ParaLensTM Microscope Attachment: Tuberculosis
Background
It is estimated that 1/3 of the world’s population is infected with tuberculosis (TB), and that almost two million people die each year from the disease.1 The World Health Organization (WHO) and the Stop TB Partnership have established Millennium Development Goals of reducing the prevalence of TB by 50% from 1990 levels by the year 2015, and reducing the disease to one per million population by 2050.2, 3 The key to these goals is the advocacy of Directly Observed Therapy Short Course (DOTS), a multistage approach to developing TB awareness and support. One of the five elements of the DOTS strategy involves improving the detection of Mycobacterium tuberculosis, the acid-fast bacterium (AFB) that causes TB. Traditionally, detection of AFB in suspected pulmonary TB cases has been performed using light microscopy on sputum samples prepared with ZiehlNeelsen or Kinyoun stains. While this type of stain can be effective, fluorescence microscopy, using auramine stain, is both more sensitive and faster to perform than the traditional methods.4 Thus, the WHO has recently recommended the use of fluorescence microscopy as an important part of the DOTS strategy. 5 Until recently, the fluorescence microscopes needed for these tests have been expensive and bulky, using dangerous and often fragile mercury or xenon lamps as light sources. Because of these and other significant limitations, the use of fluorescence microscopy in TB diagnosis has not been fully adopted in many parts of the world hardest hit by the disease. Additionally, despite its improved sensitivity and decreased examination time, conventional auramine stain requires approximately the same amount of preparation time (20 minutes) as Ziehl-Neelsen stain, representing a missed opportunity for faster bacilli detection and decreased workloads. This application note will demonstrate how the QBC ParaLensTM Microscope Attachment and the QBC Fluorescence and