Streptococci Flashcards
Outline all the species of streptococci
Strep pneumonia
Strep pyogenes
Strep agalactiae
What are the classification for streptococci?
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
Is streptococci Gram stain? positive or negative ?
Gram positive - thick peptidoglycan in cell wall = PURPLE STAIN
What kind of anaerobes are streptococci?
Facultative anaerobes - can survive in aerobic and anaerobic conditions
Is streptococci catalase negative or positive?
Catalase negative meaning it doesn’t have catalase enzyme
How are streptococci classified according to their hemolysis in blood agar?
Group A (alpha) and group B (beta)
ALPHA haemolytic = streptococci viridans
BETA hemolytic = streptococci pyogenes and agalactiae
State the additional structures found on streptococci?
> capsulated
flagella
non sporing
What culture medium is used for streptococci?
Glucose broth medium
Blood agar 5%
What are streptococci resistant in?
Bile
Alkaline pH
Salts
What are the pathogenic factors of GOUP A STREPT (GAS)?
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
What exotoxins are produced by streptococci?
> erythrogenin (produced in scarlet fever)
cardiohepatic toxin
streptokinase
Enzymes:
>hialuronidase
>DNA-ASE
What diseases are caused by GROUP A STREPT (GAS)?
Pyogenic:
>local = tonsilitis, otitis, sinusitis, rhinitis, cellulitis
>invasive (generalised) = meningitis, scarlet fever, endocarditis, sepsis
Post-streptococcal complications: (autoimmune)
>rheumatism
>acute glomerulonephritis
Names the species of group b streptococci?
Streptococci agalactiae
Wha diseases do group B streptococci cause?
Neonatal meningitits
neonatal pneumonia
Sexually transmitted disease: cervicitis + uthritis
sepsis
What local infection does strep. agalactiae cause?
Vaginal infection can lead to»_space; sepsis in new borns and meningitis in new borns
What biological specimens can be taken for the diagnosis of streptococci?
> nasopharyngeal swabs > CSF > blood culture > urine > genital swabs > pus wounds
Is there a vaccine for GROUP A STREP? GAS?
NO VACCINE FOR GAS
Give examples of non specific immune stimulates for streptococci infections?
Immundon
Bronhovaxome
Give examples of specific therapy for streptococci infection?
ALL GAS are PENICILLIN SENSITIVE - CAN BE KILLED BY PENICILLIN
Macrolides: Azitromycin and Clarithromycin
Cephalosporins
