Gram Positive Cocci, Catalase Negative Flashcards

1
Q

The group is antigen is unique, placing the organism in Lancefield group A.

A

Streptococcus pyogenes

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2
Q

is attached to the peptidoglycan of the cell wall and extends to the cell
surface

is essential for virulence S. pyogenes colonizes the throat and skin
on humans making these sites primary sources of transmission

A

Strepococcus pyogenes- M Protein

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3
Q

M protein encoded by the

A

genes emm

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4
Q

molecule causes streptococcal cell to resist phagocytosis and
plays a role in adherence of the bacterial cell to mucosal cells.

A

Steptococcus pyogenes-M protein

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5
Q

is the most common serotype seen in pharyngitis

A

M1 serotype

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6
Q

are adhesion
molecules that mediate attachment to host epithelial cells.

A

Fibronectin-binding protein (Protein F) and Lipotechoic acid-

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7
Q
  • it prevents opsonized phagocytosis by neutrophils or
    macrophages. It also allows the bacterium to mask its antigens and remain
    unrecognized by its host
A

Hyaluronic acid capsule

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8
Q

Responsible for hemolysis on Sheep Blood Agar plates incubated
anaerobically, oxygen labile

A

Streptolysin O

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9
Q

yses leukocytes and is non-immunogenic
 Oxygen stable

A

Streptolysin S

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10
Q
  • spreading factor is an enzyme that solubilizes the ground
    substance of mammalian connective tissues.
A

Hyaluronidase

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11
Q

red spreading rash

A

Streptococcal pyrogenic endotoxins/erythrogenic toxins

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12
Q

It is the most common clinical manifestation of Group A Streptococcus

A

Bacterial pharyngitis

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13
Q

include impetigo, cellulitis, erysipelas, wound
infection, or arthritis

A

 Skin or pyodermal infections

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14
Q
  • a localized skin disease, begins as small vesicles that progress
    to weeping lesions
A

Impetigo

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15
Q
  • rare infection of the skin and subcutaneous tissues observed
    frequently in elderly patients
A

Erysipelas-

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16
Q

can develop following deeper invasion by streptococci.

A

cellulitis

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17
Q

An invasive infection characterized by rapidly progressing inflammation
and necrosis of the skin, subcutaneous fat, and fascia.

A

Necrotizing Fasciitis

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18
Q

Key tests are bacitracin susceptibility or pyrrolidonyl-alpha-naphtylamide (PYR)
hydrolysis

A

Streptococcus pyogenes

19
Q

have the group B-specific antigen, an acid-stable
polysaccharide located in the cell wall.

A

Streptococcus agalactiae

20
Q

There are 9 recognized capsular polysaccharide serotypes.

A

Serotypes Ia, IIb and II contain a terminal residue of sialic acid

21
Q

prevents phagocytosis but is ineffective after opsonisation.

A

The capsule

22
Q

appears to be the most significant component of the capsule
and a critical virulence determinant

A

Sialic acid

23
Q

Early onset infection -

A

<7 days old

24
Q

Late onset infection

A
  • at least 7 days old to about 3 months old
25
Q

Grows on Sheep Blood Agar as grayish white mucoid colonies surrounded by a
small zone of Beta hemolysis

A

Streptococcus agalactiae

26
Q

Todd-Hewitt
broth containing

A

10 ug/mL colistin and 15 ug/mL nalidixic acid.

27
Q

Also known as pneumococcus

A

Streptococcus pneumoniae

28
Q

Virulence Factors of Streptococcus pneumoniae

A

Capsular polysaccharide
o Hemolysin
o Immunoglobulin A protease
o Neuraminidase
o Hyaluronidase

29
Q

It is an important human pathogen that causes pneumonia, sinusitis, otitis media,
bacteremia, and meningitis.

A

Streptococcus pneumoniae

30
Q

Atypical haemolytic uremic syndrome in children

A

Streptococcus pneumoniae

31
Q

o Brain-heart infusion agar, trypticase soy agar with 5% sheep RBCs, or chocolate
agar are necessary for good growth

A

Streptococcus pneumoniae

32
Q

S. pneumoniae is susceptible

A

Optochin susceptibility-

33
Q

S. pneumoniae is bile soluble

A

Bile solubility test-

34
Q

They are constituents of the normal microbiota of the upper respiratory tract

A

Viridans Streptococci

35
Q

They were previously classified as group D streptococci.

A

Enterococcus

36
Q

he commonly identified species in clinical specimens of enterococcus are

A

Enterococcus faecalis and Enterococcus faecium.

37
Q

sometimes exhibit pseudocatalase reaction.

A

Enterococci

38
Q

they can grow in
extreme conditions and are resistant to multiple antimicrobial agents.

A

Enterococcus

39
Q

are thought to play a role in the colonization of the
species and adherence to heart valves and renal epithelial cells.

A

enterococcus

40
Q

shows similarity to bacteriocins produced by gram-positive bacteria and
is expressed by quorum-sensing mechanism.

A

Cytolysin

41
Q

Trypticase soy or brain-heart infusion agar supplemented with 5% sheep blood is
routinely used to culture

A

enterococci.

42
Q

If the clinical specimen is obtained from a contaminated site or is likely to contain
gram-negative organisms, selective media containing

A

bile esculin azide, colistin
nalidixic acid, phenylethyl alcohol, chromogenic substrates, or cephalexinaztreonam-arabinose agar should be used

43
Q

Enterococcus spp. are identified based on their

A

ability to produce acid in carbohydrate broth
 ability to hydrolyze arginine
 tolerance of 0.04% tellurite (tween 80)
 utilization of pyruvate
 ability to produce acid from methyl-α-D-glucopyranoside