Streptococcaceae and Enterococcus species

Question 1

Based on hemolysis on 5% Sheep Blood Agar Medium

Answer 1

Smith and Brown’s Classification

Question 2

denotes incomplete lysis of erythrocytes with reduction of hemoglobin and the formation of green pigment

Answer 2

α-hemolysis

Question 3

Streptococci producing such pattern of hemolysis were later on described as “green streptococci”.

Answer 3

α-hemolysis

Question 4

refers to the complete disruption of erythrocytes resulting to clearing of the blood around the bacterial growth.

Answer 4

β-hemolysis

Question 5

signifies absence of hemolysis thereby no change is seen in the medium surrounding bacterial growth.

Answer 5

γ-hemolysis

Question 6

Streptococci producing such pattern of hemolysis were later on described as “indifferent streptococci”.

Answer 6

γ-hemolysis

Question 7

a small zone of intact erythrocytes immediately adjacent to bacterial colony is surrounded with a zone of complete erythrocyte hemolysis.

Answer 7

α’ (alpha prime)-hemolysis (wide zone of alpha hemolysis)

Question 8

This type of hemolysis maybe confused with β-hemolysis.

Answer 8

α’ (alpha prime)-hemolysis (wide zone of alpha hemolysis)

Question 9

Discovered by Rebecca Lancefield in the 1930s based on group-specific antigens which are either cell wall polysaccharides, AKA C-substance, (as in human group A, B, C, F, and G streptococci); or lipoteichoic acids as in the group D streptococci and Enterococcus species These antigens stimulated formation of antibodies with differing specificities.

Answer 9

Lancefield Classification

Question 10

Typing with specific antiserum causing agglutination is generally done only for groups A, B, C, F, and G.

Answer 10

Lancefield Classification

Question 11

Based on temperature for growth particularly at 10OC and 45OC.

Answer 11

Academic/ Bergey’s Classification

Question 12

consists of streptococci that do not grow at both 10OC and 45OC.

Answer 12

Pyogenic group

Question 13

includes streptococci which fail to grow at 10OC but can be recovered at temperatures up to 45OC.

Answer 13

Viridans group

Question 14

are streptococci that grow at both 10OC and 45OC.

Answer 14

Enterococcus group

Question 15

comprise of streptococci that are frequently recovered in dairy products, can grow at 10OC but fail to grow at 45OC.

Answer 15

Lactic group

Question 16

Group A β-Hemolytic Streptococci (GAS): Streptococcus pyogenes: Habitat

Answer 16

human throat and skin

Question 17

Group A β-Hemolytic Streptococci (GAS): Streptococcus pyogenes: Transmission

Answer 17

respiratory droplets or contact with cutaneous lesions.

Question 18

The most common infection caused by S. pyogenes.

Answer 18

Pharyngitis or streptococcal sore throat

Question 19

Although it may occur at any age, it occurs most frequently between the ages of 5 and 15 years.

Answer 19

Pharyngitis or streptococcal sore throat

Question 20

Characterized by acute sore throat, malaise, fever, and headache

Answer 20

Pharyngitis or streptococcal sore throat

Question 21

Typically involves the tonsillar pillars, uvula, and soft palate, which become red, swollen, and covered with a yellowwhite exudate. The cervical lymph nodes that drain this area may also become swollen and tender.

Answer 21

Pharyngitis or streptococcal sore throat

Question 22

Usually self-limiting (illness resolves on its own even without medical intervention). Typically, the fever is gone by the third to fifth day, and other manifestations subside within 1 week.

Answer 22

Pharyngitis or streptococcal sore throat

Answer 23

Pharyngitis or streptococcal sore throat

Question 24

Caused by lysogenized strains of S. pyogenes that produce pyrogenic exotoxins A - C

Answer 24

Scarlet Fever

Question 25

Occurs in association with streptococcal pharyngitis

Answer 25

Scarlet Fever

Question 26

The buccal mucosa, temples, and cheeks are deep red, except for a pale area around the mouth and nose (circumoral pallor).

