Microbiology Lab Exam 3 Study Guide

Comprehensive practice questions covering Streptococcus and Staphylococcus identification, rapid ID tests, ELISA principles, and dichotomous keys.

What does the enzyme esculinase break down in a Bile Esculin (BEA) test?

Esculin to esculetin

What substance reacts with esculetin in the BEA test to create a black precipitate?

Ferric citrate

How is the Bacitracin test conducted for Streptococcus identification?

As a Kirby-Bauer antibiotic test but with blood agar

What are the three types of blood hemolysis to know for the Streptococcus ID?

Alpha, beta, and gamma hemolysis

What is the concentration of NaCl in the NaCl broth test?

$6.5\,\%$ NaCl

Which pH indicator is used in the NaCl broth test?

Bromcresol purple

What color does NaCl broth turn when it is positive for acid?

Yellow

What are the three specific ingredients in Mannitol Salt Agar (MSA)?

Mannitol, phenol red, and NaCl

What type of organisms does MSA select for?

Halophiles

What color indicates a positive result for mannitol fermentation on an MSA plate?

Yellow

What enzyme is responsible for the breakdown of DNA in the DNA hydrolysis test?

DNase

Which reagent is added after growth in the DNA hydrolysis test to precipitate DNA?

$$HCl$$

What indicates a positive result for DNA hydrolysis?

A clearing zone

What component of rabbit serum is converted into fibrin by the enzyme coagulase?

Fibrinogen

What is the physical indicator of a positive coagulase test result?

The formation of a clot

By what method is the Novobiocin test performed for Staphylococcus identification?

As a Kirby-Bauer antibiotic test

What category of test is the Staphylococcus Rapid ID?

An agglutination test

In the Staphylococcus Rapid ID, what is the antibody ($IgG$) attached to?

A latex bead

What specific clumping factor serves as the antigen in the Staphylococcus Rapid ID?

Protein A

Which organism is exclusively identified by the presence of Protein A in the Rapid ID test?

$$S. aureus$$

What type of test procedure is the Streptococcus Rapid ID?

A direct ELISA

How many primary antibodies are used to bind to the antigen in the Streptococcus Rapid ID?

Two primary antibodies

Which specific species is the target of the antigen in the Streptococcus Rapid ID?

$$S. pyogenes$$

In the control region of the Streptococcus Rapid ID, what does the secondary antibody bind to?

The enzyme-linked primary antibody

What type of ELISA was performed in Exercise 11-6?

An indirect ELISA

Which component is enzyme-linked in the indirect ELISA procedure?

The secondary antibody

What are the three essential components to understand for the wells in the indirect ELISA?

Primary antibody, secondary antibody (enzyme-linked), and antigen

How many rounds of contact were used to spread disease in the ELISA lab simulation?

Three rounds of contact

What source was used to identify the initial carrier in the ELISA lab exercise?

The infected patient list

What tool is used to identify an organism by following a path of results down to the identification point?

A dichotomous key