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Microbiology-Quiz 2
| Question | Answer |
|---|---|
| What is the difference between disinfection and antisepsis? | antisepsis is the application of chemical agents to the human body while disinfection is the use of a germicide to destroy infectivity of an inanimate object. |
| What are the three main physical agents for killing bacteria? | 1) heat 2) filtration 3) radiation |
| Is wet or dry heat more effective for killing? | wet (disrupt H bonds) |
| What kills all bacteria including spores? | autoclave |
| What is typically sterilized by filtration? | drugs, vaccines. |
| How does ethylene oxide sterilize heat sensitive materials? | alkylating agent. |
| How does ethyl alcohol sterilize? What is ideal concentration? | denature proteins, ideal at 60 to 70% concentration. |
| How do cationic detergents sterilize? | disrupt cell membranes. (esp. quaternary ammonium salts). Anions don't work as well as they are repelled by negative charge of bacterial surface. Won't work on pseudomonas or tubercl baccilli. |
| How does hydrogen peroxide sterilize? | Good for anaerobes since they don't have catalase. (note Staph are catalase positive so won't work against them). |
| How do phenols sterilize? | denature proteins. |
| How do heavy metals sterilize? | bind to SH groups in proteins. |
| Name 3 ways that Salmonella is different from other gram negative enterics. | 1) Will not ferment lactose, only glucose. 2) Makes H2S in presence of iron. 3) has a flagella--is motile. (also urease (proteus is positive) and indole negative-e.coli is positive) |
| What are the 3 main Salmonella species? | 1) Salmonella typhi-typhoid fever. 2) Salmonella choleraesuis-bacteremia 3) Salmonella enteritidis-diarrhea |
| Who gets salmonella typhi? | Only humans. Mostly in developing countries. |
| How does salmonella adhere/what kind of toxins does it have? | Adheres via adhesins. Has pathogenicity islands from phage. Also has type 3 secretion system-needle that inserts toins into host cell. Toxin causes membrane ruffling/actin polymerization/endocytosis of the bacteria. |
| What is the most common antigen of Salmonella typhi? | Vi antigen (also use O and H antigens-2 phases) |
| Describe 3 phases of Salmonella pathogenesis | Week 1) invade peyer's patches. Can get bacteria in stool. Week 2)-bacteremic. Can get bacteria in blood Week 3) Late GI phase-bleed/diarrhea. Again bacteria in stool. |
| Where is bacteria in people who carry Salmonella typhi? | gallbladder |
| What antibiotics are good for Salmonella? | Those that can enter macrophages-fluoroquinolones or cephalosporins. (note there are also vaccines). |
| What is the source of salmonella choleraesuis? | swine! get from ingested contaminated food. Short incubation. High fever/bacteremia/microabscess. |
| What is a sign of salmonella enteritidis? | Diarrhea. (mostly associated with raw/undercooked eggs). See in developed and undeveloped places. Many Serotypes. |
| Does Shigella ferment lactose? Have a flagella? Make gas? | No. |
| What is the most common kind of Shigella in the developing world? In the US? | Developing world: Shigella dysenteriae US: Shigella sonnei, followed by flexneri |
| Is there an animal resevoir in Shigella? | No. (also none in Salmonella typhi). |
| What are the 4 F's that mediate spread of Shigella? | Food, Fingers, Feces, Flies. |
| Why does Shigella have such a low inoculum? | acid tolerant--can survive in the stomach even in low doses (vs. salmonella--need high). |
| Name 2 virulence factors for Shigella. | -T3SS injection needle-promote uptake. -Shiga toxin-intestinal ucleration caused by. |
| What is the role of Shiga toxin? | 2 subunits. Interfere with 60S rRNA/protein synthesis. kill absorptive epithelial cells and lead to blocked fluid absorption. |
