IMPACT OF GEN-PROBE\'S AMPLIFIED MYCOBACTERIUM TUBERCULOSIS DIRECT TEST ON TUBERCULOSIS DIAGNOSIS IN CHILDREN
11 slide(s) – English – 2011-06-07
The aim of the study was to evaluate the performance of Gen-Probe Amplified Mycobacterium tuberculosis Direct Test (AMTD, Gen-Probe, San Diego, California) for the diagnosis of tuberculosis in children, compared to conventional culture and clinical diagnosis. We retrospectively studied 81 children (48 males; mean age 7 years; range 1-16 years) evaluated for possible active TB. Respiratory samples (n=64/95;67%) submitted to NRLM included gastric aspirates (n=30), induced sputa (n=30), bronchial aspirates and bronho-alveolar lavage (n=4). Non-respiratory samples (n=31/95; 33%) included lymph nodes (n=20), and other sterile fluids (n=11). Specimens were examined using AFB microscopy, Gen-Probe and bacterial culture using BACTECTM MGITTM 960 (Becton Dickinson, USA) and Löwenstein-Jensen (LJ) media. The clinical diagnosis of TB was made in 34/81 (42%) children (29/34 with pulmonary disease). Direct smear was positive for AFB in 2/34 (6%) children; Mycobacterium tuberculosis (ΜΤΒ) was recovered by culture from 13/34 (38%) and AMTD was positive in 20/34 (59%). Based on clinical diagnosis, the sensitivity, specificity, PPV and NPV of the AMTD test vs. culture were 59%, 96%, 91%, and 76% vs. 38%, 98%, 93% and 69%, respectively. For pulmonary vs. extra-pulmonary disease the performance of AMTD compared to culture was: 100%, 87%, 67%, 100% vs. 75%, 96%, 75% and 96%, respectively. Nucleic acid amplification tests are more sensitive and very specific methods for the (rapid) detection of MTB compared to culture in children with TB. The Gen-Probe technique increases TB detection in children by about 55% compared to culture.