strept-entro-pnemo

Question 1

Streptococcus, gram/catalase

Answer 1

gram +, catalse -

strepto(=chain) cocci (shape)

Question 2

Some streptococci are typically seen as diplo-cocci: _________

Answer 2

Streptococcus pneumoniae

Question 3

Classification based on Hemolysis (on blood plates)
species
pneumolysin

Answer 3

b-hemolysis on blood-agar plates causes clearing at and around colonies in = Streptococcus pyogenes, staph aureus

a-hemolysis shows greening due to partial lysis of erythrocytes in S.mitis and S.pneumoniae.
pneumolysin degrades hemoglobin= green

Question 4

Streptococcal classifications

Answer 4

based on hemolysis: a, b or gamma
Lancefield groups:
serological (=antiserum) differences (mostly based on cell wall carbohydrates)
Group A: N-Ac-glucosamine + rhamnose
Group B: rhamnose + N-Ac-glucosamine + galactose

Question 5

Rapid strep throat test is based on? useful for?

Answer 5

Group A serological response.

Useful for rapid distinction from viral strep throat

Question 6

Virulence factors of streptococci

Answer 6

m protein 
capsule 
f protein 
lipoteichoic acid 
g protein 
C5a peptidase 
membrane damaging toxins 
super Ag

Question 7

m protein
where found in cell?
how many serotypes? 
Ab to this? 
binds to? effects?

Answer 7

M protein - cell wall component, >100 serotypes, membrane anchored: is an important virulence factor
• anti-M antibodies prevent infection of S.pyogenes but many serotypes. So protective immunity is type specific
• M protein binds keratinocytes, the main cell type in outer skin layer
• M protein binds fibrinogen, blocking surface from complement system components
• M protein binds complement control proteins
• Inhibits formation of opsonins by complement cascade
M protein anti-complement action through Factor H

Question 8

capsule of strep

how does group A avoid pahgo?

Answer 8

antibodies are ineffective against glycocalyx-covered surface antigens

Ø Group A strains have capsules of hyaluronic acid, mimicking
mammalian connective tissues, preventing phagocytosis.

Question 9

F protein

Answer 9

F protein (cell wall adhesin) provides adherence to the fibronectin of throat epithelial cells

Question 10

lipoteichoic acid

Answer 10

lipoteichoic acid (species-specific form) also adheres to the fibronectin epithelial cell coat

Question 11

. Capsular C3 peptidase

Answer 11

destroys opsonizing C3b complement opsonization

Thus: CR1 does not work! Phagocytosis only by IgG opsonization (FcR)

Question 12

G protein

Answer 12

G protein (cell surface) binds Fc of IgG, preventing phagocytosis based on FcReceptors

Question 13

C3b peptidase

Answer 13

Question 14

C5a peptidase in which group? how it works

Answer 14

C5a peptidase in Group A Streptococci

Question 15

membrane damaging toxins of strep. pyogenes

Answer 15

streptolysins s and o

tissue degrading enzymes

Question 16

streptolysins S, O

Answer 16

lysis of erythrocytes (direct lysis; basis of β-hemolysis) and of phagocyte lysosomal membranes (indirect lysis of leukocytes)

Question 17

secretion of tissue degrading enzymes by strep pneumo.

clinical use?

Answer 17

DNase, protease, hyaluronidase (spreading factor), streptokinase (degrades blood clots)

streptokinase is clinically useful in early vascular attack treatment because its activates plasminogen and the resulting plasmin will degrade fibrin clots formed in stroke and heart infarct.

Question 18

super Ag of strep pneumo

Answer 18

overrides t cell response= excess

SPE

Question 19

scarlet fever
strain?
virulence factor causing this?

Answer 19

Streptococcus pyogenes

Virulence factor: a superantigen SPE
Streptococcal Pyrogenic Exotoxins

Question 20

Other results of pyrogenic SPEs

Answer 20

Pyoderma (impetigo) = skin infections of face, arms, legs (pus)

Erysipelas: erythros = red, pella = skin, bullae = blisters

Question 21

streptococcal gangrene

Answer 21

Strept.pyogenes
Progression to deep, systemic infection leads to multi-organ failure and death.
necrotizing fasciitis

Question 22

Acute Pharyngitis/ Strep throat sequence and late complications

Answer 22

encounter>symptoms>recover 
late complications possible: 
glomerulonephritis- type III hyper 
rheumatic fever- type II hyper, can lead to myocarditis/ arthritis 
chorea- brain function impairment

