Lecture 4: Staph and Strep Flashcards
what is a lacefield group?
a classification system based on grouping streptococcal spp based on their possesion of specific cell surface antigens
what are the 3 species that are not groupable in the lancefield system?
uberis, parauberis, and pneumonia
strep and staph are both gram _____
positive
what species of strep are non pyogenic, meaning they are not associated with pus/purulence?
strep suis and streppenumonia
which strep is an introbilgate parasite of the mammary gland in cows and is also a commensal in the human GI tract, potentially causing neonatal septicemia and meningitis in newborn human babies? (different strains in cow vs human)
streptococcus agalactiae
what are the 6 bacteria that can cause mastitis in bovines? from least severe to most severe mastitis?
strep agalactiae
strep aureus
dysgalactiaw
uberis
klebsiella
E coli
use: AADUKE pneumonic to remember
why is the keratin plug in the teat so important in regards to mastitis?
it prevents ascending infection of bacteria into the teat canal and up into the teat cistern
strep agalactiae has 4 toxins it releases. name them
Sphingomyelinase
neuroaminidase
hemolysin
lipoeichoic acid
SNHL
what are tactics that strep agalactiae use in order to persist in the body?
- a type 3 capsular polysaccharide prevents opsonization
- serine proteases block phagocytosis
- C/R/X proteins help with colonization
- pilus for adhesion (little hair like things)
is mastitis from strep agalactiae common in canada?
no
which bacteria is a normal commensal of bovine tonsils and intestines, causes environmental mastitis, and has similar virulence factors to strep agalactiae?
strep uberis
what are some differences between strep ag and strep uberis in regards to mastitis
strep ag: obgligate parasite of the mammary gland, subclinical mastitis more commonly
strep uberis: environmental bacteria, clinical mastitis
strep dysgalactiae has two subspecies which are: _________
how do they differ?
strep equismilis: beta hemolytic, causes disease in a variety of species
and strep dysgalactiae: alpha hemolytic, cause of mastitis
what is the difference between an alpha hemolytic, a beta hemolytic, and a gamma hemolytic
alpha: these bacteria are commensals
beta: bacteria that are pathogenic
gamma: bacteria that are non pathogenic
which bacteria is a contagious bacteria AND an environmental bacteria associated with injury to the teat/udder epithelium, and causes both acute and chronic mastitis?
strep dysgalactiae
strep dysgalactiae mastitis often occurs with ________
trueperella pyogenes
list some virulence factors that strep dys has
- M like protein
- lipoteichoic acid
- fibrinolysin
- hyaluronidase
- some strains have a capsule
which bateria is an important cause of septicemia, arthritis, meningitis, and endocarditis in piglets/young pigs?
strep dysgalactiae subspecies equismilis
strep dysgalactiaw subspecies equismilis has a virulence factor called ______ that converts plasminogen to plasmin, which ______
streptokinase
breaks down fibrin
which bacteria most commonly infects pigs, is zoonotic, has multiple serotypes, carried in the palatine tosils of pigs, and is most common in weaner and growing pigs?
strep suis
what is the very broad pathogenesis in which strep suis causes disease? What two virulence factors help this bacteria?
the bacteria invades the bloodstream and seeds into joints, meninges, heart, and lungs
capsular polysaccharide: blocks opsonization by C3 and activation of alternative complement pathway
suilysin: a cytotoxic exotoxin which creates holes in target cell membranes BUT not expressed by all pathogenic strep suis
_________ + _________= clinical disease
virulent strain, stress
what are 6 symptoms/effects of a human infection with strep suis?
sepsis
meningitis
hearing loss
renal failure
endocarditis
penumonia
which bacteria is an obligate pathogen, a beta hemolytic, that causes strangles, with high morbidity and low mortality, being very very contagious?
strep equi subspecies equi
what are some clinical signs of strangles and what is the cause?
mucupurulent discharge from the nose, submandibular lyph node abscesses that may rupture, endoscope revealing abscesses in guttural pouches (acute disease) or even chondroids (carrier status)