STREPTOCOCCI Streptococci facultative anaerobe Grampositive chains or pairs

STREPTOCOCCI

Streptococci • facultative anaerobe • Gram-positive • chains or pairs • catalase negative (staphylococci are catalase positive)

Streptococcus in chains

Streptococcus pneumoniae (diplococcus). Fluorescent stain

• Streptococci • Lancefield groups *Satu atau lebih spesies per group *antigen permukaan

groupable streptococci • A, B and D – most important • C, G, F – rare

Non-groupable • S. pneumoniae – pneumonia • viridans streptococci – e. g. S. mutans * dental caries

hemolysis reaction - sheep blood agar • α (alpha) – partial hemolysis • green color • β (beta) – complete clearing – A and B • γ (gamma) – no lysis

Hemolysis • Groups A an B –β • Group D – α or γ • S. pneumoniae and viridans –γ

• hemolysis reaction + one characteristic – presumptive identification

Group A streptococcus (S. pyogenes)

• Group A streptococcal menginfeksi semua umur • Insiden tertinggi pd usia 5 -15 thn

S. pyogenes -suppurative • non-invasive – pharyngitis – Infeksi kulit, impetigo • invasive bacteremia – toxic shock-like syndrome – "flesh eating" bacteria – pyrogenic toxin

Pyrogenic toxin • superantigen • T cell mitogen • Mengaktifkan sistem imun

Scarlet fever • rash • erythrogenic toxin

non-suppurative • rheumatic fever – inflammatory disease – life threatening – Sekuel kronik • demam • jantung • sendi • rheumatic tidak sama dengan rheumatoid arthritis

Rheumatic fever -etiology Ø M protein – cross-reacts heart myosin – autoimun Ø Antigen dinding sel – sedikit dicerna in vivo – bertahan lama

Rheumatic fever • penicillin - menyembuhkan pharyngitis - Menurunkan resiko carditis

Acute glomerulonephritis • immune complex disease of kidney

Major pathogenesis factors • lipoteichoic acid/F protein – fimbriae – binds to epithelial cells • M protein – anti-phagocytic

M protein • major target – Imunitas alami • strain variation – antigenicity • re-infection – Terjadi dengan strain yg berbeda

Capsules • Anti-phagocytic – mucoid strains

Isolation and identification • β hemolytic colonies – bacitracin menghambat pertumbuhan • β hemolytic colonies – group A antigen

β hemolysis • hemolysin O – Sensitif oksigen • hemolysin S – Non sensitive oksigen

Post-infectious diagnosis (serology) • Antibodi thd streptolysin O • Penting! Bila menetap sekuel kronik terjadi

Serotyping üM üT üR

Group B streptococcus • • • neonatal meningitis septicemia transmission – vaginal flora

Group B streptococcus identification • • • β hemolysis hippurate hydrolysis CAMP reaction – meningkatkan β hemolisis S. aureus

Group D streptococcus • Tumbuh pada bile esculin agar – precipitasi hitam 6. 5% salin • Tumbuh – enterococci • Tidak tumbuh – non-enterococci

Enterococci • Hubungannya agak jauh dr streptococci lain • genus Enterococcus • Flora usus – urinary tract infection • Kontaminasi dr anus – opportunistic infections • khususnya endocarditis • Paling sering E. (S. ) faecalis

Enterococci • resisten thd banyak antibiotik – termasuk vancomycin • ujung D-ala diganti dengan D-lactat

Minute colony streptococci Various groups (e. g. group A) – berbeda scr genetik * koloni yg besar (e. g. S. pyogenes) – tdk ada demam rheuma Koloni besar Koloni kecil

Viridans streptococci • • • diverse species oral Karies gigi α hemolytic dan negatif thd tes lain non-groupable. termasuk S. mutans – endocarditis – cabut gigi