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Mod 6 - Microbiology

Microbiology The study of microorganisms (microbes): - Viruses - Bacteria - Parasites - Fungi - Others
Prokaryotes vs Eukaryotes PROKARYOTES DO NOT HAVE: - membrane bound nucleus - membrane bound organelles - DNA that is organized into chromosomes.
Prokaryotes Classification - All living cells are either prokaryotes or eukayotes - All bacteria are prokaryotic cells - Divided into (5) classes - Prokaryons in Kingdom Monera - Many classes - Earth's most abundant form - 0.5-2UM in size
Prokaryotic Cell Structures - Cytoplasm - Ribosomes - Nucleoid (chromosome) - Inclusion Bodies - Some prokaryotes secrete a capsule & have plasmids.
Prokaryotic Cytoplasm - Semi-fluid substance that fills inner cellular space - Primarily water with carbohydrates, lipids, and various enzymes.
Prokaryotic Ribosomes - Consists of RNA and protein - Used in protein synthesis
Prokaryotic Nucleoid - Chromosomes - No real nucleus
Prokaryote Inclusion Bodies Stores molecules essential to cell function.
Capsule A protective structure that serves as a defense mechanism in some prokaryotes consisting of: - Tightly bound wall with complex polysaccharide molecules that form a gel-like covering that surrounds the bacterial cell.
Plasmids Some prokayrotes contain a self-replicating extrachromosomal DNA that carry 1 or more pieces of genetic information, not required to sustain life.
Prokaryote Cell Structure Cell Wall: - Shape & stability - Contain peptidoglycan, large polymer resembling a "chain link fence" - Antibiotics target cell wall (i.e penicillin) "Eukaryotes do not have cell wall"
Prokaryote Cell Membrane (aka plasma membrane) - Regulates transport of material in and out of the cell - Made of phospholipids - Long-chain fatty acids and proteins - Selectively permeable
Peptiglycan Large polymer which makes up a prokaryote cell membrane with an immense, covalently-linked molecule linked in multi-layers resembling a "chain-link" fence
Flagellum (singular); Flagella (plural) Filamentous organelles of locomotion found on half all known bacteria
Motile Various degrees of movement
Pili (singular: pilus) Tiny, tube-like projections from the cell's surface associated with adherence
Prokaryotic Bacterial Cells: (Shape & Arrangement) - characterized by shape & size - before culture information is available, location and appearance characteristics were used
Cocci (singular: coccus) Spherical bacterial cells
Bacilli (singular: bacillus) Rod-shaped bacterial cell resembling a hot dog
Vibrios Comma shaped bacterial cell
Coccobacillus Bacterial cell shaped between cocci & bacilli
Spirillia Bacterial cell which appears loosely-coiled or wavy
Spirochetes Bacterial cell which appear tightly coiled, corkscrew-shaped rods.
Gram Stain Method used to group bacteria into 2 different catagories: - Gram positive bacteria (purple) - Gram negative bacteria (pink)
Gram-Positive Bacteria - Thick layer of peptidoglycan (thick cell wall) - Teichoic acid causes retention of crystal violet (blue) dye
Gram-Negative Bacteria - Thin layer of peptidoglycan (thin cell wall) - High lipoprotein content which releases crystal violet dye when rinsed with alcohol - The safranin (pink) counterstain is retained
Gram Stain Method 1-Sample smeared on slide & fixed with heat 2-Slide stained with crystal violet (purple)@ 1-2 mins. 3-Gram's iodine used to "fix" the crystal violet (help retain stain) 4-Acetone used to decolorize slide 5-Stain slide w/safranin (pink)
Diplococci - Cocci in pairs - Ex.: Gonorrhea
Streptococci - Cocci in chains - Ex.: Aureus, Boils
Staphylococci - Cocci in grape like pairs - Ex.: Staphylo (irregular clusters)
Culture Media - Identifing Specific Bacteria - Can be liquid or semi-solid - 3 Different Types: < Enriched Media < Selective Media < Differential Media
Tetrad - Group of four - Micrococcus - Rarely pathogenic
Enriched Media encourages the growth of most bacteria (Sheep's blood "Agar plate")
Selective Media Encourages the growth of some bacteria which inhibiting others ("MacConkey" Agar)
Differential Media Groups bacteria based on the fermentation of carbohydrates ("MacConkey" Agar)
MacConkey Agar Used in both Selective and Differential Media
Aerobes - Require atmospheric oxygen - Ex.: Staphylococcus, Streptococcus, E. coli
Anaerobes - Require no oxygen - Ex.: Colstridium species, Gangrene - Used to put candle in the container until it burns out
