Lecture 8 -- Streptococci Flashcards by amanda kastel

what bacteria causes strep throat?

streptococci pyogenes

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what disease(s) does streptococci agalactiae cause?

sepsis in newborns

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what disease(s) does streptococci pneumoniae cause?

pneumonia and meningitis

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name 3 streptococci species commonly associated with human disease

streptococci pyogenes
streptococci agalatiae
streptococci pneumoniae

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are streptococci gram (+) or gram (-)

gram (+)

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are streptococci catalase (+) or (-)

(-)

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are streptococci aerobic or anaerobic

anaerobic

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how do streptococci grow?

in pairs or chains

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do streptococci have spores? do they have flagella?

neither

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differentiate between the capsule of staphylococci and streptococci

capsule of staphylococci is made of polysaccharides

capsule of streptococci is made of hyaluronic acid that blends in with the hyaluronic acid of human connective tissue to evade the immune system

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what is unique about the requirements for streptococci to grow

streptococci has complex nutritional requirements in order to grow

produce lactic acid by the fermentation of carbohydrates

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name the 3 main GROUPS of streptococci and explain them

streptococci (different variations of carbohydrate chains called LANCEFIELD CELL WALL ANTIGENS. different from strain to strain)
pneumococcus – ONLY includes streptococci pneumoniae
viridians – resident oral microbiota

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state the important lancefield classifications relevant to human disease

group A strep – streptococci pyogenes
group B strep – streptococci agalctiae

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streptococcal groups (streptococci, pneumococcus, viridians) are also classified based on ____ patterns

HEMOLYTIC (ability to lyse red blood cells)

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explain the hemolytic pattern classification for streptococci

beta hemolytic – complete hemolysis (streptococci)

alpha hemolytic – incomplete hemolysis (pneumococcus and viridians)

gamma hemolytic = non hemolytic. dont produce porin toxins

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which streptococci are beta hemolytic? what does this mean?

streptococci (classified by lancefield cell wall antigens.GAS and GBS)— they can completely lyse RBCs

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which streptococci are alpha hemolytic? what does this mean?

incomplete hemolysis

pneumococcus and viridians

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differentiate between the capsules of streptococcus pyogenes, streptococcus agalactiae, and streptococcus pneumoniae

pyogenes – hyaluronic acid
agalactiae – sialic acid
pneumoniae – polysaccharide

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which streptococcus has M protein as a surface protein?
it is homologous to what other surface protein?

streptococcus pyogenes
it is homologous so Surface Protein A (SpA) of staphylococcus aureus – binds antibodies upside down

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which group of streptococci has strepSAgs?

streptococcus pyogenes

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what is the name of the porin protein for streptococcus pyogenes? what about streptococcus pneumoniae?

streptococcus pyogenes – streptolysin O
streptococcus pneumoniae – pnemolysin

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which group of streptococcus can cause toxic shock syndrome with the production of superantigens?

strptococcus pyogenes

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which group of streptococcus causes impetigo (school sores)

streptococcus pyogenes (group A strep GAS)

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which bacteria avoids opsonization and phagocytosis due to its capsule?

GAS (streptococcus pyogenes) – due to hyaluronic capsule. poses as host

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how does streptococcus pyogenes invade cells?

by binding to factor H -- a complement control protein on the host cell surface

besides staphylococcus aureus, what other bacteria binds fibronectin and through what?

through F protein AND lipoteichoic acid -- GAS (streptococcus pyogenes)

explain how streptococcus pyogenes can invade the host complement system

has an M protein that blocks C3b binding has C5a peptidase to inactivate C5a

what does streptococcus pyogens have that enables it to evade opsonization/neutralization

M-like surface proteins that bind the Fc regions of antibodies (upside down) hyaluronic acid

name the 5 toxins/enzymes that streptococcus pyogenes utilizes

superantigens streptolysin S -- a hemolysin streptolysin O -- a hemolysin streptokinases -- lyse clots Dnases A-D -- degrade host DNA

