chapter 10

Question 0

what is chemotherapy?

Answer 0

treatment of diseases with chemical substances

Question 1

what are drugs?

Answer 1

chemicals that affect the physiology in any manner

Question 2

chemotherapeutic agents: (3) and definitions of each

Answer 2

• antibiotics: biologically produced microbes- mostly bacter&fungi
• Semisynthetics: chemically modified anitbiotics
• syntheics: completely synthesized in the lab

Question 3

why aren’t antibiotics effective against the common cold?

Answer 3

bc common cold is caused by viruses

Question 4

Paul Ehrlich (1912): ______________, a treatment for syphilis.

Answer 4

salvarsan

Question 5

Alexander Fleming: _______________

Answer 5

penicillin

Question 6

Gerhard Domagk: prontosil, a ___________

Answer 6

sulfa drug

Question 7

Bugie and Waksman: _______________

Answer 7

steptomycin

Question 8

Benjamin Duggar:_______________

Answer 8

tetracycline

Question 9

what is selective toxicity ?

Answer 9

important for successful chemotherapy, drug is harmful to pathogen not harmful to the patient.
-selects for the pathogen not humans.

Question 10

why are there many antibacterial drugs?

Answer 10

antibacterial drugs constitute larger # and diversity of antimicrobial agents

Question 11

why are there fewer antifungal drugs ?

Answer 11

fewer drugs treat eukaryotic infections

Question 12

why are there very few antiviral drugs?

Answer 12

bc viruses replicate inside our cells.

Question 13

zone of inhibition?

Answer 13

measured as diameter, clearing zone with no growth, is measured after incubation.

Question 14

enumerate the mode of action of antibacterial and antifungal drugs:
know the examples.. 6

Answer 14

1. inhibition of cell wall synthesis
2. inhibition of protein synthesis
3. inhibition of pathogens attachment to/or recognition
4. inhibition of DNA&RNA synthesis (replication inhibited, transcription, and translation.
5. disruption of cell mem.
6. inhibition of metabolism(enzymes)-responsible for metabolic pathway.

Question 15

review structure and composition of bacterial cell wall..

Answer 15

composed of peptidoglycon & peptidoglycon is composed of NAG and NAM chains that are cross-linked by peptide bridges btween the NAM subunits.

Question 16

what is the action of penicillin on bacterial cell wall?

Answer 16

interferes with the linking enzymes and NAM subunits remain unattached to their neighbors.
-inhibits linking of the peptidoglycan layers.

Question 17

what happens to bacterial cells treated with penicillin? explain.

Answer 17

cell will burst bc of the very weak cell wall.

Question 18

is penicillin effective in growing cells or in older cells? explain.

Answer 18

will not effect dormant or older cells. cell wall is very weak/loose=lysis of cell due to osmotic pressure.

Question 19

name examples of antimicrobial drugs that inhibit protein synthesis in bacteria. be able to know the specific action of the drug…

Answer 19

• aminoglycosides=blocks initiation of translation and causes misreading of mRNA
• Macrolides= prevents the continuation of protein synthesis
• chloraphenicol= prevents peptide bonds from being formed
• Lincosamides= prevents the continuation of protein synthesis
• Oxazolidinones= interferes with the initiation of protein synthesis
• streptogramins=each interferes with a distinct step of protein syn
• tetrachylines= blocks attachment of tRNA to ribosome

Question 20

what are examples of antimicrobial drugs that are structural analogues of PABA?

Answer 20

para-aminobenzoic acid= substance to make folic acid
folic acid synthesis= needed to make purines and DNA and RNA
**PABA can bind on active cite of enzymes

Question 21

what happens is PABA is able to bind in the active site?

Answer 21

no synthesis of folic acid.

Question 22

what happens if sulfa drug is able to bind in the active site of the enzyme.

Answer 22

sulfa drug affect folic acid synthesis from PABA in bacteria but humans do not synthesis folic acid from PABA

Question 23

Why are human cells not affected by sulfa drugs?

Answer 23

• humans dont have enzymes to synthesis folic acid from PABA

- we get our folic acid from the food we eat.

Question 24

name examples of antifungal drugs and their mode of action

Answer 24

1. plasma membrane= sysnthesis/function-polyenez, azloes,alyamines 2. cell division= griseofulvin (affect mitosis of fungal cells) 3. nucleic acid synthesis= flocytosine

Question 25

name examples of antiviral drugs and their mode of action: | * cannot kill but inactivate, inhibit replication cells.

Answer 25

1. viral uncoating-effect against influenza A virus (amatadine,Rimantadine) 2. nucleic acid synthesis- effective primarily against herpes&HIV (neucleoside analoge, nonnucleoside polymerous inhibitors, non nuvleoside reverse transcriptor inhibitor) 3. assembly & release of viral particles- effective against HIV (protease inhibitiors-effective against influenza viruses) (neuraminidase inhibitor)

Question 26

can you use penicillin to treat fungal diseases?

