Chapter 5 & 20

Question 1

Sterilization

Answer 1

Process of destroying all microorganisms or viruses within or on a product (including endospores and fungal spores); no varying degrees

Question 2

Disinfection

Answer 2

A process that reduces the number of microorganisms or viruses within or on a product until they no longer represent a hazard

Question 3

Disinfectant

Answer 3

A chemical agent used to disinfect inanimate objects

Question 4

Antiseptic

Answer 4

A disinfectant that is nontoxic enough to use on human cells

Question 5

Types of Disinfectants

Answer 5

• cide: treatments that kill
• static: treatments that inhibit rather than kill
• e.g., germicide, fungicide, viricide, bacteriostatic/fungistatic agents

Question 6

Bacteriocide

Answer 6

Used to kill vegetative forms of bacteria, but not usually endospores

Question 7

Bacteriostatic or Fungistatic Agents

Answer 7

A chemical or conditions that prevent the growth of these organisms, but does not kill them

Question 8

Decontamination

Answer 8

Involves the inactivation and removal of both microbes and any toxins that may be present within or on the product

Question 9

Sanitation

Answer 9

In the food industry, decontamination on an area or product to meet public health standards

Question 10

Factors Affection Disinfectant Action

Answer 10

• Time of contact: death is not always instantaneous (may take hours)
• Temperature; usually work better at high temps but most are designed to work near room temp
• pH: work best at certain value (will vary)
• Number of microorganisms: greater number of cells, greater amount of time needed
• Presence of Extraneous Matter: organic matter may react and cause them to be less effective (soil, blood, pus, etc.)
• Concentration: in most cases, the more concentrated the shorter the killing time

Question 11

Decimal Reduction Time (D time)

Answer 11

The time it takes to kill 90% of bacteria present; usually constant over time - if it takes two minutes to kill 90% of a bacteria population, then a population of 100 would be reduced to 10 in two minutes and one in four

Question 12

Types of Microorganisms

Answer 12

• Least resistance: vegetative forms of most bacteria and viruses with membranes
• Moderate resistance: Mycobacterium tuberculosis, Staphylococcus aureus, and Pseudononas species, viruses with no membranes
• Highest resistance: bacterial endospores

Cells in the stationary growth phase are more resistant than cells that are actively growing.

Question 13

Effectiveness of Destroying Microbes

Answer 13

• High: Kill all organisms, including endospores; surface will be sterilized
• Intermediate: Kill resistant pathogens (mycobacterium tuberculosis) and non-enveloped viruses
• Low: Kill vegetative bacteria and enveloped viruses

Question 14

Antimicrobial Chemotherapy

Answer 14

The use of drugs to destroy or inhibit the growth of microorganisms that are causing disease

Question 15

Antibiotics

Answer 15

A chemical produced naturally by a microorganism (usually other bacteria or molds) that have antimicrobial effects; e.g., Streptomyces griseus (soil bacteria) are used to create streptomycin

Question 16

Synthetic Agents

Answer 16

Chemicals that have antimicrobial effects, but are produced in a laboratory (e.g., sulfa)

Question 17

Antimicrobic

Answer 17

A word that incorporates all types of antimicrobial drugs, regardless of origin

Question 18

High Selective Toxicity

Answer 18

An ideal characteristic of chemotherapeutic agents; the chemical is toxic to the microbe causing the disease, but much less so to the cells of the host (all chemicals are at least slightly toxic to a host - therapeutic index is used)

Question 19

Therapeutic Index

Answer 19

Ratio of the minimum dosage that is toxic to the host to the minimum dosage that is toxic to the microbe (MIC); e.g., 500mg/hr is toxic to humans while only 50mg/hr is toxic to bacteria - the ratio is 500/50 10:1

Question 20

MIC (Minimum Inhibitory Concentration)

Answer 20

The lowest dose that prevents the growth of a microbe

Question 21

Broad Spectrum

Answer 21

Toxic to a wide range of different species of pathogens, usually effective against both gram+ and gram- bacteria; low TI generally

Question 22

Narrow Spectrum

Answer 22

Toxic to only a few types of pathogens but fewer side effects; higher TI generally

