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Microbiology-Quiz 2

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