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Microbiology > Streptococci > Flashcards

Streptococci Flashcards

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1
Q

Gram positive cocci arranged in

A

Pairs

chains

Mostly facultative anaerobes, but range from strictly anaerobic to capnophilic

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2
Q

Gram positive cocci have … requirements, require … or …. in the medium

Catalase….

A

growth

blood or serum

negative

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3
Q

Haemolytic patterns

None =

Incomplete =

Complete =

A

None = gamma

Incomplete = Alpha

Complete = Beta

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4
Q

Has …. properties

A

Biochemical

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5
Q

Streptococcus Pneumoniae

Gram positive coccus are ….. in diameter

often …. or …. in shape

A

0.5 to 1.um

oval or lancelate

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6
Q

Streptococcus Pneumoniae only grows in

A

enriched media such as blood

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7
Q

Streptococcus Pneumoniae is catalase …. and requires ….

A

negative

blood

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8
Q

Streptococcus Pneumoniae are ….. organisms from large …. colonies

A

capsulated

mucoid

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9
Q

Non capsulated Streptococcus Pneumoniae are

A

short and fat

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10
Q

Streptococcus Pneumoniae

All colonies …. with age

A

autolyse

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11
Q

Streptococcus Pneumoniae

Alpha … when grown aerobically

A

haemolytic

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12
Q

Streptococcus Pneumoniae

Virulent strains are covered with

A

complex polysaccharide capsule

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13
Q

Streptococcus Pneumoniae

Over 90 strains recognised by typing these ….

A

POLYSACCARIDES ]

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14
Q

Streptococcus Pneumoniae

Purified antigens used as

A

polyvalent vaccine

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15
Q

Streptococcus Pneumoniae

Cell wall contains

A

choline which is important for regulation of cell wall hydrolsis

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16
Q

Streptococcus Pneumoniae

Cell wall contains

A

choline which is important for regulation of cell wall hydrolysis

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17
Q

Choline must be present for the activity of the

A

autolysin amidase during cell division

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18
Q

Some techoic acid is exposed which is called

Percipitates … reactive substance protein in the presence of calcium

A

C substance https://www.brainscape.com/decks/9736283/cards/quick?pack_id=17277361#

C

Calcium

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19
Q

Virulence factors

… componets

enzymes and ….

carried …

Has the ability to spread to

A

Structural components

enzymes and toxin

Carried asymptomatically:
- upper respiratory tract of 10-15% of adults

  • lungs
  • sinuses
  • Middle ear
  • To other sites via blood
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20
Q

Virulence factors

Colonisation mediated by

A secretory …. protease disrupts clearance from

A

binding to epithelial cells via a protein adhesion

IgA

Mucous

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21
Q

Pneumolysin is a

binds too

creates pores too

A

cytotoxin

cholesterol in the host membrane

Creates pores to destroy the ciliated epithelial cells

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22
Q

Tissue destruction is characteristic of pneumococcal infection caused by

A
  • teichoic acid
  • peptidoglycan
  • Pneumolysin
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23
Q

Penumococcal infection activates with pathways and produces what

A

activates classical and alternative complement pathway, producing C3a, C5a and also IL1 and TNF alpha

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24
Q

Virulence factors results in

A

inflammatory response

Fever

Tissue damage

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25
Q

Production of hydrogen peroxide by the bacteria causes

A

further tissue damage

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26
Q

Peumococci enter a variety of cells by binding to

A

receptors for platelet activating factor

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27
Q

Virulence factors facilitates spread through

A

blood and CNS

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28
Q

Capsule give protection from

Pneumolysin suppresses

Non capsulated (rough) strains are

A

phagocytosis

oxidative burst

avirulent

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29
Q

Clinical syndromes from Streptococcus

A

Bacterial pneumonia
Otitis media
Sinusitis

30
Q

Bacteriaemia occurs in

A

20-30% of pneumonia cases

up to 80% of meningitis cases

31
Q

Pneumonia has rapid onset:

symptoms

morality rate higher with type …

A

Fever 39-41

localised to lower lobes

Generalised bronchopneumonia

3

32
Q

Virulence factors are sensitive to:

A

Penicillin
Erthrymocyin
Tetracycline

33
Q

Control by vaccine of capsular …. for at risk patients

A

polysaccharide

34
Q

2 effective vaccines

A

Pneumovax

  • Contains 23 serotypes
  • known to cause 90% of disease

Prevenar
- Contains 13 serotypes

35
Q

B haemolytic streptocci

Is classified by …. based on cell wall polysaccharides.

