Pathogen Detection

Abstract

Detection of M. leprae by Microscopy Detection of acid-fast bacilli (AFB) by microscopy is recognized as the fastest, easiest, and least expensive tool for the rapid identification of leprosy cases. In many regions where leprosy is en-demic, diagnosis is based purely on the detection of skin lesions and sensory loss. Although serol-ogy or PCR-based procedures have shown their value for leprosy diagnosis, bacilloscopy, which consists of the detection of AFB in lymph samples or in a microtome section of a skin biopsy, is still the basis for confirming clinically suspected leprosy (see Chapter 2.4). The preparation of microscopic slides from lymph samples is simple; however, the histopathologic analysis of skin biopsies is far more complex, as it demands personnel who are trained in the collection, fixation, preparation , and interpretation of skin and/or nerve biopsy slides. Although the specificity of acid-fast microscopy is excellent for Mycobacterium species and some related genera such as Nocardia and Rhodococcus, its sensitivity is less than that of other procedures. The most commonly used staining technique to identify Mycobacterium leprae was first described by the bacteriologist Franz Ziehl (1859-1926) and the pathologist Friedrich Neelsen (1854-1898) as a simple improvement of Robert Koch's complex staining method. While Ziehl was the first to