Medical Microbiology Laboratory Lecture 4 PDF

Medical Microbiology Laboratory Lecture 4 Dr/ Fatma Mostafa Dr/ Moatasem Al-Salih PhD. Microbiology M.Sc. Immunology and Immunology Microbiology PRACTICAL MEDICAL MICROBIOLOGY BY Dr/ Fatma Mostafa Dr/ Moatasem Al-Salih PhD. Microbiology M.Sc. Immunology...

Medical Microbiology Laboratory Lecture 4 Dr/ Fatma Mostafa Dr/ Moatasem Al-Salih PhD. Microbiology M.Sc. Immunology and Immunology Microbiology PRACTICAL MEDICAL MICROBIOLOGY BY Dr/ Fatma Mostafa Dr/ Moatasem Al-Salih PhD. Microbiology M.Sc. Immunology and Immunology Microbiology Light microscope IDENTIFICATION METHOD The most important task of a bacteriologist is to identify the pathogens from the clinical sample so that appropriate treatment can be done. There are several methods to identify the different types of bacteria. 1. Staining reaction 2. Isolation in pure form 3. Morphology of bacterial colony and Cultural characteristics 4. Metabolism and Biochemical properties To examine a slide of bacteria under a bright light microscope, follow these steps: Materials Needed: Prepared bacterial slide (or bacterial smear) Bright light microscope Immersion oil (if using 100x oil-immersion lens) Staining reagents (if needed) Lens cleaning tissue Steps: 1.Prepare the Bacterial Slide: 1.If using a pre-made slide, ensure it’s clean and dry. 2.If making a bacterial smear: 1.Place a small drop of water on the slide. 2.Using a sterilized loop, add a small amount of bacteria to the water and spread it thinly. 3.Allow the smear to air dry completely. 4.Heat-fix the smear by passing the slide through a flame 2-3 times (hold the slide with a clothespin to avoid burns). Tips: Always start with the lowest magnification and work up to higher magnifications. Ensure the microscope is properly aligned and cleaned for the clearest view. Use immersion oil only with the 100x oil immersion lens; other lenses can be damaged by the oil.  Shape of Bacteria ⚫ Bacteria display these basic shapes: i. round- cocci, (from the Greek kokkos - a berry), sphere like shape ii. rod shaped – bacilli (from the Latin bacillus - a stick or rod), iii. spiral (quelled). iv. Curved rod v. Filamentous bacteria(long branching bacteria) Different Shapes and arrangement of Bacteria  i. Coccus Cluster arrangement Staphylococcus Chain like Streptococcus a b Coccus arranged in pairs a. Streptococcus pneumoniae b. Neisseria gonorrhoeae Coccus arranged in tetrads(four) Micrococcus spp. Package of eight(octet) Sarcina spp.  ii. Bacillus(rod shape) Escherichia(E.) coli Bacillus sp. (Coccobacilli) Bacilli shape(long rod) Closteridium perfringens a b Corynebacterium diphtheriae(rod shape) a- Gram stain b- Albert Stain Curved Rod Vibrio cholerae Filamentous Bacteria Streptomyces spp.  Spiral Shaped Bacteria Spirillum volutans Treponema pallidum  After the examine slides) Cleaning Up: After examination, clean the oil from the 100x lens with lens paper to prevent damage. Store the microscope and clean the slide if reusing it..