Streptococci.pptx

strepto

1. Streptococci 1/2 6/19/2012 1 Professor Sudheer Kher 1

2. 6/19/2012 2 G e n e r a l f e a t u r e s 1. Gram positive cocci in chains (short or long) & pairs 4. Grow on blood agar (fastidious) 2. Catalase negative 3. Usually sensitive to penicillin

3. 6/19/2012 3 Classification Based on O 2 Aerobes Anaerobes Peptostreptococci Growth on BA α h emolysis β h emolysis γ h emolysis Incomplete h emolysis (green color) Complete h emolysis α / β / no h emolysis Viridans streptococci Streptococci pneumoniae Enterococcus fecalis Lancefield grouping grp sp carbohydrate Ag Group A – U (21 groups) Griffith typing of Group A on MTR proteins into > 100 types

4. 6/19/2012 4 Streptococcus agalactiae (Group B) Streptococcus pyogenes (Group A) Clinically Important Species Respiratory infections Skin & subcutaneous infections Non suppurative complications Pharyngitis (sore throat) Suppurative complications Quinsy, Ludwigs angina, adenitis, otitis , mastoiditis Pyoderma , Erysipelas, impetigo Cellulitis , necrotising fasciitis ( flesh eating bacteria ) Acute rheumatic fever Acute glomerulonephritis Puerperal sepsis Neonatal meningitis --------------------------------------------------------------------------------------

5. 6/19/2012 5 Clinically Important Species Viridans streptococci Streptococcus pneumoniae Enterococcus fecalis (Group D) Endocarditis & Dental caries Pneumonia & Meningitis Empyema , pericarditis , otitis media, sinusitis, conjunctivitis, arthritis, peritonitis UTI, wound infection, endocarditis Septicemia, peritonitis, intra-abdominal abscess

6. Group A Streptococcus 6/19/2012 6 1

7. 6/19/2012 7 Group A streptococcal Diseases Respiratory infections Skin & subcutaneous infections Non suppurative complications Pharyngitis (sore throat) Suppurative complications Quinsy, Ludwigs angina, adenitis, otitis, mastoiditis Pyoderma Erysipelas, impetigo Cellulitis, necrotising fasciitis ( flesh eating bacteria ) Acute rheumatic fever Acute glomerulonephritis

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10. 6/19/2012 10 Group A Strept – virulence factors M protein & capsule Destroy PMNs Antigenic – produce ASLO Streptolysin S (SLS) Exotoxins Oxygen stable , non-antigenic Anti-phagocytic Active only under anaerobic condition Damage cardiac cells Streptolysin O (SLO) Oxygen labile Streptococcal Pyrogenic Exotoxin (SPEs) Manifestation of scarlet fever / TSS Exoenzymes Streptodornase / streptokinase / / C5a peptidase / IgAase / hyalarunidase

11. 6/19/2012 11 Non suppurative Disease Acute Rheumatic Fever (ARF) Develops 1-3 weeks after pharyngitis Acute Glomerulonephritis (AGN) Result of antigenic mimicry Antibodies against M protein of rheumatogenic strains cross react with sarcolemmal membrane leading to cardiac damage, synovium , kidney, brain Immune complex disease Soluble complex of Ab & streptococcal Ag deposit in renal basement membrane & elicit destructive inflammatory response Unlike ARF, AGN does not predispose its victim to increased susceptibility to further attack when later infected with GABHS Develops 10 days after pharyngitis or more commonly skin infections.

12. 6/19/2012 12 Lab diagnosis – GABHS BA culture: beta hemolysis Catalase Negative Specimens: throat swab, pus, blood, PYR test + Penicillin sensitive Grouping by LA (Latex agglutination) Smears: GPC in chains Bacitracin sensitive Typing - epidemiology ASO titre / ADNase B test PYR - pyrrolidonyl-arylamidas test

13. 6/19/2012 13 Treatment & Prevention GABHS Penicillin, ampicillin, macrolides, cephalosporins Prevention Treat GABHS pharyngitis as early as possible to prevent ARF Diagnose GABHS pharyngitis early for preventing the spread No vaccine available

14. Group B Streptococcus 6/19/2012 14 1

15. 6/19/2012 15 Streptococcus agalactiae (Group B) Normal flora in GIT, lower genital tract Neonatal meningitis (early / delayed) Risk factors Premature rupture < 37 wks Pyrexia during labor Poly babies Presence of GBS in vagina Previous history of sepsis Puerperal sepsis Prolonged rupture > 18 hrs

16. 6/19/2012 16 Lab diagnosis GBS BA culture: beta hemolysis Catalase Negative Specimens: CSF, blood, vaginal smears, urine CAMP Test + Hydrolysis of sodium hippurate Grouping by LA Smears: GPC in Chains Bacitracin resistance Antigen detection in urine or CSF by LA / ELISA/ CIEP

17. 6/19/2012 17 Staph streak + ve control (Grp B Strep) - ve control (Grp A strep) Test (unknown) CAMP Test – Group B Streptococcus

18. 6/19/2012 18 Staph streak + ve control (Grp B Strep) - ve control (Grp A strep) Test (unknown) CAMP Test – Group B Streptococcus

19. 6/19/2012 19 Treatment & Prevention GBS Penicillin, ampicillin, macrolides, cephalosporins Prevention Testing recto-vaginal GBS at 36 weeks Treat all GBS positives Treat all preterm pregnancy No vaccine available

20. Group D Streptococcus 6/19/2012 20 1

21. 6/19/2012 21 Group D Streptococcus Normal flora in GIT, lower genital tract Nosocomial / opportunistic pathogen Enterococcus E. fecalis E. faecium S. bovis Endocarditis in patients with GIT tumors Non-Enterococcus UTI, wound infection, endocarditis Septicemia, peritonitis, intra-abdominal abscess

22. 6/19/2012 22 Lab diagnosis -Enterococcus BA culture: alpha / beta / no hemolysis Catalase Negative Specimens: urine, pus, blood Positive growth in 6.5% Nacl Penicillin resistance Grouping by LA Smears: GPC in pairs or short chains Bile esculin positive Penicillin + gentamicin or vancomycin

23. 6/19/2012 23 Summary - Streptococcus General features Classification Clinically important species Diseases caused by these species Pathogenicity & virulence Diagnosis: Clinical / Laboratory Management Prevention & Rehabilitation

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