Microaerophilis - Require reduced oxygen & increased CO2 - Ex.: Campylobacter
Binary Fission - Term used to describe cell division - Aka "Transverse Fission" - Do not have a cell cycle replicating their DNA - Continuosly dividing &
Lag Phase - Gear up phase - Organisms not greatly increasing in #, but metabolically active < Growing, synthesizing enzymes, & producing lrg. amounts of ATP
Log Phase - Once bacteria have adapted to nutrient-rich environment, growth is exponential (Logarithmic) - Generation time: genetically determined period of log. growth - Varies by species (min to hr) - Ex.: generation = 20 min < 1000 org/ml - initial <
Stationary Phase - When the # of new cells produced is the same as the # of cells dying
Decline (Death) Phase - # of cells dying is greater than the # of new cells arising from division
Symbiosis - "Living together" in relation to bacteria - 3 Different types: < Mutualism < Parasitism < Commensalism
Mutualism - Both the host & the microorganism benefit < E. coli, a bacterium that lives in the large intestines
Parasitism - One organism benefits, the other is harmed < Tapeworm, Malaria
Commensalism - One organism benefits, the other is neutral < skin bacteria, normal flora < majority of microbes
Normal Flora - Organisms that live on or in the body but do not usually cause disease (commensals) < skin, conjunctiva, mouth, nose, throat, urinary tract, reproductive, & GI tracts. - Nutrients from oils & sweat facilitate colonization up to a dozen staph specie
Normal Flora in Infants Infant have: - not acquired normal flora - less organic acid available to minimize growth - ideal environment to grow pathogens - Pathogens include: Grp B strep & Candida (yeast)
Resident Microflora Organisms found on/in specific areas of the body
Transient Microflora Organisms that "come and go" and exist in the same areas occupied by resident flora
Pathogenicity Organism which benefits from its host and often lead to infection
Virulence Term used to describe the intensity of bacterial & other microbial infections
Pathogenic Mechanisms of Bacteria 3 Types: - Adherence - Colonization - Formation of a capsule
Adherence Bacteria use pili to cling to surface of host cells, multiply & form colonies
Colonization Once in place within host tissue, bacterial replication forms colonies and may overcome host defenses. < colonization in small #s of non-invasive organisms is normal in all animals
Formation of a Capsule Capsule contributes to organism's virulence due to thick, polysaccharides structure - helps to resist host defense processes
Invasiveness Ability of organisms to penetrate host tissue, usually by special enzyme
Enzymes contributing to Invasiveness 3 Different Types: - Hyaluronidase - Coagulase - Streptokinase and Staphylokinase
Hyaluronidase Attacks hyaluronic acid, the ground substance of connective tissue
Coagulase Breaks down collagen, the framework of muscles
Streptokinase & Staphylokinase Digest fibrin & prevent the clotting of blood < "flesh-eating bacteria" ex. of organism that produces streptokinase
Exotoxins Secreted primarily by Gram-positive organisms < Gram (+) = botulism, gas gangrene, tetanus, staphylococcal food poisoning < Gram (-) = E. coli O157:H7 Shiga toxin
Endotoxins - Release from Gram (-) bacteria when they die - Non-specific gastrointestinal symptoms such as diarrhea, cramping, & generalized malaise < Ex.: cholera, salmonella
Endospores - Dormant form - Form when conditions are unfavorable for growth - Survive under harsh conditions < excessive heat or cold - Revert to active under favorable conditions - Clostridia species that cause tetanus, botulism, & gas gangrene form endosp
Exchange of Genetic Material Bacteria can exchange genetic material 3 different ways: < Transformation < Transduction < Conjugation
Transformation - DNA is acquired directly from the environment which was released from another cell through lysis etc. - Fragments are then "spliced" into the host cell's DNA
Transduction - An asexual genetic process - Viruses (Bacteriophages or phages) transfer genes between mating bacteria
Conjugation - Requires contact between 2 bacteria - utilizes a plasmid - transfers a greater amount of DNA than transformation or transduction - DNA is to be transferred from a donor cell to a recipient cell
F-Pilus - Sex pilus - transfers DNA from one cell to another in conjugation
Plasmid Extra-chromosomal DNA in the cytoplasm of some bacteria but not required by the bacterium
