Eiman Mokaddas1,2, Suhail Ahmad1, Hanaa Eldeen2. 1. Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait. 2. Kuwait National TB Control Laboratory, Shuwaikh, Kuwait.
Abstract
OBJECTIVE: This study evaluated the performance of GeneXpert MTB/RIF (Xpert) and ProbeTec ET (PTec-ET) assays in diagnosing extrapulmonary tuberculosis (EPTB) in Kuwait. MATERIALS AND METHODS: We tested nonrespiratory clinical specimens (n = 3,995) collected from 3,995 patients suspected to have EPTB. These included cavitary fluids (n = 2,054), fine-needle aspirate (FNA)/pus/tissue biopsy (n = 1,461), urine (n = 302), cerebrospinal fluid (CSF, n = 118), and others (n = 60). All specimens were processed for acid-fast bacilli (AFB), culture in mycobacteria growth indicator tube 960 system, and nucleic acid detection by Xpert and PTec-ET according to manufacturer's instructions. RESULTS: Of 3,995 specimens, 95 were AFB-positive, 403 were culture-positive, and an additional 86 samples had histopathology suggestive of TB. Using culture as reference, the sensitivity and specificity values were 88.33 and 97.3% for Xpert and 72.95 and 97.80% for PTec-ET, respectively. Although performance of both tests was comparable in AFB-positive samples, Xpert detected significantly more cases in culture-positive samples. Among culture-negative samples, Xpert detected 18 more cases including 16 with histopathological evidence of TB. Lowest positivity was detected for both tests in cavitary fluids. Xpert performed better than PTec-ET in culture-positive FNA/pus/tissue biopsy and CSF samples. CONCLUSIONS: Although performance of both tests was suboptimal for AFB-negative/culture-positive samples, Xpert performed better than PTec-ET and also detected more cases of AFB-negative/culture-negative/histopathology-positive samples. PTec-ET was positive in 3, while Xpert was positive in all 6 culture-positive CSF specimens for rapid diagnosis of TB meningitis. Xpert was thus superior to PTec-ET or smear microscopy in rapid diagnosis of EPTB.
OBJECTIVE: This study evaluated the performance of GeneXpert MTB/RIF (Xpert) and ProbeTec ET (PTec-ET) assays in diagnosing extrapulmonary tuberculosis (EPTB) in Kuwait. MATERIALS AND METHODS: We tested nonrespiratory clinical specimens (n = 3,995) collected from 3,995 patients suspected to have EPTB. These included cavitary fluids (n = 2,054), fine-needle aspirate (FNA)/pus/tissue biopsy (n = 1,461), urine (n = 302), cerebrospinal fluid (CSF, n = 118), and others (n = 60). All specimens were processed for acid-fast bacilli (AFB), culture in mycobacteria growth indicator tube 960 system, and nucleic acid detection by Xpert and PTec-ET according to manufacturer's instructions. RESULTS: Of 3,995 specimens, 95 were AFB-positive, 403 were culture-positive, and an additional 86 samples had histopathology suggestive of TB. Using culture as reference, the sensitivity and specificity values were 88.33 and 97.3% for Xpert and 72.95 and 97.80% for PTec-ET, respectively. Although performance of both tests was comparable in AFB-positive samples, Xpert detected significantly more cases in culture-positive samples. Among culture-negative samples, Xpert detected 18 more cases including 16 with histopathological evidence of TB. Lowest positivity was detected for both tests in cavitary fluids. Xpert performed better than PTec-ET in culture-positive FNA/pus/tissue biopsy and CSF samples. CONCLUSIONS: Although performance of both tests was suboptimal for AFB-negative/culture-positive samples, Xpert performed better than PTec-ET and also detected more cases of AFB-negative/culture-negative/histopathology-positive samples. PTec-ET was positive in 3, while Xpert was positive in all 6 culture-positive CSF specimens for rapid diagnosis of TB meningitis. Xpert was thus superior to PTec-ET or smear microscopy in rapid diagnosis of EPTB.
Authors: Keertan Dheda; Tawanda Gumbo; Gary Maartens; Kelly E Dooley; Ruth McNerney; Megan Murray; Jennifer Furin; Edward A Nardell; Leslie London; Erica Lessem; Grant Theron; Paul van Helden; Stefan Niemann; Matthias Merker; David Dowdy; Annelies Van Rie; Gilman K H Siu; Jotam G Pasipanodya; Camilla Rodrigues; Taane G Clark; Frik A Sirgel; Aliasgar Esmail; Hsien-Ho Lin; Sachin R Atre; H Simon Schaaf; Kwok Chiu Chang; Christoph Lange; Payam Nahid; Zarir F Udwadia; C Robert Horsburgh; Gavin J Churchyard; Dick Menzies; Anneke C Hesseling; Eric Nuermberger; Helen McIlleron; Kevin P Fennelly; Eric Goemaere; Ernesto Jaramillo; Marcus Low; Carolina Morán Jara; Nesri Padayatchi; Robin M Warren Journal: Lancet Respir Med Date: 2017-03-15 Impact factor: 30.700