A

lancefield grouping system

  • Groups A, B, C, F and G
36
Q

Lipteichoic acid group D and

A

enterococci

37
Q

Not all groups demonstrate

A

beta haemolysis

38
Q

Group A streptococcus

Colonies may appear …

A

Capsulated

Non capsulated

39
Q

Group A streptococcus capsule of hyaluronic acid is lost during

A

the stationary phase

40
Q

Hyaluronic acid is found in ,,,, therefore in non immunogenic
-….

A

connective tissue

  • antiphagocytic
41
Q

Virulence proteins

M protein has … different types and degrades ….

A

80

C3b

42
Q

what does 29 M types produce

A

Opacity factor

43
Q

M like proteins bind the Fc portion of ,,,, and ,,,, and ….. which is a protease inhibitor

A

IgG and IgA and alpha2macroglobulin

F protein has a receptor for fibronectin

Important for attachment to epithelial cells of:

  • Pharynx
  • skin
44
Q

what are the pryrogenic exotoxins and what do they act as

A

SpeA, SpeB and SpeC

they act as superantigens

45
Q

s and o are

A

Streptolysins

46
Q

what are the 5 things that streptolysin S does

A
  • cell bound haemolysin
  • lyses erythrocytes, leukocytes and platelets
  • destroys phagocytes
  • Oxygen stable
  • non immunogenic
47
Q

what are the 3 things that streptolysin 0 does

A
  • Haemolysin activity
  • Inactivated by oxygen reversibly and irreversibly by cholestral
  • stimulates anitbody response
48
Q

What are the 2 streptokinases and what do they do

A

A and B

Lyse blood clots

49
Q

what does Dnase do

A

depolymerises cell free DNA in purulent material

50
Q

what are all the virulence factors

A

Pyrogenic exotoxins

Streptolysins o

Streptolysin S

Streptokinases. a and b

Dnase

C5a peptidase

Hyaluronidase ‘spreading factor

Diphosphopyridine nucleotidase.

51
Q

Epidemiology

Clonosises …. of childrena and young adults

transient and …. on … of production of antibodies to the particular ,,,, protein

spread by

A

oropharynx

depend on speed

M

spready by droplet infection and skin colonisation

52
Q

Suppurative clinical syndromes

Pharyngitits is a

2-4 days after exposure the 5 symptoms are

what appears on tonsils

what are the complications

lysogenised with a temperate

stimulates production of

A

sore throat

fever 
sore throat 
headache 
malaise 
abdominal pain

grey white exudate

scarlet fever

bactriophage

pyrogenic exotoxin

53
Q

Suppurative clinical syndromes

Soft tissue infections (3)

cellulitis involves deeper…

Infected wounds

Pyoderma

A
  • Erysipelas
  • skin rash face or legs
  • Preceded by respiratory tract or skin infections

tissue

ulcers
insect bites etc

Impetigo

54
Q

-suppurative clinical syndromes

Necrotising fasciitis becomes…
spreads….
What spec involved….
Follows entry of bacteria to…

high

A

infection becomes established in the fascial tissue below the skin
spreads rapidly causing tissue necrosis
skin and wound, cellulitis

mortality

55
Q

suppurative clinical syndromes

treatment involves surgical removal of …. and …. therapy

A

dead tissue and antibiotic therapy

56
Q

streptococcal toxic shock syndrome may follow …. and …. tissue infection
severe ….. organ symptoms

what spec implicated

A

throat and soft tissue

multi organ

Spec A.B.C

57
Q

Soft tissue inflammation at the site of infection with non specific symptoms

increased pain as disease progresses to multi organ ,,,, and ,,,,,

A

fever
chill
nausea

shock and failure

58
Q

Bacteriaemic and often have

Predisposing factors,

A

necrotising fasciitis

HIV , cancer, diabetics , alcohol and drug abuse

59
Q

Non suppurative disease often a complication of

rheumatic fever is associated with

Inflammation involves

can cause chronic damage to

caused by specific M groups
- … formed to cell wall …. cross react with the… of the heart

