Tuberculosis Flashcards
pathognomonic of miliary TB
choroidal tubercles
most common site of GI TB
ileum and terminal cecum
gold std of TB meningitis
CSF culture (Positive in 80%)
CNS TB contrast enhanced ring lesions
tuberculoma
induced by ESAT-6
MMP9 (recruits naive macromphages)
most potent risk factor for TB among affected individuals
HIV co infection
host responses that develop 2-4 weeks after MTB infection
1) macrophage-activating response
2) tissue damaging response
antigens of MTB that play a protective role
20kDa or 85B
ESAT-6
size of MTB
0.5 x 3 um
exacerbation in s and s in lab and xray manifestations of TB in adminisration of ART
Immune reconstitution inflammatory syndrome (IRIS)
when does IRIS occur
1-3 mos after administration of ART
patho IRIS
immune response elicited by antigens as bacilli are killed (in an improving immune function)
First priority in face of IRIS
ensure that this is not a failure of TB treatment, or development of another infection
Recommended daily dose
Isoniazid
5 mg/kg
max 300 mg
Recommended daily dose
Rifampin
10 mg/kg
max 600 mg
Recommended daily dose
Pyrazinamide
25 mg/kg
max 2 g
Recommended daily dose
Ethambutol
15 mg/kg
Age: highest incidence of TB
late adolescence
early adulthood
Molecular mechanism by which M tuberculosis induces granuloma formation
Mycobacterial protein ESAT-6
Two types of cells essential in the CMI response to TB
1) macrophages
2) T cells
The Ghon focus
Lesion forming after initial TB infection which is peripheral and accompanied by transient hillier or paratracheal lymphadenopathy
Ghon complex
Ghon focus with or without overlying pleural reaction and thickening and regional lymphadenopathy
Location of Post primary (Adult type) Tb disease
Apical and posterior segments of the upper lobes
**Superior segments of the lower lobes
“consumption”/ “phthisis”
classic galloping consumption of the past in TB
Most common presentation of extra pulmonary TB in both HIV seronegative and HIV patients
Tuberculous lymphadenitis
Most common location of Lymph node TB
posterior cervical and supraclavicular sites
% of Lymph node TB with concomitant pulmonary TB
50%
Culture positivity of Lymph node TB biopsy
70-80%
20% of extra pulmonary TB cases in US
pleural Tb
Most common complication of pulmonary TB
tuberculous empyema
Pleural fluid tests MTB
Adenosine deaminase
Interferon gamma
10-15% of extra pulmonary TB
geunitourinary TB
Frequency of abnormal urinalysis results in genitourinary TB
90% abnormal
10% of pulmonary TB
Pott’sdisease
Most common site of spinal TB in children
Thoracic
Most common site of spinal TB in adults
Lumbar
first affected in port’s disease
anterior superior of inferior angle of the vertebral body
Catastrophic complication of Pott’s disease
paraplegia
5% of extra pulmonary TB in the US
TB of the CNS
Uncommon extra pulmonary TB, only 3.5% of extra pulmonary cases
GI TB
Case fatality rate of pericardial TB
40%
This is pathognomonic of military TB in 30% of the cases
choroidal tubercles
Miliary TB rare presentation seen in elderly, chronic course with intermittent fever, anemia, meningeal involvement preceding death
a) cryptic miliary TB
b) nonreactive miliary TB
cryptic miliary TB
Acute septicaemic form of military TB due to massive hematogenous dissemination of the tubercle bacilli
a) cryptic miliary TB
b) nonreactive miliary TB
nonreactive miliary TB
less common extra pulmonary form of TB which is a soldering disease with nodules plaques and fissures
Lupus vulgaris
Where does tuberculous mastitis spread from?
retrograde lymphatic spread from the axillary lymphatics
Tb is responsible for ___% HIV related mortality
24%
Exacerbations in systemic or respiratory signs and symptoms signs and lab or radiographic manifestations of TB
IRIS or TB immune reconstitution disease
% HIV infected patients where IRIS occurs
10%
First drug for TB
streptomycin
Introduction of this drug shortened TB course to 12 months
Rifampicin
Discovery of this drug allowed the TB treatment course to be 6 months
Pyrazinamine
Rx hyperuricemia and arthralgia caused by pyrazinamide
ASA
Resistance due tours gene
aminoglycosides resistance
First line drug for ART for TB patients
2 NRTI
1 NNRTI
TB regimen for pregnant women
2 HRE (pyrazinamide contraindicated) 7 HR
why is streptomycin contraindicated in pregnancy
8th cranial nerve damage to the foetus
Units of PPD for TST
5 tuberculin units
Cut off PPD of low risk persons
> 15 induration
Cut off PPD is >=5
HIV infected Recent contacts of patient with TB Organ transplant patient Persons with fibrotic lesions consistent with old TB Immunosuppressed HR medical conditions
Treatment of latent TB
9 months isoniazid
Treatment of TB intolerant to Z
2HRE 7 HR
Treatment of TB relapses and treatment default with pending susceptibility testing
3HRZES 5HRE
define treatment failure
when sputum is positive after 3 months treatment
Mechanism for congenital TB
1) transplacental
2) drinking of amniotic fluid
2 extrapulmonary TB sites where adjunct steroids are given
Pericardial TB
TB meningitis
Gold standard for TB meningitis
CSF culture
Pathyphy of pleural TB
hypersensitivity response to MTB antigens
Acid fast Bacilli organisms other than mycobacteria
Isospora Crytosporidium Nocardia Rhodococcus Legionella