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Home > Molecular extensively drug-resistant (XDR) TB Screen
Indicate specimen source: BAL, CSF, Sputum, Sputum (induced), Stool, Urine, Tissue (specify), Processed Specimen (specify) or Other body fluid.
Indicate if patient is a Cystic Fibrosis patient (will require different decontamination), or if sample is environmental (contact laboratory before collection), or veterinary (animal type).
Sputum: >5 mL of unprocessed (raw) sputum. Collect the first early morning expectoration in a sterile 50 mL polypropylene centrifuge tube capable of withstanding 3,000 x g (i.e, Falcon, Greiner, etc).
Body Fluids or CSF: As much body fluid as possible is aseptically collected by aspiration or during a surgical procedure. CSF should be maximum volume obtained, ideally at least 2 mL.
Gastric Aspirates: Must be neutralized (pH 7) with sodium carbonate if transport time exceeds four hours from collection. Transfer 5-10 mL to a sterile container.
Tissue: =10 g or as much as possible with a biopsy. Transfer to a sterile container (without formalin or preservatives).
Urine: = 40 mL to a sterile container.
Stool: = 1 g in sterile, wax-free disposable container.
Blood: =5 mL adult; =1 mL child. If blood has to be transported before inoculation of the medium, sodium polyanethol sulfate (SPS), heparin, or citrate may be used as anticoagulants.
Ship the specimen on the day of collection via airmail or by overnight courier.
Sputum: Three sputum specimens at 8-24 hour intervals and at least one first-morning specimen. Have patient rinse mouth with water before collecting sputum to minimize contaminating specimen with food particles, mouthwash, or oral drugs, which may inhibit the growth of mycobacteria.
Induced sputum: Use sterile hypertonic saline. Avoid sputum contamination with nebulizer reservoir water which may contain saprophytic mycobacteria from tap water. Specify Sputum (Induced) on requisition form since it may resemble saliva which is not an acceptable specimen.
Bronchoalveolar lavage (BAL): Avoid contaminating bronchoscope with tap water.
CSF: Use maximum volume attainable, ideally at least 2 mL.
Gastric lavage: Aspiration of swallowed sputum from the stomach by gastric lavage may be necessary for infants, young children, and the obtunded. Fasting, early-morning specimens are recommended in order to obtain sputum swallowed during sleep. Samples of 5 to 10 mL, adjusted to neutral pH, should be collected on 3 consecutive days.
Stool: Collect specimen directly into container, or transfer from bedpan or plastic wrap stretched over toilet bowl.
Urine: Collect first morning specimen on 3 consecutive days to provide the best yield. Accept only one specimen/day.
Swabs are not recommended for the isolation of mycobacteria, since they provide limited material. They are acceptable only if a specimen cannot be collected by other means. Negative results obtained from swab specimens are unreliable.
Samples contained in waxed containers are not acceptable. Waxed containers may produce false-positive smear results.
Tissue specimens submitted in formalin are not acceptable.
Gastric aspirates that have not been neutralized are not acceptable.
Frozen sputum or stool specimen is not acceptable.
24-hour pooled urine or sputum specimen is not acceptable.
Urine from catheter bag is not acceptable.
<40 mL of urine, unless larger volume cannot be obtained, is not acceptable.
Blood collected in EDTA, ACD, or in conventional blood culture bottles and coagulated blood are not acceptable.
Specimen that leaked in transit is not acceptable.
If specimen cannot be mailed on the day of collection, keep the specimen refrigerated until the day of shipment. Specimen can be shipped at room temperature or using a cold pack.
7 days a week
Rapid molecular XDR TB Screen using line-probe assay
Mycobacteriology Lab (TB)
AFB1, AFB2, MTB4
gyrA mutation detected-resistance to fluoroquinolones.
No gyrA detected-susceptibility to fluoroquinolones.
rrs mutation detected-resistance to aminoglycosides/cyclic peptides.
No rrs mutation detected-susceptibility to aminoglycosides/cyclic peptides.
embB mutation detected-resistance to ethambutol
No embB mutation detected-susceptibility to ethambutol.
The line probe assay only indicates those resistances of MTB complex that have their origins in the gyrA, rrs, and embB regions examined here. Resistances originating from mutations of other genes or gene regions as well as other fluoroquinolone, aminoglycosides/cyclic peptides and ethambutol resistance mechanisms will not be detected by this test.
This test only screens the nucleic acid sequence and not the amino acid sequence. Therefore, it is possible that mutations that do not cause an amino acid exchange (silent mutations) will still produce the absence of one of the wild-type probes.
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Advanced Diagnostic Laboratories
1400 Jackson St
Denver, CO 80206
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