Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

X Infectious Diseases > Streptococci > Flashcards

Streptococci Flashcards

1
Q

are streps gram positive or negative?

A

positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

are streps catalase positive or negative?

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what kind of anaerobes/aerobes are streps?

A

facultative anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how are streps classified?

A

haemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is alpha haemolysis?

A

partially broken down blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what colour is alpha haemolysis?

A

green tinge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is beta haemolysis?

A

completely breaks down the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is gamma haemolysis?

A

not really haemolytic - enterococci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is viridans group?

A

alpha haemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where do viridans streptococci live?

A

mouth, pharynx, genital tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are viridans strep susceptible to?

A

penicillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

if a patient is immunocompromised, what can viridans strep cause? (opportunistic pathogens)

A

endocarditis, meningitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what kinds of strep cause dental decay?

A

strep mutans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how does strep pneumoniae haemolyse when grown anaerobically?

A

beta haemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how does strep pneumoniae haemolyse normally?

A

alpha haemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does strep pneumoniae cause?

A

pneumonia, sinusitis, endocarditis, meningitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is different about virulent strep pneumoniae strains?

A

capsulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how many strains of strep pneumoniae are there?

A

92

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how are the different strains of strep pneumoniae serotyped?

A

capsular antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

who does strep pneumoniae usually infect?

A

children and the elderly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

case study:

  • Elderly patient
  • cough and chest pain
  • purulent sputum
  • shaking chill and developed fever
  • high temp and severe chest pain

what is the diagnosis?

A

pneumonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how would you examine pneumonia?

A

chest radiograph: infiltrate
high wbc count
Gram stain of sputum
blood & sputum sent to lab for culture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what could you do to diagnose pneumonia?

A

Gram stain – easy to spot in sputum smears
Quellung reaction -anti capsular antibodies cause capsule to swell
Typical dimpled colonies
Bile solubility
Optochin sensitivity test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is quellung reaction?

A

Anticapsular antibodies cause capsule to swell

Stain with Indian ink, capsule easily visible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

is strep pneumoniae optochin sensitive or resistant?

A

sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

how are beta haemolytics classified?

A

lancefield groups - based on antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how is lancefield grouped?

A

agglutination tests

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what are the lancefield groups?

A

A, B, C, D, F, G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

which lancefield groups are most medically important and which are rare?

A

most medically important - A, B, D

most rare - C, G, F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

why cant you identify strep pneumoniae or strep viridans by lancefield grouping?

A

only beta haemolytics

31
Q

what is a key feature of lancefield group A?

A

sore throat, scarlet fever, impetigo

32
Q

what is a key feature of lancefield group B?

A

neonatal sepsis & meningitis

33
Q

what are key features of lancefield groups C and G?

A

abscesses

34
Q

what is a key feature of lancefield group D?

A

endocarditis & dental caries

35
Q

which lancefield group does strep pyogenes belong to?

A

group A

36
Q

enterococcus used to be classified as which lancefield group?

A

group D

37
Q

where is strep pyogenes found?

A

Skin, mucous membranes

38
Q

how is strep pyogenes spread?

A

person-person, droplets & direct contact

39
Q

what 4 things does non-invasive strep pyogenes cause?

A

Pharyngitis (strep throat)
Impetigo
Scarlet fever
cellulitis

40
Q

what 4 things does invasive strep pyogenes cause?

A

Toxic shock-type syndrome
Necrotizing fasciitis
Rheumatic fever
Glomerulonephritis

41
Q

what virulence factors does strep pyogenes have and what do they do?

A

fimbrae: protein F
M protein
hyaluronic acid
lipoteichoic acid

42
Q

what does fimbrae: protein F do?

A

attachment and adherence

43
Q

what does M protein do?

A

resistance to phagocytosis

44
Q

what does hyaluronic acid do?

A

prevents phagocytosis

45
Q

what does lipoteichoic acid do?

A

adheres to molecules on host epithelial cells

46
Q

how does strep pyogenes multiply?

A

M protein binds to fibrinogen and stops it from working. this blocks complement and binds to factor H

47
Q

how does strep pyogenes spread infection?

A

skin- localised
pharynx- ear, sinuses
wound- rapid spread virulence factors - proteases, DNAse, streptokinase, hyaluronidase

48
Q

what is the action of streptokinase?

A

Induces fibrinolysis which egrades fibrin and other proteins which affects clotting -> clotting localises infection so it spreads

49
Q

what does hyaluronic acid do?

A

breaks down the hyaluronic acid in connective tissue

bacteria turns off hyaluronidase production at epithelial surfaces instead of capsule formation

50
Q

what pyrogenic toxins cause damage?

A

ABC

51
Q

what are pyrogenic toxins?

A

erythrogenic toxins that suppress antibody responses and stimulate cytokines - septic shock

52
Q

what are the symptoms of a strep pyogenes throat infection?

A 
Hot
flushed
sore throat
vomiting
high temperature
red throat
greyish white exudate
enlarged lymph nodes
53
Q

what can be complications of strep pyogenes?

A

scarlett fever and rheumatic fever

54
Q

what is acute rheumatic fever?

A

life threatening fever, affects the joints and heart

55
Q

how does acute rheumatic fever affect the heart?

A

autoimmune response - antistrep antibodies cross react with heart cell antigens, causing scarring

56
Q

how do you prevent acute rheumatic fever?

A

penicillin treatment of pharyngitis

57
Q

what is necrotising fascitis?

A

‘flesh eating bacteria’

faster than antibiotics work

58
Q

what are the treatment options for necrotising fascitis?

A

amputation

59
Q

how do you diagnose strep pyogenes?

A

culture of pus and blood

lancefield agglutination tests

60
Q

is strep pyogenes bacitracin sensitive or resistant?

A

sensitive

61
Q

group B lancefield - example

A

Strep. agalactiae

62
Q

where are group B lancefields found?

A

Lower GI & female genital tracts

63
Q

what can group B cause?

A 
neonatal sepsis
neonatal meningitis 
cellulitis
arthritis
meningitis
64
Q

who does group B affect?

A

diabetics
elderly
alcoholics
immunocompromised

65
Q

are group B bacitracin sensitive or resistant?

A

resistant

66
Q

how do you treat group B infections?

A

penicillin at high concentrations

67
Q

how do group F grow?

A

microaerophilic/anaerobic

68
Q

where is group F found?

A

Normal flora oropharynx

69
Q

what is the appearance of group F on media?

A

tiny colonies

70
Q

what can group F cause?

A

abscesses in soft tissue

71
Q

what is an example of a group F?

A

Strep milleri

72
Q

where is enterococci found?

A

the gut

73
Q

is enterococci bile resistant or sensitive?

A

resistant

X Infectious Diseases (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions