Microbiologist (EQA)

In Cartridge-based Nucleic Acid Amplification Test (CBNAAT) assay, the basis for detection of rifampicin resistance is the difference between the first or early Cycle threshold (Ct) and the last or late Ct value, of M. tuberculosis-specific probes. Or the difference between probes with the maximum Ct value and minimum Ct value is greater than four.

Fluorescence Microscopy is a newer and better type of microscopy where the TB bacteria are stained using a fluorescent dye using the property of Acid Fastness. The dye will fluoresce when illuminated by UV light. When the UV light source is an LED Lamp, it is called LED fluorescent microscopy.

Here the bacilli appear as slender bright yellow fluorescent rods, standing out clearly against a dark background, as can be seen in the figure below.