CH9

Question 1

chemotherapeutic index

Answer 1

[max. tolerable] / [min for cure]

Question 2

• many effective agents to use

- topical applications (cream)

Answer 2

antimicrobial agents selective toxicity

Question 3

• larger is better

- generally smaller for drugs against eukaryotic MO’s/ viruses

Answer 3

chemotherapeutic index

Question 4

side effects of antimicrobial agents

Answer 4

toxicity

• liver and kidney damage
• nausea and diarrhea

allergy

• immune system responds to foreign substance
• rashes and anaphylactic shock

normal microbial destroyed
-superinfection- Canidia and Clostridium difficile

Question 5

two ways to determine antimicrobial sensitivity

Answer 5

• kirby- bauer method- measures zone inhibition

- dilution method- MIC (min. inhibition [ ])

Question 6

5 ways antimicrobial drugs effect MOs with examples

Answer 6

inhibition of cell wall (peptidoglycan) synthesis
-penecillin

disruption of cell pm function
-polymyxin

inhibition of protein synthesis
-tetracycline

inhibition of nucleic acid synthesis
-quinolones

action as antimetabolites
-sulfonilamide

Question 7

PABA get broken down to

Answer 7

folic acid

Question 8

• single gene

- frequency low

Answer 8

mutations

Question 9

• R-plasmids provide multiple resistance

- chromosomal genes

Answer 9

conjugation and transduction

Question 10

it kills or inhibits the microbial pathogen while damaging the host as little as possible

Answer 10

selective toxicity

Question 11

the drug level required for clinical treatment of a particular infection

Answer 11

therapeutic dose

Question 12

the drug level at which the agent becomes too toxic for the host

Answer 12

toxic dose

Question 13

degree of selective toxicity may be expressed in terms of

Answer 13

1. therapeutic does

2. toxic dose

Question 14

ratio of the toxic dose to the therapeutic dose

Answer 14

therapeutic index

Question 15

The ______ the therapeutic index, the ______ the chemotherapeutic agent in general

Answer 15

larger

better

Question 16

they are effective only against a limited variety of pathogens

Answer 16

narrow -spectrum drugs

Question 17

attack many different kinds of bacteria

Answer 17

broad- spectrum drugs

Question 18

the lowest concentration of a drug that prevents growth of a particular pathogen

Answer 18

minimal inhibitory concentration (MIC)

Question 19

lowest drug concentration that kills the pathogen

Answer 19

minimal lethal concentration (MLC)

Question 20

causing death

Answer 20

cidal

Question 21

inhibiting or retarding

Answer 21

static

Question 22

A ______ drug generally kills pathogens at levels only two to four times more than the MIC, whereas a ______ agent kills at much higher concentrations

Answer 22

cidal

static

Question 23

The wider the clear zone surrounding a disk, the

Answer 23

more susceptible the pathogen i

Question 24

Zone width also is a function of the antibiotic’s _________, ___________, and its __________ through agar

Answer 24

initial concentration, its solubility, and its diffusion rate

Question 25

bacterial resistance mechanisms with examples

Answer 25

- alteration of target (often by mutation) ex: ribosomes - acquire gene(s) for enzymes that modify/destroy antibiotic ex: beta-lactamase (penicillinase) - alteration of membrane permeability ex: polymyxin

Question 26

- inactivates penecillin | - cleaves beta-lactam ring

Answer 26

beta-lactamase

Question 27

why is treatment of fungal infections generally less successful than that of bacterial infections?

Answer 27

because as eukaryotes, fungal cells are much more similar to human cells than are bacterial cells

Question 28

strategies to inhibit/slow down development of drug resistance

Answer 28

- avoid indiscriminate use, use when necessary - over the counter, viral infections - use high doses of the proper antibiotic - test when possible, complete the treatment -switch if signs of resistance - finish entire antibiotic course - by not finishing it then you can become get sick again but worse or harm others around you that are not as susceptible as you are to the mo

Question 29

organisms that produce useful antibiotics

Answer 29

- Streptomycetes (most are produced by) - Penicillin and Cephalospyrium (fungi) - Actinomycetes (micro monospora)

Question 30

are inactive until metabolized

Answer 30

prodrugs