lab 2 lec 2.docx

 **Lab- lec 2** **Serological test** **Diagnostic virology** **Diagnostic mycology** **\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** **Serological test :** als...

 **Lab- lec 2** **Serological test** **Diagnostic virology** **Diagnostic mycology** **\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** **Serological test :** also known as antibody tests, are laboratory tests used to detect the presence of antibodies in a person blood, these tests are typically used to determine if a person has been exposed to a specific infectious agent , such as a virus or bacterium, and has developed an immune response to it, for Example **Agglutination test:** an antibody that forms clumps when reacts with cells or particular antigen, **the Agglutination of blood groups** refers to the clumping together of red blood cells ( RBCs ) when they come into contact with certain antibodies or antigens,  **the positive Agglutination of CRP latex** when patient serum sample containing CRP is added to the test , the CRP molecules present in the sample will bind to the antibodies on the latex particles. This binding causes the latex particles to clump together (**Agglutination ) ,** resulting in a visible reaction.  there are another different types of serological tests such as Toxin-antitoxin neutralization, ELISA **Diagnostic virology :** **Laboratory diagnosis of viral infection** I. **Direct demonstration of virus** 1. Detection of the virus particle By E.M. 2. Detection of inclusion bodies ( the Assembly step of virus Replication seen by L.M) 3. Detection of specific viral Ag 4. Detection of Nucleic acid of the virus By PCR II. **Virus Isolation (Cultivation of the virus )** 1. Laboratory animals 2. Embryonated eggs 3. Cell (tissue) culture - **Detection of viral growth** 1. Cytopathogenic effect (CPE) - Cell death - Rounding - Cell transformation (Tumor viruses ) 2. Inclusion bodies (They are the site of virus assembly ) III. **Detection of specific Antibodies (Serological tests)**  - **Diagnostic mycology** 1. Sample Collection: Obtaining appropriate clinical samples (e.g., skin scrapings, nail clippings, sputum,) for fungal analysis. 2. Direct Microscopic Examination: Examining clinical samples under a microscope to visualize and identify fungal structures, such as hyphae, spores, or yeast cells. 3. Culture Techniques: Culturing clinical samples on specialized media to isolate and grow fungal organisms. 4. Serological Tests: Detecting fungal antigens or antibodies in a patient\'s blood 5. Molecular Diagnostics: Using DNA or RNA-based techniques, such as polymerase chain reaction (PCR), to rapidly detect and identify fungal pathogens, 6. Antifungal Susceptibility Testing: Determining the susceptibility of isolated fungal strains to various antifungal drugs **Some commonly fungi culture** **media :** **Potato Dextrose Agar (PDA) :** for the general cultivation of a variety of fungal species, **Sabouraud Dextrose Agar (SDA):** This medium is formulated to promote the growth of pathogenic and opportunistic fungi, **Malt Extract Agar (MEA):** This medium is particularly useful for the cultivation of filamentous fungi and yeasts **The KOH (Potassium Hydroxide) test** Is a simple and widly used diagnostic technique in mycology to aid in the identification of fungal infections , particularly those affecting the skin, hair, and nails. **The KOH test used to :** Detect the presence of fungal elements : the KOH solution helps to dissolve the keratin and other organic materials in the sample, making the fungal structure observed ( hyphae, spores ). **The procedure for the KOH test is as follows :** 1.Sample Collection: \- For skin or nail infections, a small sample of the affected area is collected, such as skin scrapings, nail clippings or hair sample ( from the affected area). 2\. KOH Preparation: \- The collected sample is placed on a clean microscope slide. \- A drop of potassium hydroxide (KOH) solution, typically 10-20%, is added to the sample. 3\. Microscopic Examination: \- The slide is heated gently to facilitate the digestion of the sample by the KOH solution. \- The slide is then examined under a microscope, usually with a lower magnification( 10x or 40x ). \- In the presence of a fungal infection, the KOH solution will dissolve the human tissue, allowing the fungal structures, such as hyphae or spores, to become more visible and easier to identify. \- The morphological characteristics of the observed fungal structures can provide clues about the specific type of fungus responsible for the infection, such as dermatophytes (e.g., Trichophyton, Microsporum, Epidermophyton) or yeasts (e.g., Candida).