Bacteriology Flashcards

1
Q

What stain used for Legionella?

A

Silver stain

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2
Q

How is Treponema visualized?

A

dark-field microscopy and fluorescent antibody staining

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3
Q

Intracellular bugs that are hard to stain?

A

Rickettsia, Chlamydia

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4
Q

How is Mycobacteria stained?

A

Acid-Fast stain due to high lipid conent; mycolic acids in cell wall detected by carbofuchsin

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5
Q

What is missing from mycoplasma?

A

cell wall

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6
Q

What bugs use a Giemsa stain?

A

Certain Bugs Really Try my Patience

Chlamydia, Borrelia, Rickettsia, Trypanosomes, Plasmodium

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7
Q

What does PAS (period-acid schiff) stain?

A

stains glycogen, mucopolysaccharides

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8
Q

What is PAS used to diagnose?

A

Whipple disease - Tropheryma whipplei

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9
Q

What is India Ink used to stain?

A

Crypotcoccus neoformans (mucicarmine can also be used to stain thick polysaccharide capsule red)

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10
Q

What is Silver stain use for?

A

Legionella, Fungi (pneumocystis), helicobacter pylori

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11
Q

what bacterial structure protects against phagocytosis?

A

capsule (organized, discrete polysaccharide layer, except in Bacillus anthracia, contains D-glutamate)

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12
Q

what helps with binding to foreign surfaces?

A

glycocalyx (loose network of polysaccharides)

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13
Q

What composes the outer membrane?

A

endotoxin - Lipopolysaccharide (LPS); major suface antigen

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14
Q

where are beta-lactamases contained?

A

in the periplasmic space between cytoplasmic membrane and outer membrane

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15
Q

in what bugs is periplasmic space present?

A

gram-negative bacteria

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16
Q

What agar do use for H. flu?

A

chocolate agar

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17
Q

what agar do use for Neisseria species?

A

Thayer-Martin

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18
Q

what agar for B. pertussis?

A

Bordet-Gengou agar OR Regan-Lowe medium

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19
Q

what agar for C. diphtheriae?

A

Tellurite agar, Loffler medium

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20
Q

what agar for M. tuberculosis?

A

Lowenstein-Jensen agar

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21
Q

what agar for Mycoplasma pneumonia?

A

Eaton agar

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22
Q

what agar for Lactose-fermenting enterics?

A

MacConkey agar (colonies turn pink because of fermented acid)

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23
Q

what agar for E. coli?

A

Eosin-methylene blue (EMB) agar (colonies with green metallic sheen)

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24
Q

what agar for Legionella?

A

charcoal yeast extract agar buffered with cysteine and iron

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25
Q

what agar for fungi?

A

Sabouraud agar

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26
Q

Examples of Anaerobes and properties?

A

Fusobacterium, Clostridium, Bacteroides, Actinomyces

lack catalase and/or superoxide dismutase and susceptible to oxidative damage
FOUL SMELLING

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27
Q

What antibiotic does NOT work against anaerobes?

A

Aminoglycosides (require O2 to get into bacteria)

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28
Q

What are the obligate intracellular bugs?

A

Rickettsia, Chalmydia, Coxiella

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29
Q

What are the facultative intracellular bugs?

A

Some Nasty Bugs May Live FacultativeLY

Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia pestis
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30
Q

what are encapsulated bacteria?

A

SHiNE SKiS

Strep pneumo
H. flu
Neisseria meningitidis
E. coli
Salmonella
Klebsiella
group b Strep
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31
Q

what of encapsulated bacteria have vaccines?

A

strep pneumo, H. flu, N. meningitidis

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32
Q

how are encapsulated bacteria cleared?

A

opsonized and then cleared by the spleen

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33
Q

what are urease + bugs?

A

CHuck norris hates PUNKSS

Cryptococcus
H. pylori
Proteus
Ureaplasma
Nocardia
Klebsiella
S. epidermidis
S. saprophyticus
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34
Q

what are catalase + bugs?

A

CATs Need PLACESS to hide

CAT = catalase +
Nocardia
Pseudomonas
Listeria
Aspergillus
Candida
E. coli
Staphylococci
Seratia
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35
Q

What pigment does Actinomyces produce?

A

yellow sulfur granules

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36
Q

what pigment does S. aureus produce?

A

yellow pigment (aureus = gold)

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37
Q

what pigment does Pseudomonas produce?

A

blue-green pigment

38
Q

what pigment does Serratia marcescens produce?

A

red pigment (maraschino cherry)

39
Q

what bug expresses protein A and what is function?

A

staph aureus and to prevent opsonization and phagocytosis

40
Q

what bugs express IgA protease?

A

SHiN

strep pneumo
H. flu
Neisseria

to help colonize mucosa

41
Q

What bug expresses M protein and what is purpose?

A

group A strep

prevent phagocytosis (molecular mimicry)
possible mech associated with rheumatic fever and autoimmune response
42
Q

what exotoxin does C. diphtheriae produce?

A

diphtheria toxin

43
Q

what does diphtheria toxin do?

A

inactivates elongation factor (EF-2)

44
Q

How does diphtheria manifest?

A
pharyngitis with pseudomembranes in throat
severe lymphadenopathy (bull neck)
45
Q

what exotoxin does Pseudomonas aeruginosa produce?

A

exotoxin A

46
Q

what does exotoxin A do?

A

inactivates elongation factor (EF-2)

47
Q

what does exotoxin A cause?

A

host cell death

48
Q

what two exotoxins inhibit elongation factor (EF-2)?

A
diphtheria toxin (C. diphtheriae)
exotoxin A (P. aeruginosa)
49
Q

what exotosin does Shigella produce?

A

Shiga toxin

50
Q

what does shiga toxin do?

