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MBBS VI - SpC - Medicine > Resp - TB (II) > Flashcards

Resp - TB (II) Flashcards

1
Q

Tuberculosis:

Route of transmission?

A

Airborne - Inhale mycobacteria into lungs

Other routes:

  • Inoculation
  • Oral route
  • Organ transplant
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2
Q

Difference between infection and disease?

Difference in TB infection and active disease?

A

Infection:
- Invasion and multiplication of micro-organism not normally present in the body

Disease:
Condition of abnormal vital function involving any structure, part, or system of an organism
Set of signs and symptoms

only 10% of TB infections become active disease

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3
Q

4 outcomes in MTB infection

A

Inhalation of MTB
a) Immediate killing

b) Host-TB interaction: Primary complex
i) Localized disease (Primary TB)
ii) Dissemination of TB (Active disease)
iii) Containment (Latency)

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4
Q

Lifestyle risk factors for TB

A

Smoking and Alcohol
Socioeconomic: Stress, poverty, malnutrition
Drug addiction

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5
Q

Immunosuppression risk factors for TB

A 
DM 
HIV 
Cancer and chemotherapy 
Hematological malignancies 
Bone marrow transplant 
Solid organ transplant 
Drugs: Steroids, immunosuppressants, biologics
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6
Q

General host risk factors for TB

A

Genetics
Young or Old
Pregnant

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7
Q

Symptoms and signs of Pulmonary TB

TB infection = symptomatic?

A 
Prolonged cough 
Sputum 
Hemoptysis
Fever
Night sweat 
Weight loss 
Shortness of breath

** TB can be asymptomatic ***

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8
Q

3 different presentations of Pulmonary TB infection?

A
  • Acute presentation, pneumonia-like
  • Classic pulmonary and systemic symptoms and signs over time
  • Asymptomatic
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9
Q

Proportion of pulmonary vs extrapulmonary TB in HK?

A

Pulmonary = 75%

Extra pulmonary = 20%

Both = 5-10%

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10
Q

3 prong method to diagnose extrapulmonary TB

A

High index of clinical suspicion

Microbiological examination of fluids, biopsies

Pathohistological exam: granulomatous inflammation, ZN stain

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11
Q

2 reasons why extrapulmonary TB is difficult to Dx early?

A

TST/ IGRA not sensitive for specific enough for Dx

Specimen for microbiological studies (pleural fluid, CSF…etc) may be hard to obtain

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12
Q

Most common form of extra-pulmonary TB?

Pathogenesis?

A

Pleural TB

Breakdown of sub-pleural TB foci into pleural space&raquo_space; inflammatory response&raquo_space; pleural effusion develops

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13
Q

List 4 tests on pleural fluid for Dx of Pleural TB

A
  • Microscopy: high lymphocyte
  • AFB staining: High failure, mostly negative
  • AFB culture: High failure, Positive in < 1/3
  • Adenosine deaminase ** Gold Standard for pleuritis **
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14
Q

2 methods of pleural biopsy

A

closed pleural biopsy - Abraham needle

Pleuroscopy

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15
Q

TB Lymphadenitis.

- Clinical presentation

A

Gradual, painless enlargement of cervical LN over weeks

Overlying skin becomes shiny and thin, erythematous, fluctuant from abscess formation

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16
Q

Empirical TB treatment started upon FNA Dx of TB Lymphadenitis, but the cervical LN grows even more fluctuant and pustular.

Explain

A

Intense inflammation and abscess formation because of disrupted mycobacterial antigens released from dead bacilli

Normal, does not signify treatment failure

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17
Q

Methods to obtain cervical and mediastinal LN specimen

A

Cervical: FNAC

Mediastinal: Transbronchial needle aspirate

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18
Q

Definite Dx of TB Lymphadenitis

D/dx?

A
  • Demonstrate MTB in LN aspirate: +ve AFB stain
  • Pathohistological: Granuloma with caseous necrosis +/- AFB
  • Positive TST

D/dx:

  • Metastatic LN (e.g. NPC)
  • Lymphoma
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19
Q

Most common form for CNS TB infection?

A

TB meningitis

Common cause of neurological deficit in pediatric patients before

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20
Q

Presentation of CNS TB infection.

A 
Headache, Poor sleep
Fever
Convulsion 
Focal neurological deficit 
Impaired conscious state

CSF tap:

  • High protein, low glucose
  • PCR +ve
  • AFB culture
  • High opening pressure
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21
Q

MRC Staging for CNS TB infection?

