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Microbiology-Test 4
Chapter 21,22.4,23,25,26
| Question | Answer |
|---|---|
| A symbiosis in which both partners require the other for survival is known as | mutualism |
| Mutualism | both partners benefit from specific association |
| Amensalism/ commensalism | one partner benefits the other is unaffected |
| Parasitism | one partner harmed by specific association |
| Buchnera | obligate endosymbionts, provide host with essential nutrients, rely on host |
| Buchnera provide | tryptophan |
| How do cells differentiate between self and non-self? | Toll- like receptors |
| toll- like receptors are located | on the surface of host defense cells |
| cytokines | regulate inflammation and immunity |
| chemokines | promote migration and differentiation of lymphocytes |
| chemokines and cytokines are produced | at the onset of and throughout the infection by immune cells |
| second line of defense | phagocytosis |
| phagocytosis | the engulfing and ingestion of bacteria, fungi, virus-infected cells or other foreign bodies by phagocytes |
| first line of defense | barriers |
| physical barrier | skin, mucous membranes |
| chemical barrier | lysozyme in epidermal secretion glands, tears, persperation |
| epidermis as physical line of defense | no access to blood so only localized infection occurs |
| dermis as physical line of defense | access to blood vessels so infection here can become systemic |
| burn injuries may lead to | systemic infections |
| acute inflammation | response to tissue damage |
| chronic inflammation | response of long duration provoked by the persistent presence of a causative stimulus |
| pneumonia | bacterial, viral or fungal infection can cause inflammation of the lung with fluid filled alveoli, often secondary infection following influenza virus |
| specific defenses | 3rd line, lymphocytes, antibodies |
| third line of defense | adaptive response |
| adaptive response | the body's ability to recognize and defend itself against distinct invaders and their products |
| If nonspecific immune system has "warriors" then | specific immunity has more sophisticated "special agents" |
| adaptive response is activated in response to | antigens: substances or molecules that trigger an immune response against them |
| 2 types of specific immunity | naturally acquired (antigens encountered in daily life) and artificially acquired (vaccine) |
| B cells | antigen presenting cells that mature in the bone marrow then concentrate in lymph nodes and spleen |
| t cells | mature in the thymus (cell mediated immunity) |
| exogenous antigen | promotes the maturation of B cells into antibody secreting cells and activation of cytotoxic t cells and macrophages |
| endogenous antigen | migrates out of lymph node to target and kill any cell bearing same peptide/ MHC complex |
| the humoral (b cell) response | carried out by B lymphocytes, involves the production of the antibody, activation of b cells requires help from T cells |
| memory cells | these are the cells that increase in number with vaccination |
| antibodies are usually measured to determine the | protective titer |
| neutralization | antibody prevents bacterial adherence |
| opsonization | antibody promotes phagocytosis |
| complement activation | antibody activates complement, which enhances opsonization and lyses some bacteria |
| What does a vaccine titer test usually measure? | antibodies |
| What is more of a true test of immunity/protection? | memory B cells |
| herd immunity | protection due to high level of immunity in a population |
| the innate immune response deals with | infection first, must hold off infection until the adaptive response begins, helps regulate the adaptive response via chemokines and cytokines |
| innate response cells present | antigens to the adaptive response |
| the end result of innate and adaptive immune responses | the control and elimination of infections and protection from re-infection |
| 3 things pathogens have to do to make a person sick | attach to the cells, entry, evade any immune response |
| How do pathogens recognize the host? | detect magnesium concentration, ph, quorum sensing, 2 component signal trandsduction |
| Virulence factors allow pathogen to | invade host, capture nutrients, survive |
| examples of virulence factors a pathogen might have | attachment proteins, capsules, pili, hemolysin, toxins |
| Bacteria must adhere to | host tissue; could be by pili or surface proteins binding host cells |
| type 1 pili adhere to | mannose, grows from outer membrane |
| type IV pili | grow from inner membrane |
| exotoxins are | excreted from cell |
| endotoxins | integral part of the pathogen, LPS of gram negative bacteria |
| Toxins are | fast acting, highly toxic even in small doses, many can survive cooking even after pathogen has died |
| Pathogens excrete exotoxins that subvert host function (3 categories) | membrane disruption, inhibits translation, inhibits cell messaging |
| virulence genes are often transferred as | a block from other organisms |
| ways to tell if virulence genes have been transferred | flanked by phage or plasmid genes, GC content different from rest of genome, codons |
| Factors to consider when diagnosing a patient | symptoms, patient histories, testing of specimens |
| In what domains are pathogens found? | bacteria and eukarya |
| Clostridium toxins | botulin toxin, tetanus toxin |
| botulin toxin | botox, anaerobe, spores survive pasteurization, prevents muscle movement |
| tetanus toxin | anaerobe, grows in puncture wounds, muscles contract uncontrollably, lethal spasms |
