MICROBIOLOGY FOR STUDENTS (M4S)

Ingested RBCs inside the cyst (100X objective) 

Blastomyces dermatitidis Blastomyces dermatitidis Post By: Anil Pokhrel 1. INTRODUCTION Blastomyces dermatitidis is a thermally dimorphic fungi originally isolated from cutaneous lesions. The teleomorph of Blastomyces dermatitidis is referred to as Ajellomyces dermatitidis. At 25°C-30°C, Blastomyces grows as a mold form with conidia and septate hyphae usually within 14 days; some strains grow more slowly. Mould form produces abundant conidia from aerial hyphae and lateral conidiophores. These conidia are spherical, ovoid, pyriform measuring 2-10 µm in diameter, resembling the macroconidia of Histoplasma capsulatum. The conidia of Blastomyces are smooth. Thick walled chlamydospores 7-18 µm in diameter also may be observed in Blastomyces dermatitidis. B. dermatitidis reproduces in tissues by budding and the typical bud is characterized by its large size, attachment to the ...

 Immunity was originally considered a protective process helping the body to overcome infectious agents and their toxins. However, immune response may sometimes be harmful to the host. Sensitized individual respond to subsequent antigenic stimuli in an inappropriate or exaggerated manner leading to tissue damage, disease or even death. The term ' hypersensitivity ' thus refers to the injurious consequences in the sensitized host following contact with specific antigen. The initial contact with antigens called sensitizing dose sensitizes appropriate B or T cells and the subsequent dose of same antigen called shocking dose produces abnormal reactions.  Therefore, hypersensitivity is an abnormal immune response which produces damage either histopathological or physiological in the host. Types of Hypersensitivity  Hypersensitivity as classified by Gell and Coomb are of 4 types: •Type I: Anphylatic or IgE mediated hypersensitivity •Type II: Antibody...

1. The technique was developed by E.M. Southern in 1975. 2. The Southern blot is used to detect the presence of a particular piece of DNA as a sample. 3. The DNA detected can be a single gene, or it can be a part of a longer piece of DNA such as a viral genome. 4. The key to this method is hybridization. Hybridization : It is the process of forming a double stranded DNA molecule between a  single stranded DNA probe and a single stranded target DNA. There are two important features of hybridization. a. The reactions are specific- the probes will only bind to target with a  complementary sequence. b. The probe can find one molecule of target in a mixture of millions of related but  non-complementary molecules. Steps of hybridization i. The mixture of DNA molecule is separated by agarose gel electrophoresis. ii. The molecules are immobilized on a matrix (the nitrocellulose membrane). iii. The probe is added to the matrix to bind to the D...