tuberculosis Flashcards
when do you officially read PDD test
48-72h after placement
when is a 5 mm induration positive
HIV patients
Patients on immunosuppressants
Patients with abnormal chest radiographs
Close contacts of patients with TB
when is a 10 mm induration positive
recent immigrants from high prevalence countries
IVDU
Children <4 yo or exposed to adults at high risk
residents/employees of high risk settings
when is a 15 mm induration positive
persons at low risk for TB
when can there be a false negative
overwhelming TB, early initial infection, protein malnutrition, hodgkin’s disease, measles, sarcoidosis, AIDS or other immunosuppression, current viral infection, recent live virus vaccine administration
a positive PDD test indicates
an individual has been infected in the past and continues to carry viable mycobacteria in some tissue, may also indicate receipt of BCG vaccine
a positive PDD test does NOT reliably indicate
that active disease or immunity is present
what are the 4 major drugs for TB
RIPE–> rifampin, isoniazid, pyrazinamide, ethambutol
when to withhold pyrazinamide
pregnancy, gout, severe liver disease
rifamycin class spectrum
gram + and gram - cocci, gram + bacilli, mycobacteria, chlamydiae
most inactive against GN enteric bacilli
rifamycin class mechanism
inhibits bacterial RNA synthesis
rifamycin class monitoring
liver function tests at baseline: if normal, no need to routinely monitor throughout therapy unless symptomatic.
if elevated, routine monitoring should occur throughout therapy every other week to once/month
what is the common side effect of rifamycins
rash: typically manifests as general itching treated with antihistamines and continue anti-TB therapy. beware petechial rash which can represent thrombocytopenia caused by rifampin and you should stop it then.
drug interactions with rifamycins
oral contraceptives
warfarin
azole antifungals
proease inhibitors
counseling for rifamycin and oral contraceptives
recommend additional contraception with barrier method
what happens with rifamycin and warfarin
significant increases in warfarin dose to maintain therapeutic range
what happens with rifamycin and azole antifungals
increase the dose of the azole
what happens with protease inhibitors and rifamycin
impacts which rifamycin you use
rifabutin yes
rifampin no
adverse effects for pyrazinamide
hyperuricemia: attacks of gout have been reported, relative contraindication in gouty arthritis
arthralgia, hepatotoxicity
adverse effects for ethambutol
optic neuritis: loss of visual acuity, unable to distinguish red from green, is reversible
what is a treatment failure
positive cultures after 4 months of treatment
what is a relapse
recurrent TB at any time after completion of treatment with cure
when is a patient no longer infectious and how does this happen
no longer infectious after three sputum on consecutive days are negative
can ONLY happen with anti-TB therapy
what is the preferred regimen for latent TB
isoniazid for 9 months
4 regimen options for latent TB
- isoniazid x 9 mo
- isoniazid x 6 mo
- isoniazid + rifapentine x 3 mo
- rifampin x 4 mo
isoniazid counseling
must abstain from alcohol: increased risk hepatotoxicity
common side effect isoniazid/how to treat
peripheral neuropathy: treat with pyridoxine/vitamin b6
When is rifabutin preferred
for patients on antiretrovirals, it has less CYP450 interactions