| Meningitis | infection of membrane surrounding brain, cross blood-brain barrier |
| 2 bacterias that can cross blood-brain barrier | streptococcus pneumoniae and neisseria meningitidis |
| Meningococcus | neisseria menigitidis, obligate commensal, can cause meningitis, has type IV pili for attachment, impairs leukocyte movement |
| Meningitis infection | dangerous in bloodstream, crosses from capillary into cerebrospinal fluid, type IV pili to invade host cells |
| Clostridium botulinum has what virulence factor | toxin that blocks the excitory neurotransmitter molecules |
| Clostridium tetani has what virulence factor | toxin that blocks the inhibitory neurotransmitter molecules |
| Neisseria menigitidis has what virulence factor | type IV pili that extend/contract |
| Most common type of food poisoning | norwalk virus |
| norwalk virus | common in close quarters, can re-infect, 24-48 hrs, his to-blood group antigen-binding virulence factors |
| most common cause of bacteria gastroenteritis | campylobacter jejuni |
| Shiga toxin blocks | protein synthesis, capillary damage, loss of blood |
| Cholera Toxin does what | block g-protein, over activation of adenylate cyclase, cAMP is over-produced, cAMP activates ion transport, water follows |
| Salmonella is | endocytosed |
| Some organisms use hemolysin to | break out of the phagosome |
| How does sebum protect the body? | inhibit bacterial growth by lowering pH |
| What is the pH of the stomach | 5-6 |
| What is a probiotic? | thought to restore balance to the microbial community and return the host to good health (living microbes) |
| Why don't tons of microbes grow on our skin? | because difficult environment to grow in considering surface dryness, an acidic pH, high salinity and presence of degradative enzymes |
| What are Bacteroides doing in your gut? | sits in colon mucosal layer (non motile), 10-90% of colon and stool, eats polysaccharides |
| What are Firmicutes doing in your gut? | involved in fermentation of sugars |
| Why are butyrate enemas sometimes used? | reduces inflammation, stimulates cell proliferation, stimulate mucosal repair |
| What happens to bactericides that are starved of fiber, polysaccharides or carbohydrates? | could cause colon cancer |
| What types of white blood cells are there and where do they originate? | produced in bone marrow, PMN leukocytes, monocytes, macrophages, dendritic cells, mast cells |
| 5 signs of inflammation | redness, warmth, pain, swelling, altered function of affected site |
| Which cells produce antibodies? | white blood cells |
| What form of motility do Listeria and Shigella cells use in host cells? | polymerize actin filaments |
| What is the mucociliary elevator? | consists of ciliated mucous lining of the trachea, bronchi and bronchioles. Constantly sweeps foreign particles up and out of the lung |
| What is bordatella and what are the associated virulence factors? | whooping cough, inhibits mucocilliary elevator by binding to lung cilia |
| What are 3 causes of Clostridium difficile infection? | people carry it normally, antibiotics can cause it to over grow, hospital environments |
| Vibrio Cholerae (cholera) is caused by | fecally contaminated food or water |
| Cholera symptoms | rice- water stool (watery, colorless, stool flecked with mucus), lasting 2-3 days, lose up to 1L of water an hour, gram negative |
| Shigella is caused by | fecally contaminated hands, fecally contaminated food, person- person spread |
| Shigella symptoms | purulent bloody- stools, crampy rectal pain, fever, vomiting 2-3 days, gram negative |
| Travelers diarrhea (e.coli) is caused by | fecally contaminated food or water |
| Travelers diarrhea symptoms | nausea, vomiting and diarrheal symptoms lasting 1-3 days, non-bloody, gram negative |
| E. coli 0157:H7 is caused by | fecally contaminated milk, fruit juice, or ground beef |
| E. Coli 0157:H7 symptoms | bloody diarrhea, fatal hemorrhagic colitis, kidney failure, gram negative |
| Clostridium difficile symptoms | numerous, watery, foul- smelling stools, sporulate, gram positive |
| Salmonella is caused by | consumption of fecally contaminated meat or eggs, unpasteurized or contaminated milk, close contact with infected reptiles or humans |
| Salmonella symptoms | non bloody diarrhea, nausea, vomiting, fever, pain lasting 1-2 weeks, rash of tiny rose spots on skin, gram negative |
| Typhoid fever (salmonella typhi) is caused by | contaminated water |
| Typhoid fever symptoms | high fever, muscle and stomach pain, malaise, loss of appetite, rose colored spots, gram negative |
| Norwalk virus is caused by | contaminated food, close quarters |
| Norwalk virus symptoms | vomiting, stomach pain, nausea, diarrhea, low grade fever, usually resolves in 24-48 hours, 8 hours of vomiting, happens fast |
| Staphylococcus aureus (food poisoning) is caused by | contaminated food, can be inhaled |
| Staphylococcus aureus symptoms | vomiting, diarrhea, nausea, resolves in 24-48 hours, gram positive |
| Listeria monocytogenes (listeriosis) is caused by | contaminated fruits, vegetables, packaged food, unpasteurized cheeses, hot dogs |
| Listeriosis symptoms | mild, flu like symptoms, can lead to miscarriage or still birth, stiff neck, confusion, convulsions, gram positive |
| Camphylobacter jejuni is caused by | contaminated chicken, cross contamination of chicken with other foods |
| Camphylobacter jejuni symptoms | diarrhea, cramping, fever, more than 10 bowel movements a day lasting 2-5 days (could be bloody), gram negative |
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