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Microbiology > Bacteriology (Exam 2) > Flashcards

Bacteriology (Exam 2) Flashcards

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1
Q

What population group is most susceptible to meningitis and pneumonia due to infections by Streptococcus agalactiae?

A

neonates

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2
Q

Prevention of complement activation/fixation by factor H is a function of what bacterial protien?

A

Streptococcus pyogenes M protein

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3
Q

Over 90% of staph areaus strains are resistant to what antibiotic?

A

penicillin

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4
Q

What bacterial virulence factor reduces phagocyte killing by converting hydrogen peroxide to water and oxygen?

A

catalase

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5
Q

What are two adhesins from Gram positive bacteria?

A
  • fibronectin binding protein

- serin rich repeat protein

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6
Q

What is the function of exotoxins

A

-breakdown extracellular structures to promote movement and spread of extracellular microbes

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7
Q

What is the function of LPS on bacteria cells?

A

block access of the membrane attack complex to the bacterial plasma membrane

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8
Q

Are staphylococci gram + or -?

A

Gram positive

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9
Q

What variation of oxygen req is staph aureus?

A

Facultative anaerobe (O2 can be used if needed)

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10
Q

What bacterial species has a virulence factor that binds prothrombin

A

Staph aureus (coagulase)

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11
Q

What virulence factor of staph aureus causes puss formation?

A

leukocidin (forms pores in phagocytes)

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12
Q

converts plasminogen to plasmin, increasing invasion by digesting fibrin clots and cleaves C3b and IgG to inhibit phagocytosis

A

staphylokinase

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13
Q

What is an easy way to differentiate staph aureaus and epidermidis?

A
  • aureus is hemolytic and gold colored

- epidermidis is non hemolytic and white colored

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14
Q

What bacteria cause folliculitis that turns to furuncles that turns to carbuncles that turns to bacteremia?

A

staph aureus (puss forming leukocidins)

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15
Q

What do superantigens do?

A

override the specificity of the T-cell response

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16
Q

What are TSSTs?

A

Toxic Shock Syndrome Toxins: mass activation of T-cells leads to mass activation of inflammatory cytokines

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17
Q

TSSTs are an example of…..

A

enterotoxin exotoxins (heat stable, chromosomal genes)

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18
Q

Tampons story is about

A

TSST, staphylococci?

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19
Q

What causes Staphylococcal scalded skin syndrome?

A

exfoliative toxins A and B (causes outer layer of skin to separate)

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20
Q

Where can nosocomial staphylococci found? What is a key feature of them?

A
  • hospitals

- slime layer

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21
Q

What bacteria is associated with dental extraction risk?

A

staphylococcus epidermidis

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22
Q

60% of acute endocarditis is caused by….

A

staph aureus

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23
Q

80% of endocarditis with artificial heart valves is caused by….

A

staph epidermidis

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24
Q

Bacterial arthritis at any age is most frequently associated with…

A

staph aureus

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25
Q

What bacterial species is resistant to high temp and salt levels?

A

staph aureus

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26
Q

Pyogenes means…

A

puss forming

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27
Q

What streptococci are seen as diplococci?

A

strep pneumoniae

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28
Q

Diff between alpha and beta hemolysis?

A

Alpha: partial lysis (looks green, mitis and pneumoniae)
Beta: full lysis (clearing, pyogenes)

29
Q

Strep pyogenes and strep galactiae are both…

A

hemolytic bacteria (pyogenes is A, galactiae is B)

30
Q

What bacteria have M proteins?

A

Strep pyogenes

31
Q

What are the two ways M proteins act as virulence factors?

A
  1. binds fibrinogen which blocks surface from complement proteins (factor H)
  2. binds complement control proteins to inhibit opsonins (C3 peptidase)
32
Q

What are streptolysins?

A

cytotoxins secreted by strep pyogenes that disrupts plasma membranes of erythrocytes and phygocyte lysosomes

33
Q

What virulence factor of strep pyogenes is responsible for scarlet fever?

A

superantigen SPE

34
Q

Nectrotizing fasciitis is caused by…

A

strep pyogenes

35
Q

Glomerulonephritis is a Type ___ hypersensitivity reaction.

A

Type III

36
Q

Rheumatic fever is a Type ___ hypersensitivity reaction.