A

inactivates the 60S ribosome by removing adenine from rRNA

51
Q

how does Shigella present?

A

Gi mucosal damage –> dysentery

ST also enhances cytokine release, causing hemolytic-uremic syndrome (HUS)

52
Q

what bugs can cause HUS?

A

Shigella, EHEC serotype O157:H7

53
Q

what exotoxin does enterohemorrhagic E. coli produce?

A

Shiga-like toxin (SLT)

54
Q

how does Shiga-like toxin work?

A

inhibits the 60S ribosome by removing adenine from rRNA

55
Q

how does enterohemorrhagic E. coli present?

A

SLT enhances cytokine release, causing HUS (protypically in EHEC serotype O157:H7

EHEC does NOT invade host cells

56
Q

what exotoxin does Entertoxogenic E. coli produce?

A

heat-labile toxin (LT) or heat-stabile toxin (ST)

57
Q

how does heat-labile toxin work?

how does heat-stable toxin work?

A

LT - overactivates adenylate cyclase (increase cAMP) –> increased Cl- secretion in gut and water efflux

ST - overactivates guanylyl cyclase (increase cGMP) –> decreased reabsorption of NaCl and water in gut

58
Q

How does ETEC present?

A

watery diarrhea

59
Q

What exotoxin does B. anthracis produce?

A

Edema toxin

60
Q

How does edema toxin work?

A

mimics the adenylate cyclase enzyme (increase cAMP)

61
Q

How does Bacillus anthracis present?

A

characteristic edematous borders of black eschars in cutaneous anthrax

62
Q

What exotoxin does vibrio cholerae produce?

A

cholera toxin

63
Q

how does cholera toxin work?

A

overactivates adenylate cyclase (increase cAMP) which permanently activates Gs –> increased Cl- secretion in gut and H2O efflux

64
Q

how does cholera present?

A

voluminous “rice-water” diarrhea

65
Q

what exotoxin does Bordetella pertussis produce?

A

Pertussis toxin

66
Q

how does pertussis toxin work?

A

overactivates adenylate cycle (increase cAMP) by disabling Gi, impairing phagocytosis to permit survival of microbe

67
Q

how does pertussis present?

A

WHOOPING COUGH

- cough on expiration and whoop on inspiration

68
Q

What exotoxin does Clostridium tetani produce?

What exotoxin does Clostridium botulinum produce?

A

Tetanospasmin toxin

Botulinum toxin

69
Q

How does tetanospasmin and botulinum work?

A

proteases that cleave SNARE (which are normally required for NT release)

70
Q

How does tetanus present?

A

spasticity
risus sardonicus
“lockjaw”

Toxin prevents release of inhibitory (GABA and glycine) NTs from Renshaw cells in spinal cord

71
Q

How does botulism present?

A

Flaccid paralysis, floppy baby

toxin prevents release of stimulatory (ACh) signals at neuromuscular junction –> flaccid paralysis

72
Q

What exotoxin does Clostridium perfringens produce?

A

Alpha toxin

73
Q

How does alpha toxin work?

A

phospholipase (lecithinase) that degrades tissue and cell membranes

74
Q

how does C. perfringens present?

A

degradation of phospholipids –> myonecrosis (“gas gangrene”) and hemolysis (“double zone”) on blood agar

75
Q

what toxin does strep pyogenes produce?

A

streptolysin O

exotoxin A

76
Q

how does streptolysin O work?

how does exotoxin A work?

A

protein that degrades cell membrane

binds to MCH II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-gamma, and TNF-alpha –> shock

77
Q

How does S. pyogenes present?

A

lyses RBCS; contributes to beta-hemolysis

host antibodies against streptolysin used to diagnose rheumatic fever

with exotoxin A –> toxic shock syndrome: fever, rash, shock

78
Q

What exotoxin does Staph aureus produce?

A

Toxic shock syndrome toxin (TSST-1)

79
Q

how does TSST-1 work?

A

binds to MCH II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-gamma, and TNF-alpha –> shock

80
Q

what endotoxin is the most toxic?

A

LPS found on gram-negative bacteria

81
Q

what does LPS endotoxin cause systemically?

A

ENDOTOXIN

Edema
Nitric oxide
DIC/Death
Outer membrane
Tnf-alpha
O-antigen
Xtremely heat stable
Il-1
Neutrophil chemotaxis
82
Q

How to determine between Staphylococci using Novobiocin

A

Saprophyticus is resistant

Epidermidis is sensitive

83
Q

How to determine between Streptococci using Optochin

A

Viridans is resistant

pneumonia is sensitive

84
Q

How to determine between Streptococci using Bacitracin

A

group B strep are resistant

group A strep are sensitive

85
Q

alpha-hemolytic bacteria

A

green ring around colonies on blood agar

S. pneumo or viridans strep

86
Q

What are S. pneumo staining findings?

A

Gram +
Catalase -
Alpha-hemolytic
Optochin sensitive

87
Q

What are Viridans Strep staining findings?

A

Gram +
Catalse -
Alpha-hemolytic
Optochin resistant

88
Q

Beta-hemolytic bacteria

A

clear area of hemolysis

S. aureus, Listeria

S. pyogenes, S. agalactiae
- differentiate these two via bacitracin

89
Q

what are S. aureus staining findings?

A

Gram +
Catalase +
Coagulase +
Beta-hemolytic

90
Q

What are S. pyogenes staining findings?

A

Gram +
Catalase -
beta-hemolytic
Bacitracin sensitive

91
Q

What are S. agalactiae staining findings?

A

Gram +
Catalase -
beta-hemolytic
Bacitracin resistant

92
Q

Listeria presentation?

A

tumbling motility
meningitis in newborns
unpasteurized milk