Supported by Caring Wisely 2.0
What:
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
Why:
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
Where:
Emergency Department and Inpatient Family Medicine & Internal Medicine Services at SFGH
When:
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
Who:
Possible active pulmonary TB at risk of spreading TB in hospital or community requiring admission forEITHER:
- Clinical requirement: Admitting for inpatient care for any reason & also needing evaluation for active TB due to:
- TB symptoms (e.g. cough ≥2 weeks), OR Radiological findings suggesting TB (e.g. abnormal CXR), AND
- 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
- Public health requirement: Not allowed to enter congregate living facility until evaluated for TB transmission risk:
- Higher public health risk
- Group residential or treatment facilities (e.g. LHH, SNF, drug rehab, inpatient psychiatric care, dialysis, respite)
- Jail
- Lower public health risk: Homeless (lower b/c of shelter TB screening); SRO residents
- Higher public health risk
How:
Please follow these steps (see below for Flow Chart):
- Screen for active pulmonary TB, Isolate (respiratory), Admit prn, Test with Xpert if indicated under “Who” above
- 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)
- Order 1 Xpert (MTB complex/Rifampin by RT PCR;testcode MTBX) & 1 AFB smear/cx in CPOE/PulseCheck
- Expectorated sputum (induction only if dry cough; not available in ED). Send runner to lab – don’t tube sputum
- 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).
- Xpert TB Positive: Order high-level respiratory isolation, active TB treatment, & 2 more AFB smear/cx
- Xpert TB Negative: base triage on TB clinical probability (page us (415) 443-0080 if you have questions) & public health risk
- Low-level respiratory isolation (to collect further sputa, expectorated, or induced PRN) if EITHER
- High clinical probability: Collect 2nd Xpert & 2nd AFB smear/cx next AM, OR
- Higher public health risk only: Collect 2nd AFB smear/cx only next AM
- Regular non-isolation if Low clinical probability AND Lower public health risk
- Low-level respiratory isolation (to collect further sputa, expectorated, or induced PRN) if EITHER
- Discontinue isolation if no sputa Xpert+ OR AFB+ (1st AFB smear/cx must be negative or pending) AND
- High clinical probability: 2nd Xpert negative AND 2nd AFB smear/cx pending
- Low clinical probability AND Higher public health risk: 2nd AFB smear/cx pending
- Discharge from hospital to follow up in TB clinic when
- Higher public health risk: 3 total sputa negative by 1-2 AFB &/or 1-2 Xpert, & TB Control approval
- All other patients: 2 total sputa negative by 1-2 AFB &/or 1-2 Xpert
- Notify TB Control of discharge and follow-up plans
- 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.
- 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
- Place label on side (NOT lid) of cup
- Place patient in Demistifier tent (ED) or isolation room (Med-Surg)
- Instruct as follows:
- Relax, breath normally, & take your time, especially if in tent
- If in tent, face away from opening (only bed tent has opening)
- Inhale deeply 2-3 times; exhale hard each time
- Cough up sputum from deep inside chest (show photos below)
- Encourage mucoid, purulent, or bloody, not salivary, sputum
- Open cup to collect sputum (discourage but don’t reject if salivary)
- Do not touch rim of cup with mouth
- Repeat prn to get ≥2 mL of good-quality sputum per cup
- After collection, screw lid on tightly
Do not stand at tent opening during collection
Questions? Page “Xpert MTB/RIF Service, SFGH” on pagerbox.com or at (415) 443-0080