Lecture 9- Microbial Growth And Control

Question 1

To be a good chemical agent a disinfectant must be what?

Answer 1

Be effective against a wide variety of infectious agents at low concentrations.

Question 2

What is the purpose of use dilution tests?

Answer 2

To determine the rate at which selected bacteria are destroyed by various chemical agents.

Question 3

What are chemotherapeutic agents and what do they do?

Answer 3

Chemical agents used to treat disease.

They destroy pathogenic microbes or inhibit their growth within host.

Question 4

Selective toxicity?

Answer 4

Ability of drug to kill or inhibit pathogen while damaging host as little as possible

Question 5

Therapeutic dose/

Answer 5

Drug level required for clinical treatment.

Question 6

Toxic dose?

Answer 6

Drug level at which drug becomes too toxic for patient (I.e., produces side effects)

Question 7

Therapeutic index?

Answer 7

Ratio of toxic dose to therapeutic dose.

Question 8

Side effects?

Answer 8

Undesirable effects of drugs on host cells.

Question 9

Narrow-spectrum drugs?

Answer 9

Attack only a few different pathogens.

Question 10

Broad-spectrum drugs?

Answer 10

Attack many different pathogens.

Question 11

Cidal agents do what?

Answer 11

Kill microbes

Question 12

Static agents do what?

Answer 12

Inhibit the growth of microbes.

Question 13

Minimal inhibitory concentration (MIC)?

Answer 13

Lowest concentration of drug that inhibits growth of the pathogen.

Question 14

Minimal lethal concentration (MLC)/ Minimal Bacteriocidal concentration (MBC)?

Answer 14

Lowest concentration of drug that kills pathogen.

Question 15

List 4 mechanisms that that antimicrobial drugs can fall under.

Answer 15

• inhibitors of cell wall synthesis
• Protein synthesis inhibitors
• Metabolic antagonists
• Nucleic acid synthesis inhibition

Question 16

Factors influencing antimicrobial drugs?

Answer 16

• Ability of drug to reach site of infection
• Susceptibility of pathogen to drug
• Ability of drug to reach concentrations in body that exceed MIC of pathogen

Question 17

What are some mechanisms of rug resistance?

Answer 17

• Preventing entrance of the drug
• Drug efflux (pumping the drug out of the cell)
• Modification of target enzyme or organelle
• Use of alternative pathways or increased production of target metabolite

Question 18

In terms of drug combinations, what is synergism?

Answer 18

When the effect of two drugs together is greater than the effect of either one alone.

Question 19

In terms of drug combinations, what is antagonism?

Answer 19

When the effect of two drugs together is less than the effect of either alone.

Question 20

Sterilization?

Answer 20

Destruction or removal of all viable organisms.

Question 21

Disinfection?

Answer 21

Killing, inhibition, or removal of disease causing (pathogenic) organisms.

Question 22

Sanitization?

Answer 22

Reduction of microbial population to levels deemed safe (based on public health standards).

Question 23

Antisepsis?

Answer 23

Prevention of infection of living tissue by microorganism.

Question 24

Chemotherapy?

Answer 24

Use of chemicals to kill or inhibit growth of micro organisms within host tissue.

Question 25

Pateurization

Answer 25

Controlled heating a temperatures well below boiling

Does not sterilize but does kill pathogens present and slow spoilage by reducing the total load of the organisms present