Streptococcus pyogenes is Beta hemolytic. name the porin protein(s)

streptolysin S and Streptolysin O

GAS can cause ____ or ____ diseases

Suppurative or nonsuppurative (pus forming)

name the 5 pus forming diseases caused by GAS

-pharyngitis -impetigo -erysipelas -cellulitis -necrotizing fasciitis

name the non-supparative diseases caused by GAS

rheumatic fever acute glomerulonephritis

what is also known as scarlet fever? what causes it?

pharyngitis GAS

pharyngitis is ___ mediated

bacteriophage

what is rheumatic fever? what causes it?

complications of pharyngitis that involve the heart, blood vessels and joints occurs when GAS gets into the bloodstream

what is the only member of the GBS family

streptococcus agalactiae

streptococcus agalactiae is ___ hemolytic

beta, but there are a few gamma

of the 3 main species of streptococcus, which can colonize the GI tract? explain

streptococcus pyogenes and streptococcus agalactiae this is because pyogenes has a hyaluronic acid capsule and agalactiae has sialic acid capsule. both are well protected to survive the conditions of the GI tract

explain the significance of the fact that streptococcus agalactiae can colonize the genitourinary tract

this bacteria primarily infects newborns -- can catch right after being born or even in utero there is both early onset and late onset

what is required to kill group B strep?

the activation of both the ALTERNATIVE and CLASSICAL complement pathways

true or false group B strep has only 1 virulence factor

TRUE -- its the sialic acid capsule. avoids phagocytosis

explain the entire capsule/ outer surface of group B strep

has sialic acid capsule to avoid phagocytosis. also, has type-specific capsular carbohydrates (9 diff ones) the sialic acid capsule can bind factor H and evade the complement system by breaking down C3b also has PILLI that can bind to fibronectin on the host cell membrane

explain the difference between early onset and late onset neonatal disease of GBS

early onset == acquired in utero or at birth disease = bacteremia, pneumonia or meningitis. sepsis. signs start showing up during first 7 days of life late onset == starts showing up 1 week - 3 months after birth. EXOGENOUS SOURCE -- we're not sure where it came from bacteremia with meningitis

name the symptoms that can be caused by a GBS infection

postpartum endometriosis UTI bacteremia pneumonia bone and joint infections skin and soft tissue infections

is streptococcus pneumoniae encapsulated?

yes, with a polysaccharide capsule there are 90 different serotypes of the capsule

streptococcus pneumoniae are ____ hemolytic

alpha, but there are a few beta

which streptococci is diplococci?

streptococcus pneumoniae

which streptococcus PRODUCES lactic acid?

streptococcus pneumoniae

where does streptococcus pneumoniae colonize?

the nasopharynx and oropharynx

explain how streptococcus pneumoniae colonizes

initially colonizes through binding to PHOSPHO-CHOLINE on the host cell membrane. streptococcus pneumoniae has choline binding proteins

explain the structure of streptococcus pneumoniae

elongated, diplococci

pnemococcus primarily enters through....

inhalation

pneumococcus can cause....

pneumonia and meningitis once it gets into the bloodstream

_____________ allows for the spread of streptococcus pneumoniae

the evasion of immune-cell mediated destruction

explain how pneumococcus effectively infects the lung area

pneumococcus bacteria is inhaled in. it contains a secretory IgA protease. Thus, it degrades the IgA antibodies on the mucosal surfaces of the resporatory tract to easily infect and get into the bloodstream also has PNEUMOLYSIN to form pores in epithelial cell walls and SUPPRESS the oxidative burst of phagocytes that is meant to kill them also, activates the complement pathway to promote inflammation

name all of the virulence factors of pneumococcus

-secretory IgA protease -Neuraminidase -polysaccharide capsule -pneumolysin -surface choline binding protein

in order to develop pneumonia, what must happen?

ANTIBODY MEDIATED KILLING -- destruction of IgA by IgA protease on pneumococcus

explain what pneumonia is

when pneumococcus colonizes in the alveoli of the lungs, pneumolysin destroys many epithelial cells, creating a lot of cell debris and fluid in the alveolar spaces

besides pneumonia, what else can streptococcus pneumonia cause?

sinusitis otitis media (middle ear infection) meningitis (following a ear or sinus infection) bacteremia --- heart valve tissue destruction