• family: staphylococcaceae
• genra
  • staphylococcus
  • gemella

• S aureus
• S epidermidis
• S saprophyticus

• gram positive cocci
• multiplication in two dimensions with incomplete separation of daugther cells resulting in formation of clusters

Staph physiology: growth/mode of metabolism

• rapid growth of sharply defined, smooth opaque (light wont pass through colony) colonies on routine, nonselective media
• white color of colonies
• facultatively anaerobic (but given the choice, they would choose aerobic metabolism)

• gram positive cocci, usually in clusters
• positive for catalase

• slide coagulase test
  • if aureus, usually positive and occasionally negative
  • notice clumping of bacteria on test
• tube coagulase test- positive
  • wait longer time than slide test, but you will see the same clumping
• particle agglutination test- positive
  • detects both protein A:IgG interaction and coagulase, both causing particles to clump
• biochemical test panel

• slide coagulase test- usually negative
• tube coagulase test- negative
• biochemical test panel to ID species

• S aureus- has yellow/gold color
• S epidermidis- has white colonies (main coagulase negative staph species)

• catalases- destroy hydrogen peroxide produced by cell defenses
• coagulase- form fibrin clot (wall of site of infection)
• hyaluroindases- CT dig. (so it can infiltrate tissue)
• staphylokinase- fibrin clot lysis (allow spread)
• lipase- lipid hydrolysis (attack defense mech. of sweat antimicrobial properties)
• thermostable nuclease- nucleic acid polymer digestion (allow spread away from pus)
• penicillinase- inactivation of penicillin
  • act as beta lactamase

• membrane active toxins- lyse RBC
  • more nutrients for baceria
• Panton-Valentine leukocidin- lyses leukocytes
• Exfoliatin- disrupt integrity of epidermis
• TSS toxin 1- acts as superAg causing massive cytokine release
• enterotoxin A thru E, G: induce vomitting

• lives on:
  • skin
  • skin glands
  • mucous membranes
• preferentially colonizes nares

• live on:
  • skin
  • skin glands
  • mucous membranes
• preferentially colonize:
  • skin (S epidermis) (S lugdunensis)
  • sweat glands (S haemolyticus)
  • mucus membrane (S saprophyticus)

• capsule- inhibition of phagocytosis
• teichoic acid- adherence
  • part of cell wall
• protein A- bind IgG at Fc portion
  • part of cell wall

• "slime"- facilitate biofilm formation (attach to "foreign bodies")
  • esp. in S. epidermidis
• penicillinase- inactivate penicillin

• localized
• localized with rash
• invasive infection
• food poisoning

• folliculitis (at hair follicle)
• furuncles aka boil (aka enlarged folliculitis)
• carbuncles (clusters of furuncles)
• impetigo (superficial infection of skin usually at mouth or nose)
• cellulitis (infection of tissue)

• scalded skin syndrome (bad sun burn that opens up deeper layers of skin to infection)
• TSS (

• endocarditis (infection of heart valve)
• pneumonia
• osteomyelitis (S aureus number one cause of it)
• septic arthritis

• prosthetic valve endocarditis
• catheter associated bacteremia
• CNS shunt infection
• prosthetic device associated infection
• peritoneal dialysis catheter (associated peritonitis)
• UTI (number two cause of UTI in women is S. saprophyticus)

• gram stain
• real time PCR- detect staph DNA sequences
• microarray testing
  • simultaneous ID of several staph. species and VF's
• culture
  • nonselective media (5% sheep blood agar and chocolate agar)
  • selective medium
    • mannitol salt agar

• oxacillin R (if you detect this, it is the equivalent of detecting MRSA)
• vancomyocin R
• inducible clindamycin R

• growth on oxacillin agar
• cefoxitin disk diffusion testing
• oxacillin MIC determination (what conc. of oxacillin is needed to inh. growth of organism)
• mecA gene product (penecillin binding protein 2a) (PBP2a) detection by latex particle agglutination
• mecA gene detection by PCR

• grow on vancomycin agar
• vancomycin MIC determination

• Antibiotic for skin, soft tissue infections
• detect via D zone test
  • zone that look likes letter D