Microbiology Exam #3

• Pathology = the study of disease
• Epidemiology = the study of the spread of disease

• Etiology = the study of the cause of disease
• Pathogenisis = the development of disease
• Infection = colonization of the body by pathogens
• Disease = an abnormal state in which the body is not functioning normally

• Normal flora protect the host by:
• Occupying niches that pathogens might occupy
• Producing acids
• Producing bacteriocins

• Commensalism = one organism benefits & the other is unaffected
• Mutualism = both organisms benefit
• Parasitism = one organism benefits at the expense of the other

Live microbes applied to or ingested into the body, intended to exert a beneficial state

• Used to prove the cause of an infection
• Same pathogen must be present in every case of the disease
• Pathogen must be isolated from the disease's host & grown in pure culture
• Pathogen from the pure culture must cause the disease when inoculated into a healthy susceptible lab animal
• Pathogen must be isolated from the inoculated animal & must be shown to be the original pathogen

• Communicable Disease = spread from 1 host to another
• Contagious Disease = easily spread from 1 host to another
• Noncommunicable Disease = not transmitted from 1 host to another
• Endemic = constantly present in a population
• Epidemic = acquired by many in a given area in a short period
• Sporadic = occurs occasionally in a population
• Acute = symptoms develop rapidly
• Chronic = develops slowly
• Subacute = symptoms between acute & chronic
• Latent = disease with a period of symptoms when the causative agent is inactive
• Local Infection = pathogens are limited to a small area of the body
• Systemic Infection = an infection throughout the body
• Primary Infection = acute infection causing initial illness
• Secondary Infection = occurs after host is weakened by primary infection

• Symptom = a change in body function that is felt by a patient
• Sign = a change in a body that can be measured or observed
• Syndrome = a specific group of signs & symptoms that accompany a disease

• Incidence = fraction of a population that contracts the disease during a specific time - # of new cases
• Prevalence = fraction of a population having a specific disease at a given time - total # of cases

• 1.  Incubation Period = no signs or symptoms
• 2.  Prodromal Period = mild signs or symptoms
• 3.  Period of Illness = most severe symptoms
• 4.  Period of Decline = some lingering signs
• 5.  Period of Convalesence = recovery; no signs or symptoms

Period of Illness & Period of Decline = highest # of microbes

• Reservoirs = continual sources of infection; human - AIDS; animal - rabies; nonliving - botulism
• Transmission = contact - direct, indirect, or droplet; vehicle - transmission by an inanimate reservoir
• Vectors = arthropods (fleas, ticks, mosquitos); transmit by mechanical or biological transmission
• Nosocomial = acquired as a result of a hospital stay; due to compromised host; direct contact; fomites (catheters, breathing tubes, syringes)

• Pathogenicity = the ability to cause disease
• Virulence = the extent of pathogenicity

Portal of Entry = specific route by which a pathogen gains access to the body - done through mucous membranes (eye, respiratory tract, GI, urogenital tract), skin (can't penetrate skin but come in through hair follicles & ducts), and parenteral routes (bites, injections, wounds).

Portal of Exit = respiratory tract (coughing & sneezing), GI tract (feces & saliva), genitourinary tract (urine & vaginal secretions), and blood (biting arthropods or syringes).

• LD50 = lethal dose (of a toxin) for 50% of a test population - dependent on type of toxin
• ID50 = infectious dose for 50% of the test population - dependent on portal of entry

• Adhesins/ligands are surface projections that bind to receptors on host cells
• If ligand receptors are altered, then infection can be prevented or increased
• Biofilms provide attachment & resistance to antimicrobial agents

Capsules = prevent phagocytosis

Cell Wall Components = M protein resists phagocytosis, opa protein inhibits T helper cells, & mycolic acid layer resists digestion

Enzymes

Antigenic Variation = alter surface proteins

Penetration Into Host Cell Cytoskeleton = invasins (ruffle membrane & enter) & uses actin to move from one cell to the next

Using Host Nutrients = bacteria need iron to live but very little free iron is found in the body, so siderophores bind very tightly to Fe & remove it from host

Direct Damage = host cells can be damaged or destroyed when pathogens metabolize & multiply inside the host which disrupts host cell function, produces waste products, & produces toxins

Endotoxins = Gram -, located in outermembrane of cell wall, Lipopolysaccharide composition, systemic response (fever, decrease in blood pressure, endotoxic shock), diverse range of effects, 1 type, released during lysis or replication 

Exotoxins = Gram +, located in cytoplasm, generally very potent, specific effects in host, 3 types (A-B, membrane disrupting, & superantigens), produced as part of growth & metabolism

Consist of active component that inhibits cell processes & a binding component that attaches the toxin to the cell