Rhenumatic heart disease
- repeated attacks with different ,, types can lead to ….. disease

cu

A

initial streptococcal infection

pharyngeal infection
2-5 weeks after initial infection

Heart valves, joints and blood vessels

heart valves

antibodies formed to cell wall antigens cross react with the sarcolemma of the heart

different m types can lead to heart valve disease

60
Q

diagnosis and treatment

… stain and … characteristics

…. grouping

sensitive to

treatment
- sensitive to …..

prompt treatment prevents …

does not influence progression of

prophylaxis necessary in some cases

A

gram stain and growth characteristics

lancefield grouping

sensitive to bacitracin

sensitive to penicillin

prevents rheumatic fever.

does not influence progression to glomerulonephritis

prophylaxis necessary in some cases

61
Q

Group B streptococci. S.agalactiae.

grow as …. appearing colonies on ……

small zone of

group specific polysaccharide ….

what are the 6 enzymes

Useful for identification rather than …

colonisies of lower gas…… and g,,, tract

A

buttery
nutritionally enriched medium.

beta haemolysis

cell wall antigen

Dnases,
hyaluronidase, 
neuraminidase, 
proteases,
Hippurase 
Hemolysins.

pathogenesis

gastrointestinal and genitourinary tract

62
Q

Group B streptococci

Cause:
5 causes

Risk factors
4 risks

All serotypes but …. mostly due to type ….

<5% mortality, 15-30% of those with meningitis have neurological …

A
  • Neonatal disease,
  • Urinary tract infection
  • wound infections
  • Occasionally bacteraemia
  • 29.5% of reported neonatal bacterial meningitis
  • heavily colonised mother lacking specific antibody
  • Premature rupture of membranes
  • Pre term delivery
  • Prolonged labour and obstetric complications

meningitis mostly due to type 111

sequelae

63
Q

Group C and G streptococci

S.equisimilis and S. anginosus associated with

A

human disease

64
Q

Cause of Group C and G streptococci:

A
  • Pharyngitits

- found in wound infections

65
Q

S.anginosus also has what antigens for what group

A

polysaccharide antigens for group G

66
Q

Group G:
is part of

can cause

A

part of normal flora

can cause wound and throat infections

67
Q

Cases of bacteraemia reported for both

A

C and G

68
Q

Group F. streptococci

what group

what are the growth conditions

what odour

normal what of vaginal area

involved in deep ….

A

Milleri group

  • co2
  • minute colonies of blood agar

characteristic caramel odour

normal flora of vaginal area

involved in deep infections e,g abscesses

69
Q

Group D and the enterococci

how many species

most common species

E….. responsible for 80-90% human infections

E. 10-15%

Part of normal ….

Facultatively anaerobic cocci
- Growing optimally at ….
range ….

Grow as non haemolytic …]
- Tolerate 6.5% … and 40%

A

18

  • E.faecalis
  • E. Facecium

E. faecalis responsible for 80-90% human infections

Part of normal flora of bowelecium 10-15%.

Facultatively anaerobic cocci
Growing optimally at 35oc.
Range 10-45oc.

Grow as non haemolytic colonies
- Tolerate 6.5% salt and 40% bile salts

70
Q

Enterococci
- Few virulence factors but can cause life…

Virulence factors include:

  • aggre…
  • carb….
  • Bacte…
  • Gel…
Most important is antibiotic resistance
-amino...
beta..
vanc...
A,van.....
A

threatening disease

Aggregation susbstance
Carbohydrate adhesins
Bacteriocin
Gelatinase.

Aminoglycosides
Beta-lactams
Vancomycin (mediated by Van A,Van B and Van c genes).

Microbiology (13 decks)

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