DIAGNOSTIC ACCURACY OF XPERT ® MTB / RIF COMPARED TO MICROSCOPY-BASED METHODS FOR DIAGNOSING TUBERCULOUS LYMPHADENITIS FROM FINE NEEDLE ASPIRATES AT THE PORT MORESBY GENERAL HOSPITAL , PAPUA NEW GUINEA

Data on the accuracy of Xpert® MTB/RIF (Xpert) assay in detecting TB in lymph node aspirates in Papua New Guinea (PNG) is scanty. This study evaluated Xpert performance in diagnosing tuberculous lymphadenitis (TBLN) using lymph node needle aspirates at the Port Moresby General Hospital (PMGH). The objective of the study was to compare Xpert accuracy to acid fast bacilli (AFB) microscopy, cytomorphology, a composite reference test (CRS) and culture. A total of 107 eligible subjects were recruited out of 1080 clinic attendees. Results showed Xpert detected significantly more cases of TBLN than AFB microscopy (66 vs 35; p=0.001). Compared to AFB microscopy Xpert had a sensitivity of 45.4% (95% CI 33.1-58.1), specificity of 87.8% (95% CI 73.8-95.9), positive predictive value (PPV) of 85.7% (95% CI 71.6-93.4) and negative predictive value (NPV) of 50.0%% (95% CI 43.8-56.1). There was no difference between Xpert and cytomorphology (66 vs 60; p=0.5). Compared to cytomorphology Xpert had a sensitivity of 71.6% (95% CI 58.5-82.5), specificity of 51.1% (95% CI 35.7-66.3), PPV of 66.1% (95% CI 58.2-73.2) and NPV of 57.5% (95% CI 45.2-68.9). There was no difference between Xpert and CRS (66 vs 71; p=0.6). Compared to CRS Xpert had a sensitivity of 76.0% (95% CI 64.485.3), specificity of 66.6% (95% CI 49.0-81.4), PPV of 81.8% (95% CI 73.5-87.9) and NPV of 58.4% (95% CI 46.7-69.4). Culture was completed on 24 subjects with positive isolates in 14 giving a culture yield of 58.3%. Of the 24 subjects, Xpert was positive in 21 subjects. There was no difference between Xpert and culture (21 vs 14; p=0.8). Compared to culture Xpert had a sensitivity of 100.0% (95% CI 76.8-100.0), specificity of 30.0% (95% CI 6.6-65.2), PPV of 66.6% (95% CI 57.1-75) and NPV of 100.0%. The results suggest Xpert is more sensitive than AFB microscopy but comparable to cytomorphology and CRS for TBLN diagnosis in the PNG context. Xpert can be used for diagnosing TBLN at PMGH.

[1]  J. Ershova,et al.  The Burden of Drug-Resistant Tuberculosis in Papua New Guinea: Results of a Large Population-Based Survey , 2016, PloS one.

[2]  U. Sack,et al.  Tuberculous Lymphadenitis in Ethiopia Predominantly Caused by Strains Belonging to the Delhi/CAS Lineage and Newly Identified Ethiopian Clades of the Mycobacterium tuberculosis Complex , 2015, PloS one.

[3]  L. Rigouts,et al.  GeneXpert MTB/RIF Assay for the Diagnosis of Tuberculous Lymphadenitis on Concentrated Fine Needle Aspirates in High Tuberculosis Burden Settings , 2015, PloS one.

[4]  U. Kumar,et al.  Cytomorphological Patterns of Tubercular Lymphadenitis Revisited , 2014, Annals of medical and health sciences research.

[5]  N. Dendukuri,et al.  Xpert MTB/RIF assay for the diagnosis of extrapulmonary tuberculosis: a systematic review and meta-analysis , 2014, European Respiratory Journal.

[6]  G. Cooke,et al.  Performance of Xpert MTB/RIF in the diagnosis of tuberculous mediastinal lymphadenopathy by endobronchial ultrasound. , 2014, Annals of the American Thoracic Society.

[7]  L. Berrie,et al.  Diagnostic Accuracy of Xpert MTB/RIF for Extrapulmonary Tuberculosis Specimens: Establishing a Laboratory Testing Algorithm for South Africa , 2014, Journal of Clinical Microbiology.

[8]  M. Louw,et al.  Diagnostic yield of fine needle aspiration biopsy in HIV-infected adults with suspected mycobacterial lymphadenitis. , 2013, South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde.

[9]  L. Rigouts,et al.  Fine-needle aspiration for diagnosis of tuberculous lymphadenitis in children in Bangui, Central African Republic , 2012, BMC Pediatrics.

[10]  Stefan Niemann,et al.  Drug resistance-conferring mutations in Mycobacterium tuberculosis from Madang, Papua New Guinea , 2012, BMC Microbiology.

[11]  R. Gilman,et al.  Rapid implementation of new TB diagnostic tests: is it too soon for a global roll-out of Xpert MTB/RIF? , 2012, The American journal of tropical medicine and hygiene.

[12]  G. Simpson,et al.  Resistance patterns of multidrug-resistant tuberculosis in Western Province, Papua New Guinea [Notes from the field]. , 2011, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[13]  C. Wright,et al.  Fine-needle aspiration biopsy: a first-line diagnostic procedure in paediatric tuberculosis suspects with peripheral lymphadenopathy? , 2009, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[14]  R. Gie,et al.  Tuberculous Lymphadenitis as a Cause of Persistent Cervical Lymphadenopathy in Children From a Tuberculosis-Endemic Area , 2006, The Pediatric infectious disease journal.

[15]  P. Mcmaster,et al.  Ten-year experience with paediatric lymph node tuberculosis in Port Moresby. , 2001, Journal of tropical pediatrics.

[16]  P. Mcmaster,et al.  A retrospective review of paediatric lymph node tuberculosis in Port Moresby, Papua New Guinea , 2000, Annals of tropical paediatrics.

[17]  D. Prasoon.  Acid-Fast Bacilli in Fine Needle Aspiration Smears from Tuberculous Lymph Nodes , 2000, Acta Cytologica.

[18]  J. Yim,et al.  Accuracy of the Xpert® MTB/RIF assay for the diagnosis of extra-pulmonary tuberculosis in South Korea. , 2015, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[19]  R. Leclercq,et al.  Rapid and efficient detection of Mycobacterium tuberculosis in respiratory and non-respiratory samples. , 2011, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[20]  R. Arora,et al.  CYTOMORPHOLOGIC PATTERNS IN TUBERCULOUS LYMPHADENITIS , 1999 .