Day 2: Interpretation Flashcards
What is a positive DN’ase test
Zone of clearance around colonies
What is a negative DN’ase test
No zone of clearance around the colonies
What organisms produce a positive DN’ase result
S. aureus
M. Catarrhalis
What organisms produce a negative DN’ase result
S. epidermidis, S. saprophyticus
N. species e.g. N. meningitidis,
What is a positive mannitol salt agar test
Yellow colonies on mannitol agar indicate mannitol fermenter and salt tolerant
What is a negative mannitol salt agar test
Red colonies on mannitol salt agar indicate non mannitol fermenter but salt tolerant
What species are positive on mannitol salt - yellow/pink and growth?
S. aureus
What species are negative on mannitol salt - red/pink but growth
S. epidermidis or S. saprophyticus
What does it mean if an organism doesn’t grow on mannitol agar
It is not salt tolerant i.e. its a staphylococcus
What does pink colonies on SAIDE agar indicate
Staphylococcus aureus
What is a negative Staphaurex plus result
No agglutination
What is a positive Staphaurex plus result
Agglutination
What species will give a positive Staphaurex plus result
Only S. aureus
What species of staphylococcus give a negative staphaurex plus result?
Coag negative staph e.g. S. epidermidis or S. saprophyticus
What is a positive result for optochin susceptibility?
Susceptibility -> zone of no growth around optochin disk
What is a negative result for optochin susceptibilty?
Resistance -> growth around optochin disk
What species will give a positive optochin result?
S. pneumonia (susceptible)
What species will give a negative optochin result?
S. viridans (resistant)
What is a positive Lancefield test?
Agglutination
What is a negative Lancefield test?
No agglutination
What does a Lancefield group A indicate?
Streptococcus pyogenes
What does a Lancefield group B indicate?
Streptococcus agalactiae
What does Lancefield group C indicate?
Streptococcus equi (most probable)
Streptococcus epidemicus
Streptococcus equisimilis
What does Lancefield group D indicate?
Streptococcus bovis
Or the more probable Enterococcus -> E. faecalis
What does Lancefield group F indicate?
Streptococcus anginosus
What does Lancefield group G indicate?
Streptococcus canis
Streptococcus dysgalactiae
What is a positive bacitracin test?
Susceptible to bacitracin
What is a negative bacitracin test?
Resistant to bacitracin
What species give a positive bacitracin test?
Streptococcus pyogenes (susceptible)
What species give a negative bacitracin test?
Enterococcus species
What is a positive result for MacConkey agar?
Pink colonies
What is a negative result for MacConkey agar?
Yellow colonies
What species will give a positive result on MacConkey?
Enterococci
What species will give a negative result on MacConkey?
Streptococci
What is a positive bile aesculin test?
Blackening of the medium
What is a negative bile aesculin result
No blackening of the medium
What species will give a positive result on bile aesculin agar?
Enterococci
What species will give a negative result on bile aesculin agar?
Streptococci
What TAXO sugars does N. Meningitidis utilise?
Glucose
Maltose
What TAXO sugars does N. Gonorrhoeae utilise?
Glucose
What TAXO sugars does N. flavescens utilise?
None
What TAXO sugars does N. lactamica utilise?
Glucose
Maltose
Lactose
What TAXO sugars does N. sicca utilise?
Glucose
Maltose
Sucrose
What Neisseria species ferments glucose only?
Gonorrhoeae
What Neisseria species ferments none of the TAXO sugars ?
N. flavescens
What Neisseria species ferments glucose and maltose?
N. meningitidis
What Neisseria species ferments glucose, maltose and lactose?
N. lactamica
What Neisseria species ferments glucose, maltose and sucrose?
N. sicca
What is a positive result for the TAXO sugar test?
Yellow colour -> colour change from red to yellow upon addition of the phenol red indicator
What is a negative result for the TAXO sugar test
Red colour -> no colour change upon addition of the phenol red indicator
What is a positive catarrhalis disc test?
Blue-green colour development
What is a negative catarrhalis disc test?
No colour development within 2 minutes
What species will give a positive catarrhalis disc test?
M. catarrhalise
What species will give a negative catarrhalis disc test?
Neisseria species
What is a positive lecithinase reaction on PEMBA agar?
Zone of clearance around colonies
What is a negative lecitihinase reaction on PEMBA agar?
No zone of clearance around colonies
What is a positive mannitol fermentation reaction on PEMBA agar?
Yellow colonies
What is a negative mannitol fermentation reaction on PEMBA agar?
Blue colonies
What bacillus species will grow on PEMBA agar as blue colonies with a zone of clearance?
B. cereus or B. thuringenesis
What bacillus species will grow on PEMBA agar as blue colonies with a variable narrow zone of clearance?
B. anthracis
What bacillus species will grow on PEMBA agar as yellow colonies with no zone of clearance?
B. subtilis
How does B. cerues and B. thuringensis look on PEMBA agar?
Blue colonies with a zone of clearance
How does B. anthracis look on PEMBA agar?
Blue colonies with a narrow zone of clearance
How does B. subtilis look on PEMBA agar?
Yellow colonies with no zone of clearance
What exactly does motility look like?
Movement in a definite direction
What species of bacillus are motile
B. cerues
B. thuringenesis
B. subtilis
What species of bacillus are non motile
B. anthracis
What is a positive trehalose test
Yellow colour change
What is a negative trehalose test
No colour change = pink colour
What is a positive urease test
Pink colour change
What is a negative urease test
No colour change = yello
What species of Corynebacteria will give a positive trehalose and positive urease test?
