03 - Gram + Cocci - Streptococcus: pyogenes (Group A & B), pneumoniae, others

Question 1

Streptococcus identified by both

Answer 1

genus & species as well as group & type antigens

Question 2

Gram positive coccus in chains

Beta hemolytic colonies – referred to as “group A beta Steptococcus” consists of several antigenic types

Answer 2

Streptococcus pyogenes, Group A

Question 3

(1) Skin & Tissue infections
(2) Necrotizing fascitis
(3) Acute exudative pharyngitis
(4) Post Streptococcal complications (rheumatic fever & acute glomerluonephritis

Answer 3

Streptococcus pyogenes, Group A

Question 4

Etioloic agent of:

Skin & tissue infections -

impetigo, cellulitis, erysipelas (type of cellulitis on skin, esp. leg & face) – along with Staphyloccus aureus cases about 90% of these skin infections; may be accompanied by scarlet fever

scarlet fever– skin rash due to erythrogenic toxin *** antibody to toxin prevents rash in future infections

Answer 4

Streptococcus pyogenes, Group A

Question 5

Etioloic agent of:

Necrotizing fascitis (streptococcal gangrene, invasive cellulitis, “flesh-eating bacteria”) and Streptococcal Toxic Shock Syndrome

Answer 5

Streptococcus pyogenes, Group A

Question 6

(a) acute toxic and necrotic invasion of tissue – super-antigen effects
(b) Necrotizing fascitis – characterized by the rapid destruction of muscle and fat tissue with high fever and prominent pain; highly invasive and life threatening

Treatment?

Answer 6

Streptococcus pyogenes, GroupA

treatment — aggressive antimicrobic therapy (penicillin) and surgical intervention (debridement of affected tissue to remove toxin)

Question 7

Acute exudative pharyngitis

2- 4 days incubation

SUDDEN fever, sore throat, and exudative tonsillitis or pharyngitis with enlarged and tender cervical lymph nodes

Symptoms last a few days (3-5) w/ out Abx

Mainly children 5-15 y/o during Colder months (crowding and dry nasal passages)

Major problem is the possibility of post-streptococcal complications

Answer 7

Streptococcus pyogenes, Group A

Question 8

with rare exception, all members of a ____ have the same Gram stain morphology

Answer 8

Genus

Question 9

Post streptococcal complications

Answer 9

rheumatic fever & acute glomerulonephritis

Streptococcus pyogenes, Group A

Question 10

rheumatic fever & acute glomerulonephritis

Answer 10

Streptococcus pyogenes, Group A

post streptococcal complications

Question 11

autoimmune reaction of Ag-Ab complexes on the basal membranes of the affected organs (No live bacteria in heart or kidney tissue) – specific antigenic types are responsible

Answer 11

post streptococcal complications seen in Streptococcus pyogenes, Group A

Question 12

Ag-Ab complexes attack heart tissue – specific antigenic types; especially follows throat infections

Answer 12

Rheumatic fever (seen in Streptococcus pyogenes, Group A)

Question 13

Ag-Ab complexes attack kidney tissue – specific antigenic types; especially follows throat or skin infections

Answer 13

acute glomerulonephritis (seen in Streptococcus pyogenes, Group A)

Question 14

Virulence factors of Streptococcus pyogenes, Group A

1) Numerous –
(2) Capsule of
(3) Cell wall
(4
(5) _____ O and S

Answer 14

Virulence factors seen in Streptococcus pyogenes, Group A

(1) Numerous invasive enzymes and toxins
(2) Capsule of hyaluronic acid appears similar to “self” Ag to host defenses – slow Ab response
(3) Cell wall “M” protein is antiphagocytic
(4) Erythrogenic toxin – scarlet fever rash
(5) Streptolysin O and S — cytotoxic; basis of ASO titer and related tests

Question 15

Laboratory diagnosis of Streptococcus pyogenes, Group A

Answer 15

Culture and biochemical ID

Antigen detection / ID

(a) Direct throat swab – low sensitivity
(b) Culture confirmation – very accurate

Antimicrobic susceptibility tests usually not needed

Question 16

Cell wall “M” protein is antiphagocytic

Answer 16

Streptococcus pyogenes, Group A

Question 17

Streptolysin O and S – cytotoxic; basis of ASO titer and related tests

Answer 17

Streptococcus pyogenes, Group A

Question 18

Scarlet fever – skin rash due to erythrogenic toxin ** Antibody to toxin prevents rash in future infections

Answer 18

Streptococcus pyogenes, Group A

Question 19

Erythrogenic toxin – scarlet fever rash

Answer 19

Streptococcus pyogenes, Group A

Question 20

do we usually do Antimicrobic susceptibility tests for Streptococcus pyogenes, Group A?

Answer 20

No

Question 21

Capsule of hyaluronic acid appears similar to “self” Ag to host defenses – slow Ab response

Answer 21

Streptococcus pyogenes, Group A

Question 22

a. Causes pneumonitis and meningitis in neonates due to inoculation from vaginal flora; infection can be quite severe in newborns and leave permanent damage or cause death
b. Expectant mothers are screened around 35th week to determine if bacteria are present.

