Introduction. Mycobacterium tuberculosis and Mycobacterium leprae are acid-fast organisms with lipid-rich cell walls that resist decolorization with acidified alcohol after application of a dye with heat. The Ziehl-Neelsen and Fite Faraco staining technique, which are diagnostic tools for identification of acid-fast bacilli (AFB) found in histopathologic samples, are based on this principle. A modification of the Ziehl-Neelsen technique is described as an alternative rapid and reliable method of diagnosis for prompt detection and treatment.Methodology. One hundred and seven (107) archived tissue specimens from autopsy and dermatology cases interpreted as positive for M. tuberculosis and M. leprae were stained using the proposed modified acid-fast (MAF) technique compared with Fite Faraco (FF) staining method as reference standard. Each specimen was read by two independent evaluators.Results. The degree of diagnostic agreement of the MAF with FF was calculated. For autopsy (n=16) and dermatology (n=91) samples, the Cohen's kappas are 0.765 (substantial) and 0.397 (fair), respectively. Overall, the Cohen's kappa is 0.458 (moderate). Conclusion.The proposed modified Acid-Fast staining method may be considered as an alternative to the conventional Ziehl-Neelsen method and the Fite Faraco method in identifying positive acid-fast bacilli in tissue samples taken from clinical cases of M. tuberculosis and M. leprae.
The rabies virus is one of the most neurotropic of all viruses infecting mammals. During the terminal phases of infection, the virus spreads to peripheral tissues, including the skin. The external skin of the nose, called the nasal planum, is a sensory organ where numerous nerve bundles and terminal nerves are distributed. Therefore, the nasal planum is expected to serve as a postmortem diagnostic material.However, the distribution of rabies virus antigens in the nasal planum in rabid animals has not yet been studied. In this study, the nasal planum was obtained from 45 rabid dogs. In all rabid dogs, the viral antigen was detected in the peripheral nerve tissues, Merkel cells, and squamous cells. The viral antigen in the epidermis exhibited three patterns: first, a diffuse positive pattern from the basal layer to the squamous layer; second, a reticular positive pattern along the cell membrane in the squamous layer; and third, a basal layer pattern of the epidermis. In the dermis, viral antigens were detected more often in lamellated corpuscles just beneath the rete pegs. These results suggest that the nasal planum could serve as a useful alternative source for postmortem diagnosis in rabies endemic countries.
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