Tuberculosis
                                ============
þ WHO REQUIRES Airborne ISOLATION? (Mercy Hospital, 5/2009)
 - A guide to airborne isolation 
Non-immunocompromised algorithm:
   Has the patient had any of the following?
  + A persistent cough lasting >3 weeks
  + Bloody sputum (hemoptysis)
  + 2 or more of the following:
   - night sweats
   - weight loss >10 lbs
   - anorexia
   - fever >2 weeks/chills 
   - A positive AFB smear/culture on any respiratory specimen
   - A radiograph that could be consistent with TB
  If NO, don't isolate. If YES:
  Does the patient meet any of the following criteria?
   - No definitive cause yet found for symptoms
   - History of having known someone with TB
   - History of significant exposure (>6 months) to an endemic TB area
   - Homeless, in shelter or incarcerated within the last 2 years
   - Prior positive TB skin test/History of having TB
   - Prior INH therapy
   - IVDA
   - HIV
   If NO, don't isolate. If YES, isolate and call infection control 412-692-2566

Immunocompromised algorithm:
   Does the patient have a chest radiograph that could be consistent with TB?
   If YES but  there a known history of infection with mycobacteria other 
   than tuberculosis, and chest radiograph is unchanged, don't isolate
   If YES ISOLATE and notify Infection Control 412-692-2566
   
   If CXR clear or no CXR yet, ask the following questions
   Has the patient had any of the following? DA persistent cough lasting >3 weeks
   - Bloody sputum (hemoptysis)
   - Night sweats
   - Fever > 2 weeks
   - Unexplained weight loss > 10 lbs
   - a + AFB smear/culture on any respiratory specimen
  If NO, don't isolate. If YES ask the following:
  Does the patient meet any of the following criteria?
   - No definitive cause for symptoms
   - History of having known someone with TB
   - History of significant exposure (>6 months) to an endemic TB area
   - Homeless, in shelter or incarcerated within the last 2 years
   - Prior positive TB skin test/History of having TB
   - Prior INH therapy
   - IVDA
   - HIV 
  If YES to any, then ISOLATE and notify Infection Control 412-692-2566 
  If NO, don't isolate
  
þ Skin Testing
  Positive is:
  - 5 mm induration
   + with HIV infection
   + other severe cell-mediated immune deficiency
   + very likely to have TB (e.g., close contact with those infected
   + those with fibrosis or calcification on CXR consistent with previous TB
  - 10 mm induration in those in groups with high prevalance of infection
   + immmigrant from endemic area
   + prisoner
   + homeless
   + IVDA
   + NH resident
   + chronically ill
  - 15 mm induration for those with no identifiable risks
  [MMWR 49:RR-6, 2000]

þ Symptoms of TB
 - Fever, cough, night sweats, weight loss, and hemoptysis are
   typical symptoms of a patient with active tuberculosis.
 - As many as 20% of patients with active tuberculosis may be asymptomatic.

þ BCG
 - attenuated live vaccine
 - Mantoux skin test stays positive but disappears rapidly
 - if has had BCG but in US now, ignore BCG, do skin test, and assume + skin
   test means disease
 - Although receiving the BCG vaccine makes the PPD skin test difficult to
   interpret, a patient is still considered to have a positive test if there
   is 10 mm or more of induration on a PPD test and the patient received BCG
   at birth.  If the patient received BCG as an adult, then 30 mm or more of
   induration is considered a positive test.
   [emedicine.com - http://www.emedicine.com/emerg/topic618.htm]
 - risk of severe reaction very low to Matoux skin test.

þ Reactor vs. Convertor
 - treat all convertors

þ Overall incidence worldwide
 - about 33%

þ Skin test + and treated
 - probably immune, even to multi-drug resistant TB
 - ideal for high-risk area (e.g., ED nurse in NY).
 - having had TB is probably protective

þ Treatment
 - INH hepatitis common if over 35
 - Tuberculosis treatment should begin with 4 drug therapy.  Three drug
   therapy is no longer recommended, at least until culture results with
   sensitivities have returned.
   [emedicine.com - http://www.emedicine.com/emerg/topic618.htm]

þ Prevention
 - HEPA masks (High-Efficiency Particulate Air):  inlet port filtered, but
   EXIT port is NOT; no good for patients.
 - best to put patient in mask (any kind).
 - HEPA masks very expensive.
 - risk of a 10-minute exam is minimal.

þ Vectors
 - about an hour of drying will kill TB on a fomite.

þ Infectiousness
 - Three sputums negative for AFB are required for a patient to be considered
   non-infectious.  This usually requires 4 weeks of therapy.
 - Patients with tuberculosis usually transmit the disease through respiratory
   droplets.  Transdermal and gastrointestinal spread has been reported,
   however.