chapter 8 Flashcards
What is the general concept of aseptic techniques used in laboratory preparation and analysis?
Procedures performed under sterile conditions to prevent introduction of unwanted organisms or contaminants into an environment
Differentiate between sterilization, disinfection, and sanitization.
Sterilization: Destruction or removal of all microorganisms.
Disinfection: Use of a physical process or chemical agent to destroy vegetative microbes and viruses.
Sanitization: Cleaning technique that mechanically removes microorganisms and debris to reduce contamination.
What are the different types of culture media based on physical state?
Liquid, semisolid, solid
What are the key steps in the microbiological process known as the Five I’s?
- Inoculation
- Incubation
- Isolation
- Inspection
- Identification
What is inoculation in microbiology?
Producing a culture using a medium for inoculation and sterile instruments
What is the incubation temperature range for most organisms?
Generally between 20ºC and 40ºC, with optimal growth at approximately 37ºC
What are the characteristics of liquid media?
Water-based solutions that do not solidify at temperatures above freezing and allow growth throughout the container
What is a streak plate technique used for?
To spread millions of cells over the surface of a solid medium to separate individual cells and produce pure cultures
What is the purpose of fixation in microscopy?
To kill and adhere organisms to glass slides for staining and observation
What is the most widely used differential stain in microbiology?
Gram stain
What colors indicate gram-positive and gram-negative bacteria in a Gram stain?
Gram-positive: Purple
Gram-negative: Red/pink
What are the two main types of chemical classification of media?
- Chemically defined (synthetic)
- Complex (nonsynthetic)
What is the purpose of selective media?
To contain agents that inhibit the growth of certain microbes while favoring others
What type of media is blood agar?
Enriched media that differentiates species based on hemolysin production
What are the physiological/biochemical characteristics used for microbial identification?
- Hydrogen sulfide production
- Citrate use
- Phenylalanine deamination
- IMViC tests
- Litmus milk reactions
What is the role of immunologic techniques in serologic analysis?
To detect, identify, and quantify antigens in clinical samples
Fill in the blank: The process of reducing the number of microbes on human skin is called _______.
Degermination
What is the function of agar in solid media?
Provides a firm surface for growth and is solid at room temperature
What is the purpose of the pour plate technique?
To produce isolated colonies and determine the number of organisms in a sample
True or False: Animal inoculations are commonly used in diagnostic laboratories today.
False
What are the morphological classifications of bacteria?
- Bacilli
- Cocci
- Spirilla
- Vibrios
- Spirochetes
- Coccobacilli
What is the significance of differential media?
To grow several types of microorganisms and show differences in colony size, color, or media color change
What is a negative stain?
An indirect staining process that provides a dark background against the organism
What is the purpose of the acid-fast stain?
To differentiate acid-fast bacteria from non-acid-fast bacteria