• Released during lysis of bacteria or during replication
• Cause release of immune factors resulting in high fever & shock
• They can allow bacteria to cross the blood-brain barrier by increasing blood vessel leakiness

• Stop mitosis
• Cell fusion
• Cell lysis
• Inclusion bodies
• Antigenic & chromosomal changes

• Fungal waste products may cause symptoms
• Chronic infections provoke an allergic response
• Capsules prevent phagocytosis
• Ergot Toxin
• Aflatoxin
• Proteases

• Waste products may cause symptoms
• Can avoid host defenses by growing in phagocytes
• Antigenic variation

• Use host tissue for growth
• Presence of parasite interferes with host functions
• Parasite's metabolic waste can cause symptoms

Substance produced by a microbe that, in small amounts, inhibits other microbes

Drug that kills harmful microbes without harming host

• Broad = affect a diverse range of microbes
• Narrow = affect only a specific group of microbes (gram +)

Inhibit Cell Wall Synthesis = penicillin - inhibits peptidoglycan synthesis leading to cell lysis; effective against gram + bacteria

Inhibition of Protein Synthesis = Chloramphenicol binds 50s subunits which inhibits peptide bond formation; Aminoglycosides change the shape in the subunit; Tetracyclines bind to 30s subunits interfering with tRNA attachment to mRNA-ribosome complex; Streptogramins bind to 50s subunits & cause release of incomplete polypeptide; Macrolides bind to 50s & block the funnel of ribosomes preventing translation

Plasma Membrane Disruption = Polymyxin B inhibits fatty acid synthesis

Inhibition of Nucleic Acid Synthesis = Rifamycin inhibits RNA synthesis; Quinolones/Fluoroquinolones inhibit DNA gyrase

Competitive Inhibitors = Sulfonamides inhibit folic acid synthesis & affect nucleic acid synthesis

• Natural = produced by penicilium & affective against gram + & spirochetes
• Semi-Synthetic = made in lab, resistant to penicilinases & has a broader range of activity

Damage plasma membranes by inhibiting ergosterol synthesis & increasing membrane permeability allowing disruption

1.  Nucleoside & Nucleotide Analogs

2.  Enzyme Inhibitors = inhibit attachment & uncoating

3.  Interferons = produced by body to prevent viral spread; also have synthetic alpha interferons; Imiquimod is a drug that stimulates interferon production

1.  Disk Diffusion = AKA Kirby-Bauer Test; a drug soaked disc is placed on a lawn of microbes - look for zone of inhibition (MIC - minimal inhibitory concentration)

2.  Broth Dilution = microbe is grown in a broth containing different concentration of the drug - lowest concentration of the drug that still kills is the MBC (minimal bacteriocidal concentration)

• Enzyme destruction of drug
• Prevention of penetration of drug
• Alteration of drug's target site
• Rapid ejection of the drug

Causative Agent = Endotoxin from gram - bacteria

Identifying Characteristics = caused by endotoxin, drop in blood pressure (septic shock)

Causative Agent = Enterococcus, Group B Strep, S. aureus

Identifying Characteristics = nosocomial

Causative Agent = Streptococcus pyogenes

Identifying Characteristics = childbirth fever, handwashing prevents spread, Semmelweiss

Causative Agent = S. aureus mostly

Identifying Characteristics = infection of endocardium, arises from focal infection usually from tooth extraction, rapid destruction of heart valves

Causative Agent = Streptococcal (Group A, hemolytic)

Identifying Characteristics = autoimmune complication displaying as arthritis or heart inflammation, follows strep throat, anti-strep antibodies cross-react with heart tissue or with strep antigens in joints

Causative Agent = Francisella tularensis

Identifying Characteristics = rabbit reservoir, ulcer at entry site, septicemia & pneumonia, possible bioterrorist agent

Causative Agent = Bacillus anthracis

Identifying Characteristics = endospores cause infection, 3 types:  1.  cutaneous (most common) 2.  GI (moderate mortality) 3.  pulmonary (100% mortality), 2 toxins = edema & lethal toxin

Causative Agent = Clostridium perfringens

Identifying Characteristics = soft tissue death due to lack of oxygen, susceptible to anaerobic bacteria, amputation recommended

Causative Agent = Yersinia pestis

Identifying Characteristics = vector is rat flea, rats are reservoir, bubonic has bruises & buboes, pneumonic leads to pneumonia

Causative Agent = Borellia sp.

