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. 2013 Jul;51(7):2396–2399. doi: 10.1128/JCM.00151-13

Table 2.

Comparison of the Xpert MTB/RIF assay with culture identification and phenotypic RIF susceptibility testing for specimens positive or indeterminate for mycobacteria by culture or Xpert assay (n = 29)

Specimen type and no(s). Specimen sourcea Xpert assayb
 AFB smear resultc Culture identificationd Rifampin susceptibility (culture based)e Roche Cobas TaqMan M. tuberculosis identification
M. tuberculosis detection Rifampin resistance
Respiratory
    1 BAL Negative ND Negative M. avium ND Negative
    2 Br asp Negative ND Negative M. chimaera ND Negative
    3 Sputum Negative ND Positive M. kansasii ND Negative
    4, 5, 6 Sputum Negative ND Positive M. vulneris ND Negative
    7 Sputum Negative ND Positive M. avium ND ND
    8 Sputum Positive (vl) Indeterminate Negative Negative ND Negative
    9 Sputum Positive (vl) Indeterminate Positive M. tuberculosis Susceptible Positive
    10 BAL Positive (vl) Positive Negative M. tuberculosis Susceptible Positive
    11 Sputum Positive (vl) Positive Positive M. tuberculosis Susceptible Positive
    12 Sputum Positive (l) Negative Negative Negative ND Positive
    13 BAL Positive (l) Negative Positive M. tuberculosis Susceptible Positive
    14, 15, 16 Sputum Positive (l) Negative Positive M. tuberculosis Susceptible Positive
    17 Sputum Positive (l) Negative Positive M. tuberculosis Susceptible ND
    18, 19 Sputum Positive (m) Negative Positive M. tuberculosis Susceptible Positive
    20 Sputum Positive (m) Negative Positive M. africanum Susceptible Positive
    21, 22, 23 Br asp Positive (m) Negative Positive M. tuberculosis Susceptible Positive
    24 Sputum Invalid result ND Negative Negative ND Negative
Nonrespiratory
    25 Biopsy No result ND Negative Negative ND Inhibited
    26 CSF Negative ND Negative M. africanum Susceptible ND
    27 Ascitic fluid Negative ND Negative M. africanum Susceptible Positive
    28 Pleural fluid Negative ND Negative M. tuberculosis Susceptible Negative
    29 Tissue Positive (m) Negative Positive M. tuberculosis Susceptible Positive
a

BAL, bronchoalveolar lavage fluid; Br asp, bronchial aspirate; CSF, cerebrospinal fluid.

b

vl, very low; 1, low; m, medium; ND, not done.

c

AFB samples with a positive auramine-rhodamine microscopy result confirmed by positive Ziehl-Neelsen staining were scored smear positive.

d

Identification of NTM isolates was by 16S rRNA sequence analysis, which when necessary was followed by rpoB or hsp65 sequence analysis; identification of M. tuberculosis isolates by PCR was followed by the MTC line probe assay.

e

Phenotypic drug susceptibility testing for rifampin using the critical concentration of 1 μg/ml.