2 Streptococci Flashcards
Gram positive cocci arranged in chains or pairs
Streptococci
Not all streptococci catalase negative
A- true
B- false
False
Produce no heamolysis
A- alpha heamolytic streptococci
B- beta heamolytic streptococci
C- gamma heamolytic streptococci
Gamma haemolytic streptococci
Produce partial haemolysis (with greenish discolouration of blood agar).
A- alpha heamolytic streptococci
B- beta heamolytic streptococci
C- gamma heamolytic streptococci
Alpha haemolytic streptococci
Produce complete haemolysis ( with a clear zone around the colonies).
A- alpha heamolytic streptococci
B- beta heamolytic streptococci
C- gamma heamolytic streptococci
Beta haemolytic streptococci
Examples of beta haemolytic bacteria:
S.pyogenes ( gp A ) and S.agalactiae ( gp B )
It has protein layer in its cell wall
A- S.pyogenes
B- S.agalactiae
S.pyogenes
The most important protein in S.pyogenes is
M protein
M protein is the most important virulence factor as it’s antiphagocytic
A- true
B- false
True
Strains of S. pyogenes of certain M types are……….., whereas strains of other M types are……….. .
rheumatogenic, nephritogenic
Streptolysin … : antigenic, O2 labile.
Streptolycin O
Streptolysin … : non-antigenic O2 stable.
Streptolysin S
Produced by some strains of S.pyogenes. Responsible for the skin rash of scarlet fever.
Pyrogenic exotoxin A (erythrogenic toxin )
A protease that rapidly destroy tissues
Pyrogenic exotoxin B
Produced in large amounts by the strains of S. pyogenes that cause necrotizing fasciitis. These strains are called flesh eating bacteria. A- pyrogenic exotoxin A B- pyrogenic exotoxin B C- pyrogenic exotoxin C D- streptolysins
pyrogenic exotoxin B
Spreading factor :
A- streptokinase
B- Hyaluronidase
C- streptodornase
B
Fibrinolysin :
A- streptokinase
B- Hyaluronidase
C- streptodornase
A
DNAse and have 4 antigenic types (A-D) :
A- streptokinase
B- Hyaluronidase
C- streptodornase
C
The predominant type of streptodornase is
Type B
The commonest infection caused by S. pyogenes
A- impetigo (pyoderma)
B- erysipelas
C- Puerperal sepsis
D- streptococcal sore throat ( follicular tonsillitis )
streptococcal sore throat ( follicular tonsillitis )
Usually accompanied with. septicaemia :
A- impetigo (pyoderma)
B- erysipelas
C- Puerperal sepsis
D- streptococcal sore throat ( follicular tonsillitis )
C
Catalase test of streptococci pyogenes :
Negative
Sensitive to bacitracin.
S. Pyogenes
Positive PYR, Serologic grouping using specific antisera.
S. Pyogenes
S. pyogenes does not grow on bile media such as MacConkey’s agar.
A- true
B- false
True
GIVE REASON :
In case of puerperal sepsis, blood culture is better than uterine swab
to avoid possible contamination of the specimen with the normal vaginal flora
This organism inhabits about 25 % of normal adult vagina.
Group B beta heamolytic streptococci s.agalactiae
…….. are also an important cause of neonatal pneumonia.
Group B streptococci s.agalctiae
Viridans streptococci. Pneumococci (Streptococcus pneumoniae). Is :
A- alpha Haemolytic Streptococci
B- beta Haemolytic Streptococci
C- gamma Haemolytic Streptococci
A
They are normal flora of the oral cavity and upper respiratory tract.
Viridans streptococci
cause subacute bacterial endocarditis (SBE).
A- Pneumococci streptococci
B- Viridans streptococci
C- S. agalactiae
B
……… form part of the normal microbial flora of the upper respiratory tract.
Pneumococci
Pneumococci cause:
Meningitis, Pneumonia
The most important virulence factor in S. Pneumoniae is
The capsule ( antiphagocytic )
Pneumococci produce:
small alpha haemolytic colonies
The commonest infections caused by Enterococci are:
urinary tract infections
The most common and most important streptococcus gp A
S. Pyogenes
What type of antigenic sreptodornase can be used diagnostic purposes :
Type B
Local pyogenic infection :
1- Streptococcal sore throat ( follicular tonsillitis )
2- impetigo (pyoderma)
Invasive diseases :
1- Erysipelas
2- Soft tissue sepsis
3- Acute bacteriaa endocarditis
4- Puerperal sepsis
Uterine infection following labour or abortion, usually accompanied with septicaemia.
Puerperal sepsis
Wound infection, cellulitis
Soft tissue sepsis
The characteristic lesion seen in scarlet fever is
Strawberry tongue
Scarlet fever caused by ….
Streptococcal strains able to produce erythrogenic toxin. (S.pyrogens)
Post-streptococcal immunologic diseases are due to direct effect of the organism.
A- true
B- false
False, not due to ..
……. Usually follows throat infection.
Glomerulonephritis follows …….
Rheumatic fever,
skin infection
S. pyogenes can be differentiated from other groups of β haemolytic streptococci by:
- sensitive to bacteriacin
- positive PYR test
- serologic grouping using specific antisera.
Septic abortion and puerperal sepsis and occasionally urinary tract infection caused by:
S. agalactiae
Some species of ………… are involved in dental plaque and dental caries.
viridians streptococci
15-25 % of pneumococcal infections are accompanied by …..
Bacteraemia
Virulence factors of S. Pneumoniae is
Capsule, IgA1 and peumolysin.
Most strains of Enterococci react with the…………. .
Lancefield group D antisera
Pneumococci are normal inhabitants of the intestine
- true
- false
False, is Enterococci
common cause of nosocomial UTI infections, particularly in intensive care units.
Enterococci
The commonest infections caused by Enterococci are:
Urinary tract infection.
Other enterococcal infections include:
- Endocarditis
- pelvic and intra-abdominal in fractions 
- bacteremia and meningitis