lab 10 Flashcards by Melissa Dyke

Understand the effects of physical and chemical agents on different types of bacteria
Highest resistance?

Prions

- Bacterial endospores

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Understand the effects of physical and chemical agents on different types of bacteria
Moderate resistance?

protozoan cysts
some fungal sexual spores
naked viruses
bacteria with more resistant vegetative cells (some gram -/+)

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Understand the effects of physical and chemical agents on different types of bacteria
Least resistance?

typical bacterial vegetative cells
fungal spores and hyphae
enveloped viruses
yeast
protozoan trophozoites

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Define Sterilization

“complete removal” or destruction of all transmissible agents (microbes, spores, viruses)

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name 5 ways to sterilize an inanimate object

Autoclaving (steam heat)
Heat
Radiation (not UV)
Strong chemicals (liquids and gases)
Filtration

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Define Disinfection

Destruction/removal of vegetative microbes (no bacterial endospores). Used on Inanimate objects due to intensity of treatment required to be effective.
Physical agent.

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Define antisepsis

Chemical applied to body surfaces to destroy or inhibit vegetative microbes. Chemical agent

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Name 6 ways to Disinfect

Lysol
Cidex (an aldehyde, alkylating agent)
Bleach
Heat
UV
Boiling water

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Name 4 antisepsis

Alcohols (60-90%) - hand sanitizers
Hydrogen peroxide (3-6%)
Betadine (iodine compound and therefore a halogen)
Saline (>0.9%)

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Define Sanitization/Degermation

destruction/physical removal of transmissible agents to safe level on inanimate/animate surfaces

methods vary, combined physical and chemical, mechanical scrubbing, soaps, disinfection, antisepsis
Soaps - cleansing and wetting agent that enhances the physical removal of microbes and debris but does not kill microbes

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Define Microbicide

kills microbes

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Define Fungicides

kills fungal hypae, spores, yeast and molds

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Define Bactericeds

kills bacteria

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Define Viricides

kills viruses

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3 microbial control methods

Physical (boiling water, hot water, pasteurization, non ionizing and UV), Chemical (liquids) and Mechanical removal method

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What does MOIST heat kill? Temp?

Vegetative cell - 80C required to kill most resistant cells
Spores/endospores - 120C required to kill most resistant spores. More resistant to heat than vegetative cells, but not invincible to heat. Resistance aided by cortex, proteins, minerals, DPA

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Effects of Ultraviolet Light

Disinfectant which kills most but not all microbes.
UV mutate DNA by causing dimers to thymine and cytosine (pyrimidines)
Enzymes can sometimes repair DNA damage
Cause of skin melanomas
Common method used to disinfect equipment

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What is Kirby-Bauer Susceptibility Test?

standardized test that follows a specific testing procedure to determine the susceptibility of bacteria to antimicrobial agents.
results are used to determine the correct antimicrobial agent to be prescribed to the patient

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3 Kirby-Bauer Susceptibility test designation

Resistant, Intermediate, Susceptible

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Define Resistant in terms of the Kirby test

organism is NOT KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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Define Intermediate in terms of the Kirby test

organism MAY NOT BE KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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Define Susceptible in terms of the Kirby test

organism is KILLED or inhibited by the tested antimicrobial in blood or other body fluids

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Operating parameters for autoclave

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Temp, 121.5C
Pressure, 15 psi
Time, 15-20 min

Define Penicillinase

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An enzyme produced by penicillin resistant strains of bacteria to inactive penicillin

4 things that must be standardized in the Kirby Bauer sensitivity test

Mueller-Hinton agar poured at 4mm thickness Standardized antibiotic disks are used (size of disk and concentration of chemical) Standardized inoculum used. Compared to a McFarland standard Incubate plates for 18-24 hours at 37C This allows for reproducible results

Is it correct to say that dish washing sterilizes dishes?

No, its sanitizing agent only

Soaps are strong microbicides?

False

all gram negative bacteria have an outer layer of the outer membrane that consists of?