Resistance Transfer Factors Bacteria which develop a drug resistance through plasmids
Genetic Recombination By 3 different processes, transfers DNA leading to new strains of bacterium including antibiotic resistant strains
Antimicrobial Agents Substances used to specifically treat infectious microbial diseases
Antibiotics Antimicrobial agent containing substances derived from other organisms
Spectrum of Activity Antimicrobial classifications: < Broad Spectrum < Narrow Spectrum
Broad Spectrum Antimicrobials which are effective against a wide range of microorganisms including both gram (+) & gram (-) bacteria
Narrow Spectrum Antibiotics are effective against a limited # of microorganism or single taxonomic group
Bacteriocidal Drug Kills the organism
Bacteriostatic Drug Inhibit the organism growth & allows immune defenses to act against the invader
Resistance Factors (Causes of) Occurs through: - overuse of antibiotics - plasmids - genetic transfer mechanisms - development of neutralizing enzymes - alteration of pathways used by antibiotics - altering cell membrane permeability
Agar Disc Diffusion (Kirby Bauer Method) - Uses paper discs impregnated with specific concentration of the antimicrobial to be tested - Result reported as either: < Sensitive: stays away from seed; inhibiting < Intermediate < Resistant: grows up to seed
Upper Respiratory Tract Infections Pharyngitis - infections of upper tract: < pharynx < ears < eyes < sinuses < upper bronchioles - e.g. Strep throat caused by Streptococcus pyogenes
Lower Respirator Tract Infections - Pneumonias - Casulated organisms that cause pneumonias include: < haemophilus influenza < Klebsiella pheumoniae < Streptococcus pneumoniae
Gastrointestinal Bacterial Infections - Gastrointestinal - Contaminated food or water < Salmonella (raw eggs) < Shigella < Staphylococcus aureus < E. coli O157:H7 (raw hamburger, contaminated fecal material)
Nervous System Infections - Meningitis < haemophilus influenzae (children) < Neisseria meningitidis < Vaccines available for both
Toxin-Induced Infections - Botulism (Colstridium botulinum) - Tetanus (Colstridium tetani) - Toxic Shock Syndrome (Staphylococcus aureus)
Intracellular Bacteria 2 Different Classes: - Chlamydia - Rickettsias - To a lesser extent: Mycoplasmas
Chlamydia Trachomatis - intracellular organisms - require eukaryotic cell to replicate - causes variety of human infections including: < Trachoma (eye infection) < Sexually-transmitted disease causeing pelvic inflammatory dise. < Conjunctivitis in newborns
Richettsias - Obligate intracellular parasite - Transmitted by a vector (ex. ticks & lice) - Rocky Mountain Spotted Fever (RMSF) - To human transmitted through the bite of the vector - Rocky Mountian spotted fever, Lyme Disease
Mycoplasma Pneumoniae Primary atypical pneumonia "walking pneumonia"
Mycoplasmas - Tiniest free-living organisms - Do not have a cell wall - Mycoplasma pneumoniae (walking pneumonia) < causes primary atypical pneumonia
Viruses - Obligate Intracellular Parasite - Replicates w/n host cell - virus provides RNA or DNA to replicate - Host cell provides energy & resource - Contain RNA or DNA (not both) < RNA viruses contain code for reverse transcriptase, enzyme which makes D
Viral Structure - Nucleic Acid (RNA or DNA) - Capsid: protective coat enveloping nucleic acid - Envelope < present in some viruses < May have glycoprotein spikes * determine specificity * hide virus from immune system
Nucleic Acid Either a single or double strand of DNA or RNA, differing among viral groups
Capsids - Enclosed within a protective coat - Determines the shape of the virus - Composed of individual protein subunits (capsomeres) - Can be helical, polyhedral (multi-sided) or bullet-shaped
Capsomeres Individual protein subunits found in a capsid
Nucleocapsid Combined capsid/nucleic acid arrangement
Viral Envelope - External to the capsid - Acquired from combo of proteins, lipids & carbohydrates found in host cell
Spikes A projection, usually glycoprotein molecules, that attach to specific sites on host cell wall
Viral Replication Five Steps: - Adsorbtion - Penetration - Synthesis - Maturation - Release
Adsorption (Viral Replication - Step 1) Attachment of virus to host cell < specificity to certain cells
Penetration (Viral Replication - Step 2) Virus enters host cell (endocytosis or fusion) and "uncoats" (takes off envelope and capsid)
