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MCM Test 3 > B2.052 The Microbial World > Flashcards

B2.052 The Microbial World Flashcards

1
Q

what are Koch’s postulates?

A
  1. the organism is regularly found in the lesion of the disease
  2. the organism can be isolated in pure culture on artificial media
  3. inoculation of this pure culture produces a similar disease in experimental animals
  4. organisms can be recovered from the lesions in the animals
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2
Q

what did threat of ID decline in the 1900s?

A 
sanitation and hygiene
chlorination of water
antibiotics
vaccination
animal and pest control
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3
Q

why can diseases re-emerge?

A

evolution of microorganisms
intensive misuse of antibiotics (selection for the proliferation of resistant organisms)
increased globalization
decline in public health in some regions
increase in people with decreased immune function

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4
Q

what are the classes of infectious agents?

A 
priors (infectious proteins)
viruses (acellular)
bacteria (prok)
fungi (euk)
parasites (euk)
-protozoans (unicellular)
-helminths (multicellular)
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5
Q

rank microorganisms by size

A

viruses

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6
Q

what is the requirement in bacteria to be classified as the same species?

A

> 97% identity in 16s rRNA
high degree of DNA sequence identity
more arbitrary than eukaryotes

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7
Q

bacillus

A

oval

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8
Q

coccus

A

circle

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9
Q

diplococcus
streptococcus
staphylococcus

A

2 cocci
chain of cocci
collection of cocci

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10
Q

funky shaped bacteria

A

coccobacillus: halfway between coccus and bacillus
curved rod
club shaped
spirochete

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11
Q

what is unique about the spirochete shape?

A

very thin

predestined to penetrate tissues

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12
Q

what is a spore?

A

formed under stress conditions
can survive in suboptimal circumstances better than the bacteria themselves
allow colonies to survive

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13
Q

what is the function of a capsule?

A

antiphagocytic

more chronic infection

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14
Q

gram positive

A

thick peptidoglycan cell wall

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15
Q

gram negative

A

thin PG layer with a second membrane

lipopolysaccharides acyl chain linkages with second membrane

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16
Q

spirochetes

A

have lipoproteins expressed on membrane
thing PG layer
flagella in between membranes

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17
Q

acid-fast

A 
cant be stained by gram staining
waxy surface 
-mycolic acids
-porins
-arabinogalactan
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18
Q

commensal

A

microorganism in symbiotic relationship with host

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19
Q

virulence

A

degree of pathogenicity

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20
Q

etiology

A

cause of disease

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21
Q

epidemiology

A 
factors of disease spread
sporadic- small isolated cases
endemic- continually prevailing in a region
epidemic- outbreak
pandemic- worldwide outbreak
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22
Q

stages of infection disease

A

incubation period
prodrome
specific illness (localized or systemic)
convalescence

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23
Q

what is prodrome

A

nonspecific symptoms

24
Q

what is convalescense

A

after resolution of symptoms to complete recover there can be complications

  • chronic carriers
  • latent infections
  • permanent tissue damage
25
how do you measure virulence
ID50 | LD50
26
microbiome of skin
gram+
27
microbiome of respiratory tract
nares- staphylococci
28
microbiome of GI
anaerobes
29
microbiome of GU
anterior urethra- lactobacilli | vagina- lactobacilli, others
30
what parts of the body are generally sterile
upper GU | lower respiratory tract
31
what is an example of a beneficial intestinal bacteria
E.coli producing vitamin K and B
32
what are types of gut flora restoration therapy and when are they necessary?
fecal transplants probiotics need in C.difficile treatment
33
what are 5 common transmission patterns
``` oral/aerosol fecal-oral venereal vector-borne (Lyme disease) zoonotic ```
34
what are portals of entry for a pathogen
``` skin, soft tissue (trauma) skin, bloodstream (bite) respiratory (inhalation) GI (ingestion) GU (sexual transmission) transplacental ```
35
what are primary pathogens?
if present, they have a high probability of causing disease | immunizations common
36
what are opportunistic pathogens?
some commensals | cause disease under certain conditions only
37
what are nonpathogens?
rarely cause disease
38
what are the stages of bacterial pathogenesis
``` transmission adhesion colonization spread damages to host (direct or indirect by immune response) evasion of immunity transmission ```
39
what are virulence factors?
help bacteria to invade the host, cause disease, and evade host defense some are targeted by vaccines or detected by specific diagnostic tests
40
what are some virulence factor examples?
``` motility adhesins invasins exotoxins endotoxin (LPS) degradative enzymes capsules siderophores resistance to antibiotics ```
41
what are adhesins?
surface virulence factors that confer ability to adhere to host surfaces
42
what are examples of adhesins
``` pilli -type 1: adhere to mannose receptors -p pilli: adhere to Gal-Gal receptors protein adhesins biofilms: bacterial polysaccharides allow bacteria to stick to each other and attach to a surface ```
43
what are the 2 types of intracellular bacterial growth?
obligative- always require host cell | facultative- can also grow extracellularly
44
what are some mechanisms of systemic disease?
destruction of tissue barrier by tissue damaging enzymes | penetration of cell membrane
45
what are the 3 mechanisms of invasion of intracellular pathogens?
passive uptake: bacteria opsonized by complement are taken up by phagocytic cells active invasion: invasins on bacterial cell surface induce uptake by non-phagocytes transcytosis: intracellular motility by actin polymerization
46
what are exotoxins?
bacteria mediated pathogenesis
47
what are endotoxins?
host mediated pathogenesis released when cells dies LPS, gram negative and nonspecific immunity
48
what makes up the syringe complex in "syringe" secretion systems?
T3SS
49
what are examples of exotoxins?
enzymes (act on ECM, collagenase) A-B type toxins (2 subunits) membrane damaging toxins (phospholipases, pore forming toxins) superantigens
50
depict A-B toxins
B portion binds to cell surface receptor | A portion is enzymatically active and is transported into cell interior
51
give examples of A-B toxins
1. ADP ribosylating toxins - diphtheria toxin inactivated elongation factor - cholera/pertussis toxins activate adenylate cyclase (increase cAMP) 2. others - shiga EHEC cleaves rRNA - tetanus blocks release of neurotransmitter
52
describe host mediated pathogenesis
inflammation is mediated by microbial products (LPS, cell wall, some toxins), antibody and complement, and cell-mediated immunity enhances microbial killing at the expense of the host tissue autoimmunity in some chronic diseases
53
what are superantigens?
lock antigen presenting cell and lymphocytes together | results in continuous stimulation of the immune system
54
what is the mechanism of the endotoxin LPS?
released by cell lysis (not secreted) toxic due to lipid A component causes septic shock binds to LPS binding proteins and interacts w host receptor CD14
55
what are 3 ways pathogens evade host immune responses?
defense (capsules, serum resistance due to LPS modifications) offensive (toxins degrade immune components, killing of phagocytes) stealth (antigenic variation)
56
how do bacteria obtain iron for growth?
siderophores
57
where are virulence factors encoded?
chromosome: stable pathogenicity island: region of DNA plasmid: extrachromosomal smaller DNA replicon, can be transferred, dispensable for growth bacteriophage: bacterial viruses, can transfer DNA between bacteria transposons: highly mobile DNA element

MCM Test 3 (23 decks)

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