| Is Shigella invasive? | Yes-intestinal cells--important part of pathogenesis, and escape into macrophages via T3SS system. (but penetration beyond the submucosa is rare--rare bacteremia) |
| Is there a vaccine for Shigella? | none effective. Disease it causes is called Bacillary Dysentary. |
| 4 characteristics of the Enterobacteriaceae family | 1) facultative anaerobes 2) fermentation of glucose 3) oxidase negative 4) reduction of nitrates to nitrites. |
| Where does S. typhi multiply? | inside mononuclear cells (macrophages)--facultative intracellular bacteria! |
| What is a common complication of S. choleraesuis in children with sickle cell anemia? | osteomyelitis |
| What is the most common form of salmonella infection? | enteritis. (most common species is salmonella typhimurium) |
| Is ecoli an intracellular or extracellular organism? | extracellular |
| What kind of virulence factors (4) can hemmorhagic e.coli make and what does it lead to? | 1) Shiga-like toxin, cause HUD (hemolytic uremic synd)-acute renal failure. Disrupts protein synth. 2)hemolysin-pores. 3) pili-mediated attach adhesins. 4) T3SS-encoded on pathogenicity island LEE-encodes for Tir and Intiman, recruit actin)A/E lesi |
| Which e.coli is the leading cause of childhood diarrhea in developing countries? | EPEC |
| Which e.coli is responsible for traveler's diarrhea? | ETEC (makes heat labile and heat stable toxins). Behave like cholera toxin and target adenylate cyclase-incrase cAMP. (loss of fluid/watery diarrhea). |
| What is unique about e.coli's fermentation? | can ferment lactose (unlike Shigella or Salmonella). |
| What are the 7 key opportunistic gram negative infections? | 1) e.coli 2) kelbsiella 3) Serratia marcescens 4) Enterobacter cloacae 5) Proteus mirabilis 6) Pseudomonas aeruginosa 7) Acinetobacter baumanii |
| What is the most common cause of Gram negative infections? | E.coli. (can cause GI infections, UTI, bacteremia, meningitis). |
| What is the most common cause of non-hospital acquired UTI? | E.coli (different pili can allow attachment to different structures--eg. P pili associated with pylonephritis) |
| What is the leading cause of noscomial bacteremia? | E.coli. (K1 capsule)-polysiacilic acid capsule. See same capsule in neonate meningitis. |
| What is the main virulence factor of Klebsiella? | Capsule (see clinical syndromes-pneumonia, UTI, wound infection, bacteremia, meningitis, diarrhea) |
| What conditions (4) are enterobacter cloacae associated with? | 1) burns 2) wounds 3) respiratory 4) UTI |
| What color is associated with Serratia marcesens? | Red (from prodigiosins). Associated with respiratory/UTI. Swarming motility. |
| What 2 features contribute to proteus pathogenicity? | 1) Flagella-swarming motility 2) urease synthesis. |
| What color is associated with pseudomonas? | blue/green-from pyocyanin pigment. (obligate aerobe in labs "non-fermenter"). Common in lung disease (esp. CF-biofilms/slime capsule). |
| name 4 toxins made by pseudomonas | 1) endotoxin 2) exotoxin elastase 3) exotoxin phospholipase 4) T3SS |
| Name top 2 non-fermenting gram negative bacilli. | 1) pseudomonas aeruginosa 2) acinetobacter baumanii |
| Reservoir for cholera? | Water (associated with shellfish/seafood infections) |
| 2 virulence factors for cholera | 1) toxin coregulated pilus (TCP)-microcolony formation. 2) cholera toxin. ADP-Ribose toxin. Activate cAMP. Increased Cl secretion with water, decreased Cl/H20 absorption. |
| What does h.pylori make to allow it to live in acidic stomach environment? | urease. (can do carbon urea breath test to look for). |
| Source of campylobacter species? | zoonotic disease--from animals to people (esp. poultry). 1/2 of raw chicken in US grocery stores contains campylobacter! Sporadic, not endemic. |
| What is the most common cause of diarrhea in the world? | Campylobacter |
| Two examples of low innoculum diseases? | 1) Shigella 2) Campylobacter (one drop raw chicken juice!) |
