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Introducing Xpert MTB/RIF Testing for Active Pulmonary TB at Zuckerberg San Francisco General

Introducing Xpert MTB/RIF Testing for Active Pulmonary TB at Zuckerberg San Francisco General 2018-02-06T09:56:57-08:00

Supported by Caring Wisely 2.0


Molecular testing of sputum for TB using GeneXpert MTB/RIF (Xpert, under lab test code MTBX) real-time PCR, a new assay with better sensitivity, specificity, & turn-around time than serial sputum AFB smear microscopy


To improve ED flow and reduce inpatient duration of respiratory isolation for patients undergoing evaluation for pulmonary TB by replacing serial sputum AFB smear microscopy with an Xpert-based isolation triage rule


Emergency Department and Inpatient Family Medicine & Internal Medicine Services at SFGH


Monday-Friday 7:30 AM to 7:00 PM: 3-hour turn-around time from receipt of Xpert sputum sample in lab
Nights/Weekends: Turn-around time as after-hours staffing allows


Possible active pulmonary TB at risk of spreading TB in hospital or community requiring admission forEITHER:

  1. Clinical requirement: Admitting for inpatient care for any reason & also needing evaluation for active TB due to:
    1. TB symptoms (e.g. cough ≥2 weeks), OR Radiological findings suggesting TB (e.g. abnormal CXR), AND
    2. TB exposure risk factor or history (e.g. contact to TB case, immunosuppressed including HIV+, homeless, foreign-born, incarcerated, positive tuberculin skin test (TST) or Quantiferon), OR
  2. Public health requirement: Not allowed to enter congregate living facility until evaluated for TB transmission risk:
    1. Higher public health risk
      1. Group residential or treatment facilities (e.g. LHH, SNF, drug rehab, inpatient psychiatric care, dialysis, respite)
      2. Jail
    2. Lower public health risk: Homeless (lower b/c of shelter TB screening); SRO residents


Please follow these steps (see below for Flow Chart):

  1. Screen for active pulmonary TB, Isolate (respiratory), Admit prn, Test with Xpert if indicated under “Who” above
  2. Collect 2 high-quality sputa, each ≥2 mL (In ED use Demistifier portable negative air-flow tent kept in ED Stat lab)(see below for Sputum Collection Instructions)
    1. Order 1 Xpert (MTB complex/Rifampin by RT PCR;testcode MTBX) & 1 AFB smear/cx in CPOE/PulseCheck
    2. Expectorated sputum (induction only if dry cough; not available in ED). Send runner to lab – don’t tube sputum
  3. Check for Xpert result in LCR (AFB sent 9:00 AM-4:00 PM read next day by 11:00 AM; AFB sent 4:00 PM-9:00 AM read next day by 11:00 PM except Sunday).
    1. Xpert TB Positive: Order high-level respiratory isolation, active TB treatment, & 2 more AFB smear/cx
    2. Xpert TB Negative: base triage on TB clinical probability (page us (415) 443-0080 if you have questions) & public health risk
      1. Low-level respiratory isolation (to collect further sputa, expectorated, or induced PRN) if EITHER
        1. High clinical probability: Collect 2nd Xpert & 2nd AFB smear/cx next AM, OR
        2. Higher public health risk only: Collect 2nd AFB smear/cx only next AM
      2. Regular non-isolation if Low clinical probability AND Lower public health risk
  4. Discontinue isolation if no sputa Xpert+ OR AFB+ (1st AFB smear/cx must be negative or pending) AND
    1. High clinical probability: 2nd Xpert negative AND 2nd AFB smear/cx pending
    2. Low clinical probability AND Higher public health risk: 2nd AFB smear/cx pending
  5. Discharge from hospital to follow up in TB clinic when
    1. Higher public health risk: 3 total sputa negative by 1-2 AFB &/or 1-2 Xpert, & TB Control approval
    2. All other patients: 2 total sputa negative by 1-2 AFB &/or 1-2 Xpert
  6. Notify TB Control of discharge and follow-up plans
    1. Higher public health risk OR starting TB treatment. TB Control approval legally required before D/C Monday -Friday 8:00 AM-5:00 PM: call TB Clinic (415) 206-8524. Other times: call TB Control Director directly (415) 748-8000.
    2. All other patients. Instruct patient to follow-up in TB Clinic (MD hours at sftbc.org/#!our-services). Fax D/C Referral to TB Clinic (415) 206-4565.

Sputum Collection Instructions

  1. Place label on side (NOT lid) of cup
  2. Place patient in Demistifier tent (ED) or isolation room (Med-Surg)
  3. Instruct as follows:
    1. Relax, breath normally, & take your time, especially if in tent
    2. If in tent, face away from opening (only bed tent has opening)
    3. Inhale deeply 2-3 times; exhale hard each time
    4. Cough up sputum from deep inside chest (show photos below)
    5. Encourage mucoid, purulent, or bloody, not salivary, sputum
      examples of Sputum test
  4. Open cup to collect sputum (discourage but don’t reject if salivary)
    1. Do not touch rim of cup with mouth
    2. Repeat prn to get ≥2 mL of good-quality sputum per cup
  5. After collection, screw lid on tightly

Do not stand at tent opening during collection

Demistifier tent demonstration

Questions? Page “Xpert MTB/RIF Service, SFGH” on pagerbox.com or at (415) 443-0080