Efficacy of Fluorescence Light Emitting Diode (LED) Microscopy for Detection of Mycobacterium Tuberculosis in Sputum of Patients Attending a Tertiary Hospital in Osogbo Osun State, Nigeria

Abstract

For developing countries with a large number of cases and financial constraints, evaluation of rapid and inexpensive diagnostic methods has a great importance for early diagnosis of tuberculosis in order to control the spread of infection. This study was carried out to compare the efficacy of fluorescence Light Emitting Diode (LED) microscopy to bright field microscopy. Three hundred and four (304) sputum samples were collected from suspected cases of Pulmonary Tuberculosis from March, 2015 to February, 2016. These samples were processed and subjected to Auramine-O (AO) and ZN staining for detection of TB as described. Positive smears were graded according to International Union against Tuberculosis and Lung Disease and World Health Organization (IUATLD/WHO). Out of 304 sputum smears, the overall prevalence of M. tuberculosis was 8.6%with statistical significant difference (P=0.011) Males had higher prevalence rate of M. tuberculosis 7(4.6%) than female 6(3.9%) among 152 patients. Age group 31-45yrs had prevalence rate of 6(3.9%). Bight field and fluorescence microscopy detected 24 (7.9%) and 26 (8.6%) respectively with significant difference (DF = 4, X2=296.490, P=0.000). This study showed that two positive samples were missed on ZN staining but found to be positive with Auramine O staining. Sensitivity and specificity of fluorescence microscopy were 94.2% and 89.5% while Bright field microscopy had sensitivity and specificity of 91.7% and 86.8% respectively. Reliability of microscopist using Crobauch Alpha was 0.753 (75.3%). Fluorescence microscopy has a better diagnostic value in detecting TB cases and is less time-consuming compared to Bright field microscopy in diagnosing tuberculosis.