Introduction to Microbiology Study Guide Bundle
Introduction to Microbiology Study Guide Bundle
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Microbiology Exam Two Study Guide Chapters 6, 7, 8 and 12 Chapter Six Microbial Growth Physical requirements for growth ▯ Temperature ▯ ▯ Psychophiles (-10 to 20 C) ▯ ▯ Psychotrophs (0 to 30 C) ▯ ▯ Mesophiles (10 to 50 C) ▯ ▯ Thermophiles (40 to 70 C) ▯ ▯ Hyperthermophiles (65 to 110 C) ▯ ▯ Danger zone for microbial growth is 15 to 50 C H ▯ p ▯ ▯ Bacteria grow at 6.5-7.5 ▯ ▯ Fungi (mold and yeasts) grow at 5-6 ▯ ▯ Buffers help to maintain a neutral pH on media ▯ ▯ ▯ Phosphate salts, peptones, amino acids ▯ Osmotic Pressure ▯ ▯ Plasmolysis: occurs in a hypertonic solution; the inside shrivels up but the ▯ ▯ outside capsule retains its shape. ▯ ▯ Bacillus Cereus ▯ Causes Gastroenteritis and food borne illness ▯ ▯ Associated with rice from buffets ▯ ▯ Nausea and vomiting 2-5 hours after ingestion ▯ ▯ Diarrhea 8-16 hours after ingestion ▯ Gram-positive ▯ Bacillus ▯ Forms endospores ▯ ▯ Heating kills bacteria but not the spores ▯ ▯ Spores germinate as food cools ▯ ▯ Organism replicates and produces endospores ▯ Found in soil and vegetation Staphylococcus aureus ▯ Causes Staphylococcal food poisoning ▯ ▯ Most common food illness ▯ Carried in the nose and on the skin ▯ Halophilic: grows well in salt; high osmotic pressure ▯ Heat tolerant ▯ ▯ Produces an enterotoxin that survives boiling for 30 mins ▯ Vomiting 4-6 hours after ingestion ▯ ▯ Followed by cramps and diarrhea ▯ ▯ Lasts 24 hours Chemical Requirements ▯ Carbon ▯ ▯ Structural backbone of organic compounds ▯ ▯ Heterotroph: carbon from organic compounds ▯ ▯ Autotroph: carbon from CO2 ▯ Nitrogen ▯ ▯ Amino acids ▯ ▯ Nucleic acids ▯ Sulfur ▯ ▯ Some amino acids ▯ Phosphorous ▯ ▯ Nucleic acids Oxygen and Types of Growth ▯ Obligate Aerobes ▯ ▯ Only aerobic growth; requires oxygen ▯ Facultative Anaerobe ▯ ▯ Both aerobic and anaerobic growth; greater growth in the presence of ▯ ▯ oxygen ▯ Obligate Anaerobes ▯ ▯ Only anaerobic growth; stops growing in the presence of oxygen ▯ Aerotolerant Anaerobes ▯ ▯ Only anaerobic growth; but can continue in the presence of oxygen ▯ Micro-aerophiles ▯ ▯ Only aerobic growth; oxygen required in small amounts Bioﬁlm: communities of bacteria; planktonic bacteria attaching to surfaces ▯ Studied with Confocal Microscopy ▯ Slime (polysaccharide matrix with proteins and DNA) ▯ Hydrogel ▯ Forms c o l ▯ ▯ F ▯ ▯ Filamentous streamers ▯ ▯ Slime ▯ Functions ▯ ▯ Share nutrients ▯ ▯ Protection from environmental factors ▯ ▯ ▯ Host immune system ▯ ▯ ▯ Desiccation ▯ ▯ ▯ Antibiotics ▯ ▯ Help the transfer of plasmids/DNA ▯ Preventing Bioﬁlm ▯ ▯ Lactoferrin ▯ ▯ Witch hazel Quorum Sensing: communication between bacteria in a bioﬁlm to coordinate bacteriaCu Media and the Types of Bacteria They Grow ▯ Chemically deﬁned ▯ ▯ Growth of chemoautotrophs and photoautotrophs ▯ Complex ▯ ▯ Chemoheterobtrophs ▯ Reducing ▯ ▯ Obligate anaerobes ▯ Selective ▯ ▯ Suppresses unwanted microbes ▯ ▯ Encouraging desired microbes ▯ Differential ▯ ▯ Separates one colony from another ▯ Enrichment ▯ ▯ Increase desired microbes to detectable levels Binary Fission (speciﬁc to bacteria) ▯ Cell elongates and DNA is replicates ▯ Cell wall and plasma membrane begin to divide ▯ Cross-wall forms completely around divided DNA ▯ Cells separate Direct Microscopic Count ▯ Petroff-Hauser Cell Counter ▯ ▯ Relatively inexpensive ▯ ▯ Quick ▯ ▯ Requires high number of bacteria ▯ ▯ Count live and dead cells Spectrophotometer ▯ Indirect estimate ▯ Requires 10-100 million bacteria to register turbidity ▯ Can measure absorbance (plate count) vs. time Clinical Cases: Pseudomonas ﬂorescens ▯ ▯ Aerobic, gram-negative Intravenous heprin solution Survived in Catheters even after the recall Chapter Seven Control of Microbial Growth and Norovirus Sterilization: destruction or removal of all forms of microbial life, including endospores Commercial Sterilization: sufﬁcient heat treatment to kill endospores of clostridium botulinum in canned food. Disinfection: destruction of vegetative pathogens Antisepsis: destruction of vegetative pathogens on living tissue Degerming: removal of microbes from a limited area, like an injection site Sanitization: treatment intended to lower microbial counts on eating and drinking utensils to safe public health levels Efﬁcacy of antimicrobial treatment depends on: ▯ Number of microbes ▯ Environment ▯ Time of exposure ▯ Microbial characteristics ▯ ▯ Acid fast ▯ ▯ Endospores ▯ ▯ Gram-positive vs. gram-negative Physical Methods of Microbial Control Heat ▯ Autoclave ▯ ▯ Used to sterilize media ▯ ▯ Preferred method, provided that the material will not be damaged by heat ▯ ▯ or moisture ▯ ▯ 121 C for 15 mins at 15 psi ▯ Pasteurization ▯ ▯ 72 C for 15 sec ▯ Dry Heat ▯ ▯ 170 C for 2 hours ▯ Pasteurization ▯ ▯ Mild heat to kill spoilage organisms without changing taste ▯ ▯ 72 C for 15 secs ▯ ▯ Thermoduric organisms survive and cause eventual spoilage Low Temperature ▯ Bacteriostatic: keeps most bacteria from replicating ▯ Listeriosis: bacteria can grow in fridge and cause spoilage Osmotic Pressure ▯ Salt or sugar and smoking to cure meats ▯ Dehydration of fruit Filtration ▯ Relatively fast ▯ Holes of .2 u ▯ Only for clear and liquid and gases together ▯ HEPA ﬁlters: high efﬁciency particulate air (.3 u) Radiation ▯ Ionizing radiation ▯ ▯ Gamma rays, x-rays, short wavelength, high energy electron beam ▯ ▯ Destruction of bacterial DNA ▯ Non Ionizing radiation ▯ ▯ UV light ▯ ▯ ▯ Damages DNA by producing thymine dimers ▯ ▯ ▯ Can damage human eyes and cause skin cancer Phenols ▯ Most affective against Gram positive organisms ▯ Damages the lipid portion of cell membranes ▯ Examples ▯ ▯ Lysol ▯ ▯ Lister: carbolic acid as a surgical scrub Bisphenols ▯ Hexachlorophene (soaps) ▯ ▯ Effective against gram-positive staphylococci and streptococci ▯ Triclosan (plastics) ▯ ▯ Works best against gram-positive organisms Halogens ▯ Flourine ▯ Chlorine: bleach, disinfect water e n i d o ▯ I Alcohols ▯ Kill bacteria and fungi ▯ Do not kill endospores and viruses ▯ Denatures proteins in the cell membranes and dissolves lipid component ▯ Optimum concentration: 70% Quaternary Ammonium Compounds (Quats) ▯ Effective against Gram positive ▯ Affects the cell membrane ▯ ▯ Ex: Zephiran (benzalkonium chloride): acne treatments ▯ ▯ Cepacol (cetyl pyridinium chloride): mouthwashes Order of Resistance (From most to least resistant): ▯ Prions ▯ Endospores of bacteria ▯ Mycobacteria ▯ Cysts of protozoa ▯ Vegetative protozoa ▯ Gram-negative bacteria i g n u ▯ F ▯ Viruses without envelopes ▯ Gram positive bacteria ▯ Viruses with lipid envelopes NOROVIRUS ▯ Happened on a cruise ship to St. Thomas ▯ 20% of the guests got it ▯ 5% of the crew got it ▯ Lasts 1-3 days ▯ ▯ Vomiting, Diarrhea (gastroenteritis) ▯ ▯ Fever, Headache, body aches ▯ Prevention ▯ ▯ Wash hands ▯ ▯ Wash food ▯ ▯ Cook food thoroughly (survive temps as high as 140 C) ▯ ▯ Don’t prepare food when you are sick ▯ Treatment: rehydration Fungal Menengitis ▯ Mycobacterium ▯ Injections that were preservative free ▯ Not contagious ▯ 64 deaths Clinical Cases: School Nurse Nausea, vomitting, diarrhea, and fever Norovirus Quat to clean Found on the computer mouses Chapter Eight Microbial Genetics Bacteria: singular circular chromosome attached to the inner cell membrane ▯ mRNA is synthesized in the cytoplasm ▯ Transcription and translation can occur simultaneously Constitutive genes: are always on; genes for enzymes involved in glycolysis Recombination: between cells of the same generation Replication: Cell divides, between generations of cells ▯ Semiconservative replication ▯ DNA gyrase and Topoisomerase: relax supercoiling ▯ Helicase: unwinds the DNA ▯ RNA polymerase: makes an RNA copy from a DNA template ▯ ▯ Can old add nucleotides to the 3’ end ▯ DNA polymerase: synthesizes DNA; proofreads and repairs DNA ▯ DNA ligase: Joins DNA strands; Joins Okazaki fragments; joins new segments ▯ during excision repair ▯ Photolyases: repair damage cause by UV light ▯ Antiparallel strands ▯ ▯ DNA is always synthesized from the 5’ to 3’ end Transcription: DNA to mRNA, within a cell ▯ DNA read from 3’ to 5’ ▯ RNA synthesized 5’ to 3’ Translation: mRNA to protein, within a cell ▯ Sense codon: start codon (AUG) ▯ Nonsense codons: stop codons (UAA, UAG, UGA) Operon Model of Gene Expression ▯ Francois Jacob and Jacques Monod ▯ Promoter: RNA polymerase binding side on DNA ▯ Operator: stop/go for transcription ▯ Structural genes: determine the proteins produced Repression ▯ Inhibits gene expression ▯ In response to overabundance of end product ▯ Ex: Tryptophan Induction ▯ Turns on gene transcription ▯ Inducer: acts to induce transcription of a gene ▯ ▯ ex: lactose ▯ Inducible enzymes: enzymes that are synthesized in the presence of an inducer Regulation of the Lac operon ▯ In the absence of lactose the active repressor binds to the operator of the lac ▯ operon preventing transcription ▯ In the presence of lactose, lactose inactivates the repressor protein so it cannot ▯ bind to the operator and the lac operon is on. The Effect of Glucose on the Lac operon ▯ Cells prefer glucose ▯ cAMP accumulate when glucose is not available ▯ Efﬁcient transcription requires the presence of lactose and the absence of ▯ glucose ▯ Mutation ▯ Silent Mutation: base code changes but the amino acid stays the same ▯ Base substitution ▯ ▯ Missense mutation: substitution of a different aa ▯ ▯ ▯ ex: sickle cell anemia ▯ ▯ Nonsense mutation: a base substitution resulting in a stop codon in the ▯ ▯ middle of the mRNA ▯ Frameshift mutation: one or more nucleotide pairs are deleted or inserted in the A N ▯ D ▯ ▯ ex: Huntington’s disease ▯ Spontaneous mutations: occur in the absence of mutation causing agents; errors ▯ in DNA replication ▯ Mutagens: Agents that cause a mutation ▯ ▯ ex: chemicals, radiation, UV light Nitrous acid: alters A to pair with C Nucleoside analogs: have similar structure to normal nitrogenous bases but with altered pairing; results in base-pair substitutions ▯ 2-aminopurine: replaces A, pairs with C ▯ 5-bromouracil: replaces T, pairs with G X-rays and gamma rays: ▯ Ionizing ▯ Break bonds between sugar and phosphate backbone molecules causing ▯ chromosomes to break l a h t e ▯ L Ultraviolet radiation ▯ Non ionizing radiation ▯ Makes Thymine dymers: result in errors in DNA replication and transcription ▯ Positive (direct) Selection: detects the mutants directly; growing on selective agar Negative (indirect) selection ▯ Replica plating ▯ ▯ Prototroph: ‘wild type’ no special needs ▯ ▯ Auxotroph: mutant that has a speciﬁc nutrient requirement Ames test: uses bacteria as a carcinogen indicators; measures the reversion rate of histidine auxotrophs of salmonella Recombination: exchange of genes between two DNA molecules to form new combinations of genes on a chromosome Crossing over: occurs in eukaryotic cells during prophase I of meiosis Vertical gene transfer: genes are passed from an organism to