Microbiology > Final: New material > Flashcards

Final: New material Flashcards

(62 cards)

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1
Q

exotoxins

A
  • produces and secreted by bacterium
  • specific role in pathogenesis
  • may act distant from bacterium
  • our bodies produce antitoxin
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2
Q

endotoxin

A
  • a part of the bacterial cell
  • LPS
  • acts systematically on host
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3
Q

hemolysins

A

red blood cells

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4
Q

leukocidins

A

white blood cells

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5
Q

what creates a channel in the membrane

A

hemolysins and leukocidins

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6
Q

what makes a lot of channels in the membrane

A

S. aureus and S. pyogenes

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7
Q

A-B subunit toxins

A
  • toxins with two subunits
  • toxin produced with subunits together
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8
Q

B subunit

A

binds cell surface

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9
Q

A subunit

A

active component

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10
Q

diphtheria toxin

A
  • classic A-B subunit toxin
  • transcribed, translated as a single gene unit
  • post translational cleavage, reduction to active form performed by host cell
  • B subunit binds to cell surface, endocytosed
  • in acidic compartment, conformational change creates membrane pore, A subunit enters cytoplasm
  • ADP ribosylation of EF-2
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11
Q

Super antigens

A
  • toxins that bind to TCR and MHC activate immune system
  • semi specific activation 3-30%
  • results in massive overstimulation
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12
Q

medically important exotoxins

A
  • botulinum
  • tetanus
  • cholera toxin
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13
Q

endotoxins

A
  • LPS-lipopolysaccharide
  • Lipid A portion is endotoxin
  • released during cell death
  • treatment w/ antibiotics may make this worse
  • septic shock
  • disseminated vascular clotting
  • detect with limulus amoebocyte lysate assay
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14
Q

endotoxin induces…

A

fever and shock
- LPS released when bacteria are lysed in macrophage
- stimulated IL-1, tumor necrosis factor, other cytokines

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15
Q

genetics of pathogenicity

A
  • mobile genetic elements contain toxin genes
  • bacteriophage-lysogenic conversion
  • plasmids
  • transposons
  • pathogenicity islands
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16
Q

plasmids and pathogens

A

toxin genes spread very rapidly
- virulence plasmids can be passed through the population
- tetanus toxin, staph. enterotoxins

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17
Q

lysogenic conversion

A
  • bacteriophage can lyse their host or integrate into chromosome
  • lysogens may carry virulence factor genes
  • cholera toxin
  • SEA
  • diphtheria toxin
  • botulinum toxin
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18
Q

pathogenicity islands

A

genomic elements containing virulence genes
- often id by different G+C content from rest of genome
- present in pathogenic strains, absent from avirulent
- potential horizontal transfer unclear

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19
Q

antimicrobial chemotherapy

A
  • based on exploiting differences between our physiology and invading organisms
  • antibiotic targets are enzymes or structures essential to pathogens success, but different from our essential parts
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20
Q

which microbe is hardest to treat?

A

viruses
- may essential parts to them are essential to us. makes it hard to make vaccine

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21
Q

which microbe is easiest to treat?

A

fungi? bacteria?

