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46 Cards in this Set

  • Front
  • Back
Colonial Morphologies on MacConkey Agar
E. Coli: pink-->rose red
Enterobacter: mucoid, pink
Proteus: colorless [swarming]
Salmonella, Shigella: colorless
Pseudomonas: irregular, colorless-->pink
Sugar Fermentation of Neisseria
N. gonorrhoeae: glucose only
N. menigitidis: glucose + maltose
N. Sicca: glucose, maltose, sucrose
Thayer-Martin agar
respiratory, urogenital specimens
chocolate agar base w/vancomycin to inhibit gram positives
Colistin to inhibit gram negatives and non-path Neisseria
Mystatin to inhibit fungy
Trimethoprim to inhibit Proteus
Triple-Sugar-Iron agar
fermentation of glucose, lactose, or sucrose
production of gas and hydrogen sulfide
glucose only fermenters cause pH to change through out slant, acids at top oxidized rapidly + phenol red indicator remains neutral or alkaline. In butt, acids keep indicator yellow.
Ferrous ammonium sulfate and sodium thiosulfate in medium react w/H2S to form black ferrous sulfide.
TSI Rxns: yellow butt, yellow slant
conclusion: glucose + lactose fermented (E. coli)
TSI Rxns: yellow but, orange/pink slant
conclusion: glucose only fermentation (Salmonella, Shigella)
TSI Rxns: orange-red neutral butt, orange-red neutral slant
conclusion: no fermentation (pseudomonas)
TSI Rxns:
bubbles, cracks
Conclusion: gas produced
E. coli, Salmonella
TSI Rxns: black
Hydrogen Sulfide produced
Vogel-Johnson Agar
S. aureus
Lithium chloride, high glycine +K tellurite
Inhibits some gram +'s and gram -'s
S. aureus ferments mannitol (yellow color) and reduces tellurite to tellurium (black colonies)
Catalase Differentiation
differentiate Staphylococus from Streptococcus
heat-stable (68 degrees) catalase differentiates certain Mycobacteria
release oxygen from hydrogen peroxide
Coagulase differentiation
S. aureus from non-pathogenic Staphylococci
Activates plasma coagulation
Citrate Utilization Enzymes
enterics (c in IMViC)
Simmons citrate medium
Citrate as sole carbon source
Brom Thymol blue as the indicator: yellow-->green-->blue as pH changes from 6 to 7 to 7.6
nitrogen source is ammonium dihydrogen phosphate, broken down to ammonia by growing bacteria and becomes alkaline
Lysine decarboxylase (LDC)
broth w/glucose, lysine, and Brom cresol
initially purple-blue
glucose fermented --> pH acidic --> indicator turns yellow
LDC decarboxylates lysine --> cadaverine, renders medium alkaline and back to purple-blue
cover w/sterile mineral oil
yellow =negative
Phenylalanine deaminase
Proteus and Providencia from enterics
enzyme acts on phenylalanine to produce phenylpyruvate which complexes w/iron forming green precipitate.
