6.2 Tuberculosis Flashcards
What does TB result from ?
Patients with …1.. are more contagious
Patients with ..1.. are particulary contagious due to …2..
For how long can droplet nuclei be suspended in room air for ?
When does contagiousnes decrease rapidly ?
Pathophysiology of TB ? [infection slide has more info !]
What results in the following from exposure to M. tb ?
1. no TB
2. latent TB
3. Active TB
primary progressive TB is known as what ?
macrophages can not contain the bacteria ? i don’t get this !
….1.. significantly facilitates reactivation of TB
e.g. ..2…
- impaired cellular immunity
- HIV infection , immunosuppression , organ transplantation , corticosteroids, TNF-inhibitors
why does impaired cellular immunity significantly facilitate reactivation ?
Reaction to TB is a type 4 (delayed hypersensitivity) reaction which is mediated by T cells
TB typical histological appearance includes what ? [alter!!]
granulomatous necrosis with a caseous histological appearance
define granuloma
inflammatory mononuclear cell infiltrate
define tubercule
round nodule that contains caseous necrosis feature of a granuloma
define ghon focus
small area of granulomatous inflammation primary site of infection by M. tb
define ghon complex
ghon focus with lymph node involvement (hilar lymphadenopathy)
define ranke complex
calcified ghon complex - can see radiologically
difference between primary and secondary TB ?
progression of TB ?
Where is primary complex TB usually seen ?
lower / mid lobes
where in lungs is secondary TB pathology often seen ?
upper regions
M. tuberculosis:
1. full name
2. what it is ?
3. growth speed ?
- mycobacterium tuberculosis
- a bacteria - aerobic , acid fast
- very slow growing - culture can take up to 6 weeks
Confirmation of active TB infection usually done by what ?
- acid fast smear (e.g. Ziehl Neelsen)
- sputum culture
- NAAT such as PCR
Differences between latent and active TB regarding the following
- progression to / progression from
- symptoms
- cellular immune system sufficiently does / does not contain the bacteria
- number of M. tb
- tests
Latent :
1. can turn into A TB
2. asymptomatic
3. does
4. lower
5. tuberculin skin test, IGRA
Active :
1. Either previously from L TB , or from progression of primary infection
2. symptomatic
3. does not
4. higher
5. CXR, sputum acid fast smear, culture , NAAT
Tuberculosis testing Active TB
Possibility of TB should be considered in any person with risk factors fro TB exposure who has suggestive symptoms or chest x-ray abnormalities
List these suggestive symptoms
- fever
- malaise
- pleuritic chest pain
- cough longer than 2-3 weeks
- night sweats
- weight loss
- haemoptysis
- psychological symptoms
- clubbing
- erythema nodosum
what is erythema nodosum?
painful patches of skin that look red or darker than the surrounding skin
Although the presence of upper lobe infiltrates is characteristic of the disease, atypical chest x-ray presentation is common among who ?
- children
- people who are immunocompromised
- have HIV infection
- have diabetes
Chest x-ray features for someone with TB ? [change !]
- opacities in lobe
- multifocal patchy opacities
- ranke complex
- bilateral consolidation in lower zones
- very widespread randomly distributed innumerable tiny nodules in both lungs
Ranke complex is seen in …1. primary pulmonary tuberculosis and is a later manifestation of the …2.. complex.
It consists of two components:
* a Ghon lesion that has undergone ..3…
* an ..4.. node.
- ‘healed’
- Ghon
- calcification
- ipsilateral calcified mediastinal
Miliary TB represents what spread of TB infection ?
haematogenous spread of uncontrolled TB infection
What is Miliary TB ? …. [slide 21/67]
symptoms of miliary TB include what ?
- fever
- chills
- weakness
- malaise
- often progressive dyspnea
With miliary TB intermittent dissemination of tubercle bacilli may lead to what ?
a prolonged fever of unknown origin (FUO)
regarding miliary tuberculosis bone marrow involvement may cause what ?
- anemia
- thrombocytopenia
- leukemoid reaction
miliary TB on CXR …
Symptomatic patient/ suspected active TB investigations after chest x-ray , 3x sputum samples are taken what for?
- acid fast stain
- culture
- PCR (gene Xpert)
sputum acid fast bacilli smear for active TB ……
sputum culture for active TB …….
NAAT for active TB …
Do we always see abnormal chest-X-ray in TB ?
not always , so the 3x sputum samples should still be done !
extrapulmonary TB includes what ?
- Genitourinary TB
- TB meningitis
- TB peritonitis
- Pericardial tuberculosis
- Tuberculosis lymphadenitis
- Cutaneous tuberculosis
- Pott disease
- GI tuberculosis * Liver TB
Other investigations apart to consider with extrapulmonary TB ? [SPLIT THE Q depending on which TB !!]