Question 23

Rheumatic Heart Disease by Streptococci

Answer 23

Acute Rheumatic Fever:
• non-suppurative sequela with some strains of strep
• <10% of population is susceptible
• fever is non-responsive to penicillin because disease is autoimmune
• high frequency of reoccurrence
weaking of mitral valve and backflow

Question 24

Comparing Strep and Staph: characteristics

Answer 24

strep: gram + cocci in chains , b-hemolytic, cell wall with A polysac and M pro
staph: gram + cocci in clusters, cream colored, M protein

Question 25

Comparing Strep and Staph: extracellualr products

Answer 25

strep: L staph: R

Question 26

Comparing Strep and Staph: diseases caused

Answer 26

strep: L staph: R

Question 27

``` Streptococcus agalactiae group? hemolytic? aerobic? capsule? effects of children, elderly and preganant? Ab for this? ```

Answer 27

Group B, β-hemolytic (<2% non-hemolytic), chain-like growth, aerobic, polysaccharide capsule • pneumonia in neonates (neonates: <7 days of birth) • bacteremia and meningitis (neonates: >7 days of birth) • various symptoms in elderly suffering from chronic diseases (often complicated by penicillin allergy) urinary infections, bacteremia (pregnant women) Neutralizing antibodies against group B polysaccharide Ag develop quickly and protect. (maternal Abs prevent infection of neonate)

Question 28

Strains different from S.pyogenes or S.agalactiae may cause:

Answer 28

opportunistic streptococcal toxic shock syndrome (AIDS)

Question 29

``` Enterococcus faecalis gram? shape? hemolysis? virulence? aggration substance? adhesin for? cytolysin? attracts what cells? gelatinase? Ax resistance? ```

Answer 29

Gram+ cocci (Lancefield Group D streptococci) α- and non-hemolytic Facultative anaerobes, normal part of gastrointestinal flora Virulence (low): Ø aggregation substance – epithelial adhesion Ø enterococcal adhesin for collagen Ø cytolysin facilitates colonization Ø neutrophil chemo-attractant Ø gelatinase – protease for gelatin, collagen, hemoglobin Ø high, multiple antibiotic resistances (plasmid and chromosomal)* elderly; long hospitalization= (high nosocomial risk antibiotic resistance)

Question 30

Streptococcus pneumoniae hemolytic, gram, shape causes? only what strains are virulent?

Answer 30

α-hemolytic, Gram+ diplococci cause of pneumococcal pnemonia Only encapsulated strains (smooth colonies) are virulent

Question 31

pneumonia causing species

Answer 31

pnemococcal pneumonia, klebsellia pneumonia, mycoplasmal pneumonia

Question 32

pneumococcal pnemonia carrie rates and vax

Answer 32

high carrier rates and vax available

Question 33

``` klebsiella pneumonia where found? resistant? cause of? vax ```

Answer 33

enterobacteria often resistant to Ax fatal nosocomial pneumonia no vax

Question 34

mycoplamasmal pneumonia cause of? vax?

Answer 34

mild pneumo | no vax

Question 35

streptococcal pneumonia sequence

Answer 35

infection of alveoli>neutrohils invade> fluid filled> macrophages and Ax assit to beat infection

Question 36

S.pneumoniae virulence factors

Answer 36

``` a hemolysin capsule IgA protease c polaysac phosphoryl choline f antigen ```

Question 37

a hemolysins of strep pneumo

Answer 37

erythocyte lysis by pneumolysin: cholesterol-dependent action, hemoglobin destruction pneumolysin also suppresses oxidative burst in phagocytes

Question 38

capsule, s. pneumonia is anti what? what action does it facilitate?

Answer 38

``` capsule (>90 serotypes) is antiphagocytic and its anti-complement facilitates bacteremia (presence in blood circulation) and thus spreading to other tissues like brain (meningitis)*, peritonitis, arthritis, endocarditis ```

Question 39

c poly sac of s pneumonia

Answer 39

``` C polysaccharide rich in choline; precipitates CRP (C-reactive Protein, an early inflammatory signal) ```

Question 40

phosphoryl-choline of s. pneumo

Answer 40

phosphoryl-choline in cell wall activates PAF º allowing entry of bacteria into cells

Question 41

lipoteichoic acid/ F antigen of s. pneumo causes? results in?

Answer 41

alternative complement activation produces C5a | Result: typical pneumococcal leukocyte aggregation in lower respiratory tract (lungs)

Question 42

S.pneumoniae and meningitis

Answer 42

Thousands of cases of pneumococcal meningitis per year in USA is main agent with increased age, although young children more susceptible to group B strepococcus meningitis