Exam 1: Ch. 4, 9 Videos on Own Flashcards
Ch. 4: Microscopy, Staining, and Classification Ch. 9: Physical Methods of Microbial Control
What is the shortest distance between two points on a specimen that can still be distinguished as separate entities?
resolution
What is the ability of a lens to separate or distinguish small objects that are closer together?
resolution
What is the differences in intensity b/w two objects, or b/w object and background?
contrast
What does staining a specimen do?
increases contrast and resolution by coloring specimens with strains/dyes
What is the importance of heating up a slide before staining?
smear slide with specimen–> then heat slide to ADHERE specimen to slide–> then stain
What is a simple stain?
a single color added to slide and tries to stain every organism on slide to make them standout
What are differential stains?
used to distinguish one organism from another organism on the same slide
What simple stain stains purple?
crystal violet
What color does the simple stain safranin stain?
magenta/red
What color does the simple stain methylene blue stain?
blue
What simple stain stains green?
malachite green
What color does the simple stain Carbol fuchsin stain?
red
What are the three Differential Stains we need to know?
- Gram Stain
- Acid-Fast Stain
- Endospore Stain
What are the steps of the Gram Stain?
- crystal violet primary stain
- Decolorize (alcohol)–> purple is washed from Gram(-) cell b/c walls are thiner
- Counterstain = safranin; Gram (-) cells take on magenta/red color
What are the results from a Gram Stain?
- Gram (+) cells = purple
- Gram (-) cells = magenta.red
What group of bacteria does not have a typical peptidoglycan cell wall, but instead of a high waxy mycolic acid content?
Mycobacteria
What does a mycobacteria contain in their cell wall that makes them resistant to decolorization by acids during staining procedures, like the Gram stain ?
a waxy mycolic acid content
What are Mycobacteria referred to as?
Acid-Fast Bacteria
What are the steps for an Acid-Fast Stain?
- carbol fuchsin primary stain (red)
- Decolorize (alcohol); acid-fast retain red color b/c acid cannot penetrate waxy wall
- Counterstain (methylene blue)–stains only bleached, non-acid-fast cells
What are the results of an Acid-Fast Stain?
- Acid-fast cells/mycobacterium = red
- Non-Acid-fast cells = blue (includes human cells and tissue)
What are the steps for an Endospore Stain?
- Malachite green primary stain (need heat)
- Decolorize (water)
- Counterstain (safranin)
What are the results of an Endospore Stain?
- Endospores = green
- Vegetative/living cells = magenta/red
What do we call a series of paired statements where only one of two “either/or” choices applies to any particular organism?
Taxonomic Keys/ Dichotomous Keys
What is the removal or destruction of ALL microbes, including viruses and bacterial endospores, in or on an object?
sterilization
What is an environment or procedure that is free of contamination of pathogens?
aseptic
What is a use of physical or chemical agents known as disinfectants to inhibit or destroy microorganisms?
disinfection
DOES NOT guarantee that ALL pathogens are eliminated
What is it called when a chemical is used on skin or other tissue?
What is the chemical called?
antisepsis
antiseptic
What is the removal of microbes from a surface by scrubbing?
degerming
What is the process of disinfecting places and utensils used by the public to reduce the number of pathogenic microbes to meet accepted health standards?
sanitizaiton
What is the use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages?
pasteurization
What are the suffixes used to indicate that a chemical or physcial agent INHIBITS microbial metabolism and growth?
-stasis/ - static
have NOT killed them
What suffixes refer to agents that destroy or permanently inactivate a particular type of microbe?
-cide/ -cidal
DEATH
What is Microbial Death?
permanent loss of reproductive ability under ideal env.
What is Microbial Death Rate?
measurement of efficacy of an antimicrobial agent
“how effective it is”
What does a 90% microbial death rate mean?
90% efficacy rate means 90% more of the pathogen will die after a given unit of time
What are the two main categories for Actions of Antimicrobial Agents?
- Alteration of cell walls and membranes
2. Damage to proteins and nucleic acids
What occurs in the antimicrobial agent strategy of–Alteration of cell walls and membranes?
