Microbiology Final Exam Study Guide

Microbiology Final exam study guide Exam 1  Enzymesproteins, produced by living cells that catalyze chemical reactions by lowering the activation energy o Generally, they are globular proteins with characteristic 3-D shape o They are efficient and can operate at relatively low temperatures and are subject to various cellular controls o Most enzymes end in –ase o Most are holoenzymesprotein portion (apoenzyme) + non-protein portion (cofactor)  Cofactor can be metal or complex organic molecule known as a coenzyme (NAD+, NADP+, FMN, FAD, or coenzyme A)  Cofactors by themselves are not enzymes o When an enzyme combines with a substrate, the substrate is transformed and the enzyme is recovered o They are characterized by specificity, which is a function of their active sites o At high temperatures, they undergo denaturation and lose their catalytic properties; at low temperatures, the reaction rate decreases o Enzymatic activity increases as substrate concentration increases until the enzymes are saturated. o Competitive inhibitors compete with the normal substrate for the active site of the enzyme; noncompetitive inhibitors act on other parts of the apoenzyme or on the cofactor and decrease the enzyme’s ability to combine with the normal substrate o Feedback inhibition occurs when the end-product of a metabolic pathway inhibits the enzyme’s activity near the start of the pathway o Ribozymes are enzymatic RNA molecules that cut and splice RNA in eukaryotic cells  The Rate of Microbial death o Bacterial populations subjected to heat or antimicrobial chemicals die at a constant rate o Such a death curve, when plotted logarithmically, shows this constant death rate as a straight line o The time it takes to kill a microbial population is proportional to the number of microbes o Microbial species and life cycles have different susceptibilities to physical and chemical controls o Organic matter may interfere with heat treatments and chemical control agents o Longer exposure to lower heat can produce the same effect as shorter time at higher heat Scientific names and Naming & Classifying Microorganisms o Linnaeus established the system of scientific nomenclature o Each organism has two names: a genus and a specific epithet o Are italicized or underlined o The genus is capitalized; the specific epithet is lowercase o May be descriptive or honor a scientist o After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet  Staphylococcus aureus  Staphylococcusgenus  Aureusspecific name/epithet o Test Question:  Robert Kochbacterium causes anthrax; developed Koch’s postulates to prove that specific microbes cause specific diseases  Ignaz Semmelweisadvocated handwashing to prevent transmission of puerperal fever from one obstetrical patient to another  Aristotle  Carolus Linnaeusestablished the system of the specific nomenclature  Louis Pasteurdemonstrated that microorganisms are present in the air and are responsible for fermentation  Classification of microorganisms o Bacteria o Archea o Eukarya (protists, fungi, plants, animals)  Metabolic diversity among organisms Type Energy Carbon Example source source Photoautotroph Light CO2 Oxygenic (cyanobacteria and plants) vs. Anoxygenic (green and purple bacteria) Photoheterotroph Light Organic Green bacteria; purple nonsulfer compounds bacteria Chemoautotroph Chemical CO2 Iron-oxidizing (inorganic) bacteria Chemoheterotroph Chemical Organic Fermentative (organic) compounds bacteria, animals,  protozoa, fungi, bacteria   Prokaryotes vs Eukaryotes o Prokaryotes  One circular chromosome, not in a membrane  No histones  No organelles  Bacteria: peptidoglycan cell walls  Archaea: pseudomurein cell walls  Binary fission reproduction o Eukaryotes  Paired chromosomes, in nuclear membrane  Histones  Organelles  Polysaccharide cell walls  Mitotic spindle o Prokaryotes have:  Flagellum  Can be monotritious (flagella on one side) or peritrichous  Made of chains of flagellin  Attached to a protein hook  Anchored to the wall and membrane by a basal body  Axial filaments  Also called endoflagella  In spirochetes  Anchored at one end of a cell  Rotation causes cells to move  Fimbriae and pili  FimbriaeAllow attachment  Pilifacilitate transfer of DNA from one cell to another; gliding and twitching motility Functions of the glycocalyx o Carbohydrates extending from animal plasma membrane, strengthens the cell and provides a means of attachment to other cells (biofilm formation) o Bonded to proteins and lipids in the membrane (source of nutrition) o Outside the cell wall o Usually