title: Prospective evaluation of GeneXpert for the diagnosis of HIV- negative pediatric TB cases.
abstract: BACKGROUND
  The GeneXpertMTB/RIF (Xpert) assay is now recommended by WHO for diagnosis of tuberculosis (TB) in children but evaluation data is limited.
  
  
  METHODS
  One hundred and fifty consecutive HIV negative children (<15 years of age) presenting with suspected TB were enrolled at a TB referral hospital in Ho Chi Minh City, Vietnam. 302 samples including sputum (n = 79), gastric fluid (n = 215), CSF (n = 3), pleural fluid (n = 4) and cervical lymphadenopathic pus (n = 1) were tested by smear, automated liquid culture (Bactec MGIT) and Xpert. Patients were classified retrospectively using the standardised case definition into confirmed, probable, possible, TB unlikely or not TB categories. Test accuracy was evaluated against 2 gold standards: [1] clinical (confirmed, probable and possible TB) and [2] 'confirmed TB' alone.
  
  
  RESULTS
  The median age of participants was 18 months [IQR 5-170]. When test results were aggregated by patient, the sensitivity of smear, Xpert and MGIT against clinical diagnosis as the gold standard were 9.2% (n = 12/131) [95%CI 4.2; 14.1], 20.6% (n = 27/131) [95%CI 13.7; 27.5] and 29.0% (n = 38/131) [21.2;36.8], respectively. Specificity 100% (n = 19/19), 94.7% (n = 18/19), 94.7% (n = 18/19), respectively. Xpert was more sensitive than smear (P = <0.001) and less sensitive than MGIT (P = 0.002).
  
  
  CONCLUSIONS
  The systematic use of Xpert will increase early TB case confirmation in children and represents a major advance but sensitivity of all tests remains unacceptably low. Improved rapid diagnostic tests and algorithm approaches for pediatric TB are still an urgent research priority.
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. giangdc@oucru.org.|Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. giangdc@oucru.org.
authors.forename: Do Chau
authors.initials: do C
authors.lastname: Giang
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. ngocduong_06@yahoo.com.
authors.forename: Tran Ngoc
authors.initials: TN
authors.lastname: Duong
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. hadtm@oucru.org.
authors.forename: Dang Thi Minh
authors.initials: DT
authors.lastname: Ha
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. nhanht@oucru.org.
authors.forename: Ho Thi
authors.initials: HT
authors.lastname: Nhan
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. mwolbers@oucru.org.
authors.forename: Marcel
authors.initials: M
authors.lastname: Wolbers
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. nhuntq@yahoo.com.vn.
authors.forename: Nguyen Thi Quynh
authors.initials: NT
authors.lastname: Nhu
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. dheemskerk@oucru.org.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Heemskerk
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. ngocduong_06@yahoo.com.vn.
authors.forename: Nguyen Dang
authors.initials: ND
authors.lastname: Quang
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. ngocduong_06@yahoo.com.vn.
authors.forename: Doan Thanh
authors.initials: DT
authors.lastname: Phuong
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. phamhang1971@yahoo.com.vn.
authors.forename: Pham Thu
authors.initials: PT
authors.lastname: Hang
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. loc3725@yahoo.com.
authors.forename: Tran Huu
authors.initials: TH
authors.lastname: Loc
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. ngoclan0456@yahoo.com.
authors.forename: Nguyen Thi Ngoc
authors.initials: NT
authors.lastname: Lan
authors.affiliation: Pham Ngoc Thach Hospital, Ho Chi Minh City, Vietnam. bshuydung@yahoo.com.
authors.forename: Nguyen Huy
authors.initials: NH
authors.lastname: Dung
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. jeremyjfarrar@yahoo.com.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Farrar
authors.affiliation: Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. mcaws@hotmail.com.|Department of Clinical Sciences, Liverpool School of tropical Medicine, Pembroke Place, L3 5QA, UK. mcaws@hotmail.com.
authors.forename: Maxine
authors.initials: M
authors.lastname: Caws
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D015658:HIV Infections / Q000175:diagnosis; D006801:Humans; D007223:Infant; D008297:Male; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis*; D014744:Vietnam
chemical_list: D004269:DNA, Bacterial