M20 LEC 5 - Strategies of Microbial Control

Microbe

Able to reproduce at certain ranges of temperatures

Optimum temperature

Temperature level where microbial growth is most supported

Mesophile

Microorganisms that survive in temperature that also support human life

6.5 to 7.5

pH range where bacteria grow best

Acidophile

Type of bacteria that grow in pH below 4

Alkalinity

Inhibits microbial growth

High to low

Based on osmotic pressure, water flows from _______ to _______ water concentration

Obligate aerobe

Type of microbe that needs oxygen to survive

Obligate anaerobe

Oxygen is toxic to their survival

Facultative anaerobe

Grow with less or no oxygen

Catalase & Superoxide dismutase (SOD)

Enzymes that allow toxic forms of oxygen to be neutralized for it to be used

Most

For facultative anaerobes, growth is best where _______ oxygen is present [Least, Most, No]

Aerotolerant anaerobe

Type of microbe that performs only anaerobic growth, but growth continues in presence of oxygen

Double

At half-life, the number of bacterial organisms would _______

Stationary

Phase in bacterial division that is a period of equilibrium; microbial deaths balance production of new cells

Lag

Phase in bacterial division with intense activity preparing for population growth, but no increase in population

Death

Phase in bacterial division in which population is decreasing at a logarithmic rate

Log

Phase in bacterial division with logarithmic or exponential increase in population

Log

The phase where it is effective for microbial control mechanisms to act on as this is when there is an exponential increase in population

Antisepsis

Destruction of vegetative pathogens on living tissue

Disinfection

Destruction of vegetative pathogens on inanimate objects

Sanitization

Intended to lower microbial counts to safe public health levels and minimize the chances of disease transmission from one user to another

Sterilization

Removal or destruction of all living microorganisms

Degerming/degermation

Removal of microbes from a limited area

Number of microbes, environmental influences, time of exposure, & microbial characteristics

The rate of microbial death is affected by the following 4 factors

-cide

Suffix that refers to "kills microbes"

-stasis

Suffix that refers to "inhibit growth but does not necessarily kill the microbe"

Protein denaturation

Causes a protein to lose its function because it becomes misfolded

Disruption of free -SH groups

Causes ineffective formation of disulphide bonds between amino acids that leads to loss of function

Single-strand breaks, double-strand breaks, UV exposure, & monoalkylation

Kinds of damages to nucleic acids that compromise their integrity

Thymine dimer

Forms when ultraviolet light damages the nucleic acid

Boiling or flowing steam; protein denaturation

What is the method and mechanism of action of the following physical method of controlling microbial growth: Kills vegetative bacterial and fungal pathogens and many viruses within 10 min; less effective on endospores

Autoclaving; Protein denaturation

What is the method and mechanism of action of the following physical method of controlling microbial growth: Very effective method of sterilization; at about 15 psi of pressure (121 C), all vegetative cells and their endospores are killed in about 15 min

More

Time for solid materials to undergo autoclaving is _______ than liquid materials

Pasteurization; Protein denaturation

What is the method and mechanism of action of the following physical method of controlling microbial growth: Heat treatment for milk (72 C for about 15 sec) that kills all pathogens and most nonpathogens

Pasteurization

Method applied to more viscous material and to food with high fat content

Direct flaming; Burning contaminants to ashes

What is the method and mechanism of action of the following physical method of controlling microbial growth: Very effective method of sterilization; used for inoculating loops

Incineration; Burning to ashes

What is the method and mechanism of action of the following physical method of controlling microbial growth: Very effective method of sterilization; used for disposal of contaminated dressings, animal carcasses, and paper

Hot-air sterilization; Oxidation

What is the method and mechanism of action of the following physical method of controlling microbial growth: Very effective method of sterilization but requires temperature of 170 C for about 2 hr; used for empty glassware

Filtration; Separation of bacteria from suspending liquid

What is the method and mechanism of action of the following physical method of controlling microbial growth: Removes microbes by passage of a liquid or gas through a screenlike material; most filters in use consist of cellulose acetate or nitrocellulose; useful for sterilizing liquids (e.g. enzymes, vaccines) that are destroyed by heat

0.3 mm

High-efficiency particulate air (HEPA) filters remove almost all microorganisms larger than about _______ in diameter

Refrigeration; Decreased chemical reactions and possible changes in proteins

What is the method and mechanism of action of the following physical method of controlling microbial growth: Has a bacteriostatic effect

Deep-freezing; Decreased chemical reactions and possible changes in proteins

What is the method and mechanism of action of the following physical method of controlling microbial growth: An effective method for preserving microbial cultures, food, and drugs

Lyophilization; Decreased chemical reactions and possible changes in proteins

What is the method and mechanism of action of the following physical method of controlling microbial growth: Most effective method for long-term preservation of microbial cultures, food, and drugs

Reduced

Metabolic rate of most microbes at temperatures of ordinary refrigerators is _______ that they cannot reproduce or synthesize toxins, inhibiting growth

High Pressure; Alteration of molecular structure of proteins and carbohydrates

What is the method and mechanism of action of the following physical method of controlling microbial growth: Preserves colors, flavors, nutrient values of fruit juices

Desiccation; Disruption of metabolism

What is the method and mechanism of action of the following physical method of controlling microbial growth: Involves removing water from microbes; primarily bacteriostatic

Osmotic pressure; Plasmolysis

What is the method and mechanism of action of the following physical method of controlling microbial growth: Results in loss of water from microbial cells

Ionizing radiation; Destruction of DNA

What is the method and mechanism of action of the following physical method of controlling microbial growth: Used for sterilizing pharmaceuticals and medical and dental supplies