| What bacteria accounts for 1/2 of all gastric cancers? | H. pylori |
| Major virulence factor for Haemophilus? | capsule (also basis of vaccine) Type b is most dangerous. |
| Name two pathogenic mechanisms for haemophilus | 1) IgA protease 2) ciliary stasis via LPS decoration with host choline. *note if complement in host doesn't work, more susceptible to disease. |
| What bacteria is associated with otitis media? | Haemophilus. (also S. pneumoniae) |
| Hib requires what 2 growth factors? | Factors X (hemin) and V (NAD) Staph secretes NAD and can get satellite Hib colonies. |
| 2 stages of B. pertussis infection? | 1) catarrhal stage-low grade fever, cold symptoms. 2) paroxysmal-coughing/vomiting. |
| 5 virulence factors of B. pertussis? (lead to lymphocytosis) | 1) Pertussis toxin: ADP ribosylating toxin. Increase CAMP (via stimulation of inhibitory G protein). 2) Adenylate cyclase toxin (calmodulin stimulated). 3) Dermonecrotic toxin. -vascular smooth muscle contraction. 4) trachael cytotoxin 5) pili. |
| Where is legionella found in nature? | water-esp. in cooling towers. (infection airborne) |
| What does legionella do to macrophages? | induce apoptosis |
| What disease is a pseudomembrane associated with? | Cornybacterium diptheriae (gram positive rods) |
| Do Legionella/Corneybecterium diptheriae produce systemic infections? | no (in diptheria do get systemic symptoms from exotoxin). |
| What is the role of diptheria toxin? | blocks eucaryotic protein synthesis by inactivating elongation factor 2. (same as pseudomonas) |
| What three vaccines take advantage of toxoids? | diptheria, pertussis, tetanus |
| What is the treatment for diptheria? | horse anti-toxin. |
| What bacteria causes atypical pneumonia? | mycoplasma (also Coxiella, Chlamydia, and Legionella as well as viral)--can't be treated with penicillin (no cell wall) and has spotty infection instead of lobular. |
| Name 3 obligate intracellular bacteria | 1) Rickettsia 2) Chlamydia-can't make ATP. 3) mycobacterium leprae |
| Two stages in the developmental cycle of Chlamydia | 1) elementary bodies-small, non-multiplying, rigid wall, transmission form. 2) Initial bodies-large, multiplying, non-infectious. |
| 3 species of chlamydia imp. in pathogenesis-name them | 1) chlamydia psittachi-psittacosis-birds, interstitial pneumonia. 2) pneumoniae-adult pneumonia. 3) trachomatis-conjunctivits, infant pneumonia, urethritis (D-K serotypes)-venereal disease. (trachoma)-A,B,C or LVD-STD. |
| What disease is an exception to the rule that Rickettsia diseases are parasites of arthropods | Q fever-inhale placental tissue of sheep. |
| What arthropod causes primary epidemic typhus (rickettsia prowazekii) | body louse (recrudescent disease-Bill-Zinsser) |
| What arthropod causes endemic murine typhus (Rickettsia typhi) | flea-milder then epidemic typhus. |
| What arthropod causes Rocky Mountain spotted fever (rickettsia rickettsii)? | tick. Rash on hands/feet spreads to trunk. |
| What arthropod causes Rickettsial pox? | mite. (often see in large apartment houses)-city. |
| What causes Q fever? | Coxiella burnetti (has "spore-like stage") Interstitial pneumonia. |
| What arthorpod causes ehrlichoioses? | tick |
| What sugar(s) does neisseria gonnorhea ferment? | glucose only |
| what sugar(s) does neiseria meningitids ferment? | glucose and maltose. (note non-pathogens also ferment lactose). |
| What two bacteria secrete a protease that splits IgA | Neisseria and Hib. |
| What are the top two cuases of neonate meningitis? | Group B strep or E. coli K1. (note that neisseria has predilection for children below 5 but maternal antibodies protect for neisseria) |
| What is waterhouse-friedrichson syndrome? | can be rarely caused by meningitis-adrenal failure. |
Created by:
act99
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