Exam 1 Core Flashcards
Staphylococcus aureus
Gram stain: (+), cocci in clusters
Morphology:
Biochemical tests:
Catalase (+), Coagulase (+)
Staphylococcus epidermidis
Gram stain: (+), cocci in clusters
Morphology:
Biochemical tests:
Catalase (+), Coagulase (-)
Staphylococcus saprophyticus
Gram stain: (+), cocci in clusters
Morphology:
Biochemical tests:
Catalase (+), Coagulase (-)
Staphylococcus lugdunensis
Gram stain: (+), cocci in clusters
Morphology:
Biochemical tests:
Catalase (+), Coagulase (-)
Streptococcus pyogenes
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Virulence Factors:
- Surface
- Hyaluronic acid capsule
- M protein cell surface antigen
- Enzymes
- Streptolysin O & S
- Streptokinases
- Streptococcal pyrogenic exotoxins (SPE’s)
- DNAse
Human Pathogenic Potential:
- Via exotoxin: strep throat, scarlet fever, [streptococcal] pharyngitis, skin infections, [streptococcal] toxic shock syndrome
- Antibody-mediated, i.e. delayed (sequelae): rheumatic fever, acute glomerular nephritis,
Streptococcus agalactiae
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Other beta hemolytic streps
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Streptococcus anginosus (milleri) group
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Streptococcus pneumoniae
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Group D streptococci
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Viridans strep group
Gram stain:(+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Member organisms:
Viridans strep group
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Member organisms:
Enterococcus faecium
Gram stain:
Morphology:
Biochemical tests:
Catalase (-)
Micrococcus sp.
Gram stain:
Morphology:
Biochemical tests:
Catalase ()
Diphtheroids
Gram stain:
Morphology:
Biochemical tests:
Fastidious alpha streptococci
Gram stain: (+), cocci in chains
Morphology:
Biochemical tests:
Catalase (-)
Member organisms:
Abiotropha, Aerococcus, Leuconostoc, Pediococcus, Gemella
Corynebacterium diphtheriae
(RF p. 155 [sp.])
Gram stain:
Morphology:
Biochemical tests:
Corynebacterium jeikeium
(RF p. 155 [sp.])
Gram stain:
Morphology:
Biochemical tests:
Corynebacterium urealyticum
(RF p. 155 [sp.])
Gram stain:
Morphology:
Biochemical tests:
Listeria monocytogenes
(RF p. 156-157)
Gram stain:
Morphology:
Biochemical tests:
Arcanobacterium haemolyticum
Gram stain:
Morphology:
Biochemical tests:
Arcanobacterium pyogenes
Erysipelothrix rhusiopathiae
(RF p. 156 [sp.])
Gram stain:
Morphology:
Biochemical tests:
Lactobacillus
(RF p. 156)
Gram stain:
Morphology:
Biochemical tests:
Actinomyces
Gram stain:
Morphology:
Biochemical tests:
Rhodococcus equi
Gram stain:
Morphology:
Biochemical tests:
Structural Bacterial Virulence Factors
Capsule
Pili (Fimbrae)
Etc.
Endotoxin/Exotoxin
Endotoxin:
Exotoxin:
Physical disinfection methods
UV light
Etc.
Chemical disinfection methods
Ethylene oxide
Etc.
Blood agar, sheep (SBAP)
Allows for determination of hemolysis patterns
Gram stain
Carried out by: crystal violet, iodine, decolorizer, safranin
Gram (+) - thick cell wall holds CV; stains purple
Gram (-) - thinner cell wall decolorized more easily; stains pink/red
Trypticase soy agar
Wha???
Columbia CNA agar with 5% sheep blood
I forget..
Also need to mention Phenyl ethyl alcohol agar (PEA)
Mannitol salt agar
Selective: only organisms that can tolerate (percentage) salt will grow
Differential: only organisms that ferment mannitol will turn the red medium (contains pH indicator) yellow
Coagulase test
Differentiates Staphylococcus aureus (+) from other Staphylococcus sp. (-)
Can test for clumping factor (slide coagulase test) or for free coagulase (tube coagulase test)
Staph latex agglutination
Test for presence of clumping factor
Catalase test
Differentiates Staphylococci and Micrococcae from other Gram(+) cocci. Staphylococci and micrococcae produce catalase, which cleaves hydrogen peroxide into water and oxygen.
Procedure:
- Smear colony onto slide
- Cover bacteria in 3% H2O2
Results:
Positive (staphylococci): many bubbles of O2 form, for sustained period (distinguished from small “oxidative burst” that may be observed in Enterococcae [or just E. faecalis??]
Novobiocin susceptibility test
Differentiates …
Bacitracin susceptibility test
Differentiates …
Bile esculin agar
Selective: only organisms that use 40% bile can grow
Differential: only organisms that reduce esculin into esculetin + (what?) will produce brown/black color
Sodium hippurate broth
Differentiates …
Positive result gives purple color
6.5% sodium chloride broth
Selective:
Optochin susceptibility test
Differentiates:
Zone size must be measured
– >15 mm for 6mm disk
– >20…fill in
Bile solubility test
Differentiates:
Tests for presence of autolysin(?)
PYR test
Differentiates:
Tests for presence of
CAMP test
Differentiates: Group B streptococci from other streptococci. Group B streptococci produce CAMP factor, a diffusible extracellular protein that acts synergistically with beta-lysin of S. aureus.
Procedure:
- Streak a beta-lysin-producing S. aureus down the center of SBAP plate
- Streak test organism perpendicular to S. aureus (not touching, but within about 5 mm of S. aureus)
- Incubate overnight (35 C, ambient)
Results:
- Positive (S. agalactiae, i.e. GBS) : arrowhead-shaped zone of enhanced beta hemolysis at juncture of test organism and S. aureus
- Negative (
Motility test
In tube: looks at whether or not there are flagella
TSI agar slant
pink/pink
pink/yellow
yellow/yellow
Never yellow/pink??
Urea agar
Test for urease
Nitrate broth
Test for ability to metabolize nitrate