Identifying Characteristics = spirochete bacteria, transmitted by soft ticks, fever, jaundice, rose colored spots, recurs several times

Causative Agent = Borellia burgdorfer

Identifying Characteristics = tick transmission, bulls eye rash, neurological symptoms

Causative Agent = Rickettsia prowazekii

Identifying Characteristics = human body louse transmits in feces, prevalent in crowded unsanitary living conditions, rash, fever, stupor

Causative Agent = Rickettsia rickettsii

Identifying Characteristics = tick found on spotted deer, rash looks like measles

Causative Agent = EBV

Identifying Characteristics = tumor on jaw, virus latent in immune cells causing tumor in immunosurpressed, mono is transmitted by saliva, causes proliferation of atypical lymphocytes & flue like symptoms

Causative Agent = CMV


Identifying Characteristics = cytomegaly (enlargement of cells), transmitted in body fluids, latent in immune cells, congenital issues if crosses the placenta

Causative Agent = Yellow Fever Virus

Identifying Characteristics = fever, chills, headache, jaundice, no tx but vaccine available, transmitted by mosquito

Causative Agent = Dengue Fever Virus

Identifying Characteristics = mosquito, fever, muscle joint pain, rash, can lead to shock

Causative Agent = Ebola, Marburg, Lassa Fever; Hantavirus Viruses

Identifying Characteristics = Ebola, Lassa:  filoviruses, disrupts clotting system causing massive internal bleeding & bleeding out, Hantaviurs:  inhalation of dried rodent feces (pulmonary syndrome)

Causative Agent = Trypanosoma cruzi

Identifying Characteristics = vector is kissing bug, intracellular parasite with undulating membrane, passed in feces when rubbed into bite site or eyes, acute fever then can result in mega colon due to damage in nerves controlling peristalsis

Causative Agent = Toxoplasma gondii

Identifying Characteristics = sexual stage is in cats, humans get infected by meat or infected feces, cyst stage can occur in brain leading to damage & vision problems, immunocomprimised - AIDS, pregnancy

Causative Agent = Plasmodium sp.

Identifying Characteristics = chills, fever, headache at 2 - 3 day intervals, transmitted by mosquito, infect RBCs, control in nets

Causative Agent = Leishmania sp.

Identifying Characteristics = transmitted by sandflies, reproduce in liver, spleen, & kidneys, cutaneous with sore at bite site or visceral with organ enlargement & flue-like symptoms

Causative Agent = Schistosoma sp.

Identifying Characteristics = blood fluke, adults live in veins of liver & bladder, coat with host proteins to avoid detection, lead to heptosplenomegaly

Causative Agent = Cercaria of Schistomes

Identifying Characteristics = free living stage of fluke, penetrate skin of humans & can cause allergic reaction in skin

Causative Agent = Group A Streptococci (Streptococcus pyogenes)

Identifying Characteristics = inflammation of mucous membranes, fever, sometimes tonsillitis & ear infections

Causative Agent = Erythrogenic-producing S. pyogenes (toxin production results from phage lysogeny)

Identifying Characteristics = symptoms include a spotted strawberry appearance of tongue & a pinkish red rash due to toxin, tongue can swell & lose upper membrane

Causative Agent = Exotoxin-producing Corynebacterium diptheria (toxin results from phage lysogeny)

Identifying Characteristics = exotoxin produces a membrane of fibrin & dead cells in the throat & can block air passage, exotoxin inhibits protein synthesis & can cause heart, kidney, or nerve damage, vaccine = DTaP

Causative Agent = S. penumonia, S. pyogenes, Staph aureus, Hemophilus influenza, & others

Identifying Characteristics = earache - complication of nose & throat infections, pus accumulation causes pressure on ear drums

Causative Agent = Bordetella pertussis

Identifying Characteristics = whooping sound occurs from gasping for air between cough, bacteria destroy ciliated cells in respiratory tract causing slowing of mucociliary escalator & accumulation of mucus in lungs, can be sever in children with violent coughing fits

Causative Agent = Mycobacterium tuberculosis

Identifying Characteristics = acid fast bacteria, form lesions called tubercles with dead macrophages & bacteria, TB skin test can indicate past exposure or active case of TB, main symptom is coughing which can be blood-stained as tissues are damaged

Causative Agent = Streptococcus pneumonia

Identifying Characteristics = encapsulated strains are virulent, symptoms include difficulty breathing, high fever, & chest pain with rust-colored sputum

Causative Agent = Legionella pneumophila

Identifying Characteristics = high fever, cough, & pneumonia-like symptoms, not transmitted between people, bacteria found in water & disseminated in air from air-conditioning cooling towers

Causative Agent = 200 different viruses (rhinovirus accounts for 50% of all colds)

Identifying Characteristics = sneezing, nasal secretions, & congestion

Causative Agent = Number of different viruses but Respiratory syncytial virus common in children

Identifying Characteristics = RSV causes fusion of cells (syncytium) when grown in culture

Causative Agent = Influenzavirus

Identifying Characteristics = viral strains identified by antigenic differences in hemaggluttinin & neuroamindase spikes as well as protein coats - antigenic shift which makes immunity very hard to develop & vaccines of limited use, minor annual variation in virus makeup called antigenic drift