Answer 26

Scarlet Fever

Question 27

Punctate hemorrhages appear on the hard and soft palates, and the tongue becomes covered with a yellow-white exudate through which the red papillae are prominent (strawberry tongue).

Answer 27

Scarlet Fever

Question 28

A diffuse red “sandpaper” rash appears on the second day of illness, spreading from the upper chest to the trunk and extremities.

Answer 28

Scarlet Fever

Question 29

Circulating antibody to the toxin neutralizes its effects.

Answer 29

Scarlet Fever

Question 30

Infection of superficial layers of skin

Answer 30

Streptococcal pyoderma (or impetigo)

Question 31

Usually occurs in children ages 2-15 years old, with peak incidence in the 2- to 5- year age group.

Answer 31

Streptococcal pyoderma (or impetigo)

Question 32

Characterized by the formation of papules that develop into vesicular lesions and evolve into pustules. These pustules break down over the next 5 to 7 days to form thick scabs.

Answer 32

Streptococcal pyoderma (or impetigo)

Question 33

Lesions are often seen on the lower extremities and may also involve other pathogens such as S. aureus.

Answer 33

Streptococcal pyoderma (or impetigo)

Question 34

An infection of the dermis and subcutaneous tissues

Answer 34

Erysipelas

Question 35

Organism enters through a small wound or incision on the face or extremities

Answer 35

Erysipelas

Question 36

Characterized by edema and erythematous (red) lesion that is hot, and often vesicular with rapidly advancing, well-demarcated edges

Answer 36

Erysipelas

Question 37

Infection usually occurs on the face and commonly in association with a history of streptococcal sore throat.

Answer 37

Erysipelas

Question 38

Pain, and systemic manifestations, such fever and lymphadenopathy are evident.

Answer 38

Erysipelas

Question 39

An acute, rapidly spreading infection of the skin and subcutaneous tissues.

Answer 39

Cellulitis

Question 40

Occurs following streptococcal infection of preexisting lesions (i.e. mild trauma, burns, wounds, or surgical incisions).

Answer 40

Cellulitis

Question 41

Symptoms include pain, tenderness, swelling, and erythema particularly occurring within the affected area.

Answer 41

Cellulitis

Question 42

Cellulitis:

Differentiated from erysipelas by two clinical findings:

Answer 42

In cellulitis, the lesion is not raised, and the line between the involved and uninvolved tissue is indistinct.

Question 43

Consists of extensive and very rapidly spreading necrosis of the skin, tissues, and fascia.

Answer 43

Necrotizing fasciitis (streptococcal gangrene)

Question 44

Organism enters at the site of localized trauma or previous surgery, or via hematogenous seeding of subcutaneous muscles and soft tissue.

Answer 44

Necrotizing fasciitis (streptococcal gangrene)

Question 45

Affected tissues become gangrenous, with sloughing of devitalized tissues and extensive subcutaneous tissue necrosis.

Answer 45

Necrotizing fasciitis (streptococcal gangrene)

Question 46

Group A streptococci that cause necrotizing fasciitis are termed “flesh-eating bacteria”.

Answer 46

Necrotizing fasciitis (streptococcal gangrene)

Question 47

Bacteria other than S pyogenes can also cause necrotizing fasciitis.

Answer 47

Necrotizing fasciitis (streptococcal gangrene)

Question 48

Occurs in women following child birth (either by vaginal or abdominal/Csection) or abortion.

Answer 48

Puerperal fever

Question 49

Organisms colonizing the genital tract or from an obstetrical personnel invade the upper genital tract, causing endometritis, lymphangitis, bacteremia, necrotizing fasciitis, and streptococcal toxic shock syndrome.

Answer 49

Puerperal fever

Question 50

Intrapartum (occuring during pregnancy) transmission of group A streptococci, may lead to severe and often fatal group A streptococcal disease in the neonate.

