Micro Final Exam

LETS KILL ITTTTTT

Sterilization

Destruction or removal of all forms of microbial life, including endospores

How is sterilization performed?

Steam under pressure or sterilizing gas such as ethylene oxideHow

Commercial sterilization

sufficient heat treatment to kill endospores of Clostridium botulinum in canned food

Disinfection

destruction of vegetative pathogens

How is disinfection performed?

physical or chemical methods

Antisepsis

destruction of vegetative pathogens on living tissue

How is antisepsis performed?

chemical antimicrobials

Degerming

Removal of microbes from a limited area, such as the skin around an injection site

How is degerming performed?

Mechanical removal by an alcohol soaked swab

Sanitization

treatment intended to lower microbial counts on eating and drinking utensils to safe public health levels

How is sanitization performed?

High temperature washing or by dipping into a chemical disinfectant

\-cidal agents

act of killing

\-static agents

stationary

The rate of cell death is

exponential

when one log decreases, how much of the population is killed?

90%

What are the factors influencing microbial control?

Number of microorganisms initially present, time of exposure, environmental influences, characteristics of microorganisms

What are environmental influences for microbial growth?

Presence of organic substances and pH

What is the basis for antimicrobial treatments?

changes to membrane permeability, damage to proteins, damage to nucleic acids

What are the proteins that can be damaged by antimicrobial treatments?

enzymes and transport proteins

What are physical antimicrobial treatments?

Heat, filtration, high pressure, desiccation, osmotic pressure, and radiation

Thermal death point (TDP)

Lowest temperature at which all microorganisms are killed in 10 mins

Thermal death time (TDT)

minimum times for all microorganisms in a liquid culture to be killed at a particular temperature

Decimal Reduction Time (DRT)

Time required for 90% of microorganisms to be killed a particular temperature

How does moist heat kill microorganisms?

denatures proteins in the microorganism

What are examples of moist heat?

Boiling, autoclaving, pasteurization

How does dry heat kill microorganisms?

by oxidizing organism molecules in the microorganism

What are examples of dry heat?

Incineration and dry-air ovens

Autoclaving

used for items that can waistband high temeprature and pressure

What temperature and PSI does autoclaving use?

121C and 15 psi

Pasteurization

used mainly for foods to reduce the number of microorganisms that can cause disease and or spoilage

Standard pasteurization

63C for 30 minutes

HTST Pasteurization

72C for 15 seconds

UHT Treatment

140C for

Incineration and Dry Air Ovens

kills microorganisms by a different method than moist heat; requires higher temperatures and times than moist heat

Hot air sterilization

170C for 2 hours

Filtration

often used when substance to be sterilized cannot tolerate heat; works best with liquids and gases, does not work well with solids

What are two examples of filtration

HEPA and membrane filters

Examples of radiation

ionizing, non-ionizing, microwaves

Chemical treatments

only a few achieve sterility; microorganisms differs in their susceptibility to different agents?

What are the most resistant to chemical treatments?

Prion and endospores of bacteria

What are the least resistant to chemical treatments?

Viruses without envelopes, gram positive bacteria, viruses with lipid envelopes

Phenol and phenolics

Carbolic acid (lister); stable, persistent, active in presence of organics, affect membrane integrity, good surface disinfectants

Bisphenols

affect membrane lipid synthesis

Halogens

chemically reactive

Iodine

antiseptic, tincture and iodophors, inhibit protein synthesis and affect membranes

Chlorine

surface disinfectant and water treatment; hypochlorous acid, hypochlorite, chloramines, strong oxidizing agent

Chemical treatments are generally inactivated by presence of

organic material

alcohols

cause protein denaturation and dissolving of lipids, not appropriate as antiseptic for wounds

what are the most common alcohols used?

ethanol and isopropanol

Alcohols are used to enhance the _______ of other chemical agents

effectiveness

Heavy metals use what type of action

oligodynamic

What are the heavy metals?

Silver, copper, zinc, mercury

Oligodynamic action

acts by denaturation/inactivation of proteins

Soaps and detergents\`

poor antiseptic/disinfectant; good degerming agents

Quaternary ammonium compounds (Quats)

Especially effective against gram + bacteria; affect membranes

Aldehydes

effective disinfectants and inactivate proteins

What are examples of aldehydes?

Formaldehyde and glutraldehyde

Sterilizing gases

denature proteins (alkylation), penetrating, suspected carcinogens, toxic, explosive

What are examples of sterilizing gases?

ethylene oxide, propylene oxide, and beta-propriolactone

What are other chemical treatments?

Peroxygen agents, strong oxidizing agents, ozone, peroxides (hydrogen peroxide and bezoyl peroxide)

EFFECTIVENESS OF CHEMICAL MICROIALS chart

x

Who thought of the magic bullet?

Paul Ehrlich

Antimicrobial drugs

sulfa drugs, Salvarsan, antibioticsA

Antibiotics

produced by microorganisms

Penicillin

the first antibiotic, found by Alexander Fleming

What year was penicillin discovered?

1929

MO: Bacillus subtilis (gram +)

A: Bacitracin

MO: Paenibacillus polmyxa (gram +)

A: polymyxin

MO: streptomyces nodosus (actinomycete)

A: amphotericin B

MO: streptomyces venezuelae (actinomycete)

A: chloramphenicol

MO: Streptomyces auerofaciens (actinomycete)

A: Chlortetracycline and tetracycline

MO: Saccharopoluspora erythraea (actinomycete)

A: Erythromycin

MO: Streptomyces fradiae (actinomycete)

A: neomycin

MO: streptomyces griseus (actinomycete)

A: streptomycin

MO: Micromonospora purpurea (actinomycete)

A: gentamicin

MO: Cephalosporium spp (fungi)

A: cephalothin

MO: Penicillium griseofulvum (fungi)

A: griseofulvin

MO: Penicillium chrysogenum

A: penicillin

What makes a good antibiotic?

effectiveness against microorganisms, significant advantage over existing drugs, selective toxicity

What is selective toxicity?

Therapeutic index, toxic concentration, therapeutic concentration

Spectrum of activity

narrow spectrum and broad spectrum

What is the broadest spectrum antibiotic?

Tetracycline

Streptomycin spectrum of activity

mycobacteria and gram negative bacteria

Penicillin G spectrum of activity

Gram postive bacteria

Tetracycline spectrum of activity

gram negative bacteria, gram positive bacteria, chlamydias, and rickettsias

Isoniazid spectrum of activity

mycobacteria

Ketoconazole spectrum of activity

fungi

Mefloquine (malaria) spectrum of activity

Protozoa

Niclosamide (tapeworms) spectrum of activity

helminths

Praziquantel (flukes) spectrum of activity

helminths

Acyclovir spectrum of activity

viruses

Mechanisms of action for antibiotics

inhibitors of cell wall synthesis

inhibitors of protein synthesis

inhibitors of nucleic acid synthesis

damaging of plasma membrane

inhibition of biochemical pathways

\
Inhibition of cell wall synthesis

Penicillin, cephalosporins, natural penicillins, penicillinase-resistant penicillin, extended-spectrum penicillins, vancomycin, bacitracin

Pencillins and cephalosporins

Beta-lactam drugs; inhibit penicillin binding proteins (PBP’s)

What are the natural penicillins

penicillin G and V

Penicillin G is administered

by injection

Penicillin V is administered

orally

Penicillin is converted into what acid?

Penicilloic acid

What enzyme converts penicillin into penicilloic acid?

Penicillinase

Penicillinase-resistant penicillins

methicillin, oxacillin, nafcillin