Tuberculosis Flashcards
What are clinical manifestations of tuberculosis
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DDx
URTI, Pneumonia, COVID-19 Asthma, COPD Heart failure GERD Lung cancer Captopril
DDX FOR PEDIA
Infection - URTI, Pneumonia, COVID-19, pertussis Inflammatory - Asthma Neoplastic - Mediastinal mass Digestive - GERD Iatrogenic - ACE inhibitors Irritant - Smoke Cardiac - Heart failure Congenital / Hereditary -Cystic fibrosis, Structural abnormality FBA
Primary history
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ROS
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Tertiary history
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PE
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Algorithm for tb mgt in pedia
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How to diagnose tuberculosis (pedia)
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What to request?
TST if pedia *what age? CXR - Pneumonia? TB? Heart failure? Sputum AFB Nasopharyngeal swab - COVID 19 Gene xpert Culture with DST if with treatment failure already
CBC - check WBC bac vs viral
creatinine - imp’t in drug dosage
Spirometry, if highly suspcious of asthma/COPD
CT, if suspicious of malignancy
How many are latent infected?
1.7 billion, 1/4 of human population
What is positive TST
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Drug dosages for TB
ADULTS Isoniazid 5mkd max 300mg Rifampicin 10mkd max 600mg Pyrazinamide 25mkd, max 2g Ethambutol 15 mkd
PEDIATRICS Isoniazid 10 (7-15) mkd, max 300mg Rifampicin 15 (10-20) mkd, max 600mg Pyrazinamide 35 (30-40) mkd Ethambutol 20 (15-25) mkd
How to treat LTBI?
- ISONIAZID FOR 6-9MONTHS
Adults 5mkd, max 300mg
Children 10mkd - RIFAMPIN for 3-4 months
Adults 10mkd
Children 10mkd (max: <45kg, 450mg; >45kg, 600mg)
MOA of Isoniazid
What’s the target mycobacterial population?
Inhibits synthesis of mycolic acid, which are essential components of mycobacterial cell walls
MOA of Rifampicin
What’s the target mycobacterial population?
binds to B subunit of bacterial DNA-dependend RNA polymerase, and thereby inhibits RNA synthesis
bactericidal
can kill organisms that are pooorly accessible to many other drugs, eg intracellular organisms and those sequestered in abscesses and lung cavities
- *strongly induces most cytochrome p450 isoforms
- -> increases elimination of other drugs, eg. anticoagulants, anticonvulsants, contraceptives
MOA of Pyrazinamidw
What’s the target mycobacterial population?
converted to pyrazinoic acid - the active form - by mycobacterial pyrazinamidase
pyrazinoic acid disrupts mycobacterial cell membrane metabolism and transport functions
used as “sterilizing” agent acctive against INTRACELLULAR organisms that may relapse
What are adverse reactions for Rifampicin
orange urine rashes thrombocytopenia (major) nephritis (major) hepatitis
What are A/E of Isoniazid
Hepatitis - m/c major toxic effect
»> loss of appetite, N/V, jaundice, RUQ pain
»> may be fatal
Peripheral neuropathy (minor a/e) >>>occurs in 10-20% of px given > 5mkd, but is infrequent in std 300-mg adult dose >>>more likely to occur in px with malnutrition, alcoholism, DM , AIDS, and uremia >>> d/t pyridoxine deficiency (isonizid promotes excretion of pyridoxine >>> readily reversed by administration of pyridoxine in as low as 10mg/day
Other CNS toxicities: memory loss, psychosis (major), ataxia, seizures (major)
MOA of Ethambutol
What’s the target mycobacterial population?
inhibits mycobacterial arabinosyl transferases (involved in polymerization rxn of arabinoglycan, an essential component of mycobacterial cell wall)
What are A/E of Pyrazinamide
hepatotoxicity (1-5%)
photosensitivity
hyperuricemia
—not a reason to stop the drug if px is asymptomatic
What are A/E of Ethambutol
Retrobulbar neuritis
- leads to loss of VA and red-green color blindness
- less if 15mkd or less is used
- do baseline and monthly VA and color discrimination testing, with particular attention to patients on higher doses or with impaired renal fxn
What are minor adverse effects of TB drugs?
