Strep ID gauntlet questions

What tests are used for ID of streptococci on BOTH Beta and Alpha streptococci?

LAP, Bile Esculin, NaCl, PYR

What tests are used for ID of beta streptococci?

Bacitracin resistance, CAMP

What tests are used for ID of alpha/ gamma streptococci?

Bile Solubility, Optochin

What organisms are positive (bubbles) in the catalase test?

Staphylococci, and some Enterococci (weakly)

What organisms are negative in the catalase test?

Streptococci!

What organisms are positive (red spot appearing on disk) in the LAP test?

Streptococci (all of them) and Enterococci

What organisms are negative in the LAP test?

Leuconostoc and most aerococcus (these two are species that can be mistaken for strep, but otherwise we don’t need to know much about them)

What organisms are positive (blackening of medium) in the Esculin hydrolysis (Bile Esculin Agar) test?

Group D streptococcus (in both alpha and beta hemolytic groups), and Enterococcus species (which are also in both alpha and beta hemolytic groups)

What organisms are negative in the Esculin hydrolysis (Bile Esculin Agar) test?

Everything but Enterococcus species and Group D species

What organisms are positive (show turbid growth) in the NaCl test?

Enterococcus and group B streptococcus (variable) and staphylococcus!

What organisms are negative in the NaCl test?

Everything but enterococcus, group B streptococcus (variable) and staphylococcus

What organisms are positive (turn red) in the PYR test?

Group A strep, and enterococcus

What organisms are negative (turn red) in the PYR test?

Everything but group A strep and enterococcus

What organism(s) are Susceptible (form ZOI) in the Optochin susceptibility test?

only streptococcus pneumoniae

What organism(s) are Resistant in the Optochin susceptibility test?

Enterococcus species, Group D alpha streptococci, and Not group D alpha streptococci

What organism(s) are positive (cleared tube solution) in the Bile Solubility test?

Streptococcus Pneumoniae

What organism(s) are negative in the Bile Solubility test?

Everything but streptococcus pneumoniae

(LIKELY NOT ON QUIZ) What organism(s) are positive (Negative staining - clearing around organism stained with methylene blue) in the Quellung test?

Streptococcus pneumoniae

(LIKELY NOT ON QUIZ) What organism(s) are negative in the Quellung test?

Everything but streptococcus pneumoniae

What organism(s) are Susceptible (ZOI) in the Bacitracin test?

Beta streptococcus (group A)

What organism(s) are Resistant (no ZOI) in the Bacitracin test?

Anything but Beta streptococcus (group A)

What organism(s) are Positive (form arrowhead) in the CAMP test?

beta streptococcus (group B)

What organism(s) are negative in the CAMP test?

Everything but beta streptococcus (group B)

(LIKELY NOT ON QUIZ) What organism(s) are positive (purple) in the Sodium Hippurate test?

Beta streptococcus (group B)

(LIKELY NOT ON QUIZ) What organism(s) are Negative in the Sodium Hippurate test?

Everything but Beta streptococcus (group B)

Relevant tests for group A

Beta hemolysis, PYR+, Bacitracin susceptible

Relevant tests group B

Beta hemolytic, CAMP +, NaHippurate +, NaCl + (usally)

Relevant tests group D

Usally alpha or gamma hemolytic, Esculin + (NaCl- and PYR-, unlike enterococcus)

Relevant tests Streptococcus pneumoniae

alpha hemolytic, optochin susceptible, Bile solubility +, quellung test +

Enterococcus relevant tests

Alpha or gamma hemolytic, esculin +, NaCl +, PYR +,

Alpha streptococcus (not group D) relevant tests

Negative for alpha strep differentiation tests (resistant / negative for everything but LAP)

Beta streptococcus ( not group A, B and D)

negative for beta strep differentiation tests (resistant / negative for everything but LAP)