Microbiology Chris Exam 1 Study Guide Part 1 PDF

Topic Introduction to General & Clinical Microbiology Bacterial Structure and Function Observation and Classification of the Microbial World Microbial Metabolism Microbial Nutrition and Growth Total Hours 1 Instructor Dr. Basu No of questions 5 3 2 (in-class+online) Dr. Basu Dr. Basu 20 8 Dr. Basu D...

Topic Introduction to General & Clinical Microbiology Bacterial Structure and Function Observation and Classification of the Microbial World Microbial Metabolism Microbial Nutrition and Growth Total Hours 1 Instructor Dr. Basu No of questions 5 3 2 (in-class+online) Dr. Basu Dr. Basu 20 8 Dr. Basu Dr. Basu 20 12 65 3 2 1 hour 30 minutes (90 mins) Introduction to General & Clinical Microbiology (Unit 1) The Microbial World Is Cataloged into Unique Groups, Microorganisms are a large and diverse group of organisms existing as single cells or clusters; they also include viruses, which are microscopic but not cellular - Microorganisms o Include living and nonliving microscopic organisms ▪ Living – cellular microbes (includes bacteria, archaea, some algae, protozoa, fungi) Requires all following features common to living things o Hereditary material o Complex biochemical patterns o Reproduction o Response to stimuli o Evolutionary adaptations ▪ No living – acellular (includes viroids, prions, viruses) o Disease-causing microbes referred to as germs (colloquial) and pathogens (scientific) ▪ Cause two types of disease Infectious diseases o Pathogen colonizes, causes disease, leads to infection (MRSA, Gas gangrene) Microbial intoxications o Produces toxin in vivo, person ingests toxin, toxin leads to symptoms (staph food poisoning, foodborne botulism) o Non-pathogens do NOT cause disease o Microbes/flora live on and in our bodies referred to as indigenous, normal microbiota ▪ Fixed or transient ▪ Example is the GI tract microbiota Prevent infectious disease Aid in breakdown of food Provide essential nutrients humans cannot make on their own Communicate with brain and immune system ▪ Can be opportunistic (infectious given the right circumstances) - Categorizations of microbes o Acellular infectious agents - ▪ Prions ▪ Viruses o Cellular microorganisms ▪ Prokaryotes Bacteria Archaea ▪ Eukaryotes Algae Fungi Protozoa Classification of Microbes o Prokaryotes (do not contain a nucleus, DNA in cytoplasm) ▪ Bacteria, Archaea, Archaebacteria Unicellular, LACK NUCLEI (makes them different to protozoa) Asexual reproduction Much smaller than eu Bacterial cell walls contain PEPTIDOGLYCAN, not all bacteria contain cell walls Archaea cell walls of polymers, NOT PEPTIDOGLYCAN Read DNA and make proteins simultaneously 100,000,000x magnification Differential staining, Gram stain and the acid-fast stain. The Gram stain differentiates between Grampositive bacteria (which stain purple) and Gram-negative bacteria (which stain pink). The acid-fast stain differentiates between acid-fast bacteria such as members of the genus Mycobacterium (which stain bright reddish pink) and non-acid-fast bacteria (which stain blue). - Staining o Incr contrast and res o Must prepare specimens o Chromosphere is colored portion of dye o Acidic dyes stain basic structures o Basic dyes stain acidic structures (more common since most cells negatively charged) - Simple Stains o Single dye ▪ i.e. Crystal violet, Safranin, Methylene Blue o To determine size, shape, arrangement of cells - Differential Stains o >1 dye used to distinguish between diff cells, chems, or structures o Common differential stains ▪ Gram Stain Gram positive cells are purple, Gram negative cells pink To differentiate between gram positive and negative; usually the first step in ID ▪ Acid-Fast ▪ ▪ ▪ ▪ ▪ For mycolic acid-dense cells Pink to red acid-fast cells and blue non-acid fast Distinguish btw Mycobacterium/Nocardia from other bacteria Endospores Stain (a special stain) Green endospore and pink to red vegetative cells (produce endospores) Highlights the presence of endospores produced by Bacillus and Clostridium Histological Stain HE stain GMS stain Capsule Stain/Negative Capsule Stain (A Special Stain) Background is dark, cells untainted or stained with simple stains To reveal bacterial capsules Flagellar Stain (A Special Stain) Bacterial Flagella become visible Allows determination of number and location of bacterial flagella Fluorescent Stains (for immunofluorescence, a special stain) Tag antibodies for finding antigens within tissues To determine pathogen from known antibodies Antibodies and antigens tagged Heat fixation, simple stains technique, cell morphology, negative stains technique, differential staining procedure, Gram stain, acid-fast technique, spore-stain technique - Stain Procedure/Preparing Specimens for Staining o Must first prep microbes by attaching them to microscope slide ▪ Involves making a smear and fixing it to slide If microbe in liquid, spread small drop of broth across surface If solid surface (i.e. agar), microbes mixed into small drop of water Either case: thin film of organisms on the slide is a smear ▪ Smear is air-dried and attached/fixed to surface ▪ Then one of two things: Heat fixation o Slide gently heated by passing slide, smear up, through a flame Chemical Fixation o Applying a chemical i.e. methyl alcohol to smear for one minute and then desiccate (1min) to kill orgs ▪ Dry slide necessary for EM ▪ Coat, not stain, slides for scanning EM o Simple Staining Technique ▪ Procedure 1) Soak smear in dye 30-60 seconds 2) Rinse o Gram Staining Technique Procedure 1) Crystal Violet 1min and rinse, all cells now purple 2) Iodine 1min, rinse; iodine a mordant, all cells still purple 3) Ethanol and Acetone 10-30sec, rinse, decolorized smear Gpos are purple and Gneg colorless 4) Safranin 1min, rinse, blot dry; result is Gpos purple and Gneg pink o Acid-Fast Technique ▪ Procedure 1) Cover smear with small piece tissue paper 2) flood with red primary stain (Carbolfuchsin) several minutes while warming over steaming water o Drives stain through waxy, mycolic acid dense cell wall and into cell 3) Remove tissue paper, cool slide, decolorize with alcohol 4) Acid-fast cells retain color 5) Counterstain with methylene blue which stains only bleached, non-acidfast cells o Endospore Stain Technique ▪ Procedure 1) Malachite green + heat to get dye into endospore 2) Decolorize with water and counterstain with safranin 3) Get green endospores and red veg cells o Negative Stains Technique ▪ To stain background and leave cells colorless ▪ Acidic dyes are negative stains because cells will repel the dye (bc neg charged) ▪ Exs are eosin and nigrosin ▪ To reveal presence of neg charged bacterial capsules Have halo surrounding capsule ▪ Morphology of Prokaryotic Cells, spherical (coccus) or cylindrical (bacillus) in shape, Bacteria divide by binary fission and form characteristic growth arrangements, which are indicated by set prefixes including diplo- (pairs of cells), strepto- (chains of cells), sarcinae- (packets of cells) and staphylo(clusters of cells). For example, spherical bacteria that grow in long chains are called streptococci. Some bacteria grow in multicellular associations, such as the mycobacteria, and many bacteria grow in polymer-encased communities called biofilms Nomenclature Assigns a Scientific Name to Organisms, organismal taxonomy, classification, taxon, taxa, family, order, class, phylum, phyla, kingdom - Taxonomy classifies organisms o Consists of classifications (assigning of organisms based on similarities), nomenclature (rules to naming organisms), and identification (where an individual or organisms belongs to a taxa) o Species are groups that interbreed (reproduce sexually) ▪ Hard to do for asexually reproducing microbes (i.e. bacteria)