Microbiology Tech Info

  Introduction: The Modified Ziehl-Neelsen stain is a type of differential bacteriological stain used to identify acid-fast organisms such as Mycobacterium leprae, Actinomycetes, Nocardia and Cryptosporidium parvum. Those Acid fast organisms are capable of retaining the primary stain when treated with an acid. Members of the Actinomycetes, Nocardia sp. (N. brasiliensis and N. asteroides are opportunistic pathogens) are partially branching acid-fast bacteria. Oocysts of coccidian parasites, such as Cryptosporidium and Isospora, are also acid-fast. Hence they can also be detected and identified by Modified Ziehl Neelsen staining procedure. Modified Ziehl Neelsen staining for Mycobacterium leprae Purpose: To demonstration of Mycobacterium leprae in slit skin smear (sss) is a time-tested technique by microscopic examination.  This is acid fast bacilli (AFB) in a skin smear is one of the three cardinal signs of leprosy. Principle: ...

Purpose:      To demonstrate acid-fastbacilli in the given specimen. Principle:   Mycobacterium possesses cell walls that contain Mycolic acid (long-chain fatty acids).  The presence of Mycolic acid and lipids in the Mycobacterial cell wall accounts for the property of resisting decolorization with strong acids. Once stained with primary stains, they resist decolourisation with strong acids. This feature is called Acid fastness and it is associated with the intact cell wall and the presence of large quantities of lipidecolorisationds and mycolic acid. Performance characteristics:  This test cannot find out the exact species of Mycobacteria. It can only differentiate whether the Acid Fast Bacilli are present or not. Further tests must be performed to confirm the species of Mycobacteria spp. Type of samples:   Sputum, transtracheal aspiration, laryngeal swab, bronchoscopic specimens, bronchoalveolar lavage.  Extra-Pulmonary Specimens: Uri...