Tuberculosis Flashcards
describe mycobacterium tuberculosis
aerobic and anaerobic
extra and intracellular
multidrug resistance
slow growing, latent
describe the pathophysiology of Tb
very communicable spreads easily
aerosolized droplets
enter the bronchials then alveoli and settle in lower lobe
first line macrophage immunity followed by t cell over 2-8wks
risk factors for exposure
close contacts endemic areas - northern ca poor living conditions, crowded, correctional facilities health care workers homelessness
results of tests in latent TB
negative xray, sputum stain and culture
symptoms of latent TB
asymptomatic
spreads to regional lymph nodes
latent or dormant in seeded foci (ghon node) for months - years
NOT CONTAGIOUS
how does tst test work
heat sterilized protein derivative
delayed hypersensitivty response delayed 48-72hrs
what can cause false negatives
cutaneous anergy (absence of an IR to an antigen) preconversion neonate elderly HIV chemo lymphoma corticosteroids ** use positive control mumps or candida
tst does not distinguish latent from what
active TB
BCG vaccination
other mycobacterial infection
interferon gamma assay
blood test measures t cell release of interferon gamma
does not distinguish from active disease but most specific with patients vaccinated with BCG
TST result <4mm indicates
negtive result
TST result >/=5
positive in certain people HIV exposure in past 2 years fibronodular disease on chest xray ESRD therapy with immunosuppressants
TST result >10
TST conversion within 2 years
when should you treat latent TB how effective is it
90% effective
only if exposure to infectious TB wihtin the previous 2 years
assess risk vs benefit
standard latent TB therapy
isonazid daily for 9 months
alternative latent tb therapy
isonazid 6 months
isonazide/rifampin 3mon
rifampin 4 months
when does primary tb occur
early within 4-12 months
risk factors for primary tb
age
immune function
disseminated primary including cns tb most common in who
young and immunocompromised
most common place for primary tb
lymph node or pleural disease
when does reactivation tb occur
18-24 months after infections
what is most common for reactivation tb
pneumonia - upper lobe pulmonary
extra pulmonary in immunocompromised
high risk factors for active tb
silicosis HIV AIDS chronic renal disease head and neck carcinoma recent TB infection abnormal chest xray-fibronodular disease immunosuppresive therapy
moderate risk factors for active tb
diabetes
glucocorticoids
TNFalpha
0-4 years old when infected
diagnosis for active pulmonary tb
signs and symptoms
radiograph
microbiology testing
clinical signs and symptoms
dry then productive cough >2weeks
fever, night sweats
anorexia, weight loss
hemoptysis, chest pain
microbial testing for active disease
acid fast bacilli smear stain - rapid inexpensive
mycobaterial culture/susceptibility - gold standard, 2-8wks
molecular diagnositics - pcr and susceptibility
radiograph for active disease
apical and upper lobe patchy infiltrates
volume loss and cavitation
goals of treatment for active tb
eradicate the bug to cure the disease, prevent complications, and reduce mortality
prevent AM resistance
prevent transmission
how often do you follow up sputum samples
monthly until to consecutive negatives
how long is someone with active tb in isolation
initial 2 weeks and until 3 consecutive negative results
principles of active tb AM
combo therapy
adherance important
both to optimize killing and decrease resistance
standard regimen 1 for active tb
isonazid, rif, ethambutol, pyranzinimide for 2 months
then inh and rif for 4 months
regimen 2 for active tb
inh, rif, emb for 2 months
then inh and rif for 7 months
what regimen should elderly use for active tb
regimen 2, higher hepatooxicity in the older people
what regimen should pregnant women use for active tb
either one
what is direct observed therapy
initial 2 months instead of daily 5x a week and then for the continuation 3x a week at higher doses
why is ethambutol added
in case there is resistance to the other agents can discontinue once results come back that its senstive to the others
risk factors for ressitance
high local resistance rates
previous tb infection
exposure to resistant tb
isonazid dose
5mg/kg max 300
rifampin dose
10mg/kg max 600
pyranzinamide dosing
20-25mg/kg
ethambutol dosing
15-20mg/kg
second line drugs for active tb
levofloxicin, moxi
ampikacin
ampikacin dosing
15mg/kg injection
which drugs have to be changed in hemodialysis
pyranzinimide 25- 35 3x a week
ethambutol 15-25 3x a week
which are cidal
rif, inh, pyr
which are static
emb
which are extracellular
inh, rif
which are intracellular
pyr, emb, rif
inh adverse effects
hypersensitivity
hepatotoxicity
NV
peripheral neuropathy
what can you do to prevent peripheral neuropathy
give vit B6
what drug should be avoided when on therapy
tylenol - affects liver
what increases the incidence of hepatotoxicity
age >35 female pre existing liver disease other hepatotoxic drugs alcohol use
when should you monitor for hepatotoxicity
baseline then in 2 weeks then monthly
inh drug interactions
inhibits cyp 2C9 and 3A4
antacids reduce absorption
rifampin adverse effects
hypersensitivity
hepatotoxicity
orange discoloration of saliva urine and tears
rifampin drug interactions
inducer of 3A4 and pgp
max in 7 days and returns to baseline in 14
pyranzinamide adverse effects
hepatotoxicity
hypersensitivity
hyperuricemia - gout if preexisting, arthralgias
ethambutol adverse effects
ocular neritis - eye exams indicated, dose dependent (high dose long time)
CNS, peripheral neuritis
hypersensitivity - rash, fever, dermatitis
what to do if the patient gets a drug induced rash
stop all drugs and start second line agent
review other potential causes
once rash resolves start inh
in 3 days start rif (can take off second line here)
in 3 days start emb
if no rash assume it was pyr
if rash occurs with any step then discontinue and restart all the others, adjust regimen based on those continues
what to do if patient experiences drug induced hepatotoxicity AST or ALT >5x ULN or clinical jaundice
discontiue all meds and start second line agent
check for other causes , cehck viral hep serologies
when levels normal start rif
after 2 weeks start inh
if normal transaminases after 2 weeks assume pyr and do not rechallenge
if hepatitis occurs with any then discontinue and restart the others
adjust treatment based on remaining
