General Charset of Streptococci + Streptococcus Pyogenes

Streptococcus Pyogenes Gram

Positive

Catalase

Negative

Gaseous Status

Facilitative Anaerobes

---

except peptostreptococci

Media needed

enriched → Blood Agar

Classification

1. Blood Hemolysis

2. Serologic/ Antigenic

3. DNA_DNA hybridizations

4. Gaseous Need

Blood Hemolysis classification

alpha → pyogenes

beta → Pneumoniae

Gamma → Bovis

Antigenic/ Serologic classification

1. Lancefield classification

2. Griffith classification

3. Capsular classification

Lancefield classification

• C ptn

• no I & J

Griffith classification

• M ptn

• pyogenes → 150 distinct type

Capsular classification

according to Capsular Antigenicity

Pneumoniae & Group B streptococci

DNA-DNA hybridization ,S16 rRNA sequence classification

6 Groups

Pyogenic Group

Beta hemolysis

Pyogenes, Agalactia

Mitis Group

Alpha Hemolysis

Pneumoniae & Oral & Mitis & Sanguis

Anginosus Group

alpha/ Gamma hemolysis

Anginosus & intermedus

Salivarius

Bovis

Mutans group

Alpha/ Gamma Hemolysis

Every alpha hemolytic streptococci is

Virulent except for Pneumoniae

some strains of Pyogenes are

Capsulated

Virulence Factors of Pyogenes

1. Endogenous

2. Exogenous

Endogenous Virulence Factors of pyogenes

1. M ptn

   - > antiphagocytic , anticomplementary

   - > nephrogenic , Rheumatogenic

2. Hyaluronic Acid

   • Retard Phagocytosis

3. F Factor

   • Adherence

4. Lipoteichoic Acid

   • Adherence

Exogenous Virulence of pyogenes

1. Toxins

2. Enzymes

Enzymes of pyogenes

1. Streptokinase

2. Streptodornase

3. Hyaluronidase

4. C5a Peptidase

Toxins of pyogenes

2 types

1. Streptolysins

2. Exotoxins

Types of streptolysins

1. O => Oxygen Labile

   • immunogenic

2. S => Oxygen Stable

   • responsible for hemolysis

Types of Exotoxins

1. A => Erythrogenic

2. B

3. C
   

Types of Diseases caused by Pyogenes

1. Local pyogenic

2. Invasive

3. toxigenic

Local Pyogenic Diseases

1. Tonsillitis

2. Pyoderma (Impetigo)

What follows Tonsillitis

• AGN or ARF

What follows impetigo

AGN

Invasive Diseases

1. Erysipelas

2. Soft Tissue Sepsis

3. Acute Bacterial Endocarditis

Toxigenic Diseases

1. Fulminant infection and Necrotizing Fasciaitis

2. Scarlet Fever

What Exotoxin cause Scarlet fever

Exotoxin A Erythrogenic

what Post-streptococcal Infections

1. AGN

2. ARF

Charset of AGN

1. 3 weeks

2. after Tonsillitis or impetigo

3. Type 3 Hypersensitivity

Charset of ARF

1. 4 weeks

2. After only tonsillitis

3. Cross Reactivity

4. reinfection happen

Diagnosis of streptococcal infection

1. Major Criteria

   • JONES

2. Minor Criteria

   • ELevated PR segment

   • Fever

   • Arthralgia

   • Raised ESR/CRP

   • Leukocytosis

Laboratory Diagnosis

Specimen

1. ASO

2. CRP

3. ESR

Diagnosis of Scarlet Fever

1. Schultz Charlton → inject antitoxin

2. Dick’s test → inject toxin

TTT of streptococcal diseases

G Penicillin

Erytromycin azithromycin → if allergy present

Prompt ttt of ARF

Long acting Penicillin