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Table 2 Comparison between PTB and EPTB regarding laboratory diagnostic methods (AFB smear, LJ culture and Gene Xpert MTB/RIF assay)

From: Diagnostic utility of GeneXpert MTB/RIF assay versus conventional methods for diagnosis of pulmonary and extra-pulmonary tuberculosis

Laboratory methods PTB(n = 449) EPTB(n = 133) X2 Pvalue
AFB smear
 Negative 300 (66.8%) 81 (60.9%) 2.22 0.70
 + 40 (8.9%) 12 (9.0%)
 ++ 31 (6.9%) 10 (7.5%)
 +++ 44 (9.8%) 18 (13.5%)
 ++++ 34 (7.6%) 12 (9.0%)
AFB smear
 Negative 300 (66.8%) 81 (60.9%) 1.59 0.21
 Positive 149 (33.2%) 52 (39.1%)
LJ culture
 Positive 122 (27.2%) 38 (28.6%) 0.10 0.75
 Negative 327 (72.8%) 95 (71.4%)
Gene Xpert MTB/RIF assay
 Invalid 42 (9.4%) 11 (8.3%) 1.55 0.46
 Positive 111 (24.7%) 40 (30.1%)
 Negative 296 (65.9%) 82 (61.7%)
Rifampicin resistance (n = 111) (n = 40)   
 Yes 14 (12.6%) 13 (32.5%) 7.92 0.005*
 No 97 (87.4%) 27 (67.5%)
  1. X2 Chi square test
  2. *Significant statistical difference