FA Gram + Cocci Flashcards
Gram positive cocci in clusters
Staph aureus
What is the virulence factor for S aureus?
Protein A
How does protein A work?
Binds Fc-IgG, inhibiting complement fixation and phagocytosis
TSST is a superantigen that binds to WHAT causing WHAT?
MHC II and T cell receptor –> poly T cell activation
Presentation of toxic shock syndrome
Fever, Vomiting, Rash, Desquamation, Shock, End organ failure
S aureus food poisoning is due to ingestion of
preformed antigen
What types of inflammatory diseases can staph aureus cause?
skin infections, organ abscesses, penumonia
What types of toxin-mediated diseases can staph aureus cause?
Toxic shock syndrome (TSST-1)
Scalded skin syndrome (exfoliative toxin)
Rapid onset food poisoning (enterotoxins)
What is the toxin that causes toxic shock syndrome?
TSST-1
What is the toxin that causes scalded skin syndrome?
exfoliative toxin
What is the toxin that causes staph aureus rapid-onset food poisoning?
enterotoxins
Name an important cause of serious nosocomial and community-acquired infections
MRSA
Why is MRSA resistant to beta lactams?
Altered penicillin-binding protein
5 broad types of infections caused by MRSA (this is a read my mind question)
- Inflammatory disease
- Toxin-mediated disease
- MRSA
- Acute bacterial endocarditis
- osteomyelitis
How can staph lead to abscess?
forms fibrin clot around self
Staph make catalase because they have more staff (compared with strep). Bad staph (aureus) make
coagulase and toxins
Infects prosthetic devices and intravenous catheters by producing adherent biofilms. Component of normal skin flora; contaminates blood cultures
Staph epidermidis
What is the most common cause of MOPS: meningitis otitis media (in kids) pneumonia sinusitis
Strep pneumo
strep pneumo is the most common cause of what four conditions
meningitis
otitis media (in kids)
pneumonia
sinusitis
Lancet-shaped, gram positive diplococci
Strep pneumo
encapsulated bacteria that carries IgA protease
Strep pneumo
Rusty sputum pneumonia
Strep pneumo
Sepsis in sickle cell
Strep pneumo
Sepsis in asplenic pt
strep pneumo
to what is strep pneumo sensitive?
s pneumo MOPS are Most OPtochin Sensitive
Strep pneumo would have no virulence without its
capsule
Dental caries
Strep mutans (viridans, group D)
subacute bacterial endocarditis
Strep sanguis (viridans, group D)
type of hemolysis for strep viridians (group d)
alpha
how to differentiate viridans from strep pneumo
Viridans is optochin resistant, but strep pneumo is optochin sensitive
How does s sanguis stick to damaged valves by making
glycocalyx
viridans are normal flora where?
oropharynx
Viridians group strep live in the mouth because they are not afraid …. (joke)
of the chin! (optochin resistant)
strep pyogenes is also called
group A strep
pyogenic manifestations of strep pyogenes
pharyngitis, cellulitis, impetigo
toxigenic manifestations of strep pyogenes
scarlet fever, toxic shock-like syndrome, necrotizing fasciitis
immunologic manifestations of strep pyogenes
rheumatic fever, acute glomerulonephritis
How to differentiate strep pyogenes and agalactiae
bacitracin (pyogenes is sensitive)
BLANK enhances host defenses against Strep pyogenes, but can also give rise to rheumatic fever
ANTIBODIES to M protein (note: imm response NOT bacteria that cause rheumatic fever)
how would you detect a recent s pyogenes infection?
ASO titer
What are the jones criteria to diagnose rheumatic fever
Joints (polyarthritis)
s chorea
Strep pyogenes PHaryngitis can result in (the stupidest mnemonic ever)
rheumatic PHever and glomerulonePHritis
BLANK more commonly precedes PSGN than pharyngitis
impetigo
scarlet rash SPARING face, strawberry tongue, scarlet throat
scarlet fever
beta hemolytic + bacitracin resistant =
Strep agalactiae (group B strep)
colonizes vagina; causes pneumonia, meningitis, and sepsis, mainly in babies
Strep agalactiae (group B strep)
S agalactiae produces what factor?
CAMP factor (note this is not cyclic AMP)
CAMP factor does what?
enlarges area of hemolysis formed by S aureus (ugh wait what? why is staph aureus here too?)
what test would you do to confirm strep agalactiae presence?
hippurate
because group B hits babies, you should screen pregnant women at
35-37 weeks
if a pregnant woman has group B positive cultures, she should receive
intrapartum penicillin prophylaxis
There are two general classes of group D streptococci
Enterococci
Strep bovis
name two important enterococci (group B strep)
E faecalis
E faecium
Enterococci are normal colonic flora that are all resistant to what?
Penicillin G
Three types of infections caused by enterococci
- UTI
- Biliary tract infections
- Subacute endocarditis
Lancefield grouping is based on differences in the
C carbohydrate on the bacterial cell wall.
Lancefield group D includes
enterococci and nonenteroccal group D streptococci
group D strep hemolysis?
variable
To distinguish enterococci from nonenterococcal group D
enteroccci can grow in 6.5% saline and bile
Some enterococci have become resistant to WHAT –> important cause of nosocomial infection
Vancomycin –> VRE
Colonizes the gut; can cause bacteremia and subacute endocarditis in colon cancer patients
Strep bovis (group D)
Bovis in the blood =
cancer in the colon
word association: strep bovis
colon cancer