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ID > Taxonomy, Structure, Virulence Factors, and Toxins > Flashcards

Taxonomy, Structure, Virulence Factors, and Toxins Flashcards

1
Q

What are the components of the bacterial cell envelope?

A

Inner cell membrane
Cell wall (peptidoglycan layer)
Outer cell membrane
Cell capsule

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2
Q

What color are gram + organisms? What color are gram - organisms?

A

Gram + stain blue

Gram - stain red

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3
Q

What enzyme is responsible for formation of the peptidoglycan cell wall? What class of drugs inhibit this enzyme?

A

Transpeptidase (penicillin binding protein)

Penicillins

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4
Q

What are key antigenic determinants for gram + / gram - bacteria?

A

Gram + : Lipoteichoic acid

Gram - : O-antigen

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5
Q

What is the major component of the outer cell membrane of gram - bacteria?

A

LPS

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6
Q

What component of LPS is an endotoxin?

A

Lipid A

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7
Q

What are the 5 major shapes of bacteria?

A 
Cocci
Rods
Branching filamentous
Pleomorphic
Spiral forms
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8
Q

Classically, there are 7 gram + bugs that cause disease. Which of these are rods and which are cocci?

A

4 rods- Bacillus, Clostridium, Corynebacterium, Listeria

3 cocci- Streptococcus, Enterococcus, Staphylococcous

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9
Q

Of the gram - organisms there are only 2 genera that are cocci; moreover, both are diplococci. What are these two genera?

A

Neisseria

Moraxella

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10
Q

What bacterial genus does not have a cell wall and only has a cell membrane?

A

Mycoplasma

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11
Q

What bacterial genus is acid fast?

A

Mycobacterium

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12
Q

Bacteria have 70s ribosomes. What are the ribosomal subunits? What drug class targets each subunit?

A

30s- Tetracyclines, Aminoglycosides

50s- Macrolides, Chloramphenicol, Clindamycin, Linezolid

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13
Q

What 2 genera of bacteria form endospores?

A

Bacillus

Clostridium

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14
Q

Define exotoxin.

A

Toxin secreted by bacteria

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15
Q

Define a bacterial neurotoxin.

A

Exotoxin that acts on nerves or motor end plates

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16
Q

Define enterotoxin.

A

Exotoxin that acts on GI tract to cause diarrhea.

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17
Q

Contrast infectious diarrhea and food poisoning.

A

Infectious diarrhea: bacteria colonize GI tract and release enterotoxin
Food poisoning: bacteria grow in food and release enterotoxin in the food

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18
Q

List the bacteria that produce exotoxins that increased intracellular levels of cAMP.

A

Cholera (Vibrio cholera; Cholera toxin)- Permanent activation of Gs
Anthrax (Bacillus anthracis; Edema toxin)- Mimics AC
Montezuma’s revenge (ETEC; Heat labile toxin)- Permanent activation of Gs
Pertussis (Bordatella pertussis; Pertussis toxin)- Disables Gi

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19
Q

What is glycocalyx?

A

Loose network of polysaccharides that mediates adherence to surfaces.

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20
Q

What gram negative rods are enteric bacteria?

A 
Bacteroides
Campylobacter
E. coli
Enterobacter
Helicobacter
Klebsiella
Proteus
Pseudomonas
Salmonella
Serratia
Shigella
Vibrio
Yersinia
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21
Q

What gram negative rods cause respiratory illness?

A

Bordetella
Haemophilus
Legionella

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22
Q

What gram negative rods are zoonotic?

A

Bartonella
Brucella
Francisella
Pasteurella

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23
Q

What gram + bacteria are branching filamentous?

A

Actinomyces

Nocardia

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24
Q

What gram negative bacteria are spirochetes?

A

Borrelia
Leptospira
Treponema

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25
Q

What organisms stain with Giemsa?

A 
Chlamydia
Rickettsia
Borrelia
Trypanosomes
Plasmodium
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26
Q

PAS (periodic acid-Schiff) stains glycogen. What disease is it used to diagnose?

A

Whipple disease- T. whipplei

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27
Q

What organisms is silver stain used for?

A

Fungi
Leginoella
Helicobacter pylori

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28
Q

What cytokines are induced by lipoteichoic acid?

A

TNF
IL-1
IL-6

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29
Q

What is the location of gram negative β-lactamase?

A

Periplasmic space

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30
Q

What media is used to isolate H. influenzae?

A

Chocolate agar

31
Q

What media is used to isolate Neisseria?

A

Thayer-Martin agar

32
Q

What media is used to isolate C. diptheriae?

A

Tellurite agar

33
Q

What agar is used to isolate M. tuberculosis?

A

Lowenstein-Jensen agar

34
Q

What media is used to isolate M. pneumoniae?

A

Eaton agar

35
Q

Lactose-fermenting enterics can be isolated using what agar?

A

MacConkey

36
Q

What media is used to isolate E. coli?

A

Eosin-methylene blue (EMB) agar

37
Q

What media is used to isolate fungi?

A

Sabouraud agar

38
Q

TNF-α inhibitors can cause reactivation of what bacterial pathogen?

A

M. tuberculosis

39
Q

Are aminoglyosides effective against anerobes?

A

No- require oxygen to enter the bacterial cell

40
Q

What agar is used to isolate B. pertussis?

A

Bordet-Gengou agar

41
Q

What bugs are obligate intracellular pathogens?