Answer 26

no bc its a bacterial antibiotic.. which only targets bacterias

Question 27

can you use penicillin to treat diseases caused by mycoplasmas?

Answer 27

no bc the cell wall is absent in mycoplasmas and penicillin targets the cell wall of bacteria

Question 28

what is meant by structural analogue?

Answer 28

they are similar in structure.

Question 29

PABA is needed for the synthesis of _______________ which are needed for the synthesis of tetrahydrofolic acid in bacteria.

Answer 29

dihydrophobic acid

Question 30

Tetrahydrofolic acid is needed for the synthesis of ____________ which are needed for the synthesis of DNA and RNA in bacteria.

Answer 30

nucleotides

Question 31

what are the characteristics of an ideal chemotherapeutic drug?

Answer 31

1. readily available 2. inexpensive 3. chemically stable 4. easily administered 5. non toxic and non allergenic 6. selectively toxic against wide range of pathogens

Question 32

what are some side effects from toxicity of antimicrobial agents?

Answer 32

- decolorizing the teeth (tetrodycon) | - forming black hairy tongue

Question 33

what is meant by broad spectrum and narrow spectrum antibiotics

Answer 33

broad- different kinds of microbes are affected in the body ex: sulfonomides narrow- smaller # of microbes are affected in the body ex: arildone

Question 34

what are the test used to determine the sensitivity of antibiotics?

Answer 34

1. diffusion susceptibility test 2. minimum inhibitory concentration (MIC) 3. minimum bactericidal concentration (MBC)

Question 35

what are examples of diffusion susceptibility test?

Answer 35

- kirby-bauer | - E-Test

Question 36

what is MIC?

Answer 36

lowest concentration of drug that prevents growth of organisms

Question 37

what is MBC?

Answer 37

lowest concentration of drug that kills 99.9% of bacteria

Question 38

how is kirby bauer test done? what is observed?

Answer 38

imprinted with antibiotics, disc placed on agar plate with swab, 24 hours.... observes the zone of clearing. * the wider the zone of clearing the more susceptible bacteria is to antibiotics

Question 39

how kirby bauer test results interpreted?

Answer 39

zone size interpretive chart.

Question 40

determining MIC....

Answer 40

smallest amount of drug that will inhibit growth of bacteria.

Question 41

determining MBC...

Answer 41

minimum amount of drug that will kill concentration of antibacterial drug.

Question 42

how is E-test done? what results can be observed?

Answer 42

- determine if drug is effective - 2 test can be measured, MIC and E-test * zone of clearing shaped like a tear drop or oval.

Question 43

what are the routes of administration of antimicrobial drugs?

Answer 43

1. topical application 2. oral 3. intramuscular 4. intravenous (IV)

Question 44

what route delivers the antimicrobial drugs to the blood the fastest?

Answer 44

IV

Question 45

vancomycin affects the __________ in bacteria while tetracycline affects the ___________ in bacteria

Answer 45

- cell wall | - translation

Question 46

what is meant if the bacteria are no longer killed by antibiotics?

Answer 46

they are resistant

Question 47

how do bacteria acquire resistance to antibiotics ..2

Answer 47

1. by spontaneous mutation which occurs at frequency of ~10^-9. its a vertical transfer and VERY RARE. 2. by acquiring antibiotic resistance genes. vertical transfer * parent to offspring

Question 48

what are the 3 types of gene transfer in bacteria? vertical or horizontal transfer?

Answer 48

1. transduction 2. transformation 3. conjugation * horizontal

Question 49

how do drug-resistant bacteria develp?

Answer 49

- population of bacteria on table/skin there are 1 or 2 bacteria that are resistant to antibiotics - cells that are sensitive to drug are killed and others are not - sensitive cells are eliminated; therefore resistant cells have more room to grow and take over.

Question 50

Extensive use of antibiotics inhibits the growth of _____________ and facilitates the multiplication of ________________

Answer 50

sensitive cells, resistant cells

Question 51

what are the mechanisms that made some bacteria developed resistance to antibiotics?

Answer 51

1. produce enzymes that inactivate the drug 2. induce changes cell mem. -prevent entry of drug 3. altering drug receptor to prevent binding 4. altering cells metabolic pathways 5. pumping the drug out of the cell

Question 52

what happens when disease causing bacteria become resistant to antibiotics?

Answer 52

1. often cause infections that are more difficult to treat 2. may result in long and costlier hospitalization 3. must be treated with stronger antibiotics that may cause more serious side effects .

Question 53

what can a physician do to minimize the development of bacteria resistance to antibiotics?

Answer 53

1. making accurate diagnosis 2. using appropriate antibiotic combinations 3. considering use of a narrow spectrum antibiotic in simple infections 4. urge patient compliance 5. increase surveillance

Question 54

how can we help minimize the development of bacteria resistance to antibiotics?

Answer 54

1. dont demand antibiotics 2. use antibiotics as prescribed 3. dont save them for next time 4. never use someone else's prescription 5. only use antibacterial soaps, etc when defenses weakened.