Microbiology Media Growth Patterns Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the purpose of AUREUS protein A in Staphylococcus?

To inhibit phagocytosis

How does staphylokinase contribute to the spread of infection?

Dissolve fibrin clot

What is the function of lipase in Staphylococcus?

Hydrolysis of lipids

What is the role of hyalurodinase in Staphylococcus infection?

Hydrolyzing hyaluronic acid in tissues Signup and view all the answers

What is the function of DNAse in Staphylococcus?

Degrades/hydrolyze DNA Signup and view all the answers

How do exofoliatins contribute to skin diseases?

Hydrolyze tissue through cleavage of stratum granulosum Signup and view all the answers

What is the purpose of the Modified Oxidase Test (Microdase test) in bacteriology?

To differentiate between Staphylococcus and Micrococcus. Signup and view all the answers

Explain the purpose of the CHO Oxidation Fermentation Test.

The test determines if glucose is utilized. If glucose is utilized, the medium turns acidic (yellow); if not, it remains alkaline (green). Signup and view all the answers

What is used to seal the Closed tube in the OF tube test?

VASPAR (vaseline and paraffin) or Mineral oil. Signup and view all the answers

What is the most important pathogenic determinant of S.aureus?

Coagulase. Signup and view all the answers

How is the slide method of the Coagulase test performed?

It detects cell-bound coagulase (clumping factor) using Rabbit's plasma. Signup and view all the answers

What is the alternative reagent used in the Coagulase test if Rabbit's plasma is not available?

Human plasma. Signup and view all the answers

What is the appearance of Staphylococcus growth on Blood Agar Plate?

creamy white, pinhead colonies with hemolytic pattern Signup and view all the answers

Describe the appearance of Alpha prime hemolytic pattern on a Blood Agar Plate.

Small zone of alpha pattern (inner) - green inside surrounded by clearance Signup and view all the answers

What color indicates a large zone of beta pattern on a Blood Agar Plate?

clear color Signup and view all the answers

What is the color of growth for S.aureus on Loeffler’s Serum Slant?

golden yellow Signup and view all the answers

What is the pH indicator used in Mannitol Salt Agar?

phenol red Signup and view all the answers

How can you differentiate Staphylococcus from Streptococcus in a Catalase test?

by observing effervescence (bubbles) with 3% Hydrogen peroxide (H2O2) Signup and view all the answers

Study Notes

Growth on Blood Agar Plate

Staphylococcus grows as creamy white, pinhead colonies with an alpha hemolytic pattern.
If the petri dish is from the fridge, an alpha prime hemolytic pattern is observed.
The alpha hemolytic pattern has a small zone of green color inside, surrounded by clearance.
The beta hemolytic pattern has a large zone of clear color on the outer side.

Growth on Loeffler's Serum Slant

S. aureus grows as golden yellow.
S. citreus grows as lemon yellow.
S. albus (epidermidis) grows as porcelain white.

Growth on Mannitol Salt Agar

Mannitol is the CHO (carbon source) and phenol red is the pH indicator.
Inhibitor: 7.5%-10% NaCl.
S. aureus utilizes carbohydrate and turns yellow.
S. epidermidis is a non-mannitol fermenter and turns pink.
S. saprophyticus is variable and may ferment or not ferment.

Catalase Test

The catalase test is used to differentiate Staphylococcus from Streptococcus.
Reagent: 3% Hydrogen peroxide (H2O2).
(+) result: effervescence (bubbles) is observed.
Staphylococcus is catalase (+), while Streptococcus is catalase (-).

Differentiation of Staphylococcus and Micrococcus

Micrococcus is differentiated from Staphylococcus using the modified oxidase test (Microdase test).
Reagent: Tetramethyl-p-phenylenediamine dihydrochloride with Dimethylsulfoxide.
Negative result: clear.
Positive result: blue.

Toxins and Enzymes of Staphylococcus

Protein A: inhibits phagocytosis.
Coagulase: converts fibrinogen to fibrin clot.
Staphylokinase (fibrinolysin): capable of producing and dissolving clot.
Lipase: hydrolyzes lipids.
Hyalurodinase: capable of hydrolyzing hyaluronic acid in tissue.
DNAse: degrades DNA.
Exofoliatins: hydrolyzes tissue through cleavage of stratum granulosum.
Leukocidins: lyse neutrophil and macrophage.
Hemolysin: capable of lysing RBC.
Enterotoxins: cause food poisoning.

Family Streptococcaceae

Gram-positive, non-motile, non-spore forming, facultative anaerobes.
Catalase negative.
Streptococcus is divided into two types of classification: Lancefield and Brown's classification.

Lancefield Classification

Based on antigenic characteristic of a group-specific cell wall polysaccharide.
Single Lance group includes many ang.

Brown's Classification

Based on the pattern of hemolysis.
More than 20 groups, with the first 4 being clinically significant.

Coagulase Test

Most important pathogenic determinant of S. aureus.
Detects cell-bound coagulase (clumping factor).
Reagent: Rabbit's plasma.
Alternative reagent: human plasma.
Rabbit's plasma + inoculum = (+), clumping.
S. aureus is the only coagulase (+) under Staphylococcus.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on different growth patterns of Staphylococcus on blood agar plate, Loeffler's serum slant, and Mannitol salt agar. Identify the characteristics of colonies and hemolytic patterns observed on each specific media.