Microbiology Chapter 14 Test Questions – Flashcards
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| Symbiosis |
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| "to live together" |
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| Mutualism |
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| Type of symbiosis - 2 species living together with both benefiting. +/+ |
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| Commensalism |
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| Type of symbiosis - 2 species live together w/ 1 benefiting & the other not affected. +/0 |
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| Parasitism |
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| Type of symbiosis - 2 species live together w/ 1 benefiting and the other harmed. +/- |
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| Relationship between evolutionary development & severity of effects of pathogen> |
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| less harm to host>more developed the parasite |
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| Normal Flora |
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| don't cause disease. 2 types:resident - part of normal flora for life; Transient - temporary (usually eliminated by competition of normal flora or by host's immune system. |
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| When is normal flora acquired? |
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| During birth and shortly after from food, air, handling, etc. |
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| NF become OP - Immune Suppression |
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| Weakened immune system makes us susceptible to normal flora becoming opportunistic. |
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| What can weaken the immune system? |
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| Already sick, stress, diet, hormonal changes. |
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| NF become OP - Changes in Normal Flora |
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| Normal flora exclude pathogens, but changes open up body areas for pathogens. (antibiotics) |
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| NF become OP - Introduction of NF into unusual body site |
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| Ex: E. coli in urinary tract. How? Possible poor hygiene |
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| Exposure - Contamination |
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| Presence of microbes in/on body |
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| Exposure - Infection |
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| Microbes overcome external body defenses, multiply, and establish themselves in body |
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| Portals of Entry - Skin |
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| through breaks. though hookworms can borrow through skin. |
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| Portals of Entry - Mucous Membranes |
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| Respiratory, GI, Urinary and Reproductive Tracts, plus conjunctiva. Some pathogens, fungi, & viruses enter this way. |
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| Portals of Entry - Placenta |
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| in 2% of pregnancies pathogens cross placenta. (TORCH test: Toxoplasmosis, Other, Rubella, CMV, Herpes) syphilis, HIV. |
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| Portal of Entry - Parenteral |
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| deposition of pathogens directly onto tissues below skin or mucous membranes - HOW - cuts, shots, medical procedures. |
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| Adhesins |
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| bacterial ligands - found on fimbriae, flagella, glycocalyces |
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| Attachment Proteins |
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| Viral Ligands |
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| Adhesion Factors |
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| Surface lipoproteins and/or glycoproteins (ligands) that aid binding to cell receptors. *avirlulent forms often lack adhesion factors. |
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| Disease (morbidity) occurs when... |
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| infection damages host enough to interfere with normal body functions. |
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| Symptoms |
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| subjective characteristics (how does patient feel?) |
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| Signs |
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| Objective characteristics (fever, rash, swelling, vomiting, etc.) |
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| Syndrome |
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| Group of symptoms and signs that characterize a particular disease. |
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| Some infections are asymptomatic or subclinical (no symptoms), even though signs may be detected in lab tests |
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| Etiology |
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| Cause of disease |
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| Koch |
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| proposed postulates to determine which pathogen causes a disease. (also developed media and stain techniques) |
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| Koch's Postulates |
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| *suspected pathogen must be found in EVERY case of disease. *That pathogen must be isolated and cultured. *The pathogen must cause disease when introduced into healthy host. *Same pathogen must be isolated from diseased host. |
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| Exceptions to Koch's Postulates |
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| *some pathogens can't be cultured in lab. *some diseases caused by multiple pathogen(s) and environmental/genetic cofacters. *can't ethically apply them to human-only diseases. |
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| Virulence Factors of Infectious Agents |
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| Pathogenicity - Ability of microbe to cause disease. Virulence - Degree of pathogenicity (relative ability to infect host and cause disease) |
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| Hyaluronidase & collagenase |
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| Virulence Factor - Extracellular enzyme - allow invasion of deeper tissues. |
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| Coagulase |
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| allows microbes to hide from immune system in clots |
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| Kinases |
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| digest clots and allow invasion of damaged tissues. |
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| Quorum Sensing |
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| bacteria use chemicals to communicate. |
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| Exotoxins |
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| Virulence Factor - Toxin harm tissues or trigger damaging host immune response. Secreted by microbes. Include CYTOTOXINS, NEUROTOXINS, & ENTEROTOXINS (digestive tract). |
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| Endotoxins |
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| Virulence Factor - Toxin harm tissues or trigger damaging host immune responses. Lipid A from G- cell walls. Released when cells die, divide, or digested by phagocytes. Causes fever, inflammation, diarrhea, shock, hemorrhaging, blood coagulation. |
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| Antiphagocytic factors |
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| Virulence factor - prevent phagocytosis & destruction of microbe. |
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| Capsule |
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| Virulence Factor - often made of substances normally found in body so ignored by hosts immune system. |
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| Antiphagocytic Chemicals |
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| Virulence Factor - May prevent fusion of lysosomes w/ phagocytic vesicles. Some bacteria release leukocidins - kill white blood cells. |