Causative Agent = Histoplasma capsulatum

Identifying Characteristics = subclinical respiratory infection acquired by inhaling condidia which have accumulated in bird & bat droppings

Causative Agent = Pneumocystis jirovecii

Identifying Characteristics = primary indicator of AIDS, affects immunosuppressed patients, P. jirovecii has charachteristis of both a protozoan & fungus

Causative Agent = Streptococcus mutans

Identifying Characteristics = bacteria adhere to teeth using sticky sugars forming plaques, produce acid that destroys enamel

Causative Agent = Staphylococcus aureus

Identifying Characteristics = caused by enterotoxin produced in improperly stored foods that are contaminated with bacteria

Causative Agent = Shigella bacteria

Identifying Characteristics = ulceration of intestines & blood & mucous in stool, abdominal cramps & fever

Causative Agent = Salmonella enteric

Identifying Characteristics = nausea, pain, diarrhea occurs after eating large numbers of salmonella, can prevent by proper cooking of food

Causative Agent = Salmonella typhi

Identifying Characteristics = transmitted in feces, fever & malaise over 2 week period, bacteria can be harbored in gall bladder of carriers

Causative Agent = Vibrio cholerae

Identifying Characteristics = exotoxin alters membrane permeability of intestine resulting in vomiting & diarrhea

Causative Agent = Escherichia coli

Identifying Characteristics = "traveler's diarrhea," Shiga toxin producing strains of E. coli cause inflammation & bleeding of colon, can also affect kidneys

Causative Agent = Helicobacter pylori

Identifying Characteristics = bacteria produces ammonia which neutralizes stomach acid allowing bacteria to colonize, lead to peptic ulcer disease

Causative Agent = Clostridium difficile

Identifying Characteristics = occurs following antibiotic therapy leading to diarrhea & colitis, usually acquired in hospitals & nursing homes

Causative Agent = Mumps virus

Identifying Characteristics = virus enters respiratory tract, causes inflammation of partid glands & pain during swallowing, testes can also become inflamed (orchitis)

Causative Agent = Hepatitis A virus

Identifying Characteristics = transmitted in food & water, virus grows in intestine, liver, kidney, spleen, & blood, most cases are subclinical

Causative Agent = Hepatitis B virus

Identifying Characteristics = frequently serious, can be transmitted in blood & other body secretions, infection can be chronic & lead to liver damage & failure

Causative Agent = Hepatitis C virus

Identifying Characteristics = transmitted in blood, disease is usually mild but can become chronic & cause liver damage, kills more people than AIDS

Causative Agent = Rotaviurs or Noravirus

Identifying Characteristics = causes vomiting & diarrhea, very low infective dose for viruses

Causative Agent = Claviceps purpruea

Identifying Characteristics = caused by mycotoxin from contaminated grains, causes gangrene & hallucinations

Causative Agent = Aspergillus flavus

Identifying Characteristics = caused by aflatoxin, found in peanuts, problem for livestock & linked to liver cirrhosis & cancer in humans in India & Africa

Causative Agent = Giardia lamblia

Identifying Characteristics = causes nausea, abdominal cramping that persists for weeks, transmitted in contaminated water

Causative Agent = Cryptosporidium hominis

Identifying Characteristics = diarrhea in immunosuppressed, transmitted in water

Causative Agent = Entamoeba hystolyica

Identifying Characteristics = amoeba feeds on RBCs & GI tract tissues, results in abscesses

Causative Agent = Taenia solium (pork) & Taenia saginatus (beef)

Identifying Characteristics = transmitted in undercooked meat containing cysticerci, adult lives in intestine & sheds eggs in feces

Causative Agent = Enterobius vermicularis

Identifying Characteristics = anal itching due to female laying eggs, diagnosis made by finding eggs on scotch tape

Causative Agent = Necator americanus, Ancyclostoma duodenale

Identifying Characteristics = hookworm attaches to intestine & feeds off blood & tissue, causes pica (craving for peculiar foods with clay)

Causative Agent = Ascaris lumbricoides

Identifying Characteristics = worms migrate throughout body & can exit through nose, navel, mouth, or anus, transmitted by ingestion of eggs

Causative Agent = Trichinella spiralis

Identifying Characteristics = larva encyst in muscle tissues of humans & animals, contracted by eating undercooked meat containing larva or chewing fingernails after handling raw infected meat, symptoms can include swelling around eyes, fever, & upset GI tract

Competitive exclusion

Etiologic agent

Syndrome

Vehicle transmission

Iron

Cytopathic effects

30S subunit & interfere with tRNA attachment

• A broader range of activity
• Resistance to penicillinase

Synthesis of nucleic acids

Enzymes

Gram +

Plasma membranes

• Uncoating
• Entry into the host cell