its offspring Horizontal gene transfer: genes are passed to microbes of the same generation ▯ Transformation: acquisition of DNA from the environment ▯ ▯ Competent: Cells that can take the donor DNA ▯ ▯ ex: Bacillus, streptococcus, staphylococcus, Haemophilus, Neisseria, ▯ ▯ Acinetobacter ▯ Transduction: involves a virus ▯ ▯ DNA is transferred from one cell to another using a virus ▯ ▯ Generalized transduction: all genes are equally likely to be transferred ▯ ▯ Specialized transduction: lysogenic virus; only gemes next to the ▯ ▯ prophage insertion site are transferred ▯ Conjugation: involves two different strains of bacteria ▯ ▯ Mediated by a plasmid ▯ ▯ One way transfer of DNA Plasmids: self-replicating, circular pieces of DNA ▯ Conjugative plasmid: F factor; codes for sex pili and transfer of the plasmid ▯ Dissimilation plasmid: code for enzymes that trigger catabolism of unusual ▯ substrates ▯ Resistance factors: contain genes that make the host resistant to antibiotics or ▯ toxins Transposons: small pieces of SNA that can move from one region to another region of the same chromosome or a different chromosome ▯ Found in chromosomes, plasmids, and viruses Clinical Cases: Serrated colorectal poyps DNA undergoes mutations BBQ place Ames test Chapter Twelve The Eukaryotes: Fungi, Protozoa, and Helminths Malaria: 350-500 million cases of malaria a year, one million people die Fungi ▯ Cause nosocomial infections with people with compromised immune systems ▯ Heterotrophic ▯ Has sterols in the cell membrane ▯ Reproductive spores ▯ Sensitive to polyenes, imidazoles, and griseofulvin ▯ ex: Bread, mushrooms, penicillin Molds ▯ Aerobic ▯ Multicellular ▯ Hyphae ▯ ▯ Septate: like a straw ▯ ▯ Nonseptate: bamboo ▯ ex: Rhizopus stolonifer, Aspergillus niger, Penicillium notatum ▯ Aspergillus niger ▯ Conidophore that end in conidia ▯ Septate hyphae ▯ Used to produce citric acid for sodas ▯ Penicillium notatum ▯ Conidiophores that end in conidia ▯ Green-grey color ▯ Septate hyphae ▯ Used to make penicillin and blue cheese ▯ Rhizopus stolonifer ▯ Nonseptate hyphael; rhizoids hyphae ▯ Common bread mold Yeast ▯ Facultative anaerobes ▯ Unicellular ▯ Reproduce by budding ▯ ex: Saccaromyces cerevisiae ▯ Saccaromyces cerevisiae ▯ Used to make bread, beer, wine, and hepatitis B vaccine Fungal Diseases ▯ Systemic mycoses ▯ ▯ Histoplasmosis ▯ Cutaneous mycoses ▯ ▯ Degrade keratin ▯ ▯ Ringworm and athlete’s foot ▯ Opportunistic pathogens ▯ ▯ Pneumocystis ▯ Yeast infections-Candidiasis ▯ ▯ Thrush ▯ ▯ Vulvovaginitis Histoplasmosis ▯ Caused by Histoplasmosis capsulatum ▯ Airborne; found in bird feces ▯ Causes lung lesions ▯ Treatment: amphotericin B or itraconazole ▯ Cryptococcus neoformans Meningitis ▯ Yeasts ▯ Polysaccharide capsule ▯ Transmitted by inhalation of contaminated soil ▯ 30% mortality rate ▯ Test: latex agglutination test to detect antigens ▯ Treatment: amphotericin B and ﬂucytosine Dermatomycoses Ringworm ▯ Located in hair, nails, and skin ▯ Topical treatment: miconazole and clotrimazole ▯ Systemic treatment: griseofulvin Pneumocystis ▯ Leading cause of death for AIDS patients ▯ Found in the lining of the lungs ▯ Treatment: trimethoprim-sulfamethoxazole Candidiasis ▯ Candida albicans ▯ Opportunist ▯ Yeast ▯ Leads to: trush and vulvovaginitis ▯ Treatment: ﬂuconazole Protozoa ▯ Unicellular ▯ Eukaryotic ▯ Chemoheterotrophic ▯ Trophozoite: feeding and growing stage of protozoa Phylum Apicomplexa ▯ Obligate intracellular parasites ▯ Has enzymes that penetrate host tissue ▯ ex: Plasmodium vivax (malaria) ▯ ▯ Plasmodium Vivax ▯ Sporozoites ▯ Merozoite ▯ Mosquito is the deﬁnite host (holds sexually reproducing plasmodium) ▯ Human is the intermediate host (plasmodium is reproducing asexually) ▯ Causes fever, anemia, clogging blood vessels ▯ Treatment: quinine (chloroquin) ▯ People who have sickle cell anemia are resistant Why is a malaria vaccine hard to make? ▯ Different species of plasmodium ▯ Different stages (sporozoite) ▯ Mutated gene ▯ When it is located in the cells the host immune system can’t get to it Toxoplasma Gondii ▯ Intracellular parasite ▯ Tachyzoite: reproduces sexually and asexually ▯ Deﬁnitive host: cats ▯ ▯ Excreted in feces ▯ Cryptosporidiosis ▯ Outbreaks in Dallas ▯ Acid-fast ▯ Fecal-oral transmission ▯ Symptoms: vomitting, diarrhea, and abdominal cramps ▯ Detection: oocysts in feces ▯ Treatment: Nitazoxanide ▯ CHLORINE IS NOT AFFECTIVE Helminths ▯ Parasitic round worm or ﬂat worm ▯ Multicellular and Eukaryotic ▯ ▯ Trematodes: ﬂukes ▯ ▯ Platyhelminths: ﬂatworms, tape worms ▯ ▯ ▯ Taenia solium ▯ ▯ ▯ Taenia saginata ▯ ▯ Nematodes: ▯ ▯ ▯ Enterobius vermicularis: pinworm ▯ ▯ ▯ Ascaris lumbricooides: round worms ▯ ▯ ▯ Necator americanus: hook worm ▯ ▯ ▯ Trichinella spiralis Trematodes ▯ Intermediate host: snail ▯ Treatment: praziquantel ▯ Prevention: sanitation and elimination of snails Pinworms ▯ Humans are the only host ▯ Fecal oral transmission ▯ Found in the small intestine Hook Worms ▯ Necator americanus ▯ In small intestine ▯ Larva penetrate host skin ▯ Round worms (Asacarids)▯ ▯ Ascaris lumbricoides ▯ In the small intestine ▯ ▯ Feeds on semidigested food ▯ ▯ Causes pot belly ▯ Fecal oral transmission Trichinosis ▯ From eating undercooked pork ▯ Symptoms: fever, swelling around the eyes, upset GI ▯ Diagnosis: muscle biopsy ▯ Treatment: mebendazole Arthropods ▯ Segmented bodies ▯ Hard exoskeletons ▯ Jointed legs ▯ Vectors: arthropods that carry pathogenic microorganisms ▯ Arachnida ▯ ▯ Spiders, mites, ticks ▯ Insecta ▯ ▯ Lice, ﬂeas, ﬂies, mosquitos Pediculosis (Lice) d o o l b n o d e e ▯ F ▯ Eggs are called nits ▯ Humans are the only host ▯ Contagious ▯ Treatment: Nix (permethrin), Rid (pyrethrin), oral ivermectin Lyme Disease ▯ Non contagious ▯ Symptoms: Bull’s eye rash, arthritis, bells palsy, ﬂu like symptoms, ▯ ▯ menegitis, encephalitis ▯ Cause: Borrelia burgdorferi ▯ Vector: Tick, Ixodes scapularis, Ixodes paciﬁcus ▯ Reservoir: ﬁeld mice ▯ Treatment: doxycycline Rocky Mountain Spotted Fever ▯ Cause: Rickettsia rickettsii ▯ Vector: Tick (dermacentor) ▯ Symptoms: measles like rash, fever, headache, liver and kidney failure ▯ Treatment: tetracycline and chloramphenicol ▯ No vaccine ▯ Clinical Cases: Dog is ill Mass in the lungs Fungal infection Cryptococcus gattii Read over study guide Read updates she sent Reach clinical cases in each chapter Do and study practice test Mastering bio chapter quizzes Exam Three Study Guide Chapters 13, 14, and 15 Chapter 13 Viruses and Prions Adolf Mayer: demonstrated transmission from an affected plant to a healthy plant Dimitri Iwanowski: ﬁltered the sap of infected plants through a porcelain ﬁlter; ‘ﬁlterable agent’ Wendell Stanley: isolated the TMV and electron microscope was invented Walter Reed: yellow fever Carlos Juan Finley: showed yellow fever was transmitted by mosquitos Yellow Fever: ﬁrst human disease associated with a ﬁlterable agent ▯ First Disease shown to be transmitted by mosquito ▯ Flavivirus: has an envelope ▯ Zoonotic ▯ ▯ Sylvatic cycle: mosquitos transmit the disease from monkey to monkey ▯ ▯ and from monkey to man ▯ ▯ Urban cycle: aedes aegypti mosquitoes transmit the disease from human ▯ ▯ to human ▯ Diagnosis: based on clinical signs, rise in antibodies, or isolation of the virus from d o o l ▯ b ▯ NO TREATMENT ▯ Prevention: ▯ ▯ Vaccine ▯ ▯ Mosquito control ▯ ▯ ▯ Drain standing water ▯ ▯ ▯ Insecticides ▯ ▯ ▯ Insect repellants ▯ ▯ ▯ Mosquito netting Virus ▯ Obligatory intracellular parasite ▯ Can pass through .2u ﬁlters ▯ ▯ Filterable agents of disease ▯ Some have envelopes ▯ No ribosomes or ATP generation ▯ Sensitive to interferon Viral Host Range ▯ Most are species speciﬁc Phage Therapy Center: provides an effective treatment solution for patients who have bacterial infections that do not respond to conventional antibiotic therapies. Viral attachment sites: Cell wall, ﬁmbriae, and ﬂagella Virion: fully developed, infectious viral particle composed of nucleic acid and protein coat Non enveloped: consist only of the nucleic acid and capsid Host Reaction ▯ Infection by a virus should result in production of antibodies to the viral surface ▯ proteins and inactivation of the virus ▯ Some viruses can change their surface proteins so that the antibodies are not ▯ longer effective ▯ Ex: you can get some diseases like inﬂuenza more than once Icosahedron: 20 equilateral triangles ▯ ex: poliovirus (+ssRNA) and adenovirus (dsDNA, spikes) Helical Virus ▯ ex: Filovirus (ssRNA) (ebola) and Lyssavirus (ssRNA) (Rabies) Enveloped Helical Virus ▯ Inﬂuenza virus (ssRNA) Enveloped Icosahedral Virus ▯ Herpesviridae (dsDNA) ▯ Cold Sore, genital herpes, mononucleosis, chicken pox, shingles Complex Viruses ▯ (dsDNA) enveloped ▯ Causes smallpox and cowpox Inﬂuenza ▯ Family: Orthomyxoviridae ▯ Genus: Inﬂuenza virus ▯ Capsid ▯ Envelope ▯ 8-separate RNA segments ▯ Spikes of neuraminidase (release) and hemagglutinins (attachment) ▯ ▯ Used to identify the strain ▯ ▯ H-spikes: allow the virus to attach to speciﬁc host cell receptors; cause n o i t a n i t u l g g▯ ▯ a ▯ ▯ ▯ H1, H2, H3: human infecting strains ▯ ▯ ▯ H4 and H5: infect animals (bird and swine) ▯ ▯ N- spikes: help the virus separate from infected cells after replication via ▯ ▯ enzyme neuraminidase ▯ Symptoms: chills, fever, headache, muscle aches ▯ Prevention: annual vaccination (nasal now allowed) (different each year) ▯ Treatment: Prevent uncoating (amantidine, rimantidine) ▯ ▯ Neuraminidase inhibitors- decrease the length of disease (Relenza ▯ ▯ and Tamiﬂu) ▯ Aerosol transmission ▯ Groups bases on antigens of their protein coats: ▯ ▯ Inﬂuenza A: regular outbreaks; also infects animals and birds ▯ ▯ Inﬂuenza B: sporadic outbreaks in limited areas (nursing homes) ▯ ▯ Inﬂuenza C: common; rarely causes disease symptoms Inﬂuenza Pandemic of 1918 ▯ Spanish ﬂu ▯ Genome has been mapped from frozen tissue samples to show an avian ▯ H1N1 virus with 10 changes in amino acids ▯ This strain became endemic in the swine population in the USA ▯ The pandemic probably originated with swine in Kansas and spread to ▯ military barracks nearby ▯ Killed 675,000 people in the USA and 20-50 million worldwide ▯ Highest mortality rate in young adults (18-25) ▯ Death within hours ▯ Produced hemorrhagic viral pneumonia Antigenic Shifts: caused by major genetic recombination ▯ Anitbodies formed against one strain will usually not be protective following an ▯ antigenic shift. ▯ High mutation rates are characteristics of RNA viruses. Vaccine Production ▯ Takes months to develop vaccine ▯ Identify new strains in February ▯ ▯ Vaccines come out in October ▯ Vaccines are 70-90% affective for up to 3 years Bacteriophages ▯ Phages are mixed with the bacterial host in a soft agar and the mix is poured ▯ over a hard agar plate ▯ The “lawn” is the area of conﬂuent bacterial growth ▯ The “plaque” is the clear area where bacterial cells have been lysed due to viral ▯ infection of the host cells. ▯ Lytic cycle: virulent phage; ends with the death of the cell ▯ ▯ Attachment: phage attaches to host