Validation of LED fluorescence microscopy for tuberculosis diagnosis in Cuba

Abstract

LED fluorescence microscopy (MF LED) has been recommended by the World Health Organization for tuberculosis (TB) diagnosis. The aim was to validate this technique in the National Reference Laboratory for Tuberculosis, Leprosy and Mycobacteria (NRLTBLM). A validation study of the MF LED was carried out at the NRLTBLM of the “Pedro Kourí” Institute, from February-July 2018. A total of 98 slides were included: 49 smears that had a positive culture for mycobacteria and 49 slides with a negative culture. The results of the LED FM were compared with bright field microscopy (BFM) and conventional fluorescence microscopy (CFM). With the LED FM and CFM, 14 positive smears were identified that had been negative by BFM, the positivity rate being increased to 13,3%. By both fluorescent techniques, more smears (18/98) were detected with scanty acid fast bacilli than the BFM (8/98). The agreement between MF LED and BFM was considered good (k = 0,6773) and between MF LED and CFM very good (k = 0,8711). The sensitivity of the MF LED was higher (77,55%) than the BFM (48,98%). The higher sensitivity of the MF LED was confirmed, validating this technique as an alternative to Zielh Neelsen staining in the NRLTBLM. Its implementation in Cuba would be very useful in detecting and monitoring the follow up cases, as well as the management of patients with suspected TB.