LPS, Lipid A and porin proteins

Disinfection is a cleansing process that destroys vegetative pathogens and endospores

False

Autoclaving uses steam heat as a sterilizing agent. Of the following choose which method of controlling microbes this fits a. chemical b. physical c. mechanical d. chemical and mechanical

Physical

a fungicidal agent has what effects?

destroys fungal spores, hyphea and yeast growth

Which of the following is safe to use on or near living tissue a. antiseptic d. disinfectant c. aldehydes d. ethylene oxide

Antiseptic

Starting at the core of an endospore the protective layers from the inside out?

cortex, spore coat, exosporium coat

when attempting to sterilize endospores using autoclace the temp must reach 100c at 3psi for 5 min.

False temp 121C 15psi 15-20 min to effectively destroy bacterial spores and endospores. The pressure drives the steam heat into the cells and keeps water from boiling.

UV radiation is usually considered a disinfectant rather than a sterilizer. UV radiation is 99% effective in decreasing concentration of air borne microbes

True

The Kirby Bauer method determines susceptibility of organisms to antimicrobial agents. The results are compared to a standardized range for each drug and a determination is made as to whether the organism is susceptible, resistant, or intermediate to a particular drug concentration.

True

``` What is gram negative and what is gram positive of the following: Staphylococcus aureus Bacillus sp Escherichia coli Pseudomonas sp ```

Staphylococcus aureus Gram Positive Bacillus sp Gram Positive Esherichia coli Gram Negative Pseudomonas sp Gram Negative

Which organisms are spore former?

Bacillus sp and C-Dif

Cell envelope structure of Gram positive, from out to in

``` Wall teichoic acid Lipoteichoic acid Thick Peptidoglycan Periplasmic space Cell membrane Membrane proteins ```

Cell envelope structure of Gram negative, from out to in

``` Porin proteins LPS Outer membrane layer Phospholipids Lipoproteins Thin peptidoglycan Periplasmic space Cell membrane Membrane protein ```

Bacterial endospores contain?

``` Exosporium Spore Coat Outer Membrane Cortex Intermembrane Spore Cell *highly resistance due to membranes/materials ```

Define Sporocide

Kills all spores

Define decontamination

The mechanical removal of most microbes

Mueller Hinton plate info

Standard medium 4mm thick agar neutral pH Grows most non-fastidious bacteria

What do we call a microbe that thrives in a rich carbon dioxide environments?

Capnophile- obligate anaerobes

How are Autoclaves routinely tested?

Using spore strips from Bacillus stearothermophilus - commonly used thermophile used to validate sterilization processes and the checking growth

3 forms of heat? Effects?

Dry, moist and steam Gradual exposure to increasing temperatures may enable cells to adapt to higher "lethal" levels by producing heat shock protein in attempt to protect cell integrity

Define cidal (evaluation of chemical antimicrobial agents)

If the chemical kills the microorganism, it said to be cidal

Define static (evaluation of chemical antimicrobial agents)

If the chemical inhibits growth, it is said to be static

What does MIC stand for?

Minimum Inhibitory Concentration | Smallest concentration of drug in the series that visibly inhibits growth

What does MIC useful for?

Useful in determining the most effective dosage of a drug and in providing a comparative index against other antimicrobial.

Similarities between agar diffusion (Kirby Bauer) and tube dilution sensitivity tests

Similarities: Both test organisms for antimicrobial susceptibility Standardized tests Determine the specific antimicrobial that is most effective in treating that particular strain of bacteria

Differences between agar diffusion (Kirby Bauer) and tube dilution sensitivity tests

Differences: KB uses a Mueller-Hilton agar, MIC uses a dilution tray containing a supporting medium MIC provides the minimum dilution of an antibiotic that would be effective in treating a specific bacterial infection, KB does not

Moist heat and dry heat differ in their modes of action as well as in their efficiency.

Moist heat operates at lower temperatures and shorter exposure time to achieve the same effectiveness as the dry heat

Kirby Bauer test infor

Agar diffusion Measure diameter in mm around disc If not clear enter 6mm for disk diameter If overlap, use radius X2

lab 10 Flashcards

(55 cards)