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)
what are some virulence factors of strep equi equi
- hyaluronic acid capsule (prevents phagocytosis)
- iron acquisition
- streptolysin S (toxin with beta hemolytic activity)
- streptokinase (break down clots)
- antiphagocytic M proteins which prevents opsonization
- superantigens to stimulate an oversalous immune response
- IgG endopeptidases (destroy antibodies)
HISSASI penumonic
strep equi equi has something called equibactin. explain what this does
it is a siderophore that can be sent out to obtain iron (strep species generally do not have sideophores so this is unique)
what are some complications with strangles?
usually if drainage is acheived the horse will clear the infection, but complications can occur such as:
- guttural pouch disease
- persistent carriers
- metastatic abscessation/bastars strangles
- purpura hemorrhagica
describe how a horse with strangles becomes a persistent carrier
rupture of the retropharyngeal lymph nodes into the guttural pouch causes guttural pouch empyema (collection of pus), leading to dysphagia and eventually aspiration penumonia. chonrdoids also form in the guttural pouch
what is bastard strangles?
occurs in 2-20% of strangles cases where the abscesses can spread via blood or lymph to any organ system. clinical signs depend on oragn system being affected
what purapura hemorrahgica?
a type 3 hypersensitivty reaction that occurrs rarely after vaccination or natural exposure in horses that have been previously vaxxed or exposed. the horse will have petechiae and ecchymosis on the skin
what is the proper way to diagnose strangles?
use a nasal swab, culture it, or do PCR for strep equi M protein
describe how strep equi equi is spread
it does not last long in the environment, direct contact or shared objects is needed to transmit, it can live in water up to 6 weeks, and the disease severity is related to the exposure dose
which bacteria is a commensal and oppotunistic pathogen that is zoonotic and infects many species with a wide variety of clinical signs? it is know to cause shipping fever in horses
strep equi subspecies zooepidemicus
what types of things predispose a horse to develping shipping fever?
- heat stress
- transport stress
- virus infection/suppressed immune system
bacteria: strep equi sub zooepidemicus
list some viruelcen factors of strep equi subsp zooepidemicus
simiarl to strep equi
- lacks an M protein, has something similar
- capsule is variabiliy expressed (some have some do not)
- less superantigens
- protease
which bacteria is a beta hemolytic, an anal mucosa main carrier site in dogs, and is a common pathogen in cats?
strep canis
strep canis affects what organs in cats?
- skin
- lymph nodes (abscesses)
- metritis
- septicemia in kittens
it is common for kittens of first time queens to get a strep canis infection. why?
the mother was not exposed beforehand and so did not provide any immunity in the colostrum or via uterine transfer, leaving the kittens susceptible
what bacteria causes pharyngitis, impetigo, rheumatic fever and acute glomerulonephritis in humans? rarely causing disease in animals
strep pyogenes
which bacteria causes flesh eating disease in humans?
strep pyogenes
what are 5 things that most strepspecies have in common?
- gram +
- most are faculative/aerotolerant anaerobes
- most cause pus/abscesses
- most block phagocytosis
- most have hemolysins
what are the 3 main staph species of veterinary relevance?
staph aureus
staph pseudintermedius
staph hyicus
most staph species are gram _______ and are facultative _____, and re a part of normal ______
positive, anaerobes
skin flora
many staph species have coagulase as a virulence factor. what does coagulase do?
it converts fibrinogen into fibrin, creating crosslinked fibrin nets that the bacteria can hide in
many staph species have coagulase as a virulence factor. what does coagulase do?
it converts fibrinogen into fibrin, creating crosslinked fibrin nets that the bacteria can hide in
which staph species is non hemolytic?
staph hyicus
staph species have somethin called catalase, explain what this does
it avoids degredation in the phagolysosome
list some of the virulence factors that staph aureus has
- adhesins and invasins
- protein A interfers with opsonization
- capsule and coagulase interfere with phagocytosis
- toxins to damage host cells
- often shows antimicrobial resistance
what is the difference betwene coaglulase and staphlyokinase?
coagulase forms clots and staphylokinase breaks down clots
what is enterotoxigenic and toxic shock syndrome toxin?
a superantigen. they are responsible for causing diarrhea and vomitting in staph food poisoning. these “fake” antigens activate T cells without normal antigenic activity and put the immune system into overdrive
what kind of mastitis is usually seen with staph aureus and why?
usually chronic, or could be subclinical, because the bacteria can wall itself off up higher in the mammary gland and does not respond well to antibiotics (either from resistance or difficulty penetrating the area)
you have a dairy cow that recently had a teat injury a little while back, and now she has decreased milk production and has mastitis that will not go away and it turning chronic. what bacteria causes this? what should you do?
staph aureus
either cull this animal or milk them last/separately
bumblefoot is caused by what bacteria? how does the animal get this?
staph aureus
abrasions/cuts lead to infection
neonatal septicemia and wound or surgical site infection can both be caused by what bacteria?
staph aureus
which bacteria is that primary pathogen in canine pyoderma, rarely causes systemic disease, and is associated with predisposing factors like skin folds and hypersensitivites, even endocrin disease?
staph pseudointermedius
what bacteria causes greasy pig disease? how do pigs usually look (besides greasy LOL)
staph hyicus
pigs will have exudative epidermitis
which bacteria is a commonsal organism on pig skin, and trauma is necessary for colonization?
staph hyicus
list 3 virulence factors of staph hyicus
- exfoliation and epidermitis inducing exotoxins
- adhesions like fibronectin binding proteins
- capsular polysaccharides and protein A both block phagocytosis
what is MRSA? why is it important?
methicillin resistant staph aureus
it is important because clinically you may see a wound infection, surgical site infection, UTIs, etc, that are not going away with antibiotics, it is transmissible from pet to human (zoonotic), and it a threat to veterinarians working on animals that have it!
in regards to MRSA, what makes the bacteria so resistant?
the mecA gene leads to generalized resistance to beta lactam antimicrobials
most animals that encounter a MR staph have no problem, so when does it actually become a problem?
if an opportunistic infection develops (it can be VERY serious!)
true or false, MR staphs are often also resistant to other classes of antimicrobials
truuuuuuuu
what are 7 things that most staph species have in common?
- gram +
- facultative anaerobes
- coagulase + means they are pathogenic
- opportunistic epithelial infections usually
- pus/abscessation
- antimicrobial resistance
- zoonotic