sticky o Capsule: neatly organized o Slime layer: unorganized and loose (protection against dehydration) o Extracellular polysaccharide allows cell to attach        o Capsule prevents phagocytosis (increased virulence) Endospores o Resistant to desiccation, heat, chemicals o Sporulation: endospore formation o Germination: return to vegetative state o Endospores are resting structures formed by some bacteria; they allow survival during adverse environment conditions Cell walls o Protoplasta wall-less cell; in the presence of lysozyme, gram-positive cell walls are destroyed and the remaining cellular contents are referred to as a protoplast o L formswall-less gram positive or negative cells that swell into irregular shapes o Mycoplasmasbacterial genus that naturally lacks cell walls; sterols in plasma membrane o Animal cellsdon’t have a cell wall, but instead a cell membrane o Fungihave a cell wall made of cellulose, chitin, glucan or mannan; plants and algae also have cell walls Mismatched o Bacteriostatickills vegetative bacterial cells without harming them otherwise o Germicidekills microbes o Virucideinactivates viruses o Sterilantdestroys all living organisms o FungicideDOES NOT kills yeasts and molds  Fungicides are used to kill or inhibit fungi or fungal spores Disk-diffusion o A method to detect zones of inhibitions of organisms; a disk of filter paper is soaked with a chemical and placed on an inoculated agar plate; a larger zone of inhibition indicates more effectiveness Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in the laboratory like insulin) and antibiotics (substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms) Ethylene oxide is the gas most frequently used for sterilization o It penetrates most materials and kills all microorganisms by protein denaturation Famous scientists o Robert Hookeobserved that cork was composed of “little boxes”; he introduced the term cell; laid the groundwork for development of cell theory o Anton Van Leeuwenhoekusing a simple microscope, was the first to observe microorganisms       o Robert Kochproved that microorganisms cause disease; developed Koch’s postulates (particular microorganisms cause particular diseases) o Louis Pasteurdemonstrated that microorganisms are present in the air and are responsible for fermentation o Carolus Linnaeuscame up with the nomenclature system Archaea vs bacteria o Archaea  Consist of prokaryotic cells; they are either wall-less or lack peptidoglycan in their cell walls (pseudomurein cell walls)  Include methanogens, extreme halophiles, and extreme thermophiles which live in extreme environments Aerobic cellular respiration (after glycolysis) o Synthesis of acetyl-CoA o Krebs cycle o Redox reactions by electron transport chain o Respiration and fermentation  Respriation  Glycolysis (glucose)pyruvic acidacetyl CoAKrebs cycleETC  Fermentation  Glycolysis (glucose)pyruvic acidpyruvic acid (or derivative)formation of fermentation end-products  Alcohol fermentationproduces ethanol and CO2  Lactic-acid fermentationproduces lactic acid Krebs cycle is not utilized in fermentation process Inhibitors o Competitive inhibitorscompete with the normal substrate for the active site of the enzyme o Noncompetitive inhibitorsact on other parts of the apoenzymes or on the cofactor o Decrease enzyme’s ability to combine with the normal substrate Oxidative phosphorylation o ATP synthesis is powered by redox reactions that transfer electrons from food to oxygen o Produces almost 90% of the ATP generated by respiration o Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the ETC o Substrate level phosphorylationan enzyme transfers a phosphate group from an organic molecule (the substrate) to ADP, forming ATP When H20 is oxidized by green plants, algae, and cyanobacteria, O2 is produced; when H2S is oxidized by the sulfur bacteria, S0 granules are produced o Photosynthesis  Oxygenic: 6 CO2 + 12 H2O + light -------> C6H12O6 + 6 O2      Anoxygenic: 6 CO2 + 12 H2S + light------> C6H12O6 + 12 S “Magic Bullet” o Paul Ehrlich speculated that this magic bullet could destroy a pathogen without harming the host o In 1910, he developed a synthetic arsenic drug to treat syphilis o In 1930s: sulfonamides were synthesized o Test question  Jennerinoculated a person with cowpox virus, who was then protected from small poxdiscovered immunity  Listerintroduced the use of a disinfectant to clean surgical wounds in order to control infections in humans  Pasteur and Semmelweis already talked about above Preserving foods o BiguanidesDO NOT preserve foods ; they damage plasma membranes of