Lc 11 Flashcards
Type of staphylococci
Gram positive cocci
They grow in _________
Clusters
Staph’s characteristics
*Non-motile, non-spore forming
* facultative anaerobe
Facultative anaerobe does ____respiration
They do _____without _____
Aerobic,fermentation, oxygen
All staphylococci are……
So can differentiate from other gram positive cocci
Catalase positive
Is ROS toxic to bacteria?
Yes
All Staphylococcus detoxifies ROS.
Yes
What is catalase test?
Add peroxide(h2o2) to culture,
And if staphylococcus is present , then bubbles will show up
How do you differentiate different species of staphylococcus?
phenotype on blood agar ,coagulase test, mannitol fermentation, and rapid diagnostic test
There are two types of things that can be seen on blood agar by different species of staph.
What are they and explain it.
Pigment production: s.aureus is gold, s.epidermidis is white
Hemolysis: s. Aureus is beta-hemolytic and s.epidermid is is gamma hemolytic
Explain two types of coagulase in staph.
Surface bound and extracellular and they both contribute
to blood clotting
Coagulase slide test:
one with 듬성듬성 clots—> ?
one with opaque stain —>?
Tube test:
Liquid —>?
Clot—>?
Slide test : +,-
Tube test : -,+
Most staph species are coagulase negative except for…
S.aureus and S.argenteus
Does staph.aureus ferment mannitol?
Yes
What are the selective and differential characteristic features that mannitol salt agar shows for staph.aureus?
Selective: all staphylococcus can grow in high concentrations of salt.
Differential: differentiate by color ( gold) —> pH indicator( phenol red) will turn gold
Why is stph.aureus yellow in blood agar ?
And is that a virulence factor?
Due to staphyloxanthin, and yes it is virulence factor.
What is the main colonization area of s. Aureus?
Anterior nares ( nose picking area)
What are the virulence factors of s.aureus?
Adhesins, invasins, immune evasion, miscellaneous toxins,
Name three types of adhesins and their subtypes
MSCRAMM ( protein A) - surface bound , host attachment factor —> vWFplatelets
SERAM (Eap) - secretable adhesive molecule, host attachment factor —> fibrinogen, fibronectin
Teichoic acid
What does invasins do and name three components of invasins and their types
Invasins lyse cells and promote spread
Cytolytic toxic :pore forming
-hemolysins ( lyse erythrocytes and other mammalian cells), Panton Valentine Leukocidin ( lyse neutrophils and macrophages)
Exoenzymes : spreading
Degrade host cell components
Name three types of immune evasion and their functions
Protein A - impair phagocytosis ( binds to Fc portion of antibodies impairing phagocytosis)
Staphyloxanthin, catalase- detoxify reactive oxygen species
Hemolysins( alpha), panton valentine leukocidin - lyse immune cells or inhibit cell migration and recruitment
Name three types of miscellaneous toxins and their functions
Exfoliative toxins( ETA)
Toxic shock syndrome toxin (TSST)- ex. Superantigens
Staphylococcal enterotoxins ( SEA, B, C, D E, G, H, I ) - ex. Superantigens
What are the three s.aureus infections?
Cutaneous, systemic, toxigenic
Rank severity of cutaneous infection from lowest to highest.
Superficial folliculitis, deep folliculitis, furuncle, carbuncle
Describe folliculitis
Superficial infection of hair follicles.
Clusters of small red bumps
Non bullous impetigo
Superficial skin infection!
Honey colored bubble like epidermal swelling
Explain furuncle( boil)
Skin abscess with pus
Explain carbuncle
Aggregate of connected furuncles.
Several pustular openings
List systemic infections
Bacteremia, septic arthritis, infective endocarditis, osteomyelitis, pneumonia
What kind of infection is bacteremia? What is its characteristic?
Bloodstream infection, incidence increases w age with high mortality rate
Septic arthritis what kind of infection + function
Infection of joint cavity causing inflammation, swollen joints
Explain infective endocarditis +function
Infection of endocardium ( lining of heart chamber , valve)
Heart disease, flu like symptoms
Explain osteomyelitis +function
Infection of bone or bone marrow, mainly in children , common site is metaphysis of long bone,
Explain pneumonia +function
Infection of the lungs, community acquired: aspiration
Hospital acquired:mechanically ventilated patients
PV leukocidin
List toxigenic diseases
Staphylococcal scalded skin syndrome, bullous impetigo, toxic shock syndrome, staphylococcal food poisoning
Explain ssss + characteristics
Affects newborns,exfoliative toxins that cause epidermal- dermal separation ( desquamation)
Explain bullous impetigo + characteristics
Localized form of ssss, exfoliative toxin ETA, fluid filled vesicles and blisters ( bullae)
Explain TSS, + characteristics
Menstrual TSS- s.aureus multiplies in tampons , TSST-1 absorbed and enters bloodstream,
Nonmenstrual TSS- most cases in women (75%)
Staphylococcal food poisoning ( SFP) + characteristics
Food borne disease, staphylococcal enterotoxins,— > resistant to heat, acid
Explain coagulase negative staph.
Do not ferment mannitol, majority isolates gamma hemolytic
Is coNS important nosocomial pathogen?
Also what does commensal—> pathogens infection called?
Yes, opportunistic infections
Name all the virulence factors of s.epidermidis
Adhesins, accumulation factors( biolfilm formation), exoenzymes, immune escape
What are the types of adhesins in s. Epidermidis?
Hydrophobic surfaces( polystyrene), host matrix proteins ( MSCRAMMs)
Types of accumulation factors
Exopolysaccharide ( PIA), accumulation associated protein ( Aap)
List two exoenzymes
Lipase, protease
Is s.epidermidis the most common species in cons infections?
Yes
What are some other CoNs s?
S.haemolyticus, S.saprophyricus, S.lugdunensis
S.haemolyticus characteristics
Virulence factor: cytotoxin ( hemolysin)
Highest level of anitbiotics resistance among the coNs
S.saprophyticus. Characteristics
Important UTI pathogens
Virulence factors: enzyme ( urease) urease hydrolysis
S.lugdunensis characteristic
Severe infections similar to S.aureus
Virulence factor: s.lugdunensis synergistic hemolysins ( SLUSH)
Infections: infective endocarditis
