1. Streptococcal Diseases
Streptococcus pyogenes

2. Streptococcus pyogenes Pyogenes means pus producing
One of the most important pathogens
Gram positive cocci in chains
Lancefield Serological Group A
Beta Hemolytic on blood agar

3. Gram Stain of S. pyogenes

4. Hemolysis on Blood Agar Plates
Alpha hemolysis-organism excretes hemolysins which partially break down rbc (incomplete hemolysis) thus a greenish zone appears around colony. S. pneumoniae
Beta hemolysis-organisms excretes potent hemoysins which completely lyse rbc (complete hemolysis) thus a clear zone appears around colony. S. pyogenes

5. S.pyogenes
S. pneumonia
Beta hemolysis
Alpha hemolysis

6. Diseases caused by S. pyogenes
Strep throat
Impetigo
Erysipelas
Cellulitis
Invasive Strep A infections
Necrotizing fasciitis
Myositis
Toxic shock-like syndrome

8. Erysipelas
Acute infection and imflammation of the dermal layer of skin.
Painful red patches which enlarge and thicken
Treatment -penicillin or erythromycin

9. Erysipelas

10. Strep Throat Most common of all Strep diseases
Spread by saliva or nasal secretions
Incubation period 2-4 days
Sore throat, slight fever (101)
Important to treat immediately to avoid post strep diseases

11. Diagnosis and treatment of Strep Throat
Tell tale symptoms are slight fever associated with sore throat and visual of pus in back of throat
Quick diagnostic tests (Molecular) available but must be confirmed by throat swab and growth on blood agar (beta hemolysis)

12. Diagnosis and treatment of Strep Throat
If the strain of S. pyogenes is lysogenic for a particular phage which expresses an erythrogenic toxin the result is Scarlet fever
Rash appears and characteristic is the strawberry colored tongue

13. Strawberry Tongue

14. Treatment of Strep Penicillin G or Erythromycin are drugs of choice
Although the disease is self-limiting it is important to treat immediately to avoid post strep complications

15. Poststreptococcal diseases
Rheumatic Fever-autoimmune disease involving heart valves,joints, nervous system. Follows a strep throat
Acute glomerulonehritis or Bright’s Disease-inflamatory disease of renal glomeruli and structures involved in blood filter of kidney. Due to deposition of Ag/Ab complexes

16. Rheumatic Fever
Most common cause of permanent heart valve damage in children
Exact cause not yet known but there appears to be some antibody cross reactivity between the cell wall of S. pyogenes and heart muscle

17. Rheumatic Fever Diagnosis is based on symptoms and is difficult
Occurs most frequently between ages of 6 and 15
US it is about 0.05% of pop having strep infections
100x more frequent in tropical countries

18. Rheumatic Fever
Treatment is via salicylates (aspirin derivatives) and corticosteroids to decrease inflammation and fever.

19. Glomerular Nephritis
Diagnosis based on history of Strep throat and clinical findings.
Symptoms include fever, malaise,edema, hypertension and blood or protein in urine
Occurs in 0.5% of those having strep throat.

20. Glomerular Nephritis Treatment and Recovery
Penicillin or erythromycin to eradicate and residual strep infection
80-90% of cases recover with bed rest lasting for months
Kidney damage in the remainder is often permanent resulting in chronic glomerular nephritis

21. Streptococcus Pneumonia
Caused by infection with Streptococcus pneumoniae
Gram positive, alpha hemolytic, not of lancefield serotype A
Often part of normal flora of respiratory track and becomes infective once hosts resistance is lowered. Classified as an endogenous infection.

22. Strep Pneumonia

23. Strep Pneumonia
S. pneumoniae
Alpha hemolysis

24. Strep pneumonia
Predisposing factors: upper respiratory viral infection, diabetes, alcoholism
60-80% of all pneumonias

25. Strep Pneumonia

26. Cause of strep pneumonia
Primary virulence factor is the capsular polysaccharide which protects the organism against phagocytosis
Pathogenesis is due to rapid growth of bacteria in alveolar spaces

27. Symptoms of Strep Pneumonia
Onset abrupt
Chest pains
Chills
Labored breathing

28. Diagnosis of Strep pneumonia
Chest Xray
Culture and staining
Biochemical tests of isolated organism

29. Treatment of Strep Pneumonia
Typically treated with Penicillin G cefotaxime, oflaxacin or for those allergic to penicillins can be treated with erythromycin or tetracycline
Pneumococcal vaccine (Pneumovax 23 or Pnu-immune 23) is available for the elderly

30. Staphylococcal infections
One of the most common of all infections
Staphylococcus are divided into pathogens and non pathogens based on possession of the enzyme coagulase
Coagulase + are usually S. aureus and pathogenic
Coagulase - are organisms like S. epidermidis are less invasive

31. Diseases of Staphylococcus

32. Toxic Shock Syndrome Most in women using superabsorbant tampons
Staphylococcus aureus-Gram positive cocci
Low blood pressure, fever, diarrhea, skin rash can be fatal

33. Toxic Shock Syndrome
Symptoms mainly caused by toxic shock syndrome toxin 1(TSST1)
Several other enterotoxins also involved

34. Staph skin infections
Most common cause of acne, boils, furuncle and cabuncles
Treatment can be difficult because of antibiotic resistance.Usually can be treated with methicillin, cephalosporins,or vancomycin
Methicillin resistant strains=MRSA

35. Staph skin infections Furuncle (infected hair follicle
Deep folliculitis
superficialfolliculitis
Carbuncle
Multiple abcesses
Around many hair
follicles
Scalded skin
syndrome
Staph impetigo

36. Scalded Skin Syndrome
Due to strains of S. aureus containing a special toxin-exfoliatin

37. Diagnosis Culture and stain-gram positive in grape-like clusters
Catalase and coagulase tests
DNA fingerprinting

38. S. aureus