vegetative cells o Nisin and natamycin are antibiotics used to preserve foods, especially cheese o SO2, sorbic acid, benzoic acid and proprionic acid inhibit fungal metabolism and are used as food preservatives Glycolysis o The oxidation of glucose to pyruvic acid to produce ATP and NADH o 2 glucose-3-phosphateoxidized to 2 pyruvic acid  4 ATP produced  2 NADH produced o Glucose (six carbon sugar)split into 2, 3-carbon sugarsrearranged to form pyruvate o Energy investment phase  ATP provides activation energy by phosphorylating glucose (2 ATP/glucose; 2 ATP2 ADP) o Energy payoff phase  ATP is produced by the substrate-level phosphorylation and NAD+ is reduced to NADH (4 ADP4 ATP; 2 NAD+2 NADH) o NET  Glucose2 pyruvate + 2 H2O  2 ADP + 2 Pi2 ATP  2 NAD+ 2 NADH + 2 H+ Osmotic pressure o Isotonic solutionno net movement of water occurs o Hypotonic solutionwater moves into the cell; if the cell wall is strong, it contains the swelling; if the cell wall is weak or damaged, the cell bursts (lysis) o Hypertonic solutionwater moving out of the cell, causing its cytoplasm to shrink (plasmolysis)        An increase in salt or sugars is called plasmolysis Oxidative phosphorylation (ETC and chemiosmosis) o Look at slide 73 Chapter 5 Cell walls o Gram-positive  Teichoic acids  Lipoteichoic acid links to plasma membrane  Wall teichoic acid links to thick peptidoglycan  May regulate movement of cations  Polysaccharides provide antigenic variation  Acid fast  2 ring basal body  Sensitive to both lysozyme and penicillin o Gram-negative  Lipopolysaccharide-lipoproteinphospholipid outer membrane surrounds a thin peptidoglycan layer  Has a periplasmic space  The outer membrane protects the cell from phagocytosis, penicillin, lysozyme and other chemicals; penicillin interferes with peptidoglycan synthesis  4 ring basal body  Endotoxin  Sensitive to tetracycline  Looks like two bricks (gram-positiveone brick)  Look at slide 36 chapter 4 for comparison Comparing prokaryotic and eukaryotic cells o Prokaryotic and eukaryotic cells are similar in their chemical composition and reactions o Prokaryotic cellslack membrane-enclosed organelles (including nucleus); peptidoglycan found in cell walls  Reproduce by binary fission o Eukaryotic cellsmembrane-bound nucleus and other organelles Spirochetes contain axial filaments Mismatched o Ribosomesprotein synthesis occurs; NOT protein storage o Metachromatic granulesphosphate reserves o Polysaccharide granulesenergy reserves o Sulfur granules and lipid inclusionsenergy reserves o CarboxysomesCO2 fixation o Gas vacuolesprotein-covered cylinders; flotation Some cell wall parts     o Chloroplastscontain chlorophyll and enzymes for photosynthesis in eukaryotes. Like mitochondria, they contain 70S ribosomes and DNA and multiply by binary fission  Contains chlorophyll, green pigment where the color of a leaf comes from  Plays an important part in the absorption of light energy during photosynthesis o Cytoplasmfluid component inside the plasma membrane  Mostly water, with organic and inorganic molecules, DNA, ribosomes and inclusions  Cytoplasm of a prokaryote contains numerous 70S ribosomes; ribosomes consist of rRNA and protein o Chromatophoresphotosynthetic pigments of bacteria (prokaryotes) are located on these foldings; also on thylakoids o Mesosomesirregular foldings of the plasma membrane; they are artifacts and not true cell structures o Ribosomesconsist of rRNA and protein; protein synthesis occurs in these; it can be inhibited by certain antibiotics Look at slide 20 Chapter 4all different types of flagella (peritritious, monotrichous, lipotrichous, amphitrichous) Gram stain o Gram-positive  Alcohol dehydrates peptidoglycan; CV-I crystals don’t leave o Gram-Negative  Alcohol dissolves outer member and leaves holes in peptidoglycan; CV-I washes out; decolorized Population dynamics o Lag phase  Time for bacteria to adapt; NO DIVISION o Exponential (log) phase  Rate of cell division depends on bacterial strain and condition o Stationary phase  Dividing and dying bacteria at equilibrium  Reduced nutrients; increase in toxic materials o Death (decline) phase  More deaths than new cells Biofilms o Microbes adhere to surfaces and accumulate as biofilms on solid surfaces in contact with water o Biofilms form on teeth, contact lenses, and catheters o Microbes in biofilms are more resistant to antibiotics than are freeswimming microbes       Organisms based on oxygen requirements o Aerobesundergo aerobic respiration o Anaerobesdo not use aerobic metabolism o Facultative anaerobescan maintain life via fermentation, anaerobic