[2S] UNIT 3.2 Gram (+) Cocci - Streptococci Flashcards
GENERALITIES
Belong to the family Streptococcaceae
Streptococcus and Enterococcus spp.
GENERALITIES
Gram (+) cocci in chains, except
S. pneumoniae (diplococci)
GENERALITIES
T/F: Streptococci behave like facultative anaerobes
T
GENERALITIES
Grow in the presence of oxygen but are unable to
use oxygen for respiration, hence, they are considered aerotolerant anaerobes
Streptococcus
GENERALITIES
Can metabolize sugar in the presence or absence of oxygen
Streptococcus
GENERALITIES
Major end product of Strep
Carbohydrates metabolized fermentatively with lactic acid (gas is not produced)
GENERALITIES
T/F: Strep are non-motile and non-spore formers
T
GENERALITIES
Result of strep to catalase test
Negative, gram (+) cocci (pairs / chains)
GENERALITIES
T/F: A negative catalase test result differentiates
streptococci and enterococci from staphylococci. Weak false-positive catalase reactions can be seen when growth is taken from media containing blood, owing to the peroxidase activity of hemoglobin
T
GENERALITIES
Compared with the cells of other gram-positive cocci,
those of enterococci and some streptococci appear more ______ than spherical. The streptococcal cells are more likely to appear in chains when grown in broth cultures
elongated
GENERALITIES
T/F: Some may require 5-10% CO2 for growth (some can be capnophilic)
T
GENERALITIES
Sole product of glucose fermentation is lactic acid and no gas formation
Homofermentative
GENERALITIES
Poor growth on nutrient media (e.g., trypticase soy
agar): More pronounced growth on media enriched with blood or serum.
Streptococcus
GENERALITIES
Colonies are usually small and transparent.
Streptococcus
GENERALITIES
If you want to grow Streptococcus spp. you may use “______ ____ system”
candle jar
Medium required for strep & entero
Enriched / Supportive : BAP (w/ Antibiotics)
T/F: Streptococcus & Enterococcus are susceptible to Vancomycin
T
Causes a wide spectrum of infections, such as UTIs,
sepsis, pharyngitis, endocarditis, tissue abscess, meningitis, rheumatic fever, and impetigo
Streptococcus & Enterococcus
T/F: Classification to Enterococcus is simpler compared to Staphylococcus which is diverse
F; Classification to Staphylococcus is simpler compared to Enterococcus which is diverse
CLASSIFICATION OF STREPTOCOCCI AND
ENTEROCOCCI
Basis of sherman’s classification wherein Streptococci and
Enterococci are group as pyogenic, viridans, lactic, and enterococcal
Physiological Characteristics
PHYSIOLOGICAL CHARACTERISTICS
grows at 37°C; pus forming
Pyogenic
PHYSIOLOGICAL CHARACTERISTICS
grows at 37°C and 45°C and alpha hemolytic
VIridans
PHYSIOLOGICAL CHARACTERISTICS
grows at 10°C and 37°C
Lactic
PHYSIOLOGICAL CHARACTERISTICS
grows at 10°C, 37°C, and 45°C
Enterococcal
PHYSIOLOGICAL CHARACTERISTICS
S. pyogenes
Pyogenic
PHYSIOLOGICAL CHARACTERISTICS
S. salivarius, S. mutans, S. mitis, S. sanguis
Viridans
PHYSIOLOGICAL CHARACTERISTICS
S. lactis
Lactic
PHYSIOLOGICAL CHARACTERISTICS
E. faecalis*, E. faecium, E. durans, E. avium
Enterococcal
The members of Streptococci and Enterococci can be
differentiated or distinguished based on a certain cell wall component found in these groups of organisms
Rebecca Lancefield Classification
Basis: Grouped based on the cell wall polysaccharide
(Common C Carbohydrate) Antigen and cell wall teichoic acids
- Reaction to Lancefield’s Anti-sera
Rebecca Lancefield Classification
REBECCA LANCEFIELD CLASSIFICATION
cell wall polysaccharide
A, B, C, F, and G
REBECCA LANCEFIELD CLASSIFICATION
cell wall teichoic acids
D and Enterococcus
2 members of streptococci not classified under rebecca lancefield
Viridans streptococci
Streptococcus pneumoniae
CLASSIFICATION OF STREPTOCOCCI AND
ENTEROCOCCI
Basis: Hemolytic Patterns
Brown’s Classification
BROWN’S CLASSIFICATION
partial hemolysis
α
BROWN’S CLASSIFICATION
complete zone of hemolysis
β
BROWN’S CLASSIFICATION
non-hemolytic
ɣ
BROWN’S CLASSIFICATION
wide zone alpha hemolytic
α’
BROWN’S CLASSIFICATION
○ Partial hemolysis in inner zone
○ Complete hemolysis in outer zone
α’
- Group A Beta Hemolytic Streptococcus
- Colonizes skin & throat
Streptococcus pyogenes
Antigenic Structure: Gr (+) cell wall (peptidoglycan) and presence of M protein
Streptococcus pyogenes
INFECTIONS
Grp A Streptococcal Infxn : Most common manifestation includes tonsilitis & pharyngitis
Strep Throat
Bacterial Pharyngitis
INFECTIONS
Resembles pharyngitis with skin rash, desquamation of skin; “strawberry tongue”
- Production of erythrogenic toxin
PYODERMAL: Scarlet Fever
INFECTIONS
Impetigo cellulitis, erysipelas
Pyodermal Infxn
GENUS STREP
Flesh eating disease
Necrotizing Fascitis
GENUS STREP
Suppurative Fasciitis, Hospital Gangrene, Necrotizing Erysipelas
Necrotizing Fascitis
GENUS STREP
Necrosis of skin, subcutaneous fat and fascia
Necrotizing Fascitis
GRP A STREP
Pyogenic Exotoxin A
GRP A STREP
Acute Rheumatic Fever & Rheumatic Heart Disease : Fever, Arthralgia, Cardiac Valvular Disease
Postreptococcal Sequelae
GRP A STREP
Acute Glomerulonephritis : Edema, Hypertension, Hematuria, Proteinuria & RBC Casts
Postreptococcal Sequelae
Group A Strep DOC
Penicillin / Erythromycin
Other infections : Otitis media, pneumonia, and bacteremia
Group A Strep