Question 23

Characteristics of Ideal Chemotherapeutic Agents

Answer 23

• High selective toxicity
• Does not induce the development of resistant strains
• Will not cause hypersensitivity to the host (creating an immune response by the host - allergic reaction)
• Does not interfere with the hosts own defense mechanisms

Question 24

Targets of Antimicrobial Drugs

Answer 24

• Cell wall synthesis (High TI)
• DNA replication (Low TI)
• Transcription (Low TI)
• Protein Synthesis (Medium TI)
• Cell membrane function (Very low TI)
• Metabolic pathways (High TI)

Question 25

Mode of Action

Answer 25

The adverse effect on a microorganism; how the cell is killed

Question 26

Tincture

Answer 26

Combination of iodine with alcohol

Question 27

Iodophors

Answer 27

Combination of iodine and detergent

Question 28

Sulfonamides (synthetic)

Answer 28

Drugs that interfere with a unique metabolic pathway: - Mode of Action: function as competitive inhibitors in a chemical pathway (broad spectrum) - Toxicity: nearly harmless to humans, as folic acid is not produced in our bodies (High TI); there are some allergic reactions - Current Effectiveness: most bacteria are resistant to the effects, as the drugs have been used extensively since the 1930s; can still be effective at high levels which can only be obtained in the urinary tract

Question 29

Folic Acid

Answer 29

Used in many important metabolic pathways; it is a component of an enzyme that is used to synthesize certain nucleic and amino acids; humans must consume in order for metabolic reactions to occur

Question 30

Penicillins and Cephalosporins

Answer 30

Drugs that disrupt cell wall synthesis: - Mode of Action: Interferes with bacterial wall synthesis; cross linkages are prevented from forming in the the cell wall (in growing cells only,) creating a cell wall that is not capable of standing against the osmotic pressures generated within the cell (will lyse) - Toxicity: very little; since humans do not have cell walls, these drugs do not cause many side effects; a portion of the population is allergic to them, and treatment may lead to death in some severe reactions; still drug of choice due to high TI - Current Effectiveness: usually more effective against gram+ bacteria; has a hard time penetrating the outer membrane of gram- bacteria (many are narrow spectrum, some are broad)

Question 31

Glycopeptides (Vancomycin)

Answer 31

Drugs that disrupt cell wall synthesis; must be injected because it is poorly absorbed into blood stream: - Mode of Action: inhibits the synthesis of peptidoglycan, no cell wall constructed - Toxicity: few; nausea, hearing loss; high TI - Current Effectiveness: narrow spectrum; gram+ only; little resistance, but some strains of S. aureus and Enterobacteria (within the colon) are resistant

Question 32

Aminoglycosides (Streptomycin, Gentamicin)

Answer 32

Drugs that interfere with protein synthesis: - Mode of Action: attach to the 30S subunit of bacterial ribosomes, interfering with translation; mRNA is misread and proteins are incorrectly assembled - Toxicity: severe, even though drug is not actively transported into eukaryotic cells; usually used in low doses and patient closely monitored for side effects, including damage to the kidneys and inner ear; low TI - Current Effectiveness: broad spectrum, but used rarely as many bacteria are resistant; often used in conjunction with other antibiotics

Question 33

Tetracycline (Tetracycline, Doxycycline, Oxytetracycline)

Answer 33

Drugs that interfere with protein synthesis; drug of choice to treat undiagnosed disease (secondary bacterial infections): - Mode of Action: attach to the 30S subunit of bacterial ribosomes, preventing the attachment of tRNA; protein synthesis completely blocked - Toxicity: severe; nausea, diarrhea, extreme sensitivity to light; also caused liver and kidney damage, staining of teeth in children of early pregnant mothers, and can lead to secondary infections; low TI - Current Effectiveness: very broad spectrum, but resistance is more common

Question 34

Secondary Infection

Answer 34

Infection that occurs along with or immediately following another infection, usually as a result of the first infection; antibiotics may suppress normal flora to such an extent that pathogenic organisms can easily establish themselves and cause disease; especially true with broad spectrum antibiotics

Question 35

Macrolides (Erythromycin, Azithromycin)