A

1: Non-specific symptoms without changes in consciousness levels (apathy, fever, nausea, vomiting…etc)
2: Disturbed consciousness +/- focal neurological signs, Not comatose or delirious
3. Stupors (almost unconscious) or coma +/- focal neurological signs

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22
Q

2 methods to Dx CNS TB Infection

A
  • CT/ MRI brain

CSF tap:

  • High protein, low glucose
  • Lymphocytic pelocytosis (PMN at early stage)
  • TB- PCR ***
  • AFB culture
  • High opening pressure
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23
Q

Management of CNS TB infection (3)

A
  • Anti-TB drugs
  • Adjunctive steroids: anti-inflammatory to decrease ICP, prevent meninges scarring
  • Surgical drainage of obstructive hydrocephalus. excision of tuberculoma, Biopsy for Dx
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24
Q

Cause of Miliary TB?

Presentation?

Confirmation of Dx?

A

Haematogenous spread of TB to any organ

Presentation: Non-specific fever, lethargy, weight loss, cough
X-ray shows tiny millet-like shadowing

Dx: Biopsy and histology of organs involved

25
Q

Genital TB- Female

  • Typical presentation
  • D/dx?
A 
Abdominal pain 
Irregular menses 
Pelvic mass 
Ascites 
Infertility 
(3/4 normal CXR)

GREAT MIMIC OF GYNAE MALIGNANCY

26
Q

Explain why genital TB is a great mimicker of Gynaecological malignancies.
How to differentiate?

A

PET-CT shows abnormal signals compatible with CA

CA125 marker for CA ovary also elevated in TB

Endometrial aspirate for AFB culture/ biopsy by laparoscopy

27
Q

Genital TB- male

  • Typical presentation
  • Dx method?
A 
Scrotal swelling 
Sterile pyuria 
Hematuria 
Dysuria 
Infertility

Dx:

  • Early morning urine for AFB culture and TB- PCR
  • Semen for AFB culture and TB- PCR
  • Biopsy
28
Q

5 forms of cutaneous TB

A

TB verrucosa cutis

Lupus vulgaris

Scrofuloderma

Miliary TB abscessus

Tuberculid

29
Q

Feature of TB Verrucosa cutis? Location?

A

Direct inoculation of TB into skin

Purple/ brown warty growth

Knees, elbows, hands, feet, buttock

30
Q

Feature of Lupus vulgaris

A

Persistent and progressive cutaneous TB

Face

31
Q

Feature of scrofulderma

A

Extension of underlying TB LN, bone, joint

32
Q

Feature of Miliary TB abscessus

A

Micro TB abscess

From blood spread of TB

33
Q

Tuberculid features

A

Strong positive TST
Erythema induratum
Papulonecrotic tuberculid

No identifiable focus of active TB in skin

34
Q

Which form of TB is associated with high incidence and high mortality in the elderly?

A

Extensive pulmonary TB

35
Q

Risk factors of extensive pulmonary TB in elderly?

A

Comorbidities: malnutrition, immunosuppressive states

Smokers

Aging - decline in cell mediated immunity

Socio-economically deprived = late presentation and Dx

36
Q

Effect of TB on under 65 and over 65 years old? (presentation, CXR differences?)

A

Over 65:

  • Lower body weight
  • Less hemoptysis
  • Lower serum albumin
  • Less upper lobe infiltration on CXR
  • More extensive infiltration of both lungs / lower zone involvement
37
Q

Why is Cryptic miliary TB so hard to Dx?

think presentation, investigations

A

Insidious onset with non-specific symptoms

Symptoms presumed due to chronic disease or tumours

CXR: miliary shadows not obvious
Sputum: AFB negative
TST: negative

> > > Dx often very late or missed

38
Q

Definitive Dx of Cryptic Miliary TB?

When to suspect Cryptic TB?

A

Bone marrow and liver biopsy

50% Dx post-mortem

Suspect in all cases of PYREXIA OF UNKNOWN ORIGIN

> > start treatment even without definitive evidence

39
Q

5 risk factors for missed TB diagnosis.

A
  • Female
  • Ongoing malignancies (except lung cancer)
  • Old-age home rest
  • Drug abuse
  • CXR not done when alive
40
Q

Challenges in Dx of TB in young patients under 5?

A
  • Extra-pulmonary involvement common
  • Symptoms and signs not specific
  • Hard to get good quality specimen for exam
41
Q

Presenting features of TB in the very young?