GI intolerance mild or localized skin reactions orange/red urine pain at the injuection site burning sesatin in the feet due to peripheral neuropathy arthralgia due to hyperuricemia flu-like symptoms
What are major adverse effects of TB drugs?
Severe skin rash due to hypersensitivity
Jaundice due to hepatitis
impairment of visual acuity and color vusion due to optic neuritis
Hearing impairment, ringing of ears, dizziness due to damage of 8th cranial nerve
oliguria or albuminuria due to renal disorder
psychosis and convulsion
thrombocytopenia, anemia, shock
What to do if there’s adverse effects of TB drugs?
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Prognosis
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Prevention
Primary prevention -cough etiquette -use of n95 -stop smoking, reduce alcohol (<40g/day) -eat well and enough (underweight is a RF) -be loyal -BCG vaccination of newborns -
Secondary prevention
- contact tracing
- get screened if with exposure to tb patient (at least by CXR if adults, TST if child)
Tertiary prevention
-undergo treatment if with latent TB
Definition of MDR-TB
Multidrug-resistant TB (MDR TB) is caused by an organism that is resistant to at least isoniazid and rifampin, the two most potent TB drugs.
Definition of XDR-TB
resistance to the two most powerful anti-TB drugs, isoniazid and rifampicin, also known as multidrug-resistance (MDR-TB), in addition to resistance to any of the fluoroquinolones (such as levofloxacin or moxifloxacin) and to at least one of the three injectable second-line drugs (amikacin, capreomycin or kanamycin).
2013 WHO Case definitions for TB
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What is a presumptive PTB (adults)
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How should sputum specimens be collected in DSSM?
How to interpret?
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TB culture facilities in the Philippines
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When to request for sputum TB culture with DST?
Re-treatment cases
Treatment failure
Contacts of known DR-TB
*should NOT be routinely performed among new cases of PTB
When to request Gene Xpert?
As initial diagnostic test for presumptive TB
As follow-on test to smear negative but with (+) CXR findings
As initial diagnostic test for presumptive DR-TB
What’s the role of CXR in TB?
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What’s the role of TST in suspected adult TB patients?
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2013 WHO Case definitions (part 2)
New case
Retreatment case
-relapse
-treatment after failure
-treatment after lost to follow-up (TALF)
-Previous treatment outcome unknown (PTOU)
Pre-treatment evaluation
previous TB treatment risk factors for hepatic, renal, ocular toxicity Sexual history personal/social history occupation
What baseline labs to request before starting TB meds?
baseline ALT, crea
HIV screening
DM screening
Categories of TB treatment
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How to monitor treatment response?
2nd month / 5th month
3rd month / 5th month
What to do if there’s interruption in tb treatment?
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How to classify outcomes?
Cured Treatment completed Treatment failed Died Lost to follow up Not evaluated
When is DR-TB suspected?
All re-treatment cases New cases who are -non-converter of category 1 -contacts of confirmed DR-TB cases -PLHIV with signs and symptoms of TB
How is DR-tb diagnosed?
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How should DR-TB be managed
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Discuss TB with HIV
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Discuss tb in pregnant and lactating women
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risk factors for contracting tb and progression of dse?
Smokers, alcholics (i.e. >40g/day)
underweight (BMI < 20)
recent tb infection (i.e. < 2 years), upper lobe fibro-nodular dse on CXR
when to isolate?
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What infection control measures must be observed in healthcare facitlities?
ADMINISTRATIVE - triage, separation of infectious cases, minimize exposure in health care facilities, cough etiquette
SURVEILLANCE of TB dse among HCW for TB transmission
ENVIRONMENTAL CONTROL - good ventilation
use of PPE for HCW at high risk
How should job appplicants/students be managed if pre-emplyment screening suggest TB?
Workup for presumptive TB
For TB activity not entirely ruled out - periodic monitoring, rpt CXR 4-6 months
Policies of host countries prevail
Discuss infectivity period of TB
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