respiration or by aerobic respiration o Aerotolerant anaerobesdo not use aerobic metabolism but have some enzymes that detoxify oxygen’s poisonous forms o Microaerophilesaerobes that require oxygen levels from 2-10% and have a limited ability to detoxify hydrogen peroxide and superoxide radicals Most fungi grow best at pH of 5 (slightly acidic) Specific enzymes o Catalase (peroxide anion)  2 H2O2-----> 2 H2O +O2 o Peroxidase (peroxide anion)  H2O2 + 2H+ -------> 2 H2O o Superoxide dismutase (superoxide free radicals)  O2 + O2 + 2H+ ----> H2O2 + O2 Medium o Differential mediummakes it easy to distinguish colonies of different microbes o Selective mediasuppressing unwanted microbes and encourage desired microbes o Enrichment cultureencourages growth of a desired microbe Typical growth rates of different types of microorganisms in response to temperature o Psychotroph0-30 ° C o Thermophiles40-70 ° C o Mesophile10-50 ° C o Psychrophile-10—20 ° C o Hyperthermophiles65-110 ° C Effect of oxygen on growth o Obligate aerobesoxygen is required; growth only occurs where high concentrations of oxygen have diffused into the medium (mostly growth at the top of tube) o Facultative anaerobesgrowth is best where most oxygen is present, but occurs throughout tube; both aerobic and anaerobic growth o Obligate anaerobesonly anaerobic growth; ceases in the presence of oxygen; growth only occurs where there is no oxygen, usually settles to the bottom of the tube o Aerotolerant anaerobesonly anaerobic growth but continues in the presence of oxygen; growth occurs evenly, oxygen has no effect o Microaerophileonly aerobic growth; growth occurs only where a low concentration of oxygen has diffused into medium (growth clumped in the middle) o Look at slide 28 chapter 6 for pictures Test 2  Terminology of structure and function of genetic material o Phenotypeexpression of the genes  How the “blueprint” is expressed and how the finish product appears o Genetic code64 sense codons on mRNA encode the 20 amino acids  It is degenerate  tRNA carries the complimentary anticodon o Genotypethe genes of an organism  THE BLUEPRINT OF THE CELL o Geneticsthe study of what genes are, how they carry information, how information is expressed and how genes are replicated o Genea segment of DNA that encodes a functional product, usually a protein o Chromosomestructure containing DNA that physically carries hereditary information; the chromosomes contain the genes o Genomeall the genetic information in a cell  E. Coli facts o Single chromosome o 4.6 million bases o 1 mm in length o Cell = 1 um o Circular  DNA structure o Polymer of nucleotides: adenine, thymine, cytosine, and guanine o Double helix associated with proteins o “Backbone” is deoxyribose-phosphate o Strands are held together by hydrogen bonds between AT and CG o Strands are antiparallel  5’ end of one strand is aligned with the 3’ end of the opposite strand  DNA synthesis o DNA is copied by DNA polymerase  In the 5’ to 3’ direction  Initiated by an RNA primer  Leading strand is synthesized continuously  Lagging strand is synthesized discontinuously Okazaki fragments RNA primers are removed and Okazaki fragments are joined by a DNA polymerase and DNA ligase  Process is amazingly accurate (high fidelity)  Error rate contributes to spontaneous mutation frequency o Priming  DNA polymerases CANNOT synthesize DNA strands de novo  Requires a free 3’ –OH  RNA polymerases CAN synthesize RNA polymers de novo  Necessitates the involvement of RNA polymerase laying down an RNA primer  DNA ligase makes covalent bonds to join DNA strands; joins Okazaki fragments and new segments in excision repair Gene regulation o Constitutive genesexpressed at a fixed rate o Repressive genestranscribed until they are turned off; usually in response to the abundance of an end-product  Synthesis of a repressible enzyme is stopped by the corepressor (end product)-repressor complex binding to the operator o Inducible genestranscribed only in the presence of an inducer Catabolite repression the mechanism by which the presense of glucose inhibits the lactose operon o When lactose is present, and no glucose  cAMP binds to inactive CAPactive CAPbinds to promoter; RNA polymerase can bind and transcribe o Lactose and glucose present  There is an inactive lac repressor, an inactive CAP, and as a result RNA polymerase can’t bind o In the presence of glucose, cAMP levels are low; as glucose is consumed, cAMP levels rise. Transduction o The process whereby the transfer of DNA from a donor to a recipient cell is mediated by a bacteriophage o Can be generalized