Final: New material Flashcards
1
Q
exotoxins
A
- produces and secreted by bacterium
- specific role in pathogenesis
- may act distant from bacterium
- our bodies produce antitoxin
2
Q
endotoxin
A
- a part of the bacterial cell
- LPS
- acts systematically on host
3
Q
hemolysins
A
red blood cells
4
Q
leukocidins
A
white blood cells
5
Q
what creates a channel in the membrane
A
hemolysins and leukocidins
6
Q
what makes a lot of channels in the membrane
A
S. aureus and S. pyogenes
7
Q
A-B subunit toxins
A
- toxins with two subunits
- toxin produced with subunits together
8
Q
B subunit
A
binds cell surface
9
Q
A subunit
A
active component
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
11
Q
Super antigens
A
- toxins that bind to TCR and MHC activate immune system
- semi specific activation 3-30%
- results in massive overstimulation
12
Q
medically important exotoxins
A
- botulinum
- tetanus
- cholera toxin
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
14
Q
endotoxin induces…
A
fever and shock
- LPS released when bacteria are lysed in macrophage
- stimulated IL-1, tumor necrosis factor, other cytokines
15
Q
genetics of pathogenicity
A
- mobile genetic elements contain toxin genes
- bacteriophage-lysogenic conversion
- plasmids
- transposons
- pathogenicity islands
16
Q
plasmids and pathogens
A
toxin genes spread very rapidly
- virulence plasmids can be passed through the population
- tetanus toxin, staph. enterotoxins
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
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
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
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
21
Q
which microbe is easiest to treat?
A
fungi? bacteria?
22
Q
sources of antibiotics
A
natural compounds from bacteria (G+ rods), actinomycetes, fungi
23
Q
example of a microbe that is very difficult to treat and needs specialized drugs
A
mycobacteria
24
Q
bacteriostatic
A
inhibits growth
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
