Bronchial wash Gene Xpert MTB/RIF in lower lung field tuberculosis: Sensitive, superior, and rapid in comparison with conventional diagnostic techniques

Abstract

Background: Lower lung field tuberculosis (LLF TB) is an atypical presentation of tuberculosis (TB). LLF TB is common, and a proportionate number of non-resolving pneumonia cases are diagnosed to have pulmonary TB. Materials and Methods: The prospective observational study was conducted during June 2013 to December 2015 in the Department of Pulmonary Medicine, MIMSR Medical College, Latur, India; the objective of the study is clinical, microbiological, and radiological presentation of LLF TB and the comparison of yield of conventional diagnostic techniques and bronchoscopy guided modalities in LLF TB. Additional important objective of the study is to find LLF TB in patients with nonresolving pneumonia (NRP). A total of 2,600 patients with pulmonary TB were included in the study after inclusion and exclusion criteria. Ethical clearance was taken from the ethical committee of the institutional review board. Consent was taken from the patients before inclusion in the study. Statistical analysis was done using chisquare test. Results: In the present study, 300 (11.53%) cases of LLF TB of total 2600 pulmonary tuberculosis were included, females constitutes 66.66% (200/300) with mean age of 58.4 ± 11.8 years and males constitutes 33.34% (100/300) with mean age of 56.8 ± 10.6 years. Constitutional symptoms were observed as cough in 93% cases, fever in 83% cases, shortness of breath in 72% cases, anorexia in 91% cases, and weight loss in 84% cases. Radiological assessment of study cases documented the involvement of right lower zone in 84% cases and left lower zone in only 16% cases. In the studied LLF TB cases, 57 cases (20.66%) were diagnosed by routine sputum microscopic examination for acid fast bacilli (AFB) and 80 cases (28%) were diagnosed by induced sputum microscopic examination for AFB. In the study of 170 LLF TB cases, headto-head comparison between conventional diagnostic techniques (sputum microscopy and Induced sputum microscopy for AFB) made diagnosis in 60 cases, while bronchoscopy-guided sampling techniques (BAL for AFB and BAL for Gene Xpert MTB/RIF) made diagnosis in 155 cases (91.17%) (P < 0.00001). Comorbid conditions such as human immunodeficiency virus (HIV) coinfection in 36 cases (12.00%), Diabetes mellitus in 64 cases (21.33%), and chronic kidney disease (CKD) in 22 cases (7.33%) were observed. Comorbidities were observed in 41.67% of the studied cases and found very significant assessment to have successful treatment outcome (P < 0.00001). In the study of 300 LLF TB cases, 60 cases were having NRP pattern. In LLF TB cases with NRP pattern, bronchoscopy-guided bronchial wash microscopy for AFB made diagnosis in 18 cases (42%), while bronchoscopy-guided BAL for Gene Xpert MTB/RIF made diagnosis in 58 cases (96.66%) (P < 0.00001). Conclusion: LLF TB is usually underdiagnosed because of diverse clinical and radiological presentation, less diagnostic yield of conventional diagnostic modalities, and these modalities used routinely and universally. Bronchoscopy-guided diagnostic techniques ar...

Role of Bronchial Washing Gene Xpert in Sputum-Scarce Cases of Suspected Pulmonary Tuberculosis

“…Similar results were demonstrated by different researchers, such as Lyer VN et al, Mohan A et al and Shin JA et al reporting detection of TB in 30-48% in smear negative patients 16-18. Different studies validated the practical and clinical importance of bronchoscopy in PTB diagnosis 10,15,16,18,19. In all these studies bronchoscopies and BW showed increased detection of TB.…”

“…Many sputum smear negative patients are reported to have progressive disease 13,14. Previous reports in non-immune compromised patients with sputum sputum-scarce TB indicated that bronchoscope specimens and post bronchoscope sputum are helpful in establishing the diagnosis 9,15. Superiority of Gene Xpert in immunocompromised patients to detect TB as compared to microscopy is debatable.…”

Validez diagnóstica del GeneXpert para Mycobacterium tuberculosis y prueba de resistencia a rifampicina

“…En el cálculo de la concordancia de resultados de la prueba GeneXpert MTB/RIF frente a cultivo Löwenstein Jensen respecto al azar con el Índice Kappa de Cohen (K)= 0,88, mostró una concordancia clasificada como muy buena (casi perfecto), similar al estudio en Chile (K)= 0,96 13 . La prueba de GeneXpert tiene una sensibilidad de 98 % (IC 95 %), similar a las observadas en Pakistán (78/85) (92 %) 14 , India (155/170) (91 %) 6 , Corea del Sur (35/43) (81,6 %) 15 , Chile (31/33) (94 %) 16 y Sudáfrica (25/27) (93 %) 17 y una especificidad del 96 % (IC 95 %), muy parecida a la encontrada por Lee (97/97) (100 %) 15 , Vallejo (334/351) (95 %) 16 y Theron (127/133) (96 %) 17 .…”

“…La prueba semicuantitativa GeneXpert MTB/RIF de diagnóstico in vitro que detecta componentes del genoma del Mycobacterium tuberculosis (MTB) y resistencia a rifampicina (RIF) se realiza de forma automatizada, purificando y amplificando ácidos nucleicos, identificando la secuencia diana a través de ensayos de reacción en cadena de la polimerasa (PCR) y de PCR con transcriptasa inversa (RT-PCR), ambas en tiempo real. Esta prueba contiene cebadores que amplifican una porción del gen rpoB y sondas que distinguen la secuencia mutada asociada a la resistencia a rifampicina con resultados en dos horas [4][5][6] .…”

“…Se necesita de un instrumento que contiene un ordenador personal y software precargado para realizar las pruebas y ver los resultados (MTB detectado o no detectado, RIF resistencia detectada, indeterminada o no detectada), así como un cartucho autónomo desechable de un solo uso que contienen los reactivos RT-PCR y PCR [4][5][6] .…”