transferring potentially at any genomic site or specialized, transferring only to a particular site o Insensitive to DNase in surrounding medium Transformation o Genetic recombination that requires “naked” DNA o Must be homologous o Select groups of bacteria o Does NOT require cell to cell contact             o Process is sensitive to DNase in the surrounding medium Conjugation in E. Coli o Requires the presence of a Fertility factor in donor and absence of F factor in a recipient o Requires cell-to-cell contact o Insensitive to DNase in a surrounding medium Genomic libraries o They mare made of pieces of an entire genome stored in plasmids or phages o Genomic libraries are the most common form of bacterial libraries o In some cases, they are also used for eukaryotic libraries where the goal is to study genomic sequence or structure o cDNA is made from mRNA by reverse transcriptase  cDNA libraries are almost exclusively from eukaryotic organisms (HUMANS) Classification of Eukaryotes o Protists are grouped into clades based on rRNA sequence o References  Bergey’s manual of systematic bacteriologybased on rRNA sequencing Introducing recombinant DNA into bacterial cells o Conjugationtransformation of information using sex pili o Transductiontransfer of information by bacteriophages o Transformationuptake of DNA outside the cell o Protoplast fusiongenerates random recombination o Electroporationstimulates uptake of DNA by protoplasts and animal cells (no cell walls) by passing an electric current through the culture medium; this causes pores to open up Polymerase Chain Reaction o To make multiple copies of a piece of DNA enzymatically o Used to:  Clone DNA for recombination  Amplify DNA to detectable levels  Sequence DNA  Diagnose genetic disease  Detect pathogens  Identify an individual’s presence at a crime scene Blue-white screening o Determines which colony harbors a recombinant clone containing a segment of foreign DNA o Steps       The plasmid DNA and foreign DNA are cut with the same restriction enzymes Foreign DNA is inserted into the lac Z gene; bacterium with this new plasmid vector will not produce the enzyme galactosidase if foreign DNA has been inserted into the plasmid The bacterium should become ampicillin resistant because of ampR gene Spread onto the agar plate Only bacteria that have been picked up by the plasmid will grow in the presence of ampicillin; bacteria that hydrolyze the X-gal turn blue Various tests o Phage typingCan be used to rapidly distinguish different strains of salmonella  Helpful during an outbreak  Lawn of suspected salmonella is infected with various different Stock bacteriophage  Depending upon the sensitivity result, the strain of Salmonella can be identified o Flow cytometryuses differences in electrical conductivity between species  Fluorescence of some species  Cells selectively stained with antibody plus fluorescent dye  Cells with a positive charge move closer to the negative plate; different cells separate out into different collection tubes o Enterotubea multiple test system which combines 9 biochemical tests useful in identifying the members of the family Enterobacteriaceae (enteric); identifies gram-negative bacilli isolated from clinical specimens o Western Blottingif lyme disease is suspected in a patient  Electrophoresis used to separate Borrelia burgdorferi proteins in the serum; proteins move at a different rate  Bands are transferred to a filter by blotting; each band consists of many molecules of a particular protein (antigen)  The proteins (antigens) are positioned on the filter; filter is then washed  If the tagged antibodies stick to the filter, B. burgdorferi has been found o Serologyused to make a very rapid determination of a microbe in clinical setting; uses specific antibodies found in serum as a diagnostic took to identify bacteria or viruses (combine antiserum plus unknown bacteria) o Southern Blota procedure for identifying specific sequences of DNA, in which fragments on a gel are transferred directly to a second medium on which detection by hybridization may be carried out;  DNA: DNA hybridization  Three modes of genetic transfer allow recombination to take place o Conjugation o Transduction o Transformation  Important Codons o AUGstart/ met o UAA, UAG, UGAstop  Anti-codons (tRNA) o 5’-CAU-3’ will be the anti codon that recognizes the mRNA-encoded initiation codon o 5’-UUA-3’, CUA, or UCA (5’ to 3’) will all be the tRNA codons that regonize the mRNA stop codon  Ames test o More histidinetest sample contains suspected carcinogen o Same number or less histidinetest