C. ulcerans
What species of Corynebacteria will give a negative trehalose and a negative urease test?
C. diptheria
What species of Corynebacteria will give a negative trehalose and positive urease
C. pseudotuberculosis
Diptheroids
How will C. ulcerans look in the trehalose and urease tests?
Trehalose = yellow = positive
Urease = pink = positive
How will C. diptheria look in the trehalose and urease tests?
Trehalose = pink = negative
Urease = yellow = negative
How will C. pseudotuberculosis and the diptheroids look on the trehalose and urease tests?
Trehalose = pink = negative
Urease = pink = positive
What species will grow on Tinsdale agar?
Only Corynebacteria will grow on Tinsdale
How does C. diptheriae/C. ulcerans appear on Tinsdale medium?
Black colonies with brown halos
How do the diptheroids look on Tinsdale medium
Dark brown colonies without halos
What species grows on Tinsdale medium with black colonies and no discoloration of the medium?
Diptheroids such as haemophilus, klebsiella, neisseria, staphylococcus and streptococccus
What species of Corynebacteria grows on Tinsdale medium with black colonies and brown halos/discoloration of medium?
C. diptheria
C. ulcerans
What is a positive result for lactose fermentation in the lactose-gelatin tubes?
Yellow colour
What is a negative result for lactose fermentation in the lacctose-gelatin tubes?
Red colour
What is a positive result for gelatinase in the lactose-gelatin tubes?
Liquid formation
What is a negative result for gelatinase in the lactose-gelatin tubes?
Gel formation
How does C. perfringens appear in the lactose-gelatin tubes
Yellow liquid
Lactose fermentation - positive = yellow
Gelatinase - positive = liquid
How does C. tetani/ C. difficile appear in the lactose-gelatin tubes?
Red gel
Lactose fermentation - negative = red
Gelatinase - negative = gel
How does C. botulinum/ C. sporogenes appear in the lactose-gelatin tubes?
Red liquid
Lactose fermentation - negative = red
Gelatinase - positive = liquid
Which species will appear as a yellow gel in the lactose-gelatin tubes?
E. coli
Which species will appear as a yellow liquid in the lactose-gelatin tubes?
C. perfringens
Which species will appear as a red gel in the lactose gelatin tubes
C. tetani
C. difficile
Which species will appear as a red liquid in the lactose gelatin tubes?
C. botulinum and C. sporogenes
What is a positive lecithinase result for the egg yolk agar
opaque diffuse zone
What is a negative lecithinase result for the egg yolk agar
No opaque diffuse zone
What is a positive lipase result for the egg yolk agar?
Pearly/shiny layer
What is a negative lipase result for the egg yolk agar?
Absence of pearly/shiny layer
Which species will give a positive lecithinase but a negative lipase result on egg yolk agar?
C. perfringens
Which species will give a negative lecithinase and negative lipase result on egg yolk agar?
C. tetani
C. difficile
Which species will give a variable amount of lecithinase activity and a positive lipase result on egg yolk agar?
C. botulinum
Which species will give a negative lecithinase and a positive lipase result on egg yolk agar?
C. sporogenes
What is a positive Naglar test result
Disappearance of opacity
What is a negative Naglar test result
No disappearance of opacity
How does B. fragilis appear on the MID8 mastring test?
Erythromycin = Occassionally susceptible
Rifampicin = Susceptible
Colistin sulphate = Ocassionally resistant
Penicillin = Resistant
Kanamycin = Resistant
Vancomycin = Resistant
What growth factors does H. influenzae need?
X factor and V factor
What growth factors does H. parainfluenzae need?
V factor only
What growth factors does H.ducreyi need?
X factor only
What growth factors does H. aegyptius need?
X factor and V factor
What growth factors does H. aphrophilus need?
Variable growth with X only
What haemophilus species need both X and V factors to grow
H. influenzae
H. aegyptius
What haemophilus species need V factor only to grow
H. parainfluenzae
What haemophilus species need X factor only to grow
H. ducreyi
H. aphrophilus (variable growth with X only)
What is a positive result for King’s A Medium
P. aeruginosa grows at 37 degrees with green fluorescence
What is a negative result for King’s A Medium
P. fluorescence will grow but won’t be fluorescent green
E.Coli will not grow at all
What does pink/red on Brilliance chromagar suggest?
E. Coli
What does turquoise/blue-green indicate on brilliance chromagar?
Enterococcus species
What does dark blue/purple indicate on brilliance chromagar
Colliforms -> enterobacteroides
What does brown halos indicate on brilliance chromagar
Proteus
Morganella
Providencia
What does brown/green translucent indicate on brilliance chromagar
Pseudomonas
What does non pigmented indicate on brilliance chromagar
Staphylococci
Streptococci
What does pink indicate on brilliance chromagar
S. saprophyticus
What is a positive citrate test
Colour change from green to blue
What is a negative citrate test
No colour change - green colour
What is a positive indole test?
Cherry red colour development after addition of 8 drops kovaks reagent
What is a negative indole test?
No colour development after addition of Kovaks reagent
What is a positive MR test?
Maintenance of red colour following addition of MR solution
What is a negative MR test?
A yellow colour persists following addition of MR solution
What is a positive VP test?
Red colour development after addition of the VP reagent 1 and 2
What is a negative VP test?
No red colour development after addition of the VP reagents 1 and 2
What is a positive dulcitol test?
Colour change from pink to yellow
What is a negative dulcitol test?
No colour change -> pink colour
What is a positive decarboxylase test?
Purple colour
What is a negative decarboxylase test?
Yellow colour