Tuberculosis, Latent TB Infection

Clinic A/P, adults, Clinic A/P, Peds, Hospital A/P, Adults, Hospital A/P, Peds

Diagnosis
-H&P that is consistent with latent TB.
-Prior BCG Vaccination: No
–Patient screened positive.
-Test interpretation explained to the patient.
-Risk factors for acquiring TB reviewed w/ patient.
-Risk factors for developing TB also reviewed / patient.
-Pathogenesis and Epidemiology of TB reviewed.
-Will exclude active TB by getting a CXR (in addition to H&P above).
Treatment
-Treatment recommendations discussed w/ patient. Risks and benefits of treatment for the individual patient discussed.
-Different treatment regimens for LTBI reviewed.
-Baseline labs and monthly monitoring evaluations discussed.
-Vitamin B6 (Pyridoxine) to prevent the development of peripheral neuropathy if using Isoniazid to treat TB

 

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TB Pearls:

  • “Targeted screening is recommended only for individuals and groups at increased risk of TB infection” AAFP 2014
  • The risk of reactivation of TB and progression to active disease is the highest in the first 2 years of conversion (of going from negative PPD to positive PPD or Quantiferon gold)
  • In the hospital, if 3 AFB smears are negative, the patient is taken out of isolation. If coughing, they must wear a mask.
  • Quantiferon Gold is an alternative to PPD for testing for latent TB. The two tests are interchangeable.
  • Latent TB treatment isn’t really treatment but prophylaxis to prevent the development of TB.
  • If a patient has a positive PPD or a positive Quantiferon Gold and is asymptomatic, Get a CXR. If CXR is normal, they don’t have TB disease (or active TB). But they may have been exposed and have latent TB.
  • Quantiferon Gold is not reliable for kids < 5 years old. In that age group, get a PPD instead.
  • Quantiferon is as reliable as PPD
  • Quantiferon is more specific than TST and is the test of choice in populations in which BCG vaccination status raises a concern of false-positive results in TB screening.
  • If Quantiferon is indeterminate, repeat now or in 6 months.
  • Quantiferon or PPD don’t say you have active TB disease. It says you have been exposed.
  • Quantiferon is an interferon-γ release assay (IGRA)
  • “The Mantoux tuberculin skin test, also known as the TST, has been for many years the standard method of determining whether a person is infected with Mycobacterium tuberculosis. More recently, blood tests called interferon-gamma release assays (IGRAs) have also been approved for the detection of M tuberculosis.
  • Note, being infected is not the same thing as having TB disease.
  • If a pregnant woman is diagnosed with latent TB, prophylaxis is recommended starting after the first trimester.

 

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Important  Links

 

References

Notes from a presentation by Infectious disease expert, Dr. Kerkar.

https://www.cdc.gov/tb/publications/factsheets/treatment/ltbitreatmentoptions.htm

http://www.medscape.com/viewarticle/738519

Am Fam Physician. 2014 Jun 1;89(11):889-896. http://www.aafp.org/afp/2014/0601/p889.html

http://tstin3d.com/en/calc.html [Model for determining groups with increased likelihood of reactivation (determined by risk factors) so that they can be offered treatment.]

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