Paradoxical reaction (PR) in HIV negative patients with tuberculosis: Case series

Abstract

Background: Tuberculosis (TB) is a communicable disease for which an early diagnosis is essential to control the disease. The microscopy-based TB screening is the conventional method employed for TB identification in sputum smears. Fluorescence microscopy-based diagnosis provides improved sensitivity and benefits large number of TB burdened communities across the globe. Microscopic images are often corrupted by intensity variations because of inherent imperfections of the image formation process. This may result in false positives which is the potential shortcoming of fluorescence microscopy.Methods & Materials: The fluorescence-stained slides were prepared at South African National Health Laboratory Services, Groote Schuur Hospital in Cape Town. The images (N=100) were captured using a camera in monochrome binning mode attached to a 20x objective fluorescence microscope of 0.5 numerical aperture. The camera (AxioCam HR) has a resolution of 4164 x 3120 with a pixel size 6.45 m (h) x 6.45 m (v).The illumination correction methods adopted in this work include surface fitting method, multiple regression method and bidirectional empirical mode decomposition. The results of illumination correction are validated using the image sharpness measures. This includes derivative-based, statistical, histogrambased and transform-based parameters.