Microbiology Lab Tests Vocabulary

Vocabulary flashcards based on lecture notes about microbiology lab tests.

Bacitracin

An antibiotic used to differentiate group A strep (Strep pyogenes) from other beta-hemolytic strep; inhibits cell wall synthesis.

Zone of Inhibition

Area around an antibiotic disc where bacteria do not grow, indicating susceptibility.

Resistance

The ability of an organism to withstand the effects of an antibiotic without being killed or inhibited.

Susceptibility

The extent to which an organism is affected by an antibiotic, indicated by a zone of inhibition around the antibiotic disc.

Confluent Growth

Uniform, dense bacterial growth on a culture plate, often desired for susceptibility testing.

Bile Esculin Test

A test to differentiate enterococci from group D strep and group D strep from non-group D based on the ability to grow in bile and hydrolyze esculin.

Esculin Hydrolysis

The breakdown of esculin into esculetin, which reacts with iron in the media to produce a dark color change.

Bile Solubility Test

A test to differentiate Strep pneumo from other alpha-streptococci based on solubility in bile salts.

Autolysis

The breakdown of cells, especially the lysis of bacterial cells, enhancing the clearing of a colony.

CAMP Test

A test used to differentiate group B strep (Strep agalactiae) from other strep species based on the production of diffusible hemolytic protein (CAMP factor).

CAMP Factor

A diffusible hemolytic protein produced by certain bacteria that enhances the beta-hemolysis of Staphylococcus aureus.

Catalase

An enzyme that converts hydrogen peroxide into water and oxygen.

Catalase Test

A bench top test used to differentiate staph from strep; staph are catalase-positive, strep are catalase-negative.

Copious Bubbles

The presence of numerous bubbles during a catalase test, indicating a positive result.

Coagulase

An enzyme produced by Staphylococcus aureus that clots plasma.

Coagulase Test

A test used to distinguish Staphylococcus aureus from coagulase-negative staph.

Bound Coagulase

This type of coagulase is bound to the bacterial cell wall; it reacts directly with fibrinogen in plasma.

Free Coagulase

Soluble version of this protein reacts with prothrombin in plasma and activates the formation of fibrin clots. The presence of this protein/enzyme can be detected when plasma congeals due to the production of fibrin.

Optochin (P disc) Susceptibility

Susceptibility testing used to differentiate Strep pneumo from other optochin-resistant alpha-hemolytic streptococci.

PYR

A substrate hydrolyzed by the PYR enzyme; used in a test to presumptively identify group A strep and enterococci.

PYR test

A rapid test used to presumptively identify Group A streptococci and Enterococci based on the presence of pyrrolidonyl aminopeptidase enzyme.

Salt Tolerance Test

A test used to differentiate enterococci from non-enterococci based on their ability to grow in high salt concentrations (6.5% NaCl).

Novobiocin Susceptibility

A test used to identify Staphylococcus saprophyticus, a common cause of urinary tract infections in young, sexually active females, differentiating it from other coagulase-negative staphylococci.

McFarland Standard

Turbidity standards used to standardize the concentration of bacteria in a suspension for antimicrobial susceptibility testing.

Mueller Hinton Agar

A clear agar used primarily for antimicrobial susceptibility testing. Provides a consistent, reproducible medium for determining the effectiveness of antibiotics against specific bacteria, without interfering substances.