- Ultrasound, CT, MRI or imaging (Central nervous system involvement, disseminated/ miliary TB)
- Echocardiogram (pericardial TB)
- Biopsy of omentum, bowel, liver or ascitic fluid (GI TB)
- Aspiration of joint fluid or biopsy of joint (Bone TB)
- CSF culture, cytology, microscopy (Miliary/ CNS TB)
- HIV/ Hepatitis B and C testing
If there are clinical signs and symptoms consistent with a diagnosis of TB when should treatment started ?
Immediately started without waitign for cultures
& patient should be referred to a clinican with training in specialised care of people with TB
for people with active TB without central nervous system involvement what is offered for 2 months … [slide 29 alter !]
It isn’t feasible or cost-effective to screen an entire population
For latent TB NICE recommends screening for specific high-risk groups in the UK , who do these groups include ?
- close contacts of patient with TB
- healthcare workers
- immunosuppressed patients (e.g. those with HIV)
- migrants from countries where TB is common
- Mantoux tuberculin skin test (TST) is performed how ?
- when should the skin test reaction be read after administration ?
- by injecting 0.1 mL of tuberculin purified protein derivative into the inner surface of the forearm
- between 48 to 82 hours
Complete the following :
- If the Mantoux is positive ( > 5mm), assess for ..1..
- If Mantoux is positive, but active TB is excluded, consider ..2…
- If interferon gamma release assay also positive, offer treatment for …3…
- active TB
- interferon gamma release assay (IGFA)
- latent TB infection
For those with risk factors, it may be appropriate to treat for latent TB infection after only one positive result (either Mantoux or IGFA) ????
BCG vaccine full form ?
Bacillus Calmette–Guérin (BCG)
What can BCG vaccination cause ?
false-positive Mantoux test
BCG has greates effect in preventing which TB ?
miliary
BCG vaccination efficacy ?
variable- some protective effect against progression to active TB and primary infection
BCG vaccination leaves what ?
a characteristic raised scar which may be proof of previous immunisation
A reactive TST is a contraindication to BCG due to what ?
risk of severe local inflammation and swelling
Before a person receives the BCG vaccine what should they be tested for ?
latent TB infection using the TST
Relationship between doing a TST and giving BCG vaccine ?
- If a patient has a positive TST- refer to TB specialist and do not give BCG
- If the patient is negative they can receive the BCG vaccine
BCG vaccination is recommended for all babies and children <16 who:
- are born in areas of the UK where the rates of TB are high
- have a parent or grandparent who was born in a country where there’s a high rate of TB
- live with, or are close contacts of, someone with infectious TB
- Will travel for more than 3 months in an area with high rates of TB
BCG vaccination is not usually offered to people over the age of 16 because why ?
there is limited evidence of how well the vaccine works in adults
Who is the BCG vaccination not suitable for?
people with HIV, chemotherapy patients, pregnancy, SCID, immunosuppressed or those with malignancy, or infants born to a mother taking immunosuppressants during pregnancy
Which certain groups of patients with latent TB are at increased risk of developing active TB ?
HIV, excessive alcohol, IV drug users, transplant, malignancy, diabetes, immunosuppression.
For people, including those with HIV, aged younger than 65 years with evidence of latent TB offer either which drug treatments ?
- 3 months of isoniazid (with pyridoxine) and rifampicin or * 6 months of isoniazid (with pyridoxine).
contact tracing relation to TB ? [change Q!]
1) Offer screening to close contacts
2) Assess symptomatic close contacts for active TB
3) Consider BCG vaccination for close contacts
Adherence, treatment completion and follow up ….
Multidrug-resistant TB (MDR TB) refers to a strain of TB that is resistant to 2 first-line drugs which are what ?
isoniazid and rifampin
When can drug-resistant TB occur ?
when the drugs used to treat TB are misused or mismanaged
examples of misuse or mismangement of drugs include what ?
- Not completing a full course of TB treatment
- Poor quality drugs
- Drugs for treatment not available
- Wrong dose or length of time
Which people are particularly at risk to drug resistant TB ?
People using homeless hostels, shelters, and day centres, and people living in prison or detention centres,
slide 43..
Imaging is non-specific and often other conditions can have similar appearance on CXR. Examples include:
- URTI (upper respiratory tract infection )
- asthma
- COPD
- lung fibrosis (e.g. sarcoidosis, silicosis)
- lung cancer
slide 45 - don’t need to know but some you’ve probably head of so just to know…
What is leading cuase of death amongst those living with HIV ?
TB
TB screening should be offered to all people with what ?
HIV at diagnosis and HIV testing should be routinely offered to all patients with TB
Approximately …. % of TB cases know their HIV status ?
61