Answer 50

Puerperal fever

Question 51

Manifestations in the neonate include septicemia, jaundice, and cellulitis, or stillbirth.

Answer 51

Puerperal fever

Question 52

May result from streptococcal infection of traumatic or surgical wounds.

Answer 52

Bacteremia or Sepsis

Question 53

Can be rapidly fatal.

Answer 53

Bacteremia or Sepsis

Question 54

Can also occur with skin infections, such as cellulitis and rarely pharyngitis.

Answer 54

Bacteremia or Sepsis

Question 55

Are non-suppurative sequelae that occur weeks after GAS infection in the throat and/or skin.

Answer 55

Post Streptococcal Diseases

Question 56

Inflammation of the glomeruli of the kidneys caused by the M strains of S. pyogenes (nephritogenic).

Answer 56

Acute Glomerulonephritis (AGN)

Question 57

Begins 1 to 4 weeks after streptococcal pharyngitis or 3 to 6 weeks after skin infection; primarily a disease of childhood.

Answer 57

Acute Glomerulonephritis (AGN)

Question 58

May be initiated by deposition and accumulation of antigenantibody complexes on the glomerular basement membrane

Answer 58

Acute Glomerulonephritis (AGN)

Question 59

Signs symptoms: dark, smoky urine (due to blood and proteins) edema, hypertension, and urea nitrogen retention.

Answer 59

Acute Glomerulonephritis (AGN)

Question 60

Majority recover completely while some develop chronic glomerulonephritis with kidney failure, and a few die

Answer 60

Acute Glomerulonephritis (AGN)

Question 61

Considered as the most serious sequela of S. pyogenes because it results in damage to heart muscle and valves.

Answer 61

Rheumatic fever (RF)

Question 62

Occurs 1–4 weeks after S. pyogenes pharyngitis

Answer 62

Rheumatic fever (RF)

Question 63

Is an autoimmune disease, i.e., antibodies formed against streptococcal antigens cross react with the molecules of the host that trigger inflammation and injury of tissues (of the heart, joints, CNS)

Answer 63

Rheumatic fever (RF)

Question 64

Signs and symptoms: fever, malaise, arthritis, carditis, chorea (neurologic disorder characterized by involuntary jerky movements), and skin nodules

Answer 64

Rheumatic fever (RF)

Question 65

Pathologic processes of S. pyogenes infection can extend to the heart. The cross-reaction between streptococcal-induced antibodies and heart proteins have a gradual destructive effect on atrioventricular valve. Scarring and deformation change the capacity of the valves to close and shine the blood properly leading to Rheumatic Heart Disease.

Answer 65

Rheumatic fever (RF)

Question 66

Has a marked tendency to be reactivated by recurrent streptococcal infections in contrast with nephritis.

Answer 66

Rheumatic fever (RF)

Question 67

Occur more frequently in tropical countries and is the most important cause of heart disease in young people in developing countries.

Answer 67

Rheumatic fever (RF)

Question 68

major virulence factor of S. pyogenes (those that lack M protein are not virulent).

Answer 68

M Protein

Question 69

Found on the bacterial cell surface associated with fimbriae.

Answer 69

M Protein

Question 70

There are more than 200 types of S. pyogenes M proteins; immunity to infection with GAS is related to the production or presence of typespecific antibodies against M protein; subsequent infections may occur with different M serotypes;

Answer 70

M Protein

Question 71

Inhibits activation of the complement pathway by destroying C3-convertase thereby prevents formation of the opsonin C3b

Answer 71

M Protein

Question 72

A polysaccharide capsule, which is composed of hyaluronic acid

Answer 72

Capsule

Question 73

A polysaccharide capsule, which is composed of hyaluronic acid

Answer 73

Capsule

Question 74

Prevents opsonized phagocytosis by neutrophils or macrophages.

