Gram (+) Cocci, G(-) Cocci, G(+) Aerobic Rods Flashcards
Which gram positive cocci are beta hemolytic?
S. pyogenes (Group A)
S. agalactiae (Group B)
S. aureus
Which media isolates staphylococci?
Mannitol Salt Agar (MSA)
Mannitol fermentation = yellow colonies = S. aureus
Staphylococcus epidermis = growth but no color change
What does phenylethyl alcohol agar (PEA) isolate?
Gram positive bacteria
What differentiates Enterococcus from other streptococci
Bile esculin (+)
Black colonies
Which gram positive cocci are catalase positive?
Staphylococci
Micrococcus
Which gram positive cocci are catalase negative?
Streptococcus
Enterococcus
Reagent for catalase test?
3% H2O2
What does free coagulase react with?
Coagulase reacting factor (CRF)
This forms a visible clot in coagulase test tube test
What does bound coagulase not react with?
CRF
In coagulase slide test
Clumping = +
What is PYR (+)?
Enterococcus or S. pyogenes = (+)
Other streptococci = (-)
What color is PYR if positive?
Pink/red
What is positive for LAP (leucine amino peptidase)?
Streptococcus
Enterococcus
Pediococcus
Tests for enzyme that hydrolyzes peptide bonds
Bile solubility (+)?
S. pneumoniae, colonies disintegrate
Differentiates E. faecalis (-), colonies remain intact, and differentiates other alpha hemolytic strep
What is CAMP (+)?
S. agalactiae
Lyses RBCs of S. aureus
Gram stain of Staphylococcus
G(+) cocci in grape-like clusters
Staphylococcus colonies
Large
Creamy yellow
Beta hemolytic
Non-motile
Resistant to bacitracin
S. aureus
Staphylococcus Scalded Skin Syndrome
Toxic Shock Syndrome
Food poisoning
S. saprophyticus
Honeymooners Disease - UTI in sexually active women
Normal flora in urogenital tract
Novobiocin resistance (separates from S. epidermidis)
Which staphylococcus is coagulase (+)?
S. aureus
Which staphylococci is novobiocin Resistant?
S. saprophyticus
Micrococcus
Gram (+) cocci in tetrads
Strict aerobes
Normal flora of skin, mucosa, oral pharynx
Small, yellow, smooth colonies
Susceptible to bacitracin
Lysostaphin resistant (-)
Micrococcus
Bacitracin susceptible (in G + cocci, catalase +)
Micrococcus
Novobiocin resistant
S. saprophyticus
Gram stain of streptococcus
Gram (+) cocci in chains
Think: Strips
Hemolysins for S. pyogenes
Streptolysin S: stable in presence of O2, large beta hemolysis zone around colonies
Streptolysin O: inhibited when exposed to O2, enhanced hemolysis around stabs in agar
S. pyogenes diseases
Suppurative (pus)
Strep throat
Scarlet fever
Necrotizing faciitis
Bacteremia
Rheumatic fever (damage to heart valves)
S. pyogenes biochemical tests
PYR (+)
LAP (+)
Bacitracin S
S. agalactiae
Normal flora of GI tract and urogenital tract
Small, translucent, small zone of beta hemolysis
Early onset: <7 days, pneumonia and sepsis
Late onset: 1 wk-3 months, meningitis
Adults: UTI, wound/soft tissue infection, pneumoniae, bacteremia
Check in pregnant women and treat at delivery
S. pyogenes vs. S. agalactiae
Group A: PYR (+), Bacitracin S
Group B: PYR (-), Bacitracin R, Hippurate (+), CAMP (+)
S. pneumoniae (gram stain shape, normal flora)
Lancet shaped diplococci
Normal flora of nasopharynx
Alpha hemolytic
Small colonies in un-encapsulated strains, larger mucoid round colonies in encapsulated strains (Quelling reaction)
Diseases of S. pneumoniae
Bacterial pneumonia, otitis media, meningitis
S. pneumoniae biochemical tests
Optochin susceptible
Bile solubility (+)
Enterococcus faecalis/faecium
Normal human flora of GI and vaginal tract
Large, gray colonies with a sheen
Non-hemolytic
Catalase (-)
PYR (+)
Bile esculin (+)
Optochin resistant - resistant to more antibiotics than other GPC
Group D Strep (Non-Enterococcus)
PYR (-)
LAP (+)
Associated with Chlamydia
Neisseria gonorrheae
Halo around colonies
Corynebacterium on CTBA and TIN