Nonionizing radiation; Damage to DNA

What is the method and mechanism of action of the following physical method of controlling microbial growth: Radiation is not very penetrating

Hydroxyl radicals

In ionizing radiation, water is ionized that leads to the formation of highly reactive _______ _______

Chemical methods

They merely reduce microbial populations to safe levels or remove vegetative forms of pathogens from objects

False

T or F: There is a single disinfectant that is appropriate for all circumstances

Phenol; Disruption of plasma membrane, denaturation of enzymes

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Rarely used, except as a standard of comparison; seldom used as a disinfectant or antiseptic because of its irritating qualities and disagreeable odor

Lipid-containing plasma membranes

Phenols can injure _______

Joseph Lister

The use of phenols as an antiseptic was first done by ______

Phenolics; Disruption of plasma membrane, denaturation of enzymes

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Environmental surfaces, instruments, skin surfaces, and mucous membranes

Sporostatic

Most phenolic compounds are bactericidal but _______

Bisphenols; Probably, disruption of plasma membrane

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Disinfectant hand soaps and skin lotions

Biguanides (Chlorhexidine); Disruption of plasma membrane

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Skin disinfection, especially for surgical hand scrubbing; bactericidal

Gram-positive

Biguanides are most effective against this type of bacteria

Terpenes; Disruption of plasma membrane

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Plant essential oils, used in foods and disinfecting hard surfaces

Phenolic and terpene

Many essential oils reported antimicrobial actions primarily due to their _______ and _______ contents

Halogens; Iodine inhibits protein function, chlorine forms the strong oxidizing agent, hypochlorous acid alters cellular components

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Iodine is an effective antiseptic; chlorine gas disinfects water, chlorine compounds disinfect dairy equipment, utensils, household items, and glassware

Tincture and iodophor

Two forms of iodine

5 to 25%

When dealing with SARS-CoV-2, this percent range of bleach is required

Alcohols; Protein denaturation and lipid dissolution

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Bactericidal and fungicidal, but not effective against endospores or nonenveloped viruses

60 to 95%

This percent range of ethanol is required for it to be an effective antimicrobial

Heavy metals and their compounds; Denaturation of enzymes and other essential proteins

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Silver nitrate prevents ophthalmia neonatorum, silver-sulfadiazine is a topical cream, copper sulfate is an algicide

1% silver nitrate

Was historically used to prevent the occurrence of neonatal conjunctivitis caused by gonorrhea

Silver sulfadiazine (SSD)

Used as antimicrobial for burned skin

Thimerosal (Merthiolate)

Used as an antimicrobial preservative for vaccines

Zinc chloride

Content of mouthwashes

Zinc pyrithione

Content of anti-dandruff

Soaps and detergents; Mechanical removal of microbes through scrubbing

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Skin degerming and removal of debris

Acid-anionic sanitizers; May involve enzyme activation or disruption

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Sanitizers in dairy and food-processing industries

Quaternary ammonium compounds; Enzyme inhibition, protein denaturation, & disruption of plasma membranes

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Antiseptic for skin; bactericidal, bacteriostatic, fungicidal, virucidal against enveloped viruses

Organic acids; Metabolic inhibition

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Control mold and bacterial growth in foods and cosmetics

Nitrates/Nitrites; Inhibits certain iron-containing enzymes of anaerobes

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Prevents growth of Clostridium botulinum in food

Aldehydes; Protein denaturation

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Disinfects medical equipment

True

T or F: Formalin is not equal to formaldehyde

Formaldehyde; water

Formalin is a solution of _______ and _______

2%

Percent of solution of glutaraldehyde that is effective as it is bactericidal, tuberculocidal, and virucidal in 10 minutes and sporicidal in 3 to 10 hours

Ethylene oxide (sterilants); Inhibits vital cellular functions

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Sterilization of materials that would be damaged by heat

Ethylene oxide

The exception to the majority of the chemical methods that rarely achieve sterilization

Alkylation

Action of ethylene oxide that leads to cross-linking of nucleic acid and proteins and inhibits vital cellular functions for sterilization

Plasma sterilization; Inhibits vital cellular functions

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Useful for tubular medical instruments

Supercritical fluids; Inhibits vital cellular functions

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Useful for sterilizing organic medical implants

Peroxygens & other forms of oxygen; Oxidation

What is the method and mechanism of action of the following chemical method of controlling microbial growth: Contaminated water and surfaces; some deep wounds, in which they are very effective against oxygen-sensitive anaerobes

Hydrogen peroxide

Not a good antiseptic for open wounds; used in disinfecting PPEs

Gas

State of matter of hydrogen peroxide that can make it be used as a sterilant of atmosphere and surfaces

Benzoyl peroxide

Established anti-acne because it has action towards the microbial agent that contributes in formation of acne

Propionibacterium acnes

Microbial agent that contributes in formation of acne

Diffusion method

Used to know if the chemicals are able to inhibit microbial growth

Zone of inhibition

The thing that is visible after 24 hours that enable us to say that a particular chemical has antimicrobial activity against a specific microbe

Bacterial spores

Resistant to disinfectants and antiseptic agents because they have tested different disinfectants and yet most of them had no effects on these

Standard

Type of precaution for all patients

Standard

Type of precaution for those exposed to blood, secretions, or body fluids

Contact

Type of precaution for those with stool incontinence, generalized rash, draining wounds

Droplet

Type of precaution for those with respiratory viruses, Bordetella pertussis, early infection with Neisseria meningitidis