TB Diagnosis and Treatment

TB diagnosis and Treatment Diagnosis Active TB 

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Initial test should be a chest Xray (as with all respiratory infections) o Upper lobe infiltrates with cavitation o Pleural effusions Sputum Acid Fast Bacilli smear and culture for mycobacteria must be done THREE times to EXCLUDE TB o Sputum early morning 3 consecutive days  Stain with ziehl Neelsen  Auramine-rhodamine fluorescent stain o Cultures take 4-8 weeks, slow growing PCR Pleural biopsy is the most accurate diagnostic test

Diagnosis Latent TB o Test based on cell-mediated immunity TH1 cells. A protein derivative is injected and look for INDURATION 48-72 h later o Don’t look at erythema o May have allergic reaction to PPD within hours with wheal and flare reaction and NO INDURATION  Done on people who are at risk o HIV o Annually for healthcare workers  If Positive PPD do chest Xray to get baseline (don’t repeat PPD) o If people exposed to sick then do a second PPD test 8-12 weeks after o ALWAYS DO BEFORE TNF-alpha inhibitors (Chrons, UC etc)  Mantoux tuberculin skin test with Purified protein derivative (PPD) o If first PPD do twice because false negatives high 15 mm Those with no risk factors 10mm Recent immigrant Prisoner Healthcare worker Nursing home residents Close contact with TB Alcoholic, diabetes, hematologic malignancy 5mm HIV +

Steroid user Close contact someone with ACTIVE TB Abnormal chest xray Organ transplant recipient Sarcoidosis (wont have a reaction because TH1 cells are sequestered) o False Positive if BCG and nontuberculous mycobacteria o False Negative: HIV, immunodeficient people o Positive  chest xray  sputum AF stain and culture + treatment + HIV testing Conversion  Negative PPD  5mm after exposure 8 weeks MEANS EXPOSED Booster Response  Had a negative PPD  positive on a second PPD  WITHOUT EXPOSURE  Due to BCG or nontuberculous mycobacteria IGRA interferon-gamma release assay with antigen specific for TB screen for latent TB o Higher specificity o Limited in immunosuppressed patients o Advantage is that it does not cross react with BCG vaccine

Treatment Active TB  Use Directly observed therapy (DOT)    RIPE (Rifampin, INH, Pyrazinamide, Ethambutol) o 2 months 4 drugs(RIPE), 4 months 2 drugs (RI) o can stop ethambutol the susceptibility is known o Continuation phase: Extend treatment (INH and rifampin) to 9 months for  Cavitary TB+ positive sputum after two months treatment  osteomyelitis  military TB  meningitis (12 month + corticosteroids)  Pregnancy , other reasons Pyrazinamide was not used  Advantages of different medications o Pyrazinamide active against bacilli residing in macrophages  Obtain monthly smears and chest xrays  Other drugs o Aminoglycosides  Streptomycin (ototoxicity, nephrotoxicity)

 Amikacin (ototoxicity, nephrotoxicity) o Quinolones (GI upset, tendinopathy, increase QT prolongation)    Side effects of medication o INH, Rifampin, and Pyrazinamide  Stop meds when TRANSAMINASES 1. Symptomatic and 3X the upper limit of normal 2. Asymptomatic and 5X the UPPER limit of normal o If hepatotoxicity STOP MEDS  #1 get expert consultation  aminoglycoside + EMB and a fluoroquinolone (levofloxacin and moxifloxacin)  DO FOR 18-24 MONTHS IF JUST THIS  when transaminases drop to normal restart meds one at a time starting with RIFAMPIN INH  don’t add Pyrazinamide if start rising

o Before starting medication want baseline levels of  Liver function, bilirubin, alkaline phosphatase  Hep B and C  CBC  Serum creatnine  Uric acid levels  Vision acuity and red-green color discrimination o Steroids decrease risk of constrictive pericarditis and neurological complication of meningitis o Treatment in HIV patients: same but use Rifabutin, less cytochrome interactions o Pregnant women treat with INH, rifampin, and ethambutol -avoid pyrazinamide and streptomycin

Treatment latent TB 

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Positive PPD or IGRA  chest xray rule out active TB o 9 months INH 300mg + B6 (pyridoxine) 25mg o decreases risk of reactivation by 90% (10% to 1%) o risk of INH induced hepatitis increases with age so need to weigh benefits vs harm Others o if INH resistant use Rifampin 4 months o daily INH and rifampin 3 months o floroquinolone for 12 months if MDR TB

Prophylaxis for those close to TB patients 

Rifampin

TB transmission and control     

Only pulmonary TB is contagious via respiratory droplets Need to be placed in a negative pressure room/ airborne infection isolation room and wear a surgical mask Visitors need a N95 mask or PAPR (powered air-purifying respirator) This is reportable to the local health department Can be released once THREE negative acid fast bacilli sputum smear results identified + need a chest radiograph for future comparisons