Lactose-negative differentiation
pathogenic enterics
Salmonella, Shigella, Proteus lack beta-galactosidase and don't ferment lactose
identifies presumptive pathogens on MacConkey agar
E. Coli TSI Reaction Results
Slant: acidic
Butt: Acidic
Gas: +
Hydrogen S: -
Ps. aeruginosa TSI Rxn Results
Slant: alkaline
Butt: alkaline
Gas: -
Hydrogen S: -
CAMP factor
produced by Group B Streptococcus agalactiae
heat-stable protein produces synergistic hemolysis
named for Christie, Atkins, Munch-Peterson
factor X
Haemophilus speciation or from Bordetella
absolute requirement for H. influenzae + most non-para
tested on streaked plate blood agar
factor V
Nicotinamide adenine dinucleotide (NAD)
must be in media for growth of Haemophili (on blood agar)
presence of active flagella
in soft agar
differentiates S. pyogenes
Taxo A disc
topical antibiotic interferes w/third stage of peptidoglycan biosynthesis by binding to phyrophosphate
Mueller-Hinton Agar
standard medium for antibiotic determinations
S. Saprophyticus from other Staphylococci
Oral cavity/ nasopharyngeal mucosa organisms
non-pathogenic Neisseria
Obligate anaerobes- gingival crevices
Lactose- Negative Enterics
pale-colored colonies on selective and differential media (Eosin-Methylene Blue or MacConkey)
tested on TSI, phenylalanine deaminase (PDA), LDC, ODC to identify genus
Voges-Proskauer Enzymes
V in IMViC
detects acetoin (intermediate)
Barrits Reagents A&B oxidize acetoin to diacetyl which reacts w/creatine to produce a red compound
on tryptone broth
tryptophanase break tryptophan --> indole
detects w/Kovacs reagent
rearing = indole produced
Citrate (bacteria pump out carbon dioxide byproducts to turn media basic)
Identifying E. coli
Eosin-Methylene Blue
Hektoen Enteric or Brillant Green Agar
Inhibit growth of gram + and normal flora
Simmon Citrate: pH indicator
green color indicator
Diarrhea and E. coli
2. enteropathogenic
3. enterohemorrhagic (most severe)
Oxidase positive
they have cytochrom C reductase in ETC, allows them to withstand oxidative burst
Gram negative, facultative anaerobes, asporogenous rods
peritrichously flagellated
reduce nitrate --> nitrite
ferment glucose and are oxidase negative
mostly saprophytic
cause nosocomial infections, pneumonia, meningitis, cystitis
Listeria monocytogenes
gram +
aerobic, coccobacilli
neonatal meningitis
often arranged in palisades
narrow beta-hemolysis
growth at 4 degrees
colonize genital tract and infect fetus in utero
3 species: pertussis, parapertussis, bronchiseptica (rabbits)
resemble Haemophili
strict aerobes
charcoal and starch needed in medium to absorb toxic fatty acids
methicillin inhibits normal flora
H. Influenzae
endemic meningitis
otitis media, bronchitis, pneumonia, cellulitis, septic arthritis, and epiglottitis
H. aegyptius --> conjuctivitis
gram negative bacilli
hemin and NAD requirements
most important pathogen = H. influenzae (endemic meningitis)
Streptococcal differentiation
bacitracin sensitivity
CAMP test
bile-sensitivity, esculin hydrolysis
effect of temperature
latex agglutination
Gram positive
Catalase negative
Oxidase negative
Aerotolerant anaerobic homolactic ferementers
Defined by Lancefield Antigens (A-H, K-V)
S. pyogenes = A
S. agalactiae = B
S. equi = C
S. bovis = D
S. pneumoniae + viridans are major pathogens
Micrococi + Staphylococci
Skin Swab Materials
Blood Agar
Glucose phenol red broth: glucose fermentation v. aerobic growth
Vogel-Johnson agar: mannitol fermentation + tellurite reaction
Mueller-Hinton: antibiotic sensitivity
Skin Swab
found in soil and on the skin and mucous membranes
obligate anaerobes
Bile Esculin Agar
Enterococci from Streptococci
Oxgall (bile) inhibits other Gram positives and ferric citrate detects production of esculetin from esculin, resulting in dark circles around colonies
Blood Agar
Differentiation of hemolytic reactions
particularly the demonstration of beta-hemolysis from Group A Streptococci
usually sheep erythrocytes
Group D Strep
Skin and mucous membranes of the UR, GI, and GU tracts
normal flora
alpha hemolytic
hydrolyze esculin
resistant to bacitracin and high salt
MacConkey Agar
lactose, bile salts, neutral red, crystal violet
Salmonella, Shigella = resistant to bile
neutral red detects lactose-negative colonies
pale pink/white v. red-lactose+ colonies