cells ▯ ▯ Penetration: phage penetrates host cells and injects its DNA ▯ ▯ Biosynthesis: phage DNA directs synthesis of viral components by the ▯ ▯ host cell ▯ ▯ Maturation: viral components are assembled into virions ▯ ▯ Release: Host cell lyses and new virons are released ▯ ▯ Lysogenic cycle: temperate phage; host cell remains alive ▯ ▯ Phage attaches to host cell and injects DNA ▯ ▯ Phage DNA circularizes and enters lytic cycle or lysogenic cycle ▯ ▯ ------------------------------------------------------------------------------------- ▯ ▯ New phage DNA and proteins are synthesized and assembled into virions ▯ ▯ Cell lyses, releasing phage virions ▯ ▯ --------------------------------------------------------------------------------------- ▯ ▯ OR Phage DNA integrates within the bacterial chromosome by ▯ ▯ recombination, becoming a prophage ▯ ▯ Lysogenic bacterium reproduces normally ▯ ▯ Cell divisions ▯ ▯ The prophage may excise from the bacterial chromosomes by another ▯ ▯ recombination event, initiating a lytic cycle Phage conversion: the host cell may exhibit new properties Specialized Transduction ▯ Prophage exists in galactose-using host (containing the gal gene) ▯ Phage genome excises carrying with it the adjacent gal gene from the host ▯ Phage matures and cell lyses, releasing phage carrying gal genes ▯ Phage infects a cell that cannot utilize galactose (lacking gal gene) ▯ Along with the prophage, the bacterial gal gene becomes integrates into the new ▯ host’s DNA ▯ Lysogenic cell can now metabolize galactose Viral Identiﬁcation ▯ Electron microscopy ▯ Western blot: virus is detected and identiﬁed by its reaction with antibodies ▯ Observation of speciﬁc cytopathic effects ▯ Polymerase chain reactions DNA Viruses ▯ Adenoviridae: respiratory disease ▯ Poxviridae: smallpox, cow pox ▯ Herpesviridae: cold sores, genital herpes, mono, chickenpox/ ▯ shingles,mononucleosis ▯ Papovaviridae: warts ▯ Hepadnaviridae: Hepatitis B- reverse transcriptase Enveloped viruses are released by budding (may not cause death of the host) Nonenveloped viruses released through rupture (always causes death) Oncogenes: can be activated to produce cancer ▯ Activated by: mutagens, viruses, and high energy radiation ▯ 10% of cancers are caused by viruses DNA Oncogenic Viruses ▯ Herpesviridae: epstein-barr virus; causes mononucleosis, Burkitt’s lymphoma, ▯ and nasopharyneal carcinoma ▯ Hepadnavirus: hepatitis B (liver cancer) RNA Oncogenic Viruses ▯ Retroviridaw ▯ Humans: human T-cell leukemia viruses ▯ Sarcoma Virus: cats, chickens, rodents ▯ Feline Leukemia Virus in cats Latent Viral Infections: activates by stress; may not recur for months to years ▯ Human Herpes Viruses ▯ ▯ Cold sores (herpes simplex) ▯ ▯ Genital herpes ▯ ▯ Chicken pox and shingles Prions ▯ Proteinaceous infectious particle ▯ Produce spongiform encephalopathy ▯ Infectivity is reduced by treatment with proteases, but not by treatment with ▯ radiation ▯ ▯ Sheep: scrapie ▯ ▯ Cattle: mad cow disease ▯ ▯ Humans: Kuru creutzfeldt (Jakob disease) Viral Diseases ▯ ▯ Measles ▯ Polio ▯ Inﬂuenza ▯ West Nile Virus s e i b a ▯ R a l l e b u ▯ R ▯ Smallpox ▯ Ebola ▯ Hepatitis A ▯ Hepatitis B ▯ Dengue Fever ▯ Papilloma virus ▯ Reye syndrome ▯ Human Herpes Viruses ▯ ▯ Mononucleosis ▯ ▯ Chicken pox/shingles ▯ ▯ Cold sores ▯ ▯ Genital herpes Clinical Case Pharmaceutical saleswoman ▯ High fever ▯ Jaundice ▯ Abnormal liver results Infectious Hepatitis ▯ Hepatitis A from slushie machine ------------------------------------------------------- In hospital for UTI ▯ Ended up with fever, chills, and severe diarrhea ▯ He also lost 15 pounds Treated with antibiotics (ceftriaxone and ciproﬂoxacin) ▯ Still had diarrhea Positive for C. difﬁcile ▯ Treated with Metrondiazole ▯ Can not take it with other anti-biotics ------------------------------------------------------------------------------ Ophthalmologist Eight of the ten patients got inﬂammation He thinks it is Toxic anterior segment syndrome ▯ Caused by: ▯ ▯ Chemicals on surgical instruments ▯ ▯ Products introduced into the eyes during surgery ▯ ▯ Ointments or Talc from surgical gloves Endotoxins are present ▯ Bioﬁlms from pipes were wiped into enzymatic solutions ▯ Burkholderia Treatment: prednisone ▯ Topical anti-inﬂammatory drug Chapter 14 Pathology: study of disease Etiology: the cause of a disease Pathogenesis: the manner in which a disease develops Pathogen: disease causing organism Infection: the invasion or colonization of the body by pathogens; the presence of a particular microbe in a part of the body where it is not normally found. Disease: any change from a state of health; an abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions. Normal ﬂora: microbes that colonize a particular area of the body, but that do not produce disease under normal conditions Transient microbes: microbes that are present in or on an animal for a short time without causing a disease Microbial antagonism: normal ﬂora protect the host against colonization by pathogens by competing for nutrients, producing substances harmful to the invading microbes and affecting conditions such as pH and available oxygen. e.g. E. coli produce bacteriocins, proteins that inhibit the growth of other bacteria such as Shigella and Salmonella e.g. Clostridium difﬁcile is part of the ﬂora in the large intestine. The other microbes normally present keep it in check by competing for host cell receptors, competing for nutrients and producing bacteriocins. When antibiotic use kills off the