sample free of any suspected carcinogen  Frederick Griffith’s experiment was the first demonstration of genetic transformation  Conjugation in E. Coli o F+ and F- F+ and F+ after a few hours o F+ cell recombinationHfr cell o Hfr cell and F- Hfr cell and recombinant F- cell o Hfr+ most likely to transfer chromosomal traits to a recipient cell (mediates recombination)  References o Bergey’s manual of determinative bacteriology  Provides identification schemes for identifying bacteria and archaea  Morphology, differential staining and biochemical tests o Bergey’s manual of systematic bacteriology  Provides phylogenetic information on bacteria and archaea  Based on rRNA sequencing Archaea Bacteria Eukarya Cell type Prokaryotic Prokaryotic Eukaryotic Cell wall Varies; no Contains Varies; contains peptidoglycan peptidoglycan carbohydrates Membrane Branched carbon Straight carbon Straight carbon lipids chains chains chains First AA Methionine Formylmethionine Methionine Anitibiotic No Yes no sensitivity rRNA loop Lacking Present Lacking Common Arm Lacking Present Present of tRNA  Archaea contains call of the thermophiles  Plasmids/cloning vectors o An origin of replication o Encode for antibiotic resistance (R factors) o Multiple cloning site containing single cleavage sites for a variety of restriction enzymes o lacZ gene is arranged in such a way to conduct blue-white screening  Fundamental enzymes o DNA polymeraseDNA is copied by DNA polymerase in DNA synthesis; RNA primers are removed and Okazaki fragments are joined by DNA polymerase and DNA ligase o RNA PolymeraseSynthesizes a short RNA primer, which is then extended by DNA polymerase in DNA synthesis; can also synthesize RNA polymer de novo  In transcription: begins when RNA polymerase binds to the promoter sequence o DNA Ligasesin making recombinant DNA: enzyme is used to unite the backbones of the two DNA fragments, producing a molecule of recombinant DNA o Restriction endonucleasesrestriction enzymes cuts double-stranded DNA at its particular recognition sites, shown in blueproduce DNA fragment with two sticky ends  R factors o They are plasmids o They contain genes that encode drug resistance o They have the ability to transfer themselves by conjugation o By nature, they can pose problems for clinical practices  Slide agglutination test (Serology) o Clumping (agglutination) of bacterial suspension is known as a positive test o No clumping would be a negative test  Mutation o A change in the genetic material; may be neutral, beneficial or harmful o Base substitution: point mutation; may be silent o Missense mutation: change in one base; results in change in amino acid o Nonsense mutation: results in nonsense codon o Frameshift mutation: insertion or deletion of one or more nucleotide pairs     When predicting a DNA strand, be careful to pick your answer that starts at the right 5’ end o Ex: 3’-GGCTTA-5’ will hybridize with which DNA sequence? o Answer: 5’-CCGAAT and NOT 5’-TAAGCC Restriction enzymes o Cut specific sequences of DNA; usually palindromic sequences o Destroys infecting phage DNA (in bacterial cells) o CANNOT digest host DNA because of specific host modifications in form of methylated cytosines Phylogenetics o Grouping organisms according to common properties implies that a group of organisms evolved from a common ancestor  Testing either by anatomy, fossils, or rRNA Indirect ELISA o Two steps, involves two binding process of primary antibody and labeled secondary antibody o Secondary antibody binds to the primary antibody (already bond to the foreign antigen, bacteria, or virus) Test 3  The concept of immunity o Susceptibilitythe lack of resistance to disease o Immunitythe ability to ward off disease o Innate immunitythe defenses against any pathogen o Adaptive immunityimmunity or resistance to a specific pathogen  Enzymes o Coagulasecoagulates fibrinogen o Kinasesdigests fibrin clots o Hyalurodinasehydrolyzes hyaluronic acid o Collagenasehydrolyzes collagen o IgA proteasesdestroys IgA antibodies  MRSA o USA100: 92% of health care strains o USA 300: 89% of community-acquired strains o Procedure: MRSA-infected patients vs total number of patients receiving procedure  IV catheter1057 MRSA-infected vs 16,516 patients receiving treatment  Urinary bladder catheter1750 MRSA-infected vs 7919 patients receiving treatment  I just picked the top two, for a full list look at slide 46 chapter 14  Nosocomial infections Healthcare associated infections Infections as a result of treatment in a hospital or a healthcare service unit Secondary to the patient’s original condition