Answer 74

Capsule

Question 75

Allows the bacterium to mask its antigens and remain unrecognized by its host’s immune system

Answer 75

Capsule

Question 76

Formerly called streptococcal pyrogenic exotoxins (Spe)

Answer 76

Erythrogenic Toxin

Question 77

There are four antigenically distinct streptococcal pyrogenic exotoxins — SpeA, SpeB, SpeC, and SpeF.

Answer 77

Erythrogenic Toxin

Question 78

SpeA has been most widely studied.

Answer 78

Erythrogenic Toxin

Question 79

Elaborated by lysogenic S. pyogenes that contain genes from temperate bacteriophage.

Answer 79

Erythrogenic Toxin

Question 80

Act as superantigens which stimulate monocytes and T cells. When activated, these cells proliferate and produce tumor necrosis factor, which in high quantities leads to damage of the plasma membrane of blood capillaries.

Answer 80

Erythrogenic Toxin

Question 81

Responsible for the manifestations of scarlet fever

Answer 81

Erythrogenic Toxin

Question 82

is a skin test for scarlet fever that uses antitoxin to the erythrogenic toxin of Streptococcus pyogenes subcutaneously: a positive reaction is blanching of the rash in the area around the injection site.

Answer 82

Schultz-Charlton Test

Question 83

is a skin test performed to determine an individual’s susceptibility to scarlet fever. It consists of intradermal injection of diluted scarlet fever toxin on the arm of a suspected patient. Development of a red rash with a diameter of 10 mm or greater indicates lack of immunity to the disease.

Answer 83

Dick Test

Question 84

S. pyogenes elaborates two hemolytic exotoxins, proteins that not only lyse the membranes of erythrocytes but also damage a variety of other cell types.

Answer 84

Streptolysins

Question 85

The “O” refers to this hemolysin being oxygen labile. It is active only in the reduced form.

Answer 85

Streptolysin O (SLO)

Question 86

Is responsible for hemolysis on sheep blood agar (SBA) plates incubated anaerobically or subsurface hemolysis when growth occurs in cuts (stabs) made deep into the blood agar plates

Answer 86

Streptolysin O (SLO)

Question 87

It lyses a variety of host cells including leukocytes, platelets, as well as RBCs

Answer 87

Streptolysin O (SLO)

Question 88

It is highly immunogenic, and infected individuals readily form antibodies against it known as anti-streptolysin O (ASO) which blocks hemolysis caused by streptolysin O.

Answer 88

Streptolysin O (SLO)

Question 89

ASO combines quantitatively with streptolysin O and is measured in the Anti-streptolysin O Test

Answer 89

Streptolysin O (SLO)

Question 90

a test performed to determine whether an individual has had a recent infection with S. pyogenes.

Answer 90

Anti-Streptolysin O Test (ASTO or ASOT)

Question 91

It involves detection and quantitation of Anti-Streptolysin O antibodies in the serum

Answer 91

Anti-Streptolysin O Test (ASTO or ASOT)

Question 92

An abnormally high serum titer suggests either recent infection with S. pyogenes or persistently high antibody levels caused by an exaggerated immune response to an earlier exposure in a hypersensitive person.

Answer 92

Anti-Streptolysin O Test (ASTO or ASOT)

Question 93

is also related to the retro-diagnosis of rheumatic fever (to check whether rheumatic fever is caused by a previous streptococcal infection or by other etiologies).

Answer 93

Anti-Streptolysin O Test (ASTO or ASOT)

Question 94

Is responsible for hemolysis seen around colonies (surface hemolysis) incubated aerobically

Answer 94

Streptolysin S (SLS)

Question 95

It is oxygen stable, lyses leukocytes, and is non-immunogenic — does not stimulate antibody production in the host.

Answer 95

Streptolysin S (SLS)

Question 96

Transforms the plasminogen of human plasma into plasmin, an active proteolytic enzyme that digests fibrin and other proteins allowing bacteria to escape from blood clots.

