Infectious TB Flashcards
Most common and important myco
M tuberculosis
TB transmission
droplet nuclei
Higher probability of infection in
intimacy and duration of contact
degree of infectiousness of case
shared environment of contact
Most likely to transmit infection
Smear +
Cavitary disease
Laryngeal TB
Non infectious TB
Culture negative
Extra pulmonary TB
Clinical illness directly follows infection
Children and first few years of life
Severe
Non high transmissibility
Primary TB
Reactivation after bacteria has persisted for years
More infectious because of cavitation
Secondary TB
LN Pleura Genitourinary tract Bones and joint Meninges Peritoneum Pericardium
Extrapulmo TB
Tb pathogenesis
Microorganism inhaled by close bystander Majority trapped in upper airway <10% reach alveoli Phagocytosis by resident mac Initiated T cell dysregulated response
A patient who presents with symptoms and signs of TB (radio finding) even without active sx
Presumptive TB
A patient from whom a biological specimen is positive by smear microscopy culture of GeneXpert
Bacteriologically confirmed case
Patient who does not fulfill criteria of bacteriologically confirmed TB
Dx if started on treatment
Clinically diagnosed TB
Cough at least 2 w duration
Unexplained cough of any duration with close contact of known TB case
Chest Xray findings suggesive of TB with or without symptom
Presumptive TB
Presumptive TB sc
cough any duration Weight loss Fever Hemoptysis Chest pain not musculo Body malaise Easy fatigability Night sweat Shortness of breath
Proper way of collecting sputum
Spontaneous expectoration
2 sputum specimen at least 1 tsp 5-10ml in quanitity
Same day spot-spot strategy using 2 consec specimens collected 1 hr apart for Zirl Neelsen
Preferred type of microscope
LED
more sensitive and specific
DSSM +
if at least 1 sputum positive
GeneXpert requested if
Initial diagnostic in adult with presumptive TB
As follow on test to smear negative px but with chest xray finding suggestive
An initial dx test for presumptive drug resistant case
Gold standard for dx
TB culture
Culture if
Retreatment
Treatment failure
Known drug resistant
Patient never been treated for TB or has taken anti TB drug for less than 1 month
New case
Prophylactic tx
Isoniazid
Previously treated, declared cured or tx complete at end of most recent course but now dx with recurrent episode of TB
Relapse
Previously tx but declared failed to tx
Treatment failure
Previously tx declared lost to follow up at end of most recent course
Tx after lost to ff up
New pulmonary tb
New miliary tb
New EPTB except CNS bones or joint
Category I
2HRZE/4HR
CNS TB, TB of bone and joint
Class Ia
2HRZE/10HR
Retreatment of Rif susceptible PTB and EPTB except CNS/bones/joint
Category II
2HRZES/1HRZE/5HRE
Retreatment of rif susceptible CNS, bones or joint
Category IIa
2HRZE/1HRZE/9HRE
Pyrodoxine deficiency
Isoniazid
Rifampin
Urine discoloration
Pyrazinamide
Hepatotoxicity
Hyperuricemia
Ethambutol
Optic neuritis
Streptomycin
Ototoxicity
Repeat DSSM
clinically dx and baceriologically confirmed with first line
At least 1 smear at end of 2 months
Repeat after 3rd month if positive at 2nd month
Considered non infectious if
Bac confirmed no resistance rf
14d doses of tx with sputum conversion and clinical improvement
If clinically dx and no risk factor for drug resistance, px is non infectious after
5 daily doses with clinical improvement
anti TB drug that does not cause hepatitis
ethambutol
Isoniazid causes
Hepatitis
Peripheral neuropathy
Rifampicin can cause
Hepatitis
Asymptomatic jaundicr
Red stained urine
TST is + (latent) in low risk if tr size is
> /= 15 mm
TST + in >/= 5mm if
HIV
Recent contact
Organ transplant
Immunosupressed
TST is read after
48-72 hours
Read induration and transverse diameter
Most common extrapulmonary tb site
on the
lymph nodes
cervical area
scrofula
Mc site of primary TB in children
mid, lower part of upper lobe, apex of lower lobe
Most common site in secondary
Apex
Caseaous necrosis is caused by
phosphatide
Caseous necrosis virulence factor
cord factor
trehalose dimycolate
How long is treatment of Category Ia
1 year
Category Ia tx
2HRZE/10HR
1 - 1.5cm gray white inflammatory consolidation with center undergoing caseous necrosis
nodal + parenchymal lesion =
Ghon focus
Ghon complex
Radiologically detectable calcification of fibrotic ghon complex
Ranke complex
Lack of tissue hypersensitivity reaction results in
absence of caseating granuloma
Secondary TB is characteristic of
sputum prod
apical cavitation
Initial bacterial exposure with resistance and hypersensitivity (+ tuberculin skin test)
Primary TB
Crucial role in cell mediated immunity against mycobateria
Mediator of inflamm and bacterial containment:
CD4 of THI subset
IFN-y, TNF, NO
In disseminated MAC, tissue exam reveal
foamy histiocyte stuffed with atypical mycobateria
Most useful for rapid confirmation of TB in persons with AFB - status
NAAT
Ethambutol MOA
inhibits synthesis of arabinogylcan subunit
