Mycobacterium tuberculosis Complex Detection and Rifampin Resistance by PCR with AFB Culture & Stain

Abbrev Code:MTBRIFPCR   
Order Code:LAB8286Order Name:Mycobacterium tuberculosis Complex Detection and Rifampin Resistance by PCR with AFB Culture & Stain
Order Instructions:MTB/RIF PCR performed in IDDL. Test must be ordered in conjunction with AFB Culture and AFB Stain to be performed at ARUP.
Methodology:Real-time polymerase chain reaction (PCR)
CPT Codes: 87556 x1, 87556 x1
Test Includes:Note: Rifampin resistance (rpoB gene) by PCR will only be reported when MTB Complex DNA is detected.
Turnaround Time:Performed 24/7
Special Instructions:See Acid-Fast Bacilli (AFB) Culture and Smear, Non-Blood (LAB877,LAB266) for culture/smear details.

Collection Instructions

Optimal Volume:2.0 mL for MTB/RIF PCR
Minimum\Peds Volume:1.0 mL for MTB/RIF PCR
Container:Plastic leakproof container, sterile
Collection Instructions:Recommend early morning sputum collection. If a second MTB/RIF test is required, a specimen collected 8 hours after the first collecxtion is preferred.
Causes for Rejection:Samples with obvious food particles or other solid particulate matter are not acceptable for testing.
Contraindications:The Xpert MTB/RIF assay is not indicated for use with sputum samples from patients being treated with antituberculosis drugs either to determine bacteriologic cure or to monitor response to therapy. Assay interference may be observed in the present of Lidocaine (>20% v/v), mucin (>1.5% w/v), Ethambutol (>5 ug/mL), Guaifenesin (>2.5 mg/mL), Phenylephrine (25% v/v), or tea tree oil (>0.008% v/v) The performance of the Xpert MTB/RIF assay has not been evaluated with samples from pediatric patients.

Processing and Shipping

Specimen Processing:Do not process. Send immediately to laboratory.
Shipping Instructions:Send immediately to laboratory.
Stability:Specimen can be stored up to 7 days at refrigerated temperature.
Test Performed at or Referral Lab Microbiology  (UMMC East Bank)


Reference Range:Not detected.
Use:This test is FDA approved only for assessing isolation requirements for patients who are admitted to or potentially admitted to airborne precautions (negative air pressure). This test is NOT diagnostic for MTB. Cultures must also be ordered according to possible Mycobacterium tuberculosis protocols. Rifampicin (rpoB gene) resistance by PCR will be reflexed for positive tests for MTB. These results may guide treatment; however, culture with susceptibility testing is required to confirm the rifampicin results. A negative rifampicin resistance screen by Xpert MTB-RIF indicates likely susceptibility but NOT definitive susceptibility. Further testing is required.

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