Answer 96

Streptokinase

Question 97

Its action is blocked by non-specific serum inhibitors and anti-streptokinase antibody.

Answer 97

Streptokinase

Question 98

has been given intravenously for treatment of pulmonary emboli, coronary artery, and venous thromboses.

Answer 98

Streptokinase

Question 99

Liquefies purulent discharges by hydrolyzing DNA which promotes spread of the pathogen into the tissues.

Answer 99

Streptodornase

Question 100

Are antigenic and an antibody develops after streptococcal infections (especially after skin infections).

Answer 100

Streptodornase

Question 101

Dissolves hyaluronic acid, an important component of the ground substance of host’s connective tissue.

Answer 101

Hyaluronidase

Question 102

Aids in spreading the pathogen (spreading factor) into the host’s tissues.

Answer 102

Hyaluronidase

Question 103

Are antigenic and antibodies produced are specific for each bacterial or tissue source.

Answer 103

Hyaluronidase

Question 104

Causes lysis of host’s white blood cells.

Answer 104

Leukocidin

Question 105

Group B β-Hemolytic Streptococci (GBS): Streptococcus agalactiae: HABITAT

Answer 105

Part of the normal vaginal flora in approximately 5–30% of women; may also colonize lower gastrointestinal tract.

Question 106

Group B β-Hemolytic Streptococci (GBS): Streptococcus agalactiae: TRANSMISSION

Answer 106

is during birth by passage through the colonized birth canal (vertical transmission).

Question 107

GBS remains as a significant cause of invasive disease in the newborn

Answer 107

Neonatal meningitis and septicemia

Question 108

A predisposing factor in the acquisition of disease is the immunologic immaturity of neonates as antibody production does not begin until several months after birth.

Answer 108

Neonatal meningitis and septicemia

Question 109

Neonatal GBS disease is associated with two clinical syndromes:

Answer 109

Early onset infection and Late onset infection

Question 110

Occurs during the first 5 to 6 days of life, however, in more than half the
cases, infants become ill within the first 12 to 20 hours after birth.

Answer 110

Early onset infection

Question 111

Acquired either by ascending infection before delivery, through
ruptured fetal membranes, or during passage through a birth canal

Answer 111

Early onset infection

Question 112

Pathogen invades the pulmonary endothelial and epithelial cells, and
gains access to the bloodstream.

Answer 112

Early onset infection

Question 113

The disease spectrum includes bacteremia, pneumonia, meningitis,
septic shock, and neutropenia.

Answer 113

Early onset infection

Question 114

Becomes clinically evident 7 days to 3 months (average 3 to 4 weeks)
after birth.

Answer 114

Late onset infection

Question 115

Results from postnatal acquisition of the organism acquisition from the
mother, other caregivers, or nosocomially

Answer 115

Late onset infection

Question 116

Bacteremia is the predominant clinical presentation, and about 25% of
these infants also develop group B streptococcal meningitis.

Answer 116

Late onset infection

Question 117

GBS were known for many years as the cause of mastitis in cattle.

Answer 117

Bovine mastitis

Question 118

It was not until Lancefield defined streptococcal classification in the 1940s that their role in human
disease was recognized. S. agalactiae was identified in the 1970s as a significant cause of invasive
disease in the newborn.

Answer 118

Bovine mastitis

Question 119

is the major virulence factor for GBS

Answer 119

Capsule of Enterococcus species and Group D streptococci (nonenterococcus)

Question 120

A polysaccharide capsule consisting primarily of sialic acid

Answer 120

Capsule of Enterococcus species and Group D streptococci (nonenterococcus)

Question 121

Responsible for the resistance to clearance by innate immune defenses in
the bloodstream as a consequence of molecular mimicry because sialic
acid is present on human cells.

