U2.2.1 Gr (+) Cocci : Streptococcus Flashcards
Streptococcus & Enterococcus
Family
Streptococcacee
Streptococcus & Enterococcus
Morphology
Gram (+) cocci in chains
Streptococcus & Enterococcus
Morphology of S. pneumoniae
diplococci
Streptococcus & Enterococcus
Select all that apply
Generalities of Streptococcus
1. Facultative Anaerobes
2. Non motile and Non-sporeformers
3. Catalase Positive
4. Some may require 5-10% CO2 for growth
1,2,4
Catalase Negative
Streptococcus & Enterococcus
Select all that apply
Generalities of Streptococcus
1. Resistant to Vancomycin
2. Require enriched or supportive media (BAP)
3. Many members are normal flora and not opportunistic
4. Causes a wide spectrum of infections
2, 4
Susceptible to Vancomycin, 3 - are opportunistic
3 types of classification of Streptococci and Enterococci
- Sherman’s (Physiologic)
- Rebecca Lancefield Classification
- Brown’s Classification
Sherman’s Classification
Grows at 37C; Pus forming
Pyogenic
Sherman’s Classification
Grows at 37C and 45C
Viridans
Sherman’s Classification
4 species classified as viridans
S. salivarius, S. mutans, S. mitis, S, sanguis
Sherman’s Classification
Grows at 10C and 37C
Lactic
Sherman’s Classification
Grows at 10C, 37C and 45C
Enterococcal
Classification of Streptococci & Enterococci
Basis: Grouped based on the cell wall polysaccharide (Common C Carbohydrate) Antigen and cell wall teichoic acids
Rebecca Lancefield Classfication
Rebecca Lancefield Classfication
Clinically significant that has cell wall polysaccharide
A, B, C, F and G
Rebecca Lancefield Classfication
Clinically significant that has cell wall techoic acids
D and Enterococcus
Classification of Streptococci & Enterococci
Basis: Hemolytic Patterns
Brown’s Classification
Brown’s Classification
Species that show Beta Hemolysis
Group A, B, C, F & G
Brown’s Classification
Species that show Alpha Hemolysis
S. pneumoniae
Brown’s Classification
Species that show Gamma Hemolysis
Group D Enterococcus
Brown’s Classification
Species that show alpha-prime hemolysis
Viridans
Group A Streptococcus
Group A Beta Hemolytic Streptococcus & colonizers skin & throat
Streptococcus pyogenes
Group A Streptococcus
Streptococcus pyogenes
- antigenic structure [2]
Gr (+) Cell Wall (Peptidoglycan) and Presence of M Protein
Grp A Streptococcal Infections
Most common manifestation includes tonsilitis and pharyngitis
Bacterial Pharyngitis
Grp A Streptococcal Infections
Strep Throat
Bacterial Pharyngitis
Grp A Streptococcal Infections
resembles
pharyngitis with Skni rash.” desquamation of skin;
“strawberry tongue”
Scarlet Fever
Grp A Streptococcal Infections
production of ____ toxin is present in scarlet fever
eryhtrogenic toxin
Grp A Streptococcal Infections
T/F Group A Streptococcal infections also causes to impetigo cellulitis & erysipelas.
T
Grp A Streptococcal Infections
“Flesh Eating Disease”
Necrotizing Fascitis
Grp A Streptococcal Infections
“Suppurative Fasciitis”, Hospital Gangrene, Necrotizing Erysipelas
Necrotizing Fascitis
Grp A Streptococcal Infections
Necrosis of skin, subcutaneous fat and
fascia
Necrotizing Fascitis
Grp A Streptococcal Infections
caused by Pyogenic Exotoxin A
Streptococcal Toxic Shock Syndrome
Grp A Streptococcal Infections
Includes Acute Rheumatic Fever and Rheumatic Heart Disease
& Acute Glomerulonephritis
Poststreptococcal Sequelae
Grp A Streptococcal Infections
Drug of Choice
Penicillin or Erythromycin
Pathogenic Determinants of Grp A Strep (Extracellular)
causes fever; skin rash of scarlet fever; Blood brain alteration; organ damage
Erythrogenic/Pyogenic Toxins A,B,C
Pathogenic Determinants of Grp A Strep (Extracellular)
protease implicated in flesh eating streptococci
Exotoxin B
Pathogenic Determinants of Grp A Strep (Extracellular)
causes lysis of blood clots; spread of infection
Streptokinase
Pathogenic Determinants of Grp A Strep (Extracellular)
caused by mucoid colonies (capsulated); antiphagocytic
M Protein