competition, overgrowth of Clostridium difﬁcile can cause mild diarrhea to fatal colitis. Symbiosis: the relationship between the normal microbes and the host ▯ Commensalism: one of the organisms is helped and the other is unaffected ▯ ▯ ▯ e.g. Corynebacterium organisms on the skin. ▯ Mutualism: both organism beneﬁt e.g. Escherichia coli in the intestinal tract. The host provides a steady food supply for the bacteria. The bacteria produce Vitamins B and K that are absorbed and beneﬁt the host. ▯ Parasitism: one organism is beneﬁted and the other is harmed ▯ ▯ ▯ e.g. disease causing organisms hookworm, Necator americanus, beneﬁts by ingesting the blood of the human host. The host is harmed by blood loss leading to anemia. Vibrio cholera – the bacterial organism beneﬁts by having access to a warm body and grows within the small intestine. The host experiences severe diarrhea and dehydration. Opportunistic pathogens: organisms that do not cause disease in their normal habitat in a healthy person, but may do so in a different environment. e.g. Pseudomonas aeruginosa – widespread in the environment and water habitats. Cannot penetrate unbroken skin. Can cause life threatening infections if it enters the damaged skin of a burn victim. ▯ Pneumocystis pneumonia in AIDS patients Neisseria meningitidis is often found in the throat of normal adults, but it can cause meningitis The Etiology of Infectious Diseases Koch’s Postulates ▯ 1. The same pathogen is present in every case of the disease. ▯ 2. The pathogen must be isolated from the diseased host and grown in pure ▯ culture. ▯ 3. The pathogen from the pure culture must cause the disease when it is ▯ inoculated into a healthy, susceptible lab animal. 4. The pathogen must be isolated from the inoculated animal and must be ▯ shown to be the original organism. Classifying Infectious Diseases ▯ Symptoms: subjective changes a patient experiences, e.g. malaise and pain ▯ Signs: objective changes a physician can observe and measure e.g. fever ▯ Syndrome: a speciﬁc group of symptoms or signs that always accompany a ▯ particular disease Communicable disease: any disease that spreads from one host to another, either directly or indirectly. ▯ e.g. chickenpox, measles, genital herpes, typhoid fever, tuberculosis Contagious disease: disease that is easily spread from one person to another ▯ e.g. chicken pox Noncommunicable disease – any disease that is not spread from one host to another, s u n a t e t . g . ▯ e Occurrence of a Disease ▯ Incidence: the number of people in a population who develop a disease during a ▯ particular time period; indicates how easily the disease is spread ▯ Prevalence: the number of people in a population who develop a disease at a ▯ speciﬁed time, regardless of when it ﬁrst appeared; includes old and new cases Frequency of Occurrence of a Disease ▯ Sporadic disease: disease that occurs occasionally, e.g. typhoid fever in the USA ▯ Endemic disease: disease that is constantly present in a population e.g. ▯ common cold in the USA ▯ Epidemic disease: if a number of people in a given area acquire a certain ▯ disease in a relatively short time period ▯ ▯ e.g. inﬂuenza in January in the USA ▯ Pandemic disease: an epidemic disease that occurs worldwide ▯ ▯ e.g. inﬂuenza in 1918, AIDS now Severity or Duration of a Disease ▯ Acute disease: disease that develops rapidly and lasts a short time ▯ ▯ e.g. inﬂuenza ▯ Chronic disease: disease that develops more slowly, but whose effects may be ▯ continual or recurrent ▯ ▯ e.g. mononucleosis, tuberculosis, hepatitis B ▯ Subacute disease: disease that is intermediate between acute and chronic ▯ ▯ e.g. subacute sclerosing panencephalitis ▯ Latent disease: disease in which the causative agent remains inactive for a time ▯ but then is reactivated to produce symptoms of a disease ▯ ▯ e.g. shingles Herd immunity: the presence of immunity in most of a population ▯ The rate at which a disease spreads and the number of people affected are ▯ determined in part by the herd immunity. Vaccination can provide immunity to ▯ speciﬁc diseases. People who are immune to an infectious disease will not be ▯ carriers. They act as barriers to the spread of the disease. Extent of Host Involvement ▯ Local infection: the invading microbes are limited to a small area of the body, eg. ▯ abscess ▯ Systemic infection: microbes and their products are spread throughout the body ▯ by the blood or lymph. ▯ ▯ e.g. measles ▯ Focal infection: agents of a local infection enter the blood or lymphatic system ▯ and spread to other areas of the body. ▯ ▯ e.g. gingivitis and tooth abscesses may result in infections of the heart ▯ ▯ valves or kidney. ▯ Primary infection: an acute infection that causes the initial illness ▯ Secondary infection: is a disease caused by an opportunistic pathogen after the ▯ primary infection has weakened the body’s defenses ▯ ▯ e.g. Pneumocystis pneumonia in AIDS patients. ▯ Subclinical (inapparent) infection – an infection that does not cause any ▯ noticeable illness. ▯ ▯ e.g. polio, hepatitis A in certain individuals Predisposing Factor: factor or factors that make the body more susceptible to disease, ▯ e.g. gender, climate, age, fatigue, diabetes, malnutrition Incubation period: time between the initial infection and the onset of clinical signs/ symptoms ▯ Prodromal Period: early mild symptoms such as aches and malaise ▯ Period of Illness: clinical signs and symptoms are evident, an immune response ▯ is mounted, the patient will either overcome the pathogen