Answer 121

Capsule of Enterococcus species and Group D streptococci (nonenterococcus)

Question 122

Promotes resistance to opsonin-mediated phagocytosis by inhibiting
deposition of C3b on the bacterial cell surface

Answer 122

Capsule of Enterococcus species and Group D streptococci (nonenterococcus)

Question 123

A diffusible, heat-stable, pore-forming protein

Answer 123

Christie-Atkins-Munch-Peterson (CAMP) Factor of Enterococcus species and Group D streptococci (nonenterococcus)

Question 124

Promotes lysis of host’s cell by formation of pores on the cell membrane

Answer 124

Christie-Atkins-Munch-Peterson (CAMP) Factor of Enterococcus species and Group D streptococci (nonenterococcus)

Question 125

Binds to Fc region of immunoglobulins preventing opsonin-mediated
phagocytosis

Answer 125

Christie-Atkins-Munch-Peterson (CAMP) Factor of Enterococcus species and Group D streptococci (nonenterococcus)

Question 126

Acts on sphingomyelin that causes lysis of a variety of host cells.

Answer 126

β-hemolysin of Enterococcus species and Group D streptococci (nonenterococcus)

Question 127

Together with CAMP factor, produces synergistic hemolysis.

Answer 127

β-hemolysin of Enterococcus species and Group D streptococci (nonenterococcus)

Question 128

Were previously termed “enterococcal group D streptococci”, but now
reclassified into new genus Enterococcus

Answer 128

Enterococcus species

Question 129

Are part of the normal enteric microbiota and are transmitted by direct
contact with fecally-contaminated materials; urethra and female genital tract
can be colonized.

Answer 129

Enterococcus species

Question 130

Are important agents of nosocomial infections; may enter the bloodstream
during GIT or GUT manipulation.

Answer 130

Enterococcus species

Question 131

Show resistance to penicillin and other antimicrobial agents to which other
streptococci are generally susceptible; E. faecium is usually much more
antibiotic-resistant than E. faecalis.

Answer 131

Enterococcus species

Question 132

May cause endocarditis in adults, and meningitis and bacteremia in neonates.

Answer 132

Enterococcus species

Question 133

Less than one third are associated with human diseases.

Answer 133

Enterococcus species

Question 134

is the most common and causes 85–90% of

enterococcal infections

Answer 134

Enterococcus faecalis

Question 135

causes 5–10% of

enterococcal infections

Answer 135

Enterococcus faecium

Question 136

Termed the “nonenterococcal Group D streptococci” that remain in the genus
Streptococcus

Answer 136

Group D streptococci

Question 137

Compose only a small part of the enteric flora of humans and animals

Answer 137

Group D streptococci

Question 138

Implicated in UTI, endocarditis, and septicemia.

Answer 138

Group D streptococci

Question 139

is the most important species to humans (animal species in

the bovis group have been assigned to the species Streptococcus equinus)

Answer 139

Streptococcus bovis

Question 140

A normal colonizer of the upper respiratory tract of 5–40% of humans.

Answer 140

Streptococcus pneumoniae ; Common name: Pneumococcus

HABITAT

Question 141

Disease develops by endogenous spread of the organism from its habitat, esp.
among individuals with weakened respiratory defenses.

Answer 141

Streptococcus pneumoniae ; Common name: Pneumococcus

HABITAT

Question 142

Person-to-person transmission rarely occurs by respiratory droplets, usually from a
healthy carrier.

Answer 142

Streptococcus pneumoniae ; Common name: Pneumococcus

TRANSMISSION

Question 143

S. pneumoniae is the most common cause (about 80%) of community-acquired
bacterial pneumonia esp. the elderly (after 65 years), but also in infants.

Answer 143

Pneumococcal pneumonia

Question 144

Entrance of bacteria into the lungs initiates acute and massive inflammatory
response that fills the lungs (and bronchioles) with fluid; consolidation of fluid leads
to lobar pneumonia.

Answer 144

Pneumococcal pneumonia

Question 145

Produces a lobar pneumonia with symptoms that include high fever, chills, rapid
breathing, chest pain, and rust-colored sputum from blood coughed up from the
lungs.

