Streptococcus

Streptococcus

Characteristics:

• Gram (+) in pairs or chains

• Non-motile, Non-sporing, Catalse (-)

• Capnophilic (5-10%)

S. pneumoniae and Viridans

Brown’s Classification: Alpha hemolytic

Group A (S. pyogenes)

Group B (S. agalactiae)

Group C (S. dysgalactiae and S. equi)

Brown’s Classification: Beta Hemolytic

Group D - Non enterococcus (S. bovis)

Group D - Enterococcus (E. faecalis and E. facium)

Brown’s Classification: Gamma hemolytic

M protein

Virulence Factor of S.pyogenes: Anti-phagocytic; it is able to bind to beta globulin factor H, which is a regulatory protein in the alternate complement pathway involved in the degradation of C3b

Protein F and Lipoteichoic acid

Virulence Factor of S.pyogenes: Mediates attachment which causes localized infection

Streptodornase (DNases)

Virulence Factor of S.pyogenes: Degrade host DNA and RNA

Streptolysin O

Virulence Factor of S.pyogenes: Surface hemolysin (oxygen labile); induces antibody response to produce anti-streptolysin O

Streptolysin S

Virulence Factor of S.pyogenes: Surface hemolysin (Oxygen stable)

Exotoxin A

Virulence Factor of S.pyogenes = Streptococcal pyrogenic exotoxins (SPE): this is associated with Scarlet fever and Streptococcal Toxic shock-like syndrome

Dick’s test (+ Redness or Erythema)

Schultz charlton test - Diagnostic (+ Rash fades or Blanching phenomenon)

What are the tests for Scarlet fever?

Anti-M antibody

Virulence Factor of S.pyogenes: If the body produce this due to the M protein, it will cross react with the human heart tissue

S. pyogenes

Clinical infections

1. Pharyngitis and Tonsilitis

2. Pyodermal infections (purulent)

3. Necrotizing Erysipelas

4. Streptococcal Toxic shock syndrome

5. Rheumatic heart fever

6. Acute glomerulonephritis

7. Impetigo

8. Erysipelas

9. Cellulits

10. Scarlet fever

Rheumatic heart fever

Clinical infections of S.pyogenes: Cross reactive antibodies against streptococcal antigens and human heart tissue

• Throat infection = Always (+) in ASO

• Skin infection = (+) Anti-DNAse Ab

Remember S.pyogenes

• Throat infection =

• Skin infection =

Erysipelas

Clinical infections of S.pyogenes: Acute spreading erythematous lesion

S. agalactiae

Streptococcus: Capsular material interferes with phagocytic activity and complement cascade activation; 35th week of gestation = Screening for this is recommended (Swab = Todd Hewit Broth)

Diseases

1. Obstetric complications

2. Pneumonia and Meningitis in Neonates

3. Endometritis and wound infections in Mother

Group C (Large colony) and G (small colony) Strep.

Resembles S. pyogenes infections

Group D Enterococcus

Streptococcus: Extracellular surface protein, serine protease and gelatinase for adhesion; Cytolysins and Resistance to antimicrobial agents (MDR - Multidrug infections)

Infections caused:

1. Nasocomial infection

2. UTI - catheterization

3. Bacteremia and endocarditis (prosthetic heart valves due to MDR)

Viridans strep

Streptococcus: Oral flora in the upper respiratory tract

Infections:

1. Subacute bacterial endocarditis from patients with damaged heart valve

2. Bacteremia and Septicemia

3. Cavities (Dental infection) - If infected, first stop will be the heart

S. pneumoniae

Streptococcus: Capsular polysaccharide; Adult meningitis and #1 cause of MOPS (Meningitis, Ottis Media, Lobar Pneumoniae, Sinusitis)

Infection:

1. Pneumonia (Affects 1 lobe only)

2. Sinusitis, Ottis media (no capsule)

3. Bacteremia and Meningitis (with capsule)

S. pneumoniae

Morphology

• Gram (+) diplococci; Capnophilic

• LANCET OR BULLET SHAPED

• Neulfald (Quellang): Positive

1. S. pneumoniae

2. K. pneumoniae

3. P. aeruginosa

Sputum:

1. Rust colored

2. Currant jelly

3. Blue green

Bile solubility test

1. Positive = Clear (S. pneumoniae)

2. Negative = Group D strep or Viridans

Identify test: Test for the solubility to bile salt (2% sodium deoxycholate or sodium taurocholate)

1. Positive =

2. Negative =

Streptococcus

BAP: White “pinpoint” colonies

Bile esculin test

1. Positive = Blackening of agar (Group D Strep.)

2. Negative = No blackening of agar Viridans Strep.

Identify test: Determines the ability to grow in 40% bile and esculin hydrolysis; Positive = esculin reacts with ferric chloride to form brown-black ppt

1. Positive =

2. Negative =

Salt tolerance test

1. Positive = Turbid, Color change (Group D Enterococcus)

2. Negative = Lack of growth and no color change (Group D non-Enterococcus)

Identify test: Test the ability of the organism to grown in 6.5% NaCl

1. Positive =

2. Negative =

Salt tolerance test and PYR

(+) Group D enterococcus

(-) Group D non-enterococcus

What are the test to differentiate Group D Enterococcus and Group D non-enterococcus? Give the results