or the patient dies. Period of Decline: signs and symptoms of the disease subside; patient is ▯ vulnerable to secondary infections. Period of Convalescence: person regains strength and returns to pre diseased state. Recovery. Reservoirs of Infection Reservoir: continual source of the disease organism; it may be human, animal or non living Carrier: people who harbor pathogens and transmit them to others without exhibiting any signs of the disease Zoonoses: any disease that is transmissible from animals to man animal reservoirs exist for many zoonoses ▯ e.g. skunks and bats harbor the Rabies virus ▯ Nonliving Reservoirs: two major nonliving reservoirs are soil and water e.g. soil harbors fungi that cause ringworm; Clostridium botulinum the bacterium that causes botulism and Clostridium tetani, the bacterium that causes tetanus. Contaminated water is a reservoir for Vibrio cholerae which causes cholera and Salmonella typhi which causes typhoid fever. ▯ Transmission of Disease: 3 routes of transmission Contact Transmission ▯ Direct contact transmission: person to person transmission ▯ Indirect contact transmission: involves a nonliving object such as towels, ▯ bedding, cups, silverware, toys ▯ Fomite: any nonliving object involved in the spread of an infection ▯ Droplet transmission: microbes spread in droplet nuclei (coughing, laughing, ▯ sneezing, talking) that travel less than 1 meter from the reservoir to the host. Vehicle Transmission: transmission of disease agents by a medium, such as food, water or air ▯ Waterborne: cholera, Shigellosis Foodborne: tapeworms, food poisoning, ▯ ▯ e.g. Bacillus cereus ▯ Airborne: spread of agents of infection by droplet nuclei in dust that travel more ▯ than 1 meter from the reservoir to the host ▯ e.g. fungal spores in the transmission of histoplasmosis Vectors: animals that carry pathogens from one host to another ▯ Mechanical Transmission: passive transport of the pathogen on a vector’s body ▯ part ▯ ▯ e.g. a ﬂy comes into contact with feces containing Shigella organisms, ▯ ▯ then lands on food at a picnic. People ingest the food and become ill with ▯ ▯ bacillary dysentery. ▯ Biological Transmission: active process that involves replication of the pathogen ▯ inside the vector prior to transfer to another host ▯ ▯ e.g. rat ﬂea and plague, mosquitoes and heart worms, mosquitoes and ▯ ▯ malaria NosocomialthHospital Acquired) Infections ▯ 8 leading cause of death in the USA ▯ 1940s and 1950s most nosocomial infections were caused by G+ microbes ▯ including Staphylococcus aureus ▯ 1970s gram-negative bacilli, Escherichia coli and Pseudomonas aeruginosa ▯ 1980s antibiotic resistant gram-positive bacteria, Staphylococcus aureus and ▯ Enterococcus spp. ▯ 1990s 34% of the nosocomial infections are due to Staphylococcus aureus and ▯ Enterococcus spp. ▯ 32% of the nosocomial infections are due to Escherichia coli and Pseudomonas ▯ aeruginosa Most nosocomial infections (40%) are urinary tract infections. 20% of the nosocomial infections are surgical site infections. Microbes in hospitals are often resistant to antibiotics. R factor can result in new a multiple resistance factors being spread. Compromised host: one whose resistance to infection is impaired by disease, therapy, or burns. According to the CDC, handwashing is the single most important means of preventing the spread of infection. In 1997, a CDC report revealed that in one long-term care facility health care workers washed their hands before interacting with patients only 27% of the time. In 1996, researchers identiﬁed hand washing rates as low as 31% in one emergency department.” Emerging Infectious Diseases: diseases that are new or changing, showing an increase in incidence in the recent past, or a potential to increase in the near future. Epidemiology: the science that studies when and where diseases occur and how they are transmitted in populations John Snow/cholera outbreaks in London 1848-1849 John Snow was a physician who anaylyzed death records of cholera patients, gathered information on each, interviewed survivors and mapped the cases. Showed that most of the victims drank or brought water from the Broad Street pump. He concluded this pump was the source of the epidemic. The pump handle was removed, the number of cholera cases dropped. Ignaz Semmelweis, a physician in Vienna, puerperal sepsis and maternal deaths 1846-1848 ▯ puerperal sepsis (childbirth fever) nosocomial infection often caused by Streptococcus pyogenes. Death rate at First Maternity Clinic was 13-18% which was 4X that of the Second Maternity Clinic Women who gave birth at home or elsewhere had a better chance of survival Semmelweis found that the women who gave birth at the First Maternity Clinic were more likely to be examined by medical students (after they were in the autopsy room) Semmelweis ordered all medical students to wash their hands before entering the delivery room, Mortality rate dropped to under 2% Florence Nightingale ▯ recorded statistics on epidemic typhus comparing the incidence of infectious ▯ disease in English civilian and military populations ▯ The information compiled by Nightingale showed that English soldiers in the ▯ Crimean War were more likely to die of contagious diseases (primarily typhus ▯ and cholera) than soldiers in England or civilians. ▯ Contagious diseases, poor food, and unsanitary conditions were killing more ▯ soldiers than mortal wounds on the battleﬁeld. Case Reporting: procedure that requires health care workers to report