TB Flashcards
(31 cards)
TB - transmission
Droplet aerosol - inhalation of droplet nuclei [phagocytosis by alveolar macrophage]
-Humans are only reservoir
TB - highest burden countries
8 countries have 68% of global cases:
India, Pakistan, DRC, Nigeria, Bangladesh, China, Indonesia, Philippines
TB - determinants of disease
Undernourishment [RATIONS study]
HIV
Alcohol use disorder
Smoking
DM
TB - methods of infection control
Administrative controls:
-Triage people
-Respiratory separation
-Effective TB treatment
-Respiratory hygiene
Environmental controls:
-Mechanical ventilation 6-12 ACH, negative pressure
-Natural ventilation
-Germicidal UV systems
Respiratory protection:
-Particulate respirators
TB pleuritis - effusion fluid
Exudative effusion:
0.5-5 leucocytes/ml
Protein >30g/l
pH 7.3
Slightly lower glucose
Miliary TB - lab findings
Cytopenia
LFTs
SIADH [adrenal]
Low albumin
Urinalysis - proteinuria, sterile pyuria [culture negative, leucocyte positive]
TB spondylitis - presentation
Thoracolumbar > cervical - often multiple vertebral bodies
Cold abscess [psoas sign] = avoid drainage
TB spondylitis - treatment
Medical
Surgery = only if spinal instability
TB meningitis - CSF
Mildly elevated cell count
Lymphocytes - 1/3rd predominance of neutrophils
Elevated protein
Low glucose
TB meningitis - drug CSF penetration
Higher in isoniazid and pyrazinamide
Lower in rifampicin and ethambutol
Differential diagnosis of subacute meningitis
TB meningitis
Cryptococcal meningitis
Endemic mycoses
Listeriosis
Leptospirosis
Mycoplasma
Syphilis
Scrub typhus
Murine typhus
Toxoplasmosis
TB - diagnosis
Microscopy - sputum smear:
-Acid fast bacilli
-Needs 1,000-10,000 bacilli/ml sputum
Culture:
-Slow = 4-8 weeks on solid, 3-6 weeks on liquid
-Solid [Lowenstein Jensen] or liquid
-Can detect 10-20 baccili/ml
PCR - Gene Xpert
Antigen detection:
-LAM antigen in urine [better in HIV patients]
TB - diagnosing drug resistance
Phenotypic [culture] - drug susceptibility testing [DST]
-Takes 7-21 days
-Need to have cultured
Genotypic [molecular]
-Xpert = rifampicin resistance rpoB gene
-Line probe assay
-Whole genome sequencing on cultured MTB
TB - activity of drugs
Early bactericidal phase = isoniazid
Sterilisation phase = rifampicin, pyrazinamide
Role of ethambutol = prevent resistance in unrecognised baseline isoniazid resistance
Rifampicin - SE
Discolouration of bodily fluids
Hypersensitivity - rash, fever
Hepatotoxicity
Isoniazid - SE
Peripheral neuropathy - prophylactic pyridoxine [vit B6]
hepatotoxicity
Pyrazinamide - SE
Hepatotoxicity - most hepatotoxic
Arthralgia
Ethambutol - SE
Hyperuricaemia
Optic neuritis
DILI - when to stop drugs
> ALT x3 ULN if symptomatic or bili >x2 ULN
> ALT X5 ULN if asymptomatic
TB - duration of treatment for pulmonary and extra-pulmonary TB
2 month RHZE intensive
4 month rifampicin and isoniazid continuation phase
TB - duration of treatment for TB meningitis
2 months quadruple therapy
10 months continuation phase
TB IRIS - timing of ART
CD4<50 = start ART
CD4 >200 = can usually complete TB treatment course prior to ART
Drug resistant TB [DR-TB]
TB disease caused by a strain of M tuberculosis complex that is resistant to any TB medicines
Multidrug resistant TB [MDR-TB]
Resistant to rifampicin and isoniazid
