ALS Lecture 4 - Tuberculosis DONE Flashcards
factors that contribute to a person’s likelihood of contracting TB (4)
homelessness, IV drugs, AIDS, neglect of TB control programs
look at figures from TB lecture
done
TB is concentrated in certain medically underserved populations (6)
urban poor, alcoholics, IV drug users, homeless, prison inmates, people born abroad
TB occurs in
contact-based micro-epidemics
in first few weeks, host has almost no
immune defence against TB
TB bacteria
Mycobacterium tuberculosis
unrestrained bacterial multiplication proceeds for weeks, progressing as (3)
- initial focus
- lymphohaematogenous metastatic foci
- tissue hypersensitivity, cellular immunity
label the diagram of phagocytosis of mycobacterium tuberculosis by macrophages
done
CD4+ cells have a T-cell receptor capable of recognising
TB antigens presented by macrophages1
look at pictures of TB granulomas
done
label the chest x-rays of primary (miliary) and post-primary TB
done
in primary TB (2 steps)
- rapid destruction of bacteria
2. infective process stopped
after primary TB, what would be the only remaining evidence of infection?
positive skin test
miliary TB
blood dissemination of TB
post-primary TB infection usually presents in
immune deficiency, e.g. old age, alcohol
TB becomes reactivated as (2 steps)
- macrophage/granuloma break up
2. bronchial spread as necrosis occurs
extra-pulmonary TB is when TB spreads metastatically to
any organ, e.g. abdomen, bone, brain, muscle
approximately 30% of TB cases are exclusively
extrapulmonary
spinal TB
may cause back pain
kidney TB
blood in urine
specimen collection in TB
3 sputum, smear and culture
bronchoscopy can be done if there is suspicion of
TB, no sputum
method to obtain specimens, especially used in children
gastric aspiration, get swallowed sputum
CEPHAID test detects
TB specific DNA sequences
CEPHAID test is a simple
nucleic acid amplification test
CEPHAID test is easy and so good to do in
developing countries
Heaf test results
bigger the skin reaction (induration), more likely you are to have been exposed to TB
label the diagram of the CEPHAID test
done
label the diagram of Heaf test grades
done
IFN-g tests measure cell mediated immune response by measuring
IFN-g released by T cells in response to stimulation by Mycobacterium tuberculosis antigens
look at the diagram of IFN-g test
done
baseline diagnostic examinations for TB (3)
CXR, sputum specimens, drug susceptibility testing for INH, RIF and EMB
other examinations to conduct when TB treatment is initiated (5)
HIV test, CD4+ test in HIV, HepB, liver tests, colour vision tests
usually in TB, there will be a history of
TB exposure
to find out whether someone has been exposed to TB we can contact the
local health department
in TB, we must always consider
demographic factors
symptoms of TB (4)
productive prolonged cough, chest pain, haemoptysis, systemic symptoms (fever, weight loss, night sweats)
standard view used for the detection and description of chest abnormalities
posterior-anterior radiograph
in pulmonary TB, radiographic abnormalities are often seen in
apical and posterior segments of upper lobe, superior segments of lower lobe (but may be anywhere)
what kind of bacteria is TB?
obligate, intracellular (grows inside macrophages)
how does TB bacteria grow?
slowly
how does TB spread?
airborne droplets, gets to alveolus
Mycobacterium tuberculosis is inhaled, then can be (3 options)
- cleared from body by macrophages, 90%
- heal with scarring, Gohn focus lies dormant
- primary progressive disease in immunocompromised
primary TB reminds me of… because…
shingles, lies dormant and comes back when body is stressed
the risk of TB reactivation is highest in the
first few years post infection
prolonged exposure
increases risk and multiple aerosol inocula required
brief contact with someone with TB carries
little risk
infection is unlikely to occur outdoors as
aerosol disseminates
fomites pose what level of risk?
not huge
caseous necrosis is inherently unstable, especially in the lungs, where it tends to
liquify and discharge through bronchial tree, producing tuberculous cavity
we should consider TB treatment initiation when we have a
positive AFB smear
treatment should not be delayed because of ______ ___ _____ if there is high _____ ____
negative AFB smears, clinical suspicion
high clinical suspicion includes (3)
history of cough/weight loss, CXR findings, emigration from high-incidence country
label the 1st line TB drugs mechanism of action diagram
done
first line drug treatments in TB are (6)
Isoniazid, Rifampin, Pyrazinamide, Ethambutol, Rifabutin, Rifapentine
Isoniazid MOA
targets cell wall synthesis
Rifampin MOA
inhibits RNA
Ethambutol MOA
targets cell wall synthesis
first 2 months of Tb treatment
rifamycin (or Rifampicin/Rifabutin) + isoniazid + pyrazinamide + ethambutol
in the next 4-7 months after the first 2
rifamycin + iosoniazid
in TB treatment we give a _____ supplement, e.g. ____
B6, pyridoxin
rifampin turns bodily secretions _____, which is good for ______
orange, monitoring
groups at increased risk for drug-resistance TB include (5)
- history of TB treatment
- contact with person with drug-resistant TB
- foreign-born persons from areas with drug-resistantTB
- smears positive despite 2 months of drugs
- inadequate treatment for >2weeks
multi-drug resistant TB is defined as being resistant to (2)
isoniazid, rifampicin
multi-drug resistant Tb can be due to (5)
poor compliance, single drug therapy, poor calculation, malabsorption, prescribing errors
extensively drug resistant TB (XDR TB) is resistant to
any fluoroquinolone, at least one injectable second-line drug (capreomycin, kanamycin, amikacin), plus MDR-TB
TB is the main opportunistic infection for
HIV positive patients
look at the table and diagram of map TB
done