Synthesis (Viral Replication - Step 3) Utilizes host nucleus to make new genetic material
Maturation (Viral Replication - Step 4) Virus is packaged into new complete virons
Release (Viral Replication - Step 5) Departure of new virons from host cell < host cell may rupture OR < host cell remains intact & releases the virus
Uncoating Process of a virus loosing the envelope & capsid
Viral Pathogenicity Two Main Catagories: - Acute Infections - Latent/Persistent Infections
Acute Infections - Disease cycle is relatively short - Host cell ruptures; virus spreads to neighboring cells < Common cold (rhinovirus), influenza, some hepatitis viruses
Latent/Persistent Infections - Virus becomes relatively inactive by reemerges - Provirus remains in host cells - Replicates new virions when triggered by some external event (stress, fever, etc) < Herpes Virus, Epstein-Barr Virus, Human Immunodeficiency Virus (HIV); T-Helper Ce
Immune System Viruses Epstein-Barr Virus (infectious mononucleosis) & Human Immunodeficiency Virus (HIV)
Oncogenic Viruses - Possess oncongenes (cancer causing genes) that cause uncontrolled & abnormal division of host cells by altering cell cycle "checkpoints" < Hepatitis B, Hepatitis C < Human Papilloma Virus (cause of cerical cancer)
Oncogenes Uncontrolled and abnormal division of host cells
Interferon Antiviral therapy which inhibits viral activity
Prions - Infectious proteins w/o genetic material - Come in contact w/normal proteins and transform them into infectious - Affects cells of the brain - Creutzfeldt-Jakob disease ("mad cow")
Infectious Particle Infectious protein which affects the cells of the brain
Transmissible Spongiform Encephalopathies - "Spongiform" = cytopathic effect on brain tissue - "Infection" = produces microscopic holes in brain resembling a sponge
Prion Characteristics - Generally resistant to inactivation by heating to 90* - Resistant to radiation treatments - Not susceptible to enzymes that inactivate RNA & DNA - Susceptible to protein denaturing agents
Fungi - Important for decomposition & recycling - Divided into 2 different groups: < Yeasts = unicellular < Molds = multicellular - Ex.: Candida Albicans (yeast infection) & Tinea Corporis (ringworm, mold)
Spores Small deposits from the enviroment
Molds - Multicellular fungi - One or more spores grows into filamentous, thread-like mass called "mycelium" - Ex.: Athlete's foot, jock itch & ringworm
Yeasts - Unicellular fungi - important in beer, bread, and alcohol production - most common yeast infection: Candida albicans (infections: mouth & pharynx = thrush); vaginitis
Protozoa - Parasites except Helminths (worms) - found in the Kingdom Protista - single-celled organism 2 Different Stages: - Motile trophozoite > infective stage - Cyst stage > dormant state
Parasitic Organisms (Protozoa & Helminths) - Live at expense of host - Transmitted to humans by vectors > Biological = mosquito transmitting malaria > Mechanical = transmission of parasite eggs to food by flies & other insects
Helminths - Known as "worms" - multicellular - found in Kingdom Animalia - 4 Different Groups: > Flukes > Tapeworms > Roundworms > Tissue Parasites
Trophozoite Stage Stage of the protozoa which is the motile, invasive form of the organism
Cyst Stage Stage of the protozoa which allows the organism to survive in a dormant state in the external enviroment
Common Pathogenic Protozoans - Giardia Lamblia: > ingesting cysts from animal contaminated water > intense gastrointestinal (GI) distress & diarrhea - Cryptosporidium: > self-limiting GI symptoms > if infected, can become carrier > recently associated w/recreati
Anopheles Mosquito which serves as the definitive host in Malaria
Helminths (Parasitic Worms) - Hosts are definitive or intermediate > Definitive: harbor parasite when it reproduces > Intermediate: harbor parasite during a developmental stage in the parasite's life cycle > Accidental: not part of the normal cycle; "dead end" hosts
Tapeworms - Segmented worms that contain a head (scolex) and many segments call "proglottids" - Hermaphrodites - Infective stage is larvae found in cattle & swine - Most prevalent in > Beef & Pork (taenia) > Fish (Dibothrocephalus) - Several cm to meter
Roundworms (intestinal) - Live in lumen of intestinal tract - Infection occurs by ingestion of egg or penetration of the skin by larvae > Pinworms (Enterobius) > Ascarids (Giant intestinal worms) > Hookworms
Created by: snuzyque