speciﬁed diseases to local, state and national health ofﬁcials. ▯ e.g. AIDS, measles, polio, gonorrhea, tetanus, typhoid fever, tuberculosis CDC: The Centers for Disease Control and Prevention in Atlanta, GA. This is a branch of the US Public Health Service The source of epidemiological information in the USA Morbidity: the number of people who have a speciﬁc disease Mortality: the number of deaths due to a speciﬁc disease Morbidity rate: the number of people with the disease/ total population exposed to the disease Mortality rate: the number of people who died from a disease/ the number of people who were ill from the disease Chapter 15 Microbial Mechanisms of Pathogenicity Pathogenicity: the ability to cause disease Virulence: the severity of the disease Portals of entry: ▯ Mucous membranes (GI tract, respiratory tract, etc.) ▯ Skin ▯ Parenteral route Penetration or Evasion of Host defenses: ▯ Capsules ▯ Cell wall components ▯ Enzymes ▯ Siderosphores ▯ Antigenic variation ▯ Cytoskeleton Damage to Host Cells (cytopathic effects): ▯ Direct damage ▯ Toxins ▯ Lysogenic conversion Portals of Exit: ▯ Same as portals of entry Adherence ▯ Dental plaque: contains streptococcus mutans, actinomyces and dextran ▯ ▯ Leads to tooth decay ▯ ▯ Uses glycocalyx (dextran) to attach to teeth Bioﬁlms: microbial community that usually forms as a slimy layer on a surface ▯ Resistant to antibiotics and disinfectants ▯ Involved in 70% of all human bacterial infections Capsules: increased virulence, deters phagocytosis ▯ ex: streptococcus pneumoniae Extracellular enzymes ▯ Coagulase: causes clots ▯ ▯ Only pathogenic staphylococcus produce coagulase ▯ Kinases: break down ﬁbrin clots ▯ ▯ ex: ﬁbrinolysin= produced by streptococcus pyogenes ▯ Hyaluronidase: hydrolyzes hyaluronic acid (breaks apart connective tissue); ▯ blackening of the wounds ▯ ▯ ex: Streptococcus, Clostridium, Pseudomonas aeruginosa Antigenic Variation ▯ A host normally produces antibodies to an antigen (usually a protein of the ▯ pathogen). The antibodies are speciﬁc, bind to the antigen and destroy or ▯ inactivate (neutralize) it. Some pathogens alter their surface proteins to evade the antibodies of the host ▯ ▯ ex: inﬂuenza Rheumatic Fever ▯ Cause: immune response to M proteins following streptococcal sore throat ▯ Symptoms: fever and arthritis and Inﬂammation of the heart valves ▯ ▯ Leading cause of heart disease in the young Direct Damage to Host Cells ▯ Pathogens enter the host cell, replicate using the cell nutrients and replicate until ▯ the cell ruptures ▯ The production of Toxins ▯ ▯ Exotoxins (neurotoxin, cytotoxin, enterotoxin) ▯ ▯ Endotoxin Exotoxins ▯ Produced mainly in gram positive bacteria as part of their growth and ▯ metabolism. They are then secreted or released following lysis into the ▯ surrounding medium. ▯ Soluble in body ﬂuids ▯ Highly speciﬁc actions ▯ Genes on plasmids or phages ▯ Inactivated by heat ▯ Antitoxins ▯ ▯ Antibodies produced by a host to protect against a toxin ▯ Toxoids ▯ ▯ Inactivated toxins used as vaccines Action of an AB Exotoxin ▯ Bacterium produces and releases exotoxin ▯ B (binding) component of exotoxin binds to host cell receptor and exotoxin enters ▯ the cell ▯ ▯ B is the binding protein ▯ A (active) component of exotoxin alters cell function by inhibiting protein ▯ synthesis ▯ ▯ A inhibits protein synthesis and kills the host cells ▯ ▯ A is a cytotoxin ▯ ▯ ex: diphtheria toxin Diphtheria ▯ Caused by exotoxin ▯ Leading cause of death in children in the USA prior to 1935 ▯ Corynebacteriuum diphtheriae is a G+ bacillus (no spores) ▯ Found in throats of asymptomatic carriers ▯ Airborne transmission ▯ Thick, grayish membrane in throat can block the trachea ▯ Cytotoxin interferes with protein synthesis (heart and kidney) ▯ First disease for which a toxic cause was i.d. ▯ Signs/symptoms: directly related to exotoxin code of prophage (tox gene) an A-B ▯ toxin ▯ Adults are more likely to have the skin form of diphtheria ▯ Treatment: antitoxin ▯ ▯ Penicillin and erythromycin are antibiotics that kill thebacteria but do not ▯ ▯ inactivate the toxin ▯ Prevention: Vaccine is diptheria toxoid Scarlet Fever (Streptococcus pyogenes) ▯ Exotoxins ▯ Group A: beta-hemolytic streptococci ▯ ▯ Produce streptokinase (lyse clots) ▯ ▯ Produce streptolysins (cytotoxic to tissue cells, RBCs and ▯ ▯ WBCs) ▯ 3 cytotoxins (A,B,C) ▯ ▯ erythrogenic toxin that damage the plasma membranes of blood ▯ ▯ capillaries to produce a red skin rash and high fever ▯ The production of the erythrogenic toxin is due to a prophage ▯ The rash is called scarlet fever and usually is a sequel to strep throat Botulism (Clostridium botulinum) ▯ Exotoxin ▯ Obligate anaerobe ▯ Endospore forming ▯ Gram-positive bacillus found in soil ▯ Botulinum toxin formed under anaerobic conditions is THE MOST POTENT ▯ of all natural toxins. ▯ Neurotoxin that blocks the release of acetylcholine from the synaptic end of the ▯ nerve ▯ Results in progressive FLACCID PARALYSIS ▯ Death from respiratory and cardiac failure ▯ Incubation period 1-2 days ▯ Symptoms: ▯ ▯ Nausea ▯ ▯ Double vision (diplopia) ▯ ▯ Difﬁculty swallowing, weakness ▯ First described in early 1800s ▯ ▯ “sausage disease” ▯ Outbreaks associated with heat to kill competing bacteria but no endospores, ▯ anaerobic conditions and a period of time for toxin production. ▯ Found during: ▯ ▯ Sausage preparation ▯ ▯ Home canning of vegetables ▯ Botulinum is destroyed by boiling▯ ▯ Nitrites added t
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