A

Failure to thrive
TB contact
Persistent cough and fever
Extra-pulmonary TB symptoms

42
Q

Common forms of TB in children?

A

TB lymphadenopathy
Miliary TB
TB meningitis
Pleural TB

Abdominal TB (peritoneal)
Osteoarticular TB
Pericardial TB

43
Q

3 iatrogenic causes of immunosuppression

A

Systemic steroids

Immunosuppresion by drugs: transplant, auto-immune diseases, chemotherapy, biologics

Gastrectomy

44
Q

4 challenges in management of TB in immunosuppressed?

A
  • Lots of medication
  • Potential drug interactions: Rifampicin = potent CYP450 inducer
  • Additive drug toxicity to liver, kidneys, bone
  • Change in primary disease management, need isolation
45
Q

How to manage SLE patient intolerant to TB treatment?

A

High dose prednisolone to control SLE and allow TB drugs to work

46
Q

Describe the bi-directional interaction between HIV and TB

A

HIV cause immunosuppression = TB reactivation and progress

TB lesions release pro-inflammatory cytokines to increase HIV viraemia

> > > High mortality with co-infection

47
Q

Classical presentation of HIV + TB infection

A

Early stage: Haemoptysis + Upper zone lesions with cavitation, Positive TST

Severe stage: Less* hemoptysis, No zonal lesions, no cavitation, more extrapulmonary disease (LN, abdomen, CNS…etc)
Negative TST

48
Q

Which biologics is associated with high risk TB infection? Explain.
Example of diseases treated by this drug?

A

Anti-TNF Biologics (Infliximab, Etanercept)

TNF = mediator for granuloma maintenance to contain TB infection

E.g. RA, Inflammatory bowel diseases, Ankylosing spondylitis

49
Q

Procedure for TB prevention before starting biologics treatment

A
  • Screen for active and latent TB
  • Active TB = treat with standard regimen before starting biologics
  • Latent TB = Isoniazid for 9 months
50
Q

NTM:

  • Source
  • Transmission
A
  • Environment: Animal, Soil, Food, Water

- Transmission: environment acquired

51
Q

Virulence of NTM?

  • Are all NTM infectious?
  • Host factors that predispose NTM infection?
A

Only some NTM species cause infection, different strains within species have different virulence

Host factors

  • Host immunity
  • Lung disease
  • Esophageal motility disorders
  • Body morphotype
52
Q

Definitive Dx of NTM?

A

Molecular Dx:

  • Negative TB - PCR to rule out TB
  • Gene sequencing for NTM
53
Q

< cards about NTM causing resp. skin/ soft tissue, LN, Disseminated infection >

A

< TBC >

54
Q

4 major clinical manifestations of NTM lung diseases?

A
  1. Infection in previously damaged lungs
  2. Primary lung disease (middle aged or elderly)
  3. Hypersensitivity like disease
  4. Lung infection in immunocompromised patient: primary lung or disseminated
55
Q

Clinical presentation of NTM infection in previously damaged lungs?

CXR feature progression

A

Non-specific respiratory and constitutional symptoms

Progression of diseased and scarred lungs

Worsening radiological features

56
Q

Clinical presentation of NTM infection as primary lung disease in middle aged or elderly

CXR, CT features

A

Chronic cough and sputum

CXR: nodular shadowing at Mid and lower zones (unlike typical TB at apical regions)

CT thorax: Small airway inflammation as centrilobular nodules + bronchiectasis

57
Q

Clinical presentation of NTM infection as hypersensitivity like disease in lungs

Source of infection

A

Hypersensitivity pneumonitis with allergic type host response to NTM

  • Subacute cough, SOB, fever, respiratory failure
  • Nonspecific infiltrate and nodules

Hot Tub Lung: inhale mycobacteria in indoor spa bath, pool or shower

58
Q

Hypersensitivity like disease by NTM infection of lungs.

  • CT features
  • CXR features
A

Nonspecific infiltrate and nodule in CXR

CT thorax: GGO and mosaic pattern + nodules and consolidations

59
Q

Clinical presentation of NTM infection in immunocompromised?

Radiographic features?

Culture?

A
  • Variable, non-specific respiratory symptoms
  • Rapidly deteriorating if severely immunosuppressed
  • Non-specific radiographic features: consolidation, nodules, cavities, GGO
  • Mycobacteraemia (blood culture +ve)

MBBS VI - SpC - Medicine (80 decks)

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