Answer 22

Group B Streptococcus

Question 23

these infections are seen in neonates and occur during birth from mothers birth canal or vagina

Answer 23

Group B Streptococcus

Question 24

vagina microbes causing infections in babies

Answer 24

Group B Streptococcus

Question 25

a. Gram-positive coccus in pairs
b. Large, mucoid, alpha-hemolytic colonies
c. Multiple antigenic types (>90); about 6 are frequently recovered and highly infectious
d. Normal flora of upper respiratory tract in 30 to 60% of population (esp. when children are in the household). Infection usually results from transmission of normal flora into adjacent sites.

Answer 25

Streptococcus pneumoniae

Question 26

describe morphology of Streptococcus pneumoniae

Answer 26

Gram-positive coccus in pairs

Question 27

Multiple antigenic types with 6 highly infectious ones that are commonly found

often found in Upper Respiratory Tract and infections usually caused by normal flora migrating to sites outside of URT.

Answer 27

Streptococcus pneumoniae

Question 28

Streptococcus pneumoniae is an etiologic agent of?

Answer 28

(1) Lobar and bronchial pneumonia (#1 cause)
(2) Sinusitis
(3) Otitis media (~40% of all cases)
(4) Meningitis – major cause (esp. in patients older than 10 yr.) – follows invasive pneumococcal infection & bacteremia

Question 29

What is the number one cause of lobar and bronchial pneumonia?

Answer 29

Streptococcus pneumoniae

Question 30

All of the following are seen in which disease caused by which microbe?

(a) Causes 50-90% of pneumonias; esp. in children under 5 yr and elderly
(b) Invasive strains may lead to empyema, bacteremia, and/or meningitis
(c) Mortality: about 5-10%; esp. in children under 5 yr and elderly

Answer 30

Lobar and bronchial pneumonia and the number one cause is Streptococcus pneumoniae.

Question 31

Otitis media (causes ~40% of all cases)

Answer 31

Streptococcus pneumoniae

Question 32

The following are Virulence factors for which microbe?

(1) Antiphagocytic capsule
(2) IgA protease
(3) Increase in penicillin resistance (about 30% are resistant to penicillin & 15% are resistant to 2nd or 3rd antimicrobic)
(4) Some strains are invasive

Answer 32

Streptococcus pneumoniae

Question 33

How do we diagnose Streptococcus pneumoniae in the lab?

Answer 33

(1) Culture (alpha hemolytic) and biochemical identification

(2) Antigenic identification from cerebrospinal fluid

Question 34

Other Streptococci of human significance

a. Other beta-hemolytic Streptococcus species: mostly in Groups C, F, G (primarily ____ and _____) – occasional pathogens
b. ________ (this is not a species name) – a group of alpha-hemolytic and non- hemolytic species associated with various low-frequency diseases (abscesses, bacteremia & endocarditis, dental caries, etc)

Answer 34

S. dysgalactiae and S. anginosus

Viridans streptococci (not a species name)

Question 35

Gram positive cocci in chains can be either one of two choices….

Answer 35

Steptococcus pyogenes, group A

OR

Enterococcus faecalis

Question 36

Gram-positive cocci in chains (formerly a member of group D Streptococcus)

Answer 36

Enterococcus faecalis

Question 37

Enterococcus faecalis is an etiologic agent of:

Answer 37

(1) Frequent cause of nosocomial infctions - surgical wounds and urinary tract
(2) occasional cause of bacteremia (9%)

Question 38

Mulit-drug resistant strains exist with increased frequency, including Vancomycin resistance (VRE = Vancomycin Resistant Enterococcus) which is found in which microbe?

Answer 38

Enterococcus faecalis

Question 39

Gram positive cocci?

Answer 39

Staphylococcus
Streptococcus
Enterococcus

Question 40

(streptococcal gangrene, invasive cellulitis, “flesh- eating bacteria”) and Streptococcal Toxic Shock Syndrome

Answer 40

Necrotizing fascitis caused by streptococcus pyogenes group A

Question 41

a. Gram-positive coccus in chains

b. Beta hemolytic colonies

Answer 41

Streptococcus pyogenes, group A

Question 42

impetigo, cellulitis, erysipelas (type of cellulitis on skin, esp. leg & face)

Answer 42

Streptococcus pyogenes, group A

or Staphylococcus aureus

Question 43

autoimmune reaction of Ag-Ab complexes on the basal membranes of the affected organs (Post streptococcal complications)

Answer 43

(a) Rheumatic fever – Ag-Ab complexes attack heart tissue – specific antigenic types; especially follows throat infections
(b) Acute glomerulonephritis – Ag-Ab complexes attack kidney tissue – specific antigenic types; usually follows throat or skin infections

Question 44

Virulence factors
(1) Numerous invasive enzymes and toxins

(2) Capsule of hyaluronic acid appears similar to “self” Ag to host defenses – slow Ab response
(3) Cell wall “M” protein is antiphagocytic
(4) Erythrogenic toxin – scarlet fever rash
(5) Streptolysin O and S – cytotoxic; basis of ASO titer and related tests

Answer 44

Streptococcus pyogenes, group A

Question 45

skin rash due to erythrogenic toxin

** Antibody to toxin prevents rash in future infections

Answer 45

Scarlet fever (usually along with skin infections of impetigo, cellulitis, erysipelas (type of cellulitis on skin, esp. leg & face))