The infection is considered nosocomial if it first appears 48-72 hours or more after hospital admission or within 30 days after discharge Portals of exit o Respiratory tract  Coughing or sneezing o Gastrointestinal tract  Feces and saliva o Genitourinary tract  Urine and vaginal secretions o Skin o Blood  Arthropods that bite; needles or syringes White blood cells o Neutrophilsphagocytic o Basophilsproduce histamine o Eosinophilstoxic to parasites and some phagocytosis o Dendritic cellsinitiate adaptive immune response o Monocytesphagocytic as mature macrophages  Fixed macrophagesin lungs, liver, and bronchi  Wandering macrophages roam tissues o Lymphocytesinvolved in SPECIFIC immunity Overview of body’s defenses o Innate immunity  First line of defense  Intact skin  Mucous membranes and secretions  Normal microbiota  Second line of defense  Phagocytes (neutrophils, eosinophils, dendritic cells, macrophages, NK Cells)  Inflammation  Fever  Antimicrobial substances o Adaptive immunity  Third line of defense  Specialized lymphocytes: T cells and B cells  Antibodies Natural killer cells o o o o     o Lyse virus-infected cells, tumor cells, and parasites. They kill cells that do not express MHC class I antigens. NK cells are part of the second line of defense  Inflammation o Bodily response to cell damage; characterized by redness, pain, heat, swelling, and sometimes loss of function o The release of histamine, kinins, and prostaglandins cause vasodilation and increased permeability of blood vessels o Blood clots can form around an abscess to prevent dissemination of the infection o Phagocytes have the ability to stick to the lining of blood vessels margination o They also have the ability to squeeze through blood vesselsdiapedesis  Bacillus anthrasis Portal of entry ID 50 SkinLOWEST 10-50 endospores Inhalation 10,000-20,000 endospores IngestionHIGHEST 250,00-1,000,000 endospores  Compliment activation o Classical pathwayinitiated when antigen bind to antibodies  C1 is activated by binding to antigen-antibody complexes  Activated C1 splits into C2 and C4, which split into C2a/C2b and C4a/C4b  C2a and C4b activate C3, splitting it into C3b (opsonization and cytolysis) and C3a (inflammation) o Alternative pathwaydoes not involve antibodies; activated by contact between complement proteins and pathogen  C3 combines with factors B, D, and P on the surface of the microbe  Causes C3 to split into C3b (cytolysis and opsonization) and C3a (inflammation) o Lectin pathwaymannose-binding lectin (MBL) binds to mannose on surface of microbes; lectin binds to an invading cell  Bound lectin splits C2 and C4  C2a and C4b activate C3  Splits C3C3a (inflammation) and C3b (cytolysis and opsonization) o Bacteria that evade compliment  Capsules prevent C activation  Surface lipid-carbohydrate complexes prevent formation of membrane attack complex (MAC)      Enzymatic digestion of C5a Chemicals release by damaged cells o Histaminesvasodilation; increased permeability of blood vessels o Kininsvasodilation; increased permeability of blood vessels o Prostaglandinsintensity by histamine and kinin effect  Indirectly cause increased permeability of blood vessels o Leukotrienesincreased permeability of blood vessels; phagocytic attachment o Histamine and Leukotriene directly cause increased permeability of blood vessels Interferons (IFNs)a class of antiviral proteins produced by certain animal cells, such as lymphocytes and macrophages after viral stimulation o IFN-alpha and IFN-beta: cause cells to produce antiviral proteins that inhibit viral replication o IFN-gammacauses neutrophils and macrophages to phagocytize bacteria Activation of B cells to produce antibodies o Major histocompatibility complex (MHC) expressed on mammalian cells  T-dependent antigens  Intracellular  Ag presented with (self) MHC to helper T cell  Helper T cell produces cytokines that activate the B cell  T-independent antigens  Stimulate the B cell to make antibodies  Selected by free antigens  Large and repetitive and obvious structure o Process (chapter 17 slide 23)  Immunoglobulin receptors on B cell surface recognize and attach to an antigen, which is then internalized and processed. Within the B cell, a fragment of the antigen combines with MHC Class II  MHC Class II- antigen-fragment complex is displayed on B cell surface  Receptor on the T helper cell recognizes the complex of MHC Class II and antigen fragment and is activated, producing cytokines, which activate the B cell.  