Gram Positive Cocci, Catalase Negative

Question 1

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

Answer 1

Streptococcus pyogenes

Question 2

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

Answer 2

Strepococcus pyogenes- M Protein

Question 3

M protein encoded by the

Answer 3

genes emm

Question 4

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

Answer 4

Steptococcus pyogenes-M protein

Question 5

is the most common serotype seen in pharyngitis

Answer 5

M1 serotype

Question 6

are adhesion
molecules that mediate attachment to host epithelial cells.

Answer 6

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

Question 7

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

Answer 7

Hyaluronic acid capsule

Question 8

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

Answer 8

Streptolysin O

Question 9

yses leukocytes and is non-immunogenic
 Oxygen stable

Answer 9

Streptolysin S

Question 10

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

Answer 10

Hyaluronidase

Question 11

red spreading rash

Answer 11

Streptococcal pyrogenic endotoxins/erythrogenic toxins

Question 12

It is the most common clinical manifestation of Group A Streptococcus

Answer 12

Bacterial pharyngitis

Question 13

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

Answer 13

 Skin or pyodermal infections

Question 14

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

Answer 14

Impetigo

Question 15

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

Answer 15

Erysipelas-

Question 16

can develop following deeper invasion by streptococci.

Answer 16

cellulitis

Question 17

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

Answer 17

Necrotizing Fasciitis

Question 18

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

Answer 18

Streptococcus pyogenes

Question 19

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

Answer 19

Streptococcus agalactiae

Question 20

There are 9 recognized capsular polysaccharide serotypes.

Answer 20

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

Question 21

prevents phagocytosis but is ineffective after opsonisation.

Answer 21

The capsule

Question 22

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

Answer 22

Sialic acid

Question 23

Early onset infection -

Answer 23

<7 days old

Question 24

Late onset infection

Answer 24

• at least 7 days old to about 3 months old

Question 25

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

Answer 25

Streptococcus agalactiae

Question 26

Todd-Hewitt broth containing

Answer 26

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

Question 27

Also known as pneumococcus

Answer 27

Streptococcus pneumoniae

Question 28

Virulence Factors of Streptococcus pneumoniae

Answer 28

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

Question 29

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

Answer 29

Streptococcus pneumoniae

Question 30

Atypical haemolytic uremic syndrome in children

Answer 30

Streptococcus pneumoniae

Question 31

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

Answer 31

Streptococcus pneumoniae

Question 32

S. pneumoniae is susceptible

Answer 32

Optochin susceptibility-

Question 33

S. pneumoniae is bile soluble

Answer 33

Bile solubility test-

Question 34

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

Answer 34

Viridans Streptococci

Question 35

They were previously classified as group D streptococci.

Answer 35

Enterococcus

Question 36

he commonly identified species in clinical specimens of enterococcus are

Answer 36

Enterococcus faecalis and Enterococcus faecium.

Question 37

sometimes exhibit pseudocatalase reaction.

Answer 37

Enterococci

Question 38

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

Answer 38

Enterococcus

Question 39

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

Answer 39

enterococcus

Question 40

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

Answer 40

Cytolysin

Question 41

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

Answer 41

enterococci.

Question 42

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

Answer 42

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

Question 43

Enterococcus spp. are identified based on their

Answer 43

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