Streptococcus Flashcards
Streptococci grow well on … and many species secrete.. , which produce patterns of … around the colonies.
blood agar
hemolysins
hemolytic zones
Based on these ….streptococcii classified in to three groups:
hemolytic zones,
Alpha- hemolytic streptococci (a zone with an opaque greenish color), e.g. S. pneumonia e, S. viridans.
Beta- hemolytic streptococci (a clear zone of hemolysis surrounding the colony).
Gamma- hemolytic streptococci (no hemolytic zone surrounding the colony), e.g. S. faecalis.
β- hemolytic group are differentiated according to … located in the streptococcal cell wall (…) from A to U.
carbohydrate antigens
Lancefield groups
The most important beta hemolytic human pathogens group:
Group A –β hemolytic streptococci (GAS) S.pyogenes.
Group B - β hemolytic streptococci (GBS) S. agalactiae.
Alpha hemolytic streptococcal Is growing only on …. supplemented with 5% blood.
enriched media
The virulent strains of alpha hemolytic streptococcal possess a prominent … that plays an important role in the pathogenesis of pneumococcal diseases by retarding the rate of ….
The capsule composed of … and is … ( capable of stimulating antibody synthesis).
capsule
phagocytosis
polysaccharide
antigenic
Infection of alpha hemolytic streptococcal can be … by droplets, or … from the nasopharynx.
exogenous
endogenous
About 40-70% 0f healthy adults carry the organism alpha hemolytic streptococcal in ….
nasopharynx
Pneumococci have many virulence factors:
Polysaccharide capsule (antiphagocytic).
IgA protease (traps bacteria that enveloped in mucus and prevent their removal by the action of ciliated epithelial cells).
Pneumolysin toxin (binds to the host cell membrane, creates pores and causing cell lysis).
Pneumococcal diseases are most commonly associated with…… or other diseases interfere with bacterial clearance.
viral diseases (influenza, measles)
Streptococcus Viridans (S. viridans)
Also known as ……
oral streptococci.
Streptococcus Viridans (S. viridans)
Commonly found orally, including ….
S.mutans, S.mitis, S. sanguis and S. salivarius.
Streptococcus Viridans (S. viridans)
The organisms are most frequently associated with… (also known as… ) as a result of ….
dental caries
tooth decay
tooth enamel destruction.
Streptococcus Viridans (S. viridans)
After tooth extraction, bacteria reach bloodstream and cause 50-70% ….
endocarditis disease.
Streptococcus pyogenes ( S. pyogenes)
It’s also known as the …..
flesh eating bacteria.
Hyaluronic acid capsule of S.pyogenes
non-immunogenic
M protein (surface protein ):
Of s.pyogenes
major virulence factor and strongly antiphagocytosis.
M protein (surface protein ): - It associated with …… and …….
rheumatic heart disease
glomerulonephritis
- A person can have repeated infection with S. pyogens due to…
the presence of more than 80 types of M protein.
F protein: Is protein binds to ….. in epithelial cells, not leave, and it’s necessary for …..
host fibronectin
invasion
Pyrogenic exotoxins (SPE):
Also called ……
erythrogenic toxins.
Type of Pyrogenic exotoxins (SPE)
SpeA, SpeB, SpeC).
SpeB act as ..
superantigens, interacting with both macrophage & helper –T cell causing cytokines releasing, associated with shock and organ failure.
SpeA & C, responsible for …
observed skin rash in scarlet fever disease.
… , responsible for bacterial hemolytic activity ,(s.pyogenes
streptolysins: Enzymes
Streptolysin O, which is …..and…. induce ….. after S. pyogenes infection.
oxygen labile
antigenic enzyme;
antibody formation (ASO)
Streptolysin S, which is …..and….. can lyse erythrocytes, leukocytes and platelets by binding to the cell surface .
oxygen stable
non-immunogenic,
Streptokinase: Also known as …
fibrinolysin
Group A streptococci infections affect all ages with …..
peak incidence between 5-15 age,
Bacteria such as α- hemolytic and non-hemolytic streptococci are able to produce antibiotic –like substances called….. , which …..
bacteriocins
suppress group A streptococcus growth.
Scarlet fever: Is complication of streptococcal pharyngitis, resulting from ……..
pyogenic exotoxins A-C production and diffusing to the blood.
Impetigo ( pyoderma): It’s a superficial localized skin infection, mostly among children between (2-6) years old, it also known ……
school sores
Puerperal fever: Also known ….
childbed fever.
Necrotizing fasciitis:
Also known as ….
flesh-eating or streptococcal gangrene.
Streptococcus agalactiae (S. agalactiae)
Is a species of the normal flora of the…
female urogenital tract.
Streptococcus agalactiae (S. agalactiae)
Early perinatal infection causes ….., with high mortality.
pneumonia or septicemia
Streptococcus faecalis ( enterococcus faecalis):
Is a Gram-positive, commensal bacterium inhabiting the …. of humans and other mammals.
gastrointestinal tracts
E. faecalis can cause ….. in humans, especially in the ….
life-threatening infections
nosocomial (hospital) environment.
E. faecalis is a nonmotile, facultatively anaerobic microbe; it ferments…. , and does not produce a catalase reaction with hydrogen peroxide.
glucose without gas production
Enterococci survive….. including …….and…..
very harsh environments
extreme alkaline pH (9.6
and salt concentrations.