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| 5 stages of infectious disease |
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| 1. incubation 2. prodromal 3. illness 4. Decline 5. Convalescence Contagious in ALL 5! |
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| 1. Incubation |
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| time between infection and first symptom signs - variable |
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| 2. prodromal |
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| short time w/ vague, mild symptoms - not always present |
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| 3. Illness |
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| most severe stage. signs/symptoms most severe here - treatment here |
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| 4. decline |
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| body returns to normal, having fought off the disease. immune response peaks here. |
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| 5. convalescence |
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| patient recovers, body repaired - variable period |
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| Portals of Exit |
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| Same as portals of entry. Most common tho are secretions/excretions. |
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| Sources of Infectious Disease |
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| 1. Animal reservoirs 2. Human carriers 3. Nonliving reservoirs |
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| Animal Reservoirs |
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| Passed from animals to humans. 150 identified. (rabies, yellow fever - mosquitoes) Transmitted thru bites, direct contact or their wastes, and eating them. (mad cow) |
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| Human Carriers |
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| Asymptomatic humans are especially important here as carriers. Most famous - Mary Malone Typhoid Fever, new york cook, in gall bladder, wouldn't remove. |
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| Nonliving Reservoirs |
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| Soil, water and food. |
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| Modes of Infectious disease transmission - Contact |
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| Direct Contact, Indirect contact, droplet transmission |
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| Direct (Contact) Transmission |
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| Touching, kissing, intercourse. (STD's, zoonoses, staph. most virulent - Rabies, tularemia) |
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| Indirect (Contact) Transmission |
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| Most often spread through fomites such as needles, toothbrushes, toys, money, cups, sheets, medical equipment. Inanimate objects. |
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| Droplet Transmission (contact) |
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| via droplet nuclei released through exhaling , coughing, sneezing (<1m travel). |
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| Modes of infectious disease transmission - Vehicle transmission |
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| airborne, waterborne, foodborne, bodily fluid. |
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| Airborne (Vehicle) Transmission |
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| Aerosol (>1m travel). fungal spores, strap, TB, etc. |
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| Waterborne (Vehicle) Transmission |
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| many GI diseases, fecal-oral cycle. (Polio, typhoid, etc) |
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| Foodborne (Vehicle) Transmission |
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| Poorly processed or undercooked, or poor refrigeration. (Campylobacter, listeria, TB, toxoplasmosis, etc.) |
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| Bodily Fluid (Vehicle) Transmission |
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| AIDS, hepatitis, herpes |
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| Vector Transmission |
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| Biological - lives/multiples within vector & transmitted through biting. (ticks, lice, fleas, mosquitoes). Mechanical - carried on body parts. (flies, cockroaches - not needed for arthropods life cycle) |
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| Classification of Infectious Diseases |
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| Longevity and severity of a disease. (14.2) |
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| Incidence |
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| # new cases/pop./time period |
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| Prevalence |
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| new + existing cases/pop./Time period |
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| Endemic |
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| Disease normally found at a stable frequency in population |
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| Sporadic |
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| Only a few cases occur in an area or pop. |
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| Epidemic |
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| Greater than normal frequency. just more than expected |
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| Pandemic |
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| When epidemic occurs on more than one continent (AIDS, H1N1) |
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| CDCP |
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| where you notify diseases. Report numbers in MMWR each week. |
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| Descriptive Epidemiology |
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| basic data collection about a disease. Age, gender, occupation, health history, socioeconomic status, location/time. |
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| Index Case |
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| 1st case impt because could indicate the source, possible spread, and reservoir. |
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| John Snow |
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| Father of Epidemiology - Cholera epidemic. Found source of outbreak, traced it to a pump which he turned off. |
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| Analytical Epidemiology |
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| Analyzes descriptive data to determine cause, mode of transmission, and possible prevention of disease. Retrospective, includes comparisons of infected to non-infected. |
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| Experimental Epidemiology |
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| Tests a hypothesis about the cause of a disease. Koch's postulates? |
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| Hospital Epidemiology - Nosocomial infections |
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| acquired in health-care facilities. CDC estimates rate at 10% |
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| Types of Nosocomial Infections |
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| Exogenous - Due to pathogens from health care environment. Endogenous- from normal flora that become pathogenic due to factors in health care settings. Iatrogenic - Due to fomites used in medical procedures. |
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| Factors Influencing Nosocomial Infections |
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| Interaction of numerous pathogens, weakened immune systems, transmissionn among patients/staff/visitors. |
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| Control of Nosocomial Infections |
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| Disinfection. Medical asepsis (housekeeping, handwashing, bathing, sanitation). Surgical Asepsis & sterile procedures. Isolation of very contagious/susceptible patients. Establishment of nosocomial infection control committee |
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| CDC Universal Precautions of Nosocomial infections |
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| Use of sharps containers - no resheathing of sharps. Use of protective barriers to protect from bodily fluids. Immediate/thorough hand washing after bodily fluid exposure |