Answer 35

Drugs that interfere with protein synthesis; often used when patient is allergic to penicillin: - Mode of Action: prevents protein synthesis by binding to the 50S subunit - Toxicity: little; gastric distress, reversible liver damage - Current Effectiveness: narrow spectrum (gram+ and mycoplasma); gram- often resistant as cell wall is an effective barrier

Question 36

Fungicides

Answer 36

Kill fungi; fewer drugs exist because it is harder to find unique cellular targets; generally have low TI and high toxicity; most used as topicals but a few can be taken orally or by IV; often the patient must remain in the hospital as treatment is occurring

Question 37

Polyenes

Answer 37

Fungicide that disrupts fungal cell membranes resulting in cytoplasmic leakage (itching, gastrointestinal disturbance - kidney damage, anemia, respectively); IV drip, topical; Amphoterican B most commonly used

Question 38

Flucytosine (Oral)

Answer 38

Fungicide that inhibits nucleic acid synthesis (rash, diarrhea, liver damage)

Question 39

Antiviral Compounds

Answer 39

Drugs that prevent transcription and translation, or the maturation of viruses; typically have a low TI and are very toxic, with a number of side effects; no drub provides a cure but used to slow progression of the disease and treat symptoms

Question 40

Acycolvir

Answer 40

Antiviral compound that inhibits viral DNA polymerase in the herpes virus; few side effects as the drug is only activated in cells that have the virus; either used as topical or by IV to prevent recurrent herpes out-breaks

Question 41

Nucleotide Analogs (AZT, ddl, ddC)

Answer 41

Molecules with a similar, but not exact, molecular structure to four normal types of nucleotides; this molecule (drug) is then mistakenly incorporated into the DNA strand of growing viruses, but the strand is useless; DNA replication eventually halts

Question 42

Amantadine & Rimantadine

Answer 42

Antiviral compounds that prevent the uncoating of the influenza virus; help alleviate symptoms; must be given in the early stages of infection

Question 43

Drug Cocktails

Answer 43

The use of 3-4 different antiviral compounds to stop and reverse the progress of the AIDS virus; as of yet, not a cure, even though people on treatment return to normal lives and have no visible traces of the virus; if treatment ends the virus returns

Question 44

Considerations for Choosing Antimicrobial Drugs When Treating Infections

Answer 44

- Always choose a drug with the highest TI that is effective against the specific microbe causing the infection - Choose a drug that will not interact with any other medications/herbs that the patient is taking - Choose a drug that can easily diffuse into the body cavities that are infected - A mode of delivery must be determined that is most effective and most beneficial to the patient (IV drip, injection, oral) - Kidney/Liver condition must be assessed - If treatment is successful, then a drug or a new combination of drugs may be necessary in order to treat the disease

Question 45

Antagonistic Drugs

Answer 45

Two drugs make each other less effective

Question 46

Synergistic Drugs

Answer 46

Two drugs are more effective when taken together

Question 47

Additive Drugs

Answer 47

No drug interaction; neither antagonistic or synergistic

Question 48

Innate Resistance

Answer 48

If a bacteria naturally lacks a drug's cell target, then it cannot be affected by the drug (e.g., Mycoplasma has no cell wall and therefore is innately resistant to penicillin)

Question 49

Development of Bacterial Resistance to Antibiotics

Answer 49

- Innate resistance - Bacteria acquire most resistance through mutation or genetic exchange (conjugation/R plasmid) - Bacteria modify cellular target - Bacteria are able to destroy or inactivate drug - Bacteria prevent drug from entering the cytoplasm by altering membrane permeability - If drug is an enzyme inhibitor, the bacteria can produce very large amounts of the enzyme so that the metabolic pathway is never fully inhibited

Question 50

Hypersensitivities (allergies)

Answer 50

The body recognizes an antibiotic as a foreign substance and reacts against it; fever, rash, and anaphylactic shock, which may be life threatening

Question 51

Toxicity

Answer 51

Drug may cause permanent damage to a patient; antibiotics that have low TIs can be especially harmful

Question 52

Production of Resistant Strains

Answer 52

The more antibiotics are used, the better opportunity that an organism will develop resistance to it