Living in crowded condition
- Very young or very old
- Poor diet
- drug use such as cocaine
what are the signs and symptoms of TB
- persistent cough
- night sweats - faisal is drenched in sweat when he wakes up
- swollen lymph gland in both axillae
- high temperautre
- lack of appetite and weight loss
- extreem tiredness and fatigue
- coughing up blood
outside the lungs
- Persistently swollen glands
- Abdominal pain
- Pain and loss of movement in an affected bone or joint
- Confusion
- Persistent headache
- Fits
name the 4 classical symptoms of tb
■■ Cough lasting more than three weeks
■■ Unexplained weight loss
■■ Low-grade fever
■■ Night sweats
what is TB caused by
caused by a slow growing Mycobacterium tuberculosis. which forms granulomas in the lungs - can form a gohn focus in the lungs
what is a mycobacteria
non-spore-forming bacilli that are obligate pathogens (must cause disease to be transmitted from one host to another and cannot live external to the host
What types of TB are there
- Pulmonary TB = most common affects the lungs
- Non/extra – pulmonary TB – there are other forms of TB which impact the lymph nodes, bones and joints, kidneys, brain and gut and skin – usually non-infectious
also
- latent TB
- active TB
describe acid fast bacilli
- recognised by intense staining with aniline dyes (carbol-fuchsin) as well as being resistant to decolouration with acid washing (become red in acid)
• Extended Incubation required (usually 2-8 weeks).
o Sometimes difficult to diagnose quickly
Invention of the PCR has helped this significantly.
what is the bodies defect against TB
Gohn focus
- macrophages ingest TB, fail to kill it
- the centre is called a ceasseous necrosis
- round that is a ring of macrophages that are trying to kill TB
- then round this is the lymphocytes that are protecting the circle fo macrophages to make sure that the TB dos not escape
- then round this is a layer of calcium
- then round that is a layer of fibroblasts
- Macrophages ingest the bacteria in the alveoli of the lung when then try to destroy the bacillia
- Wall of M.tuberculosis, this is thicker than most others – macrophages in unable to destroy
- It is hydrophobic waxy and rich in mycolic acid and maculates
- Bacteria lie dormant in the macrophages
- Can enter the pulmonary lymphatics and are found initially in the liver, spleen, brain or bone marrow after entering the vascular system
name the 4 ways of diagnosing TB
- Mantoux skin test
- microbiological tests
- chest x ray
- histological examination of biopsy specimens
describe what you would see in a Mantoux skin test
get a circular lump between 1-12mm
describe what you would see in a chest x ray of someone with TB
- cavitation,
- calcification,
- hilar shadowing,
- opacities,
- nodular appearance
- opacities
describe what the microbiological stain of the sputum would look like
- Ziehl-Nielson (ZN) stain = stains the bacilli red.
- Aurarmine stain = is even more sensitive.
- • Bacteria appear bright orange in
- fluorescent microscope.
- Lowenstein-Jensen.
- o PCR = can be used for rapid detection (within 48 hours) with
- sputum specimen (as well as testing its resistance
describe what you would see on a histological examination of TB
o H&E = caseating granulomas (with multi-nucleate Langerhans giant cells)
how is TB spread
- Spread through the air
- When people with infectious open pulmonary TB cough sneeze
- If another person rebaths this in they can become infected
- Poor housing, poverty, and overcrowding can help the transmission
what are the 4 main antibiotics given
RIPE
- rifampicin
- isoniazid
- pyrazinamide
- ethambutol/streptomycin
describe the 4 main antibiotics given
- Rifampcin – make tears and uring organ coloured, normal
- Isoniazid – continued for 4 months, discontinuoued if resistance, give with vitamin B6
- Pyrazinamide – given for 2 months
- Ethambutol/streptomycin – two months stopped if TB isolated is fully susceptible to other drugs
what are the side effects of
- ethambutol
- isoniazid
- rifampicin
o Vision Changes (ethambutol) = vision can recover if stopped quickly o Neuropathy (isoniazid) = numbness and tingling in arms/legs
Antibiotics also interact with other drugs (such as rifampicin which interacts with oral contraceptives). Anti-Tb
treatment is very difficult during pregnancy as both the mother and the baby are at risk.
• Different doses are given in pregnancy.
what are some general side effects of the antibiotics
1/100 have very abnormal tests (symptoms of jaundice, fever, generally unwell).
• Minor Side Effects: nausea and vomiting are very common.
what is multi drug resistance TB resistant to
Resistant to Rifampicin and Isoniazid
• Patient must take second and third line anti-TB drugs (more toxic, less effective).
what are the mortality rates in multi drug resistant TB
Mortality rates can be as high as 40-50%, rising to 80% in patients with co-infection of HIV.
• Strict guidelines are in place to control transmission
describe the TB and HIV co-infection
• The recent rise in TB has been mainly due to HIV (1/3 rise in TB causes especially in sub-Saharan
Africa). TB is also more difficult to diagnose in people who are HIV-positive.
• TB and HIV act synergistically.
o Reactivation rates much higher in HIV-infected individuals.
how do you prevent TB
• Vaccination with BCG = is about 70% protective.
• Contact Tracing = all close contacts of people with infectious TB are seen and treated promptly, toprevent TB disease from developing. Also, those in high-risk groups (infants, people on steroids etc…)
o Preventative theraphy = chemoprophylaxis (usually + isoniazid, sometimes with rifampicin).
• Identifying and treating all people with TB disease = non-infections after 2 weeks (first-line treatment)
why does multi drug resistant TB occur
mismanagement of TB treatment
person-to-person transmission
what is multi drug resistant TB
Multidrug-resistant TB (MDR TB) is resistant to more than one anti-TB drug and at least isoniazid (INH) and rifampin (RIF).
how do you treat multi drug resistant TB
fluoroquinolone antibioti
- but this has many side effects