- Cells burst due to osmotic effects when damaged
- cellular contents leak out when damaged
- envelope damage prevents attachment, fatally interrupts viral replication
What occurs in the antimicrobial agent strategy of– Damage to proteins and nucleic acids?
- denatured proteins cease to function and cause cellular death
- can produce fatal mutants or halt protein synthesis
What are factors that affect the efficacy of antimicrobial methods?
- Site to be treated
2. Relative susceptibility of microorganisms
Why is “site” to be treated a factor in affecting the efficacy of antimicrobial methods?
harsh chemicals and extreme heat cannot be used on humans, animals, and fragile objects
Why is relative “susceptibility” of microorganisms a factor in affecting the efficacy of antimicrobial methods?
how resistant they are:
- prions, endospores = most resistant
- Gram (+) bacteria, enveloped viruses = least resistant
Which is more resistant to antimicrobials, Gram (+) or Gram (-) bacteria? Why?
Gram (-) bacteria is more resistant b/c they have:
- a double phospholipid bilayer
- tend to have more R plasmids
Which are more resistant, prions/endospores OR Gram (+) bacteria/ enveloped viruses?
prions/endospores
What are the two kinds of heat related methods for physical methods of microbial control?
- Moist heat
2. Dry heat
T/F. Dry heat is more effective than moist heat.
False; moist heat is more effective than dry heat
What are the 4 methods of using moist heat for microbial control?
- boiling
- autoclaving
- pasteurization
- ultrahigh-temperature (UHT) Sterilization
What type of cells does boiling kill?
What types of cells can survive boiling?
Kills: vegetative cells of bacteria and fungi, protozoan trophozoites, and most viruses
Survives: endospores, prions, protozoan cysts, and some viruses
What is critical when it comes to boiling?
time
What type of microbial control using moist heat, involves pressure being applied, and prevents steam from escaping
autoclaving
What type of microbial control using moist heat is used for milk, ice cream, yogurt, and fruit juices?
pasteurizaiton
T/F. Pasteurization is sterilization.
FALSE, it is NOT sterilization (not killing everything in the food product, it affects taste of food to)
What type of microbial control using most heat passes through superheated steam, then rapid cooling?
Ultrahigh-Temperature (UHT) Sterilization
- treated liquids can be stored at room temp (6-9 months), until opened
What is the name of the type of packaging that has been done using Ultrahigh-Temperature (UHT) Sterilization?
Aseptic packaging
As a microbial control method, what does Dry Heat use and why is it done?
hot air and incineration is used for materials that cannot be sterilized with moist heat
T/F. Dry heat requires higher temperature for longer time than moist heat
true
What is the ultimate means of sterilization?
incineration (burning/fire)
Refrigeration and Freezing–what does it do to microbes?
decreases microbial metabolism, growth, and reproduction
Refrigeration halts growth of most pathogens, what are the exceptions?
- Listeria
- Yersinia
What type of microbial control method involves drying that inhibits growth due to removal of water?
dessication (“dehydration”)
What type of microbial control method prevents formation of damaging ice crystals and is used for long-term preservation of microbial cultures?
Lyophilization (“Freeze drying”)
- like for MRE’s
What type of microbial control method involves passage of fluid through a sieve designed to trap particles and separate them from the fluid?
filtration
What type of microbial control method involves high concentrations of salt or sugar in food to inhibit growth? How does it work?
osmotic pressure
- cells in hypertonic solution of salt or sugar lose water = cell crenates
T/F. Bacteria have a greater ability than fungi to survive hypertonic environments?
False, fungi have greater ability than bacteria to survive hypertonic environments
What type of microbial control method involves electron beams or gamma rays?
ionizing radiation (work diff though)
Compare what electron beams do vs what gamma rays do in ionizing radiation.
Electron beams = effective at killing but do NOT penetrate well
Gamma rays = penetrate well, but require hours to kill microbes; also sterilizes food
How is increased shelf life of food achieved? (Ex: strawberries)
Ionizing radiation (gamma rays)
What type of microbial control method involves UV light? What is it suitable for?
non-ionizing radiation;
- UV light does not penetrate well
- suitable for disinfecting air, transparent fluids, and surfaces of objects
