Streptococci

Question 1

Outline all the species of streptococci

Answer 1

Strep pneumonia

Strep pyogenes

Strep agalactiae

Question 2

What are the classification for streptococci?

Answer 2

1) according to hemolysis in blood agar > alpha, beta, gamma
2) serological (lancefields) > A B C D G
3) ecological > pyogenic, oral, gut, anaerobic streptococci

Question 3

Is streptococci Gram stain? positive or negative ?

Answer 3

Gram positive - thick peptidoglycan in cell wall = PURPLE STAIN

Question 4

What kind of anaerobes are streptococci?

Answer 4

Facultative anaerobes - can survive in aerobic and anaerobic conditions

Question 5

Is streptococci catalase negative or positive?

Answer 5

Catalase negative meaning it doesn’t have catalase enzyme

Question 6

How are streptococci classified according to their hemolysis in blood agar?

Answer 6

Group A (alpha) and group B (beta)

ALPHA haemolytic = streptococci viridans

BETA hemolytic = streptococci pyogenes and agalactiae

Question 7

State the additional structures found on streptococci?

Answer 7

> capsulated
flagella
non sporing

Question 8

What culture medium is used for streptococci?

Answer 8

Glucose broth medium

Blood agar 5%

Question 9

What are streptococci resistant in?

Answer 9

Bile
Alkaline pH
Salts

Question 10

What are the pathogenic factors of GOUP A STREPT (GAS)?

Answer 10

associated with bacterial body:

> M-protein: antiphagocytic, anti-Co and cytotoxic activity
F-protein: frbronectin binding adhesion factor
capsule and slime

> hemolysins:

• streptolysin O > induces Ab production
• streptolysin S

Question 11

What exotoxins are produced by streptococci?

Answer 11

> erythrogenin (produced in scarlet fever)
cardiohepatic toxin
streptokinase

Enzymes:
>hialuronidase
>DNA-ASE

Question 12

What diseases are caused by GROUP A STREPT (GAS)?

Answer 12

Pyogenic:
>local = tonsilitis, otitis, sinusitis, rhinitis, cellulitis
>invasive (generalised) = meningitis, scarlet fever, endocarditis, sepsis

Post-streptococcal complications: (autoimmune)
>rheumatism
>acute glomerulonephritis

Question 13

Names the species of group b streptococci?

Answer 13

Streptococci agalactiae

Question 14

Wha diseases do group B streptococci cause?

Answer 14

Neonatal meningitits
neonatal pneumonia
Sexually transmitted disease: cervicitis + uthritis
sepsis

Question 15

What local infection does strep. agalactiae cause?

Answer 15

Vaginal infection can lead to&raquo_space; sepsis in new borns and meningitis in new borns

Question 16

What biological specimens can be taken for the diagnosis of streptococci?

Answer 16

> nasopharyngeal swabs
> CSF
> blood culture
> urine 
> genital swabs
> pus wounds

Question 17

Is there a vaccine for GROUP A STREP? GAS?

Answer 17

NO VACCINE FOR GAS

Question 18

Give examples of non specific immune stimulates for streptococci infections?

Answer 18

Immundon

Bronhovaxome

Question 19

Give examples of specific therapy for streptococci infection?

Answer 19

ALL GAS are PENICILLIN SENSITIVE - CAN BE KILLED BY PENICILLIN

Macrolides: Azitromycin and Clarithromycin

Cephalosporins