A

Type II

37
Q

Strep galactiae can cause pneumonia in ________, meningitis and bacteremia in __________, and urinary tract infections in ____________.

A

pneumonia -> neonates less than 7 days
pneumonia and bacteremia -> neonates greater than 7 days
urinary tract infections -> pregnant women

38
Q

What bacteria is considered a reservoir for antibiotic resistance?

A

enterococcus faecalis. High virulence, multiple plasmid and chromosomal Ab resistances

39
Q

Only a certain type of strains of strep pneumoniae are virulent. What are they?

A

-encapsulated strains

40
Q

How are klebsiella pneumonia and mycoplasma pneumonia different from pneumococcal pneumonia?

A

kleb and myco have no vaccine

41
Q

What are three main virulence factors of streptococcal pneumoniae?

Hint: (blood, protection, protease)

A
  • alpha hemolysis
  • capsule
  • secretory IgA protease
42
Q

Meningitis risk due to ____________ seems to increase as we age.

A

strep pneumoniae

43
Q

Are Neisseria gonorrhoeae gram positive or negative?

A

Gram negative (diplococci)

44
Q

What is unique about neisseria sp cell membranes?

A

they have lipooligosaccharides instead of LPS (lack O antigen)

45
Q

What makes N. gonorrhoeae reistant to vaccination?

A

phase and antigenic variation of pilin genes

46
Q

Does N. gonorrhoeae have a capsule?

A

no

47
Q

What two genes recombine to create a constantly changing pilus antigen on N. gonorrhoeae?

A

pilS randomly recombines with pilE for unlimited varients

48
Q

What causes frequent variation in Opa expression in N. gonorrhoeae?

A

slipped strand mispairing

49
Q

Why might a gram negative rod randomly not express genes for fimbriae?

A

phase variation: random flipping of promotor sequence. Flipped wrong way is off, flipped right way is on

50
Q

Why might IgA have no effect on N. gonorrhoeae?

A

the bacteria are coated in Fab fragments that block complement activation and binding of other antibodies

51
Q

What addition to lipooligosaccharide inhibits complement fixation to n. gonorrhoeae?

A

sialic acid

52
Q

What part of N. gonorrhoeae causes secretion of pro-inflammatory cytokines?

A

shedding of endotoxin (LOS) which binds to TLR-4

53
Q

Where does neisseria meningitidis replicate?

A

in subarachnoid space

54
Q

What are the 4 main virulence factors of N. meningitidis?

A
  1. large capsule
  2. IgA protease
  3. Pili
  4. shedding of lots of endotoxin (LOS)
55
Q

Are bacteroidales gram positive or negative?

A

gram negative

56
Q

Are bacteroidales aerobes/anaerobes, pathogens/commensals?

A
  • strict anaerobes

- commensals (opportunistic pathogens)

57
Q

Why is bacteroides fragilis the most common isolated specimen from abscesses?

A

most oxygen resistant

58
Q

What are the three virulence factors of Bacteroidales fragilis?

A
  • superoxide dismutase
  • catalase
  • polysaccharide capsule
59
Q

Bacteriodales cause what diseases?

A
  • peritonitis

- pulmonary abscess

60
Q

A disease that starts with 100’s of different species and few are left in the abscess stage.

A

-polymicrobial diseases (bacteroidales involved)

61
Q

What are the last two types of microbes left towards the end stages of an abscess?

A
  • facultative anaerobes

- some strict anaerobes (become predominant in last stage)

62
Q

What organism causes scalded skin syndrome?

A

staphylococcus aureus

63
Q

What bacterial virulence factor has an activity that results in creation of a fibrin coat around bacteria?

A

coagulase

64
Q

What role does staphylokinase play for staphylococcus aureus?

A

cleaves C3B and IgG

65
Q

What causes myocarditis in susceptible individuals?

A

rheumatic fever

66
Q

Which organism undergoes phase variation of Opa proteins?

A

Neisseria gonorrhoeae

67
Q

What factor in the most important in allowing intravascular survival of Neisseria meningitidis?

A

bacterial capsule

68
Q

Why does Bacteroidales fragilis resist phagocytosis?

A

it has a capsule

Microbiology (11 decks)

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