1. Purpose: Pyrrolidonyl arylamidase

2. Substrate: L-pyrrolidonyl-B-napthylamide

3. Color developer: p-dimethylaminocinnamaldehyde (PDAC)

4. Positive: Pink or Cherry Red = Group A strep and Enterococci

Biochemical test: PYR

1. Purpose:

2. Substrate:

3. Color developer:

4. Positive:

CAMP Test

1. Positive = Enhanced hemolysis in arrow head pattern (Group B strep - S. agalactiae)

2. Negative = No zone of hemolysis (Non-group B)

Identify test: Test for synergistic hemolysis between group B Streptococcus and B-hemolytic S.aureus

1. Positive =

2. Negative =

CAMP factor

A diffusible protein-like compound produced by Group B

Hippurate Hydrolysis

1. Positive = Deep blue / purple color (Group B - S. agalactiae)

2. Negative = Colorless or light purple (Group A - S.pyogens)

Identify the test: Determines hydrolysis of sodium hippurate to benzoic acid and glycine

1. Positive =

2. Negative =

Group A - S.pyogens

Identify the Streptococcus:

• Bacitracin Taco A: Susceptible (>10mm)

• PYR: Positive (+)

Group B - S. agalactiae

Identify the Streptococcus:

• CAMP: Positive (+)

• Hippurate Hydrolysis: Positive (+)

Group C Streptococcus

Identify the Streptococcus:

• SKT: Susceptible

Group D Enterococcus

Identify the Streptococcus:

• PYR: Positive (+)

• Salt Tolerance Test (Growth at 6.5%): Positive (+)

• MDR: Positive (+)

• Growth at 45C and 10C

Group D Non-enterococcus

Identify the Streptococcus:

• Penicillin: Susceptible

• Growth at 45C

S. pneumoniae

Identify the Streptococcus:

• Bile solubility: Positive (+)

• Neufald: Positive (+)

• Taxo P: Positive (+)

1. Susceptible = > 14 mm (S. pneumoniae)

2. Resistant = Viridans

Test: Optochin / Taco P Test

1. Susceptible =

2. Resistant =

S. bovis

Streptococcis: Gastrointestinal malignancy

1. Bile solubility Test

2. Neufald test

3. Taxo P test

Work up: How do you differentiate the Alpha Hemolytic pattern organisms?

1. Bile solubility Test

   • (+) Clear colony = S. pneumoniae

   • (-) Group D Enterococcus

2. Neufald test

   • (+) S. pneumoniae

3. Taxo P test

   • Susceptible (>14mm) = S. pneumoniae

   • Resistant = Group D Enterococcus

Work up: Differentiate the Alpha Hemolytic pattern organisms?

1. S.pneumoniae

2. Group D Enterococcus and Viridans

Bile Esculin Hydrolysis test

Work up: How do you differentiate the Group D Enterococcus and Viridans after differentiating it from S. pneumoniae?

1. Positive = Blackening of agar (Group D Enterococcus)

2. Negative = No blackening (Viridans)

Work up: Bile Esculin Hydrolysis test

1. Positive =

2. Negative =

Salt tolerance test

1. (+) Turbidity or Color change **(**Group D enterococcus)

2. (-) No turbidity or Color change **(**Group D non-enterococcus)

Work up: How do you differentiate Group D Enterococcus and Group D Non-enterococcus?

1. Positive =

2. Negative =

1. Group D Strep Entero and Non-entero

2. Salt Tolerance Test or PYR to differentiate Entoroccus and Non-enterococcus

Work up: Gamma hemolytic pattern is observed

1. what needs to be differentiated?

2. What test to perform?

1. Bacitracin Taxo A

   • Susceptible (>10mm) = S. pyogenes

   • Resistant = Others

2. PYR test

   • (+) Cherry red = Group A strep - S. Pyogenes and Enterococci faecalis

   • (-) Others

3. Hippurate test

   • (+) Deep blue / purple = S. agalactiae

   • (-) Colorless or Slight purple = Group A strep - S. Pyogenes

Work up: Beta hemolytic pattern is observed, what is the result of Group A - S. pyogenes in the following test

1. Bacitracin taxo A

2. PYR test

3. Hippurate test

1. CAMP

   • (+) Enhanced hemolysis arrow head = Group B Strep - S. agalactiae

   • (-) No zone of Hemolysis = Non-group B

2. Hippurate test

   • (+) Deep blue / purple = S. agalactiae

   • (-) Colorless or Slight purple = Group A strep - S. pyogenes

Work up: Beta hemolytic pattern is observed, what is the result of Group B - S. agalactiae in the following test

1. CAMP

2. Hippurate hydrolysis test

Susceptible: Group C Streptococci

Work up: Beta hemolytic pattern is observed, what is the result of Group C Streptococci in the following test

1. SKT

Group D Streptococcus and Viridans

If the results are the following:

• (-) CAMP and Hippurate Hydrolysis test

• (R) SKT

What is the the organism?