Exam 2

Macronutrients

Chemical substances required in large quantities.

Micronutrients

Chemical substances required in small quantities.

Essential nutrients

Any substance that must be provided to an organism.

Chemoheterotrophs

Microorganisms that derive their nutritional needs from organic compounds.

Psychrophile

Organisms that grow at low temperatures, between 0-15°C.

Mesophile

Organisms that grow at intermediate temperatures, between 20-40°C.

Obligate aerobes

Organisms that cannot survive or grow without oxygen.

Facultative anaerobes

Organisms that can survive or grow with or without oxygen.

Generation time

Time required for a complete fission cycle, from parent cell to two new daughter cells.

Viable plate count procedure

A traditional method used to observe the population growth pattern and estimate the total number of living cells over a period, a single colony on a plate represents a single cell from the original sample

Sterilization

Process that destroys or removes all viable microorganisms.

Antisepsis

The process of inhibiting or destroying microorganisms on living tissues.

Incineration

An open flame method that reduces microbes to ashes and gas, can sterlize

Pasteurization

heat treatment of perishable fluids to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of survivors and germination of spores. Prevents infection and spoilage

Broad-spectrum drugs

Antimicrobials effective against a wide variety of microbial types.

Beta-lactam ring structure

A four-membered ring structure found in many antibiotics.

Kirby-Bauer test

An agar diffusion test used to assess antimicrobial susceptibility.

Prophylaxis

Use of a drug to prevent infection in a person at risk.

Chemical agents used to target what structures

proteins, nucleic acids, cell walls, and cytoplasmic membranes.

Quats

Cationic detergents also known as quaternary ammonium compounds.

macronutrients needed to support microbes

carbon, hydrogen, oxygen

macronutrients involvement

role in cell structure and metabolism

micronutrients involvement

role in enzyme function and maintenance of protein structure

chemoautotroph

an organism that relies upon inorganic chemicals for its energy and carbon dioxide for its carbon

photoheterotroph

An organism that gets its energy from light and has an organic carbon source

thermophile

organisms that grow at high temperatures, 45-80C

Capnophile

microorganisms that thrive in high concentrations of carbon dioxide

halophile

a microbe whose growth is stimulated by salt or requires a high concentration of salt

osmophile

a microorganism that thrives in a medium having a high osmotic pressure

Acidophile

a microorganism that can survive and grow in acidic environments, preferably 2 pH

Alkaliphile

a microorganism that thrives and grows in highly alkaline environments, preferably 9 ph

Aerobes

organisms that survive/grow in an oxygenated environment

obligate aerobes

organism that can not survive/grow without oxygen

microaerophile

organisms that can only grow in reduced levels of oxygens

colony

a macroscopic cluster of cells appearing on a solid medium, each arising from the multiplication of a single cell

microbial growth curve phases

a graph that shows how a microbial population grows over time

Growth curve phase best for controlling and treatment

exponential growth phase

binary fission

the formation of two identical new cells of approximately equal size as the result of parent cell division

the top two most resistant microbes

prions and bacterial endospores

Bactericide

an agent that kills bacteria

bacteriostatic

any process or agent that inhibits bacterial growth

microbial death

the permanent loss of reproductive capability, even under optimum growth conditions

Physical control agents used to achieve sterilization

heat (autoclave), sterilants (chemical agents), radiation, filtration, ultrasonic waves, cold

disinfection

physical process or chemical agent to destroy vegetative pathogens but not bacterial endospores, removes harmful products of microorganism from material

sanitization

a cleansing technique that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels

degerming

a mechanical process that reduces the number of microbes on the human skin

asepsis

a state/condition of being free from viable pathogenic microorganisms

antiseptic

chemical substances used to do antisepsis

Dry heat

hot air or an open flame

Methods for controlling microbes with dry heat

2 methods: incineration and hot-air oven

hot-air oven

radiates heat within an enclosed compartment, destroys endospores, can sterilize

moist heat

hot water, boiling water, or steam

Methods of controlling microbes with moist heat

3 methods: boiling water: disinfection, pasteurization: disinfection of beverages, steam under pressure: autoclaving, sterilization

autoclave

a sterilization chamber that allows the use of steam under pressure to sterilize materials, common temp/pressure combination would be 121C and 15 psi

Moist heat destroys microorganisms by

coagulation and denaturation of proteins, quickly and permanently halts cellular metabolism

Dry heat destroys microorganisms by

dehydrating the cell, removing extra water that is necessary for metabolic reactions, denaturing proteins, oxidizing cells; burning into ashes

Filtration controls microbes by

using thin membranes and plastic that include pore sizes that could be controlled, can catch viruses and some proteins

Filtration

removing microbes from air and liquids

Radiation

electromagnetic waves or rays given off from an energy source and is disperse at a high velocity through matter or space

ionzing radiation

an alternative for sterilizing materials that are sensitive to heat or chemicals

Nonionizing radiation

a method of disinfect that uses UV rays to destroy fungal cells, spores, bacterial vegetative cells, protozoa, and viruses

Chemical agents that are used as antiseptics

iodine(halogen), hydrogen peroxide(oxidizing agent), chlorhexidine, organic mercury tinctures (heavy metal compounds), and some phenolic compounds

Chemical agents that are used for degerming

alcohol

Chemical agents that are halogens

iodine, sodium chlorite, sodium hypochlorites

Halogen chemical agents are used as

a topical antiseptic, disinfectant for plastic and rubber instruments

Chlorhexidine’s mode of action

targets bacterial membranes specifically ones where their selective permeability is lost, causing cell wall and proteins to denature

Alcohol’s mode of action

dissolves membrane lipids, disrupts cell surface tension, and compromises membrane integrity when concentrations is >50%

Limitations of alcohol

rate of evaporation decreases the effectiveness

Best % of alcohol for infection

50%-95%

Quats

cationic detergents, quaternary ammonium compounds

Bacterial genera that are resistant to quats

spore-forming bacteria, mycobacteria, gram-negative bacteria

Cold temperatures

can slow down the growth of cultures and microbes in food during processing and storage

Infection

Pathogens enter and penetrate host defenses to establish themselves and multiply

Antibiotics

substances produced by natural metabolic processes of some microorganism that can inhibit or destroy other microorganisms, drug-treating bacteria

narrow-spectrum drugs

antimicrobials effective against a limited arrow of microbial types

selectively toxic

should kill or inhibit microbial cells without simultaneously damaging host tissues

Beta-lactam ring function

binds to enzymes that cross-link peptidoglycans, prevents crosslinking, kills the bacteria

Therapeutic index

the ratio of the index dose to the effective therapeutic dose that is used to assess the safety and reliability of the drug

Safe dosage number

when the ratio # is much bigger, or when the index # is much closer to the toxic dose #

Common drugs used for treating fungal infections

macrolide polyene antibiotics, azoles, echinocandins, and allylamines

Antiviral drugs’ mode of action

barring penetration of the virus into the host cell, blocking the transcription and translation of viral molecules, preventing the maturation of viral particles

antibiotics not effective against viruses because

virus uses the same host cell’s mechanisms and metabolic functions that antibiotics target, making it difficult to disrupt without harming the host cell

Antibiotic resistance develops through

spontaneous mutations in critical chromosomal genes, or the acquisition of entire new genes or sets of genes via horizontal transfer from another species

Different ways bacteria can prevent/disable drugs

new enzymes are synthesized that destroy the active component in the drug, changing the cell wall permeability, modifying membrane proteins that pump out the antimicrobials quickly, or alter the number of binding sites