26 Questions
What is the primary function of differential media in microbiology?
To allow multiple bacteria to grow with distinguishable colonial characteristics
Which of the following media is an example of a combination medium?
Mannitol salt agar
What characteristic of bacteria is observable on blood agar?
Hemolytic activity
What is the primary advantage of using differential media in microbiology?
Preliminary characterization of bacteria
Which of the following statements is true about selective media?
They inhibit the growth of unwanted bacteria
What is the primary purpose of using combination media in microbiology?
To selectively grow specific bacteria while distinguishing between them
What is the primary function of phenol red in Mannitol salt agar?
To indicate a pH change due to mannitol fermentation
Which medium is used to differentiate between bacteria that ferment lactose and those that do not?
MacConkey agar
What is the purpose of thiosulfate in Sulfur indole motility (SIM) medium?
To detect the production of hydrogen sulfide gas
Which of the following media is used to detect the hydrolysis of urea to ammonia?
Urea broth
What is the primary function of intact red blood cells in Blood agar?
To facilitate the differentiation of hemolytic and non-hemolytic bacteria
Which medium is used to differentiate between bacteria that ferment sugars and those that do not?
Triple-sugar iron agar
What is the purpose of iron in Triple-sugar iron agar?
To detect the production of hydrogen sulfide gas
Which medium is used to differentiate between species of Staphylococcus?
Mannitol salt agar
What is the primary purpose of transport media in microbiology?
To preserve the viability of microorganisms in a specimen until processing
What is the role of salts in transport media?
To prevent the destruction of cells by enzymes
When would transport media be used in a microbiology laboratory?
When a specimen cannot be processed immediately
What is a characteristic of transport media?
It preserves the viability of microorganisms
What is the purpose of buffers in transport media?
To prevent the destruction of cells by enzymes
What is the result of using transport media in a microbiology laboratory?
The viability of microorganisms in a specimen is preserved
What is the primary purpose of enumeration media in microbiology?
To count the numbers of organisms in various samples
Which type of medium is used to grow anaerobic bacteria?
Reducing medium
What is the function of thioglycolic acid in reducing medium?
To absorb oxygen or slow the penetration of oxygen in the medium
What is the primary purpose of assay media in microbiology?
To test the effectiveness of antimicrobial drugs on microorganisms
What is the common feature of enumeration media and assay media?
They are both used to study microorganisms
What is the main difference between reducing medium and assay medium?
Reducing medium is used to grow anaerobic bacteria, while assay medium is used to test the effectiveness of antimicrobial drugs
Study Notes
Differential Media
- Allow multiple bacteria to grow but with distinguishable colonial characteristics.
- Allow for preliminary characterization of bacteria.
- Examples:
- Blood agar: a type of enriched medium that shows hemolytic characteristics of bacteria.
- Mannitol salt agar: selective and differential medium for Staphylococci.
- Other examples:
- MacConkey agar: differentiates between bacteria that ferment lactose and those that do not.
- Urea broth: differentiates between bacteria that hydrolyze urea to ammonia and those that do not.
- Sulfur indole motility (SIM) medium: differentiates between H2S gas producers and non-producers.
- Triple-sugar iron agar (TSIA): differentiates between fermentation of sugars, H2S production, and other characteristics.
Transport Media
- Used when specimen cannot be processed immediately.
- Preserve the viability of microorganisms in the specimen but do not allow growth.
- Most transport media contain a salt and buffer to prevent destruction of cells by enzymes.
Other Media
Enumeration Media
- Used to count the numbers of organisms in milk, water, food, soil, and other samples.
Assay Media
- Used to test the effectiveness of antimicrobial drugs on the growth of microorganisms.
Reducing Media
- Contains a substance (thioglycolic acid or cystine) that absorbs oxygen or slows the penetration of oxygen in a medium.
- Important for growing anaerobic bacteria.
This lab quiz covers practical microbiology concepts in dentistry, focusing on differential media and more. Test your understanding of microbiology principles in a dental context.
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