Staphylococcus Flashcards
What does the genus Staphylococcuslook like on a gram stain?
gram positive, clustering cocci
Compare the shapes of Staphylococcusvs. Micrococcus.
Staphylococcus is spherical, Micrococcus is not always spherical
Compare the gram reactions of Staphylococcusvs. Micrococcus.
Staphylococcus is gram positive, Micrococcus decolorizes readily
Compare the colony colors of Staphylococcusvs. Micrococcus.
Staphylococcus has white to golden colonies, Micrococcus has clear to yellow colonies
Compare the hemolysis patterns of Staphylococcusvs. Micrococcus.
Staphylococcus has some hemolytic species, Micrococcus is nonhemolytic
Compare the O2 requirements of Staphylococcusvs. Micrococcus.
Staphylococcus is faculative, Micrococcus is an obligate aerobe
Compare the salt tolerance of Staphylococcusvs. Micrococcus.
Staphylococcus has good salt tolerance, Micrococcus has poor salt tolerance
What inactivates lipases?
there is a prophage that has inserted into the lipase gene and inactivates it
What is alpha hemolysis?
the incomplete lysis of RBC’s
What is beta hemolysis?
the complete lysis of RBC’s
What is gamma hemolysis? And do we care?
no hemolysis - no we use the term ‘no hemolysis’
What type of hemolysin causes alpha hemolysis?
beta
What type of hemolysin causes beta hemolysis?
alpha
If both hemolysin are present, then what pattern of hemolysis occurs?
double zone hemolysis
What is shown here?
double zone hemolysis
What is the structure of staphylococcal alpha hemolysin?
it assembles as a mushroom shaped heptamer with a central channel
What does staphylococcal alpha hemolysin do?
it forms poers in cell membranes and produces a lot of tissue necrosis
What is the function of beta hemolysin?
it has phospholipase C activity - it causes the collapse of the erythrocyte cell membrane
T/F: Gamma hemolysin is only one protein.
False - it is made up of three proteins; A, B, and C
What properties does gamma hemolysin have?
inflammatory properties
What type of hemolysis does delta hemolysin have?
complete
What type of action does delta hemolysin have?
detergent-like action
What is the function of leukocidin and what is it active against?
it kills white cells - only active against neutrophils and macrophages
What are PNAGs?
poly-N-acetylglucosamines - extracellular polysaccharides mediating biofilm formation
What is staphylokinase and what does it do?
a spreading factor that breaks down fibrin and allows the organism to spread
What is the most important test for pathogenicity in staphylococci?
the coagulase test - free and bound tests
How does the free coagulase test work?
it converts fibrinogen to fibrin
How does the bound coagulase test work?
it agglutinates the organism in the presence of plasma
What is hyaluronidase?
a spreading factor that breaks down hyaluronic acid
What are the three superantigens?
enterotoxins, toxic shock syndrome toxin 1 (TSST1), and exfoliative toxins
What are the type of enterotoxins?
A-E, G and H
What are enterotoxins commonly a factor in (illness/disease) ?
food poisoning
Are enterotoxins heat resistant or heat susceptable?
heat resistant
What disease is exfoliative toxins commonly associated with?
scalded skin syndrome
Generally, what do the colonies of S. aureus look like?
they are gold colonies but can be white
What is S. aureusresistant to?
heat and disinfectants
What is 50 to 60 percent of the cell wall of S. aureusmade up of?
peptidoglycan
What is the role of teichoic acids in S. aureus?
it is released from the organism to tie up antibody from the host
What Staphylococcus species is protein A found in?
S. aureus and S. pseudintermedius
What is the role of protein A?
it binds to antibody via the Fc region and the bacteria then coat themselves with the host antibody making the host continually susceptible to re-infection
Does S. aureus have a capsule?
yes, but it is only present in-vivo and is quickly lost on culture
What is the role of lipases in S. aureus?
they breakdown bactericidal fatty acids on the skin and is responsible in large part for the ability of the organism to colonize this tissue
What disease in cattle, sheep, and goats is associated with S. aureus?
mastitis
What is found in some isolates of S. aureus associated with cattle?
TSST1 (toxic shock syndrome toxin)
What does S. aureuscause in dogs?
skin infections, pustular dermatitis, wound infections, otitis, urogenital (especially cystitis), acral lick dermatitis, and mastitis
What does S. aureus cause in cats?
abscesses, wounds of conquest, urinary infections
What does S. aureus cause in horses?
wounds and abscesses
What is about 80% of staph infections in horses?
S. pseudintermedius
What does S. aureus cause in avian species?
gangrenous or necrotic dermatitis, bumblefoot, and occasional ocular infections
What human are some human staph infections?
conjunctivitis, bolis, otitis, sinusitis, cystitis, osteomyelitis, bacteremia, septicemia, meningitis, toxic shock syndrome, and food poisoning
What leukocyte is very important to immunity in S. aureus?
neutrophils
What are the subspecies of Staphylococcus schleiferi?
shleiferi and coagulans
What diseases are associated with Staphylococcus schleiferi?
pyoderma, otitis externa
Is S. epidermidis coagulase negative or positive?
negative
What diseases are associated with Staphylococcus epidermidis?
mild or subclinical mastitis in dairy cattle and goats, skin infections, and septicemia in humans associated with intravenous catheters
What disease is associated with Staphylococcus hyicus subspecies 1?
exudative epidermitis (greasy pig disease)
What does S. hyicusdo to the epidermis in pigs?
separation of epidermal cells, exfoliation, erythema, and outpouring of serum
How is S. hyicus prevented in pigs?
they are vaccinated or antibiotics are used
What disease is associated with Staphylococcus hyicus subspecies 2?
mastitis in dairy cattle
What disease is S. sciuri and S. xylosus associated with?
low-grade mastitis in dairy cattle
What disease is S. saprophyticus associated with?
cystitis
What is S. gallinarum associated with?
poultry - it is commonly found on skin
What tests are used to differentiate staphylococci species?
hemolysis, coagulase, VP test, carbohydrate fermentation tests, MALDI-TOF MS, and phage typing