Answer 145

Pneumococcal pneumonia

Question 146

Bacteremia is present in 10–20% of cases particularly evident early in the disease,
when the fever is high.

Answer 146

Pneumococcal pneumonia

Question 147

Predisposing conditions for pneumonia:

Answer 147

. Antecedent influenza or measles infection: damage to mucociliary elevator
. Chronic obstructive pulmonary disorders
. Congestive heart failure
. Alcoholism
. Asplenia predisposes to septicemia

Question 148

Occuring readily in children, bacteria gain access to the paranasal sinuses
causing sinusitis; or into the chamber of the middle ear by way of the eustachian
tube and cause middle ear infection called otitis media.

Answer 148

Sinusitis and otitis media

Question 149

Most common cause of meningitis among adults, when organisms from the
respiratory tract reach the CNS; may also endocarditis and septic arthritis.

Answer 149

Systemic complications / Other infections

Question 150

Classifies pneumococci into more than 90 serotypes

Answer 150

Polysaccharide capsule

Question 151

The primary virulence factor of pneumococci, with some capsular types more
virulent than the others. In adults, capsular types 1–8 are responsible for about
75% of cases of pneumococcal pneumonia and for more than half of all
fatalities in pneumococcal bacteremia; in children, types 6, 14, 19, and 23 are
frequent causes of infection; no virulence if without capsule.

Answer 151

Polysaccharide capsule

Question 152

Delays ingestion by phagocytes thereby promoting multiplication of the
organism in the tissues of the host.

Answer 152

Polysaccharide capsule

Question 153

Enzyme that cleaves IgA, allowing bacteria to adhere to and colonize mucous
membranes.

Answer 153

IgA protease

Question 154

Exhibits toxicity for pulmonary endothelial cells and direct effect on cilia that
contributes to the disruption of endothelial barrier.

Answer 154

Pneumolysin O

Question 155

Facilitates the access of pneumococci to the alveoli and eventually their
spread beyond into the bloodstream.

Answer 155

Pneumolysin O

Question 156

Lyses phagocytes and suppresses host inflammatory and immune functions.

Answer 156

Pneumolysin O

Question 157

Also referred to as spreading factor

Answer 157

Neuraminidase

Question 158

It hydrolyses neuraminic acid, an important component of mucus that covers
cells of the respiratory tract and protects them from bacterial attachment.

Answer 158

Neuraminidase

Question 159

Is an autolysin that causes lytic dispersal of pneumolysin and hemolysin

Answer 159

Amidase

Question 160

Causes dermal hemorrhage in experimental animals

Answer 160

Purpura-producing principle

Question 161

The most prevalent members of the normal microbiota of the

oropharynx.

Answer 161

Viridans streptococci

Question 162

The most frequent cause of subacute bacterial endocarditis

(SBE) in individuals with damaged (or prosthetic) heart valve.

Answer 162

Viridans streptococci

Question 163

May enter the blood stream through dental procedure (tooth
extraction, or dental prophylaxis) or by simply brushing the
teeth; form biofilm that bind vegetations (consist of fibrin,
platelets, blood cells, and bacteria) on the damaged heart
valves; the clinical course of the diseases is gradual, but is
invariably fatal in untreated cases.

Answer 163

Viridans streptococci

Question 164

is a normal flora of the oral cavity and is responsible
for dental caries (tooth decay) due to the following activities
of bacteria when they are not removed regularly through
brushing and flossing

Answer 164

S. mutans

Question 165

S. mutans synthesizes large
polysaccharides, dextrans, that build up on the surfaces of the teeth, entrap
bacteria and food debris. The combination of dextrans, bacteria, and debris is
known as dental plaque, which fosters dental caries.

Answer 165

Biofilm formation

Question 166

S. mutans and other bacteria in plaque produce

large amounts of acids that will break down the enamel of the teeth.

Answer 166

Carbohydrate fermentation