A

Chlamydia
Coxiella
Rickettsia

42
Q

What bacteria are facultative intracellular pathogens?

A 
Salmonella
Neisseria
Brucella
Mycobacetrium
Listeria
Francisella
Legionella
Yersinia
43
Q

The capsule of bacteria is a virulence factor that inhibits phagocytosis. How are these organisms cleared from the body?

A

Opsonized, then cleared by the spleen

44
Q

What vaccines are given to asplenic individuals?

A

S. pneumoniae
H. influenzae
N. meningitidis

45
Q

In addition to S. pneumoniae, H. influenzae, and N. meningitidis, what other bugs have capsules?

A

E. coli
Klebsiella
Salmonella
Group B Strep (S. pyogenes)

46
Q

A polysaccharide antigen alone cannot be presented to T cells; however, there are vaccines that can be given to prevent infection by encapsulated organisms. How do these vaccines work?

A

Polysaccharide + protein conjugate

47
Q

What organisms produce urease?

A 
Cryptococcus
H. pylori
Proteus
Ureplasma
Nocardia
Klebsiella
S. epidermidis
S. saprophyticus
48
Q

Individuals with chronic granulomatous disease are susceptible to infections with what type of organism?

A

Catalase positive organisms

49
Q

What organisms produce pigment?

A

Actinomyces israelii- yellow sulfur granules
S. aureus- yellow pigment
Pseudomonas aeruginosa- blue-green pigment
Serratia marcescens- red pigment

50
Q

Detail the mechanism of action of the virulence factor Protein A. What bacteria expresses this virulence factor?

A

Binds Fc region of IgG- prevents opsonization and phagocytosis
Expressed by S. aureus

51
Q

Detail the mechanism of action of the virulence factor IgA protease. What bacteria expresses this virulence factor?

A

Enzyme that cleaves IgA- facilitates colonization of respiratory mucosa
S. pneumoniae
Neisseria
H. influensa

52
Q

Detail the mechanism of action of the virulence factor M protein. What bacteria expresses this virulence factor?

A

Inhibits phagocytosis

S. pyogenes

53
Q

What is the type 3 secretion system?

A

Injectisome- protein appendage that facilitates delivery of toxins into host cells

54
Q

What bacteria produce exotoxins that inhibit protein synthesis?

A

Corynebacterium- diptheria toxin
Pseudomonas- Exotoxin A
Shigella- Shiga toxin
E. coli (EHEC)- Shiga like toxin

55
Q

Diptheria toxin and Exotoxin A have the same mechanism of action. What is this mechanism?

A

Inactivate elongation factor (EF-2)

56
Q

Shiga toxin and Shiga-like toxin have the same mechanism of action. What is this mechanism?

A

Inactivates 60s ribosome- removes adenine from rRNA

57
Q

What bacteria produce exotoxins that increase fluid secretion?

A

E. coli (ETEC)- Heat labile toxin and heat stable toxin
Bacillus anthracis- Edema toxin
V. cholerae- Cholera toxin

58
Q

What is the mechanism of action of heat labile toxin? What is the mechanism of action of heat stable toxin?

A

Heat labile toxin- increases cAMP which leads to chloride secretion in gut
Heat stable toxin- increases cGMP which decreases resorption of NaCl/water in gut

59
Q

What is the mechanism of action of cholera toxin?

A

Permanently activates Gs- leads to Cl secretion in gut

60
Q

What is the mechanism of action of pertussis toxin?

A

Disables Gi- increases cAMP which impairs phagocytosis

61
Q

What bacteria produce toxins that inhibit release of neurotransmitters?

A

C. tetani- tetanospasmin

C. botulinum- botulinum toxin

62
Q

What is the mechanism of action of tetanospasmin and botulinum toxin?

A

Proteases that cleave SNARE proteins

63
Q

What cells does tetanospasmin effect?

A

Renshaw cells in spinal cord- prevent release of GABA

64
Q

What cells does botulinum toxin effect?

A

End plate motor neurons- inhibit release of ACh

65
Q

What bacteria produce toxins that lyse cell membranes?

A

Clostridium perfringens- Alpha toxin

S. pyogenes- Streptolysin O

66
Q

What bacteria produce superantigens that cause toxic shock?

A

S. aureus- TSST-1

S. pyogenes- Exotoxin A

67
Q

What is the mechanism of action of superantigens?

A

Bind to MHCII and TCR to cause release of IL-1, IL-2, IFN-γ, and TNF-α

68
Q

What is bacterial transformation? What enzyme can inhibit this processes?

A

Ability of bacteria to take up naked DNA from the environment.
Inhibited by deoxyribonuclease

69
Q

What is bacterial transposition?

A

Segment of DNA moves from one location to another (plasmid to chromosome and vice versa)

70
Q

What 5 bacterial toxins are encoded by a lysogenic phage?

A 
Shiga toxin
Botulinum toxin
Cholera toxin
Diptheria toxin
Erythrogenic toxin
71
Q

What bacterial genus has gram + cocci that are catalase positive?

A

Staphylococcous

72
Q

What bacterial genus has gram + cocci that are catalase negative?

A

Streptococcus

73
Q

What species of Staph are coagulase negative?

A

S. epidermidis

S. saprophyticus

74
Q

What gram + branching filament organism is acid fast?

A

Nocardia

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