Active TB

1.  Suspect in patients with COUGH who also have Risk Factors:
  • Cough > 3 weeks duration (if not starting to improve, & no alternative Dx) warrants CXR
  • CXR sooner for hemoptysis, fever, weight loss, night sweats
  • PPD / IGRA OK but not useful (20% false-neg; Pos. non-specific)
2.  If Abnormal CXR compatible with Active TB:
  • 3 Sputum specimens (different days) for AFB
  • Order PCR on 1st specimen if high index of suspicion
  • Begin 4-drug Tx (by DOT) if high index of suspicion
  • Isolation if high index of suspicion (confine to home)
  • If high index of suspicion: all Dx & Tx should be managed by Dept. Public Health TB Control
  • Click link for examples of active TB on x-ray
3.  Sputum Results
  • AFB smears ready in 24 hrs.
  • Smear-Positive = presumptive TB → Tx!
  • Smear-Negative may get empiric Tx pending cultures (judgment call)
  • Cultures take 1-2 weeks by radiometric technology
  • If negative, must wait full 60 days for no-growth on conventional media to say “Negative”
  • If pos., Susceptibility Results take another 1-2 wks.
Extrapulmonary TB
  • Presents with weight loss, night sweats, &/or fevers
  • Specific Sx depend on involved organ
  • Dx by FNA / Biopsy (“urine for AFB” for renal TB; CSF for TB meningitis)
  • “Caseating Granulomas” on histology = TB
  • Smear for AFB gives poor yield; must await Cultures (long wait)