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22
Q

sources of antibiotics

A

natural compounds from bacteria (G+ rods), actinomycetes, fungi

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23
Q

example of a microbe that is very difficult to treat and needs specialized drugs

A

mycobacteria

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24
Q

bacteriostatic

A

inhibits growth

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25
bacteriocidal
lyses cells
26
antibiotic resistance
- bacteria can develop resistance through several mechanisms - destruction of the antibiotic (B-lactamase) - mutations in the target site (alterations to ribosome) - efflux pumps (pump antibiotics out of cells
27
beta-lactamases
- broad or narrow spectrum - cleaves beta-lactamase ring - very widespread in medically relevant bacteria
28
target alteration
- mutations in the target site that dont affect function - affect binding of antibiotic - if antibiotic action closely associated with target activity, more difficult
29
multi-drug efflux pump
- MDR bacteria a rapidly growing concern - MDR-TB, MDR-pseudomonas - one major mechanism is efflux pump - can act on broad class of drugs
30
antibiotic resistance
- mutations may arise directly from selection pressure - antibiotics come from natural sources - organisms that make them are resistant to them - organisms may compete by developing resistance - genes for resistance spread by horizontal transfer
31
misuse of antibiotics
- Overprescription (colds, flus) - use of weakened, outdated drugs - failure to finish course - unsupervised use - long term use for sub-clinical infections
32
ramifications
- MRSA, VRE drug resistant nosocomial infections - prophylaxis before surgery now requires harsher, higher doses of antibiotics - gram-negative pathogens are almost always totally resistant B-lactams - newer antibiotics are necessarily more costly, often have more side effects
33
filamentous fungi
growing as multinucleate, branching hyphae, forming a mycelium
34
yeasts fungi
growing as ovoid or spherical single cells multiply by budding and division
35
superficial mycoses fungi
- epidermophyton - microsporum - trichophyton
35
deep mycoses fungi
- aspergillus - candida - blastomyces
36
local fugal infections
- thrush - tinea
37
systemic fungal infections
- cryptococcal meningitis - aspergillosis
38
treatment options
- far fewer drugs - ergosterol (amphotericin B - binds ergosterol) - azoles (interfere with synth)
39
protozoa
- single celled - intracellular and extracellular - systemic infections - immune evasion
40
insect borne protozoa
- leishmania - sand fly - trypanosoma - chagas disease - reduviid bug - African sleeping sickness - tsetse fly - plasmodium - anopheles mosquito
41
ingestion of cysts
- systemic disease (toxoplasma) - GI disease (amoebas, giardia, cryptosporidia)
41
treatment of cysts
- not many drugs options - metronidazole - immune evasion - quinines and related for malaria - resistance
42
helminths
- flatworms (tapeworms) - flukes (schistosomes) - roundworms (filarial worms)
43
routes of infection
- intermediate host (accidental ingestion) - active skin penetration - insect - fecal-oral route
44
schistosomiasis
- affects 300-600 million people worldwide - blood fluke - snail intermediate host - other fluke infections (liver and lung) - few available drugs
45
tapeworms
- adult form (intestinal tract) - larval forms (intermediate host, disseminated tissue, cysts in brain, organs, varies by species)
46
roundworms-nematodes
- very diverse - protective cuticle - plant parasitic - free living bacteriovorus - pathogenic (person to person, arthropod vectors, zoonotic)
47
arthropods vectors of disease
- widespread - many associations - transmit many diseases - plants, animals, humans - control insects-control disease
48
herpesviridae
- often neurotropic - causes various diseases (fever/genital herpes, chicken pox/shingles, infectious mono)
49
chicken pox/shingles
varicella zoster - childhood CP - adulthood shingles - vaccines for both
50
papilloma virus
- HPV causes common warts, genital warts, cervical cancer - very common - HPV 6 and 11 cause genital warts
51
HIV
- human immunodeficiency virus - a retrovirus - RNA genome - incorporates into host cell as cDNA - infects CD4+ T-cells
52
Infection of Host Cells by HIV
HIV surface glycoproteins bind CD4, CXCR4 molecules on T-cell
53
HIV latency andactivation
Provirus integrates into host cell genome, may be activated to produce virus particles
54
influenza
 Influenza kills ~50k per year in the US  Orthomyxovirus  Segmented genome  Surface antigens(spikes) hemagglutinin and neuraminidase  Large shifts in antigenic structure give rise to pandemics
55
antigenic drift and shift
- Drift-point mutations in H,N antigens  Flu virus reassortment leads to shift ---Pandemic strain
56
poxviridae
 smallpox, cow pox viruses  Smallpox ~30% fatality rate  NOT chicken pox (a herpes virus)  Double stranded DNA  Enveloped
57
smallpox (edward jenner)
 Smallpox was a universal disease  80% of Europeans contracted it  30% mortality  Vaccine invented by Jenner 1769  Based on cowpox (Vacca- cow)  Last natural case in 1977
58
The black death
bubonic - fleas on rates septicemic - in the bloodstream, results in septic shock
59
yersinia pestis
forms biofilm to block fleas digestive tract - starving flea will now bite people - c. elegans
60
SIR model of disease
Vaccine allows you to go from Susceptible to Recovered without passing through Infected! When S gets below 1/Ro, that is when the epidemic
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