B cell is activated by cytokines and begins clonal expansion. Some of the progeny become antibody-producing plasma cells T cytotoxic cells o CD8+ or Tc cells o Target cells are self-cells carrying endogenous antigens o Activated into cytotoxic T lymphocytes (CTLs)       CTLs recognize Ag + MHC I  Induce apoptosis in the target cell o CTL releases perforin and granzymes Types of adaptive immunity o Naturally acquired active immunityfrom infection; may be longlasting o Naturally acquired passive immunityantibodies transferred from a mother to fetus (transplacental transfer) in colostrum; immunity can last for a few months o Artificially acquired active immunityresulting from vaccination; can be long lasting o Artificially acquired passive immunityhumoral antibodies acquired by injection; can last for a few weeks The process of acute inflammation 1. Chemicals such as histamine, kinins, prostaglandins, leukotrienes, and cytokines are released by damaged cells 2. Endothelium of nearby capillaries is activated 3. Selectins are displayed on endothelial cells 4. Selectins attract and attach neutrophils, slow neutrophil and cause rolling of neutrophils along endothelium 5. Inflammatory mediators activate integrins on neutrophils 6. Integrins attach to endothelial adhesion molecules 7. Neutrophils stick and stock rolling 8. Later, neutrophils change chape, squeeze through endothelial wall (extravasation) and migrate to injury site 9. Neutrophils attach pathogen or are the cause of injury Simple explanation of inflammation 1. Chemicals such as histamine, kinins, prostaglandins, leukotrienes, and cytokines are released by damaged cells 2. Blood clot forms 3. Abscess starts to form Fever o Abnormally high temperature o Hypothalamus is normally set at 37 C o Gram-negative endotoxins cause phagocytes to release IL-1 o Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature o Body increases the rate of metabolism, and shivering occursraises temperature o Vasodilation and sweatingbody temperature falls (crisis) Antibody types o IgG        Monomer 80% of serum antibodies Fix compliment In blood, lymph and intestine Cross placenta Enhance phagocytosis (neutralize toxins and viruses); protect fetus and newborn Half life of 23 days  o IgM  Pentamer  5-10% of serum antibodies  Fix compliment  In blood, lymph and B cells  Agglutinate microbes; first Ab produced in response to infection  Half life of 5 days o IgA  Dimer  10-15% of serum antibodies  In secretions  Mucosal protection  Half life of 6 days o IgD  Monomer  0.2% of serum antibodies  In blood, lymph, and on B cells  On B cells, initiate immune response  Half life of 3 days o IgE  Monomer  0.002% of serum antibodies  On mast cells, basophils, and in blood  Allergic reactions; lysis of parasitic worms  Half life of 2 days Major action modes of antibiotic drugs o Inhibition of cell wall synthesispenicillins, cephalosporins, bacitracin, vancomycin o Inhibition of protein synthesischloramphenicol, erythromycin, tetracyclines, streptomycin o Inhibition of nucleic acid replication and transcriptionquinolones, rifampin (mRNA synthesis inhibitor) o Injury to plasma membranepolymyxin B      o Inhibition of essential metabolite synthesissulfanimide, trimethoprim Activation of CD4+ T helper cells o An APC encounters and ingests a microorganism; the antigen is enzymatically processed into short peptides, which combine with MHC class II molecules and are displayed on the surface of the APC o A receptor on the surface binds to the MHC-antigen complex; if it involves a toll-like receptor, the APC is stimulated to secrete costimulatory molecule. These two signals activate the helper T cells produces cytokines o The cytokines cause the helper T cell to become activated o In terms of the antigen, it is internalized, fragmented and then presented Beta-lactam antibiotics o Penicillin o Carbapenems o Monobactam o Antibiotic functions Occurrence of a Disease o Endemicdisease constantly present in a population o Epidemicdisease acquired by many hosts in a given area in a short time o Pandemicworldwide epidemic Sites of the body that should be sterile (axenic) o Blood o Body fluids (CSF, urine) o Body tissues o Lungs o Cervix Disk diffusion test o The antibiotic diffuses into the bacterial lawn in a circular gradient o The concentration decreases as the circle widens o Bacteria will only grow up to its susceptibility point o The zone of inhibition is measured, compared to breakpoints, and indicates the inhibition of bacterial growth by the antibiotics o Kirby-Bauer test o Equally effectivezones of inhibition the same o Most antibiotic activitybiggest zone of inhibition o Bacterium most resistantsmallest zone of inhibition