Chapter 87: Basic Principals of Antimicrobial Therapy

Question 1

Definition of Antibiotics

Answer 1

chemicals that are produced by one microorganism and can harm other microbes

Question 2

Antimicrobial drug

Answer 2

any agent that can killor suppress microorganisms

Question 3

selective toxicity

Answer 3

toxic to microbes but harmless to host
differences in the cellular chemistry of mammals and microbes
disruption of bacterial cell wall
inhibition of enzyme unique to bacteria
disruption of bacterial protein synthesis

Question 4

two classifications of antibiotics

Answer 4

classification by suceptible organism
classification by mechanism of action

Question 5

Classification by suceptible organism

Answer 5

Narrow spectrum antibiotics: are active against only a few microorganisms
Broad spectrum antibiotics: are active against a wide array of microbes

Question 6

Classification by mechanism of action

Answer 6

Bacteriocidal (kills bacteria): drugs are directly lethal to bacteria at clinically achievable concentrations
Bacteriostatic (makes bacteria weak): drugs can slow bacterial growth but do not cause cell death

Question 7

Drug resistance

Answer 7

over time, organisms develop resistance
may have been highly responsive and then became less suceptible to one or more drugs

Question 8

Four basic Actions of drug resistance

Answer 8

decrease the concentration of a drug at its site of action
inactivate drug (develops enzymes so receptor wont activate drug)
alter the structure of drug target molecules
produce a drug antagonist

Question 9

Spontaneous mutation of drug resistance

Answer 9

random changes in a microbe’s DNA
resistance to one drug

Question 10

Conjugation of drug resistance

Answer 10

kills some bacteria, but not completely
extrachromosomal DNA is transferred form one bacterium to another
gram-negative bacteria
multiple drug resistance (pass signal to bacteria to develop resistance)

Question 11

Empiric Therapy

Answer 11

antibiotic therapy for patients before causative organism is positively identified
Drug selection based on: clinical evaluation, knowledge of microbes most likely to have caused infection, risks (resistance)
match the drug with the bug (mismatches are ineffective and can further resistance - TWO BLOOD CULTURES)
Identify and drug sensitivity

Question 12

Indications for antibiotic combinations

Answer 12

initial therapy of severe infections
mixed infections
prevention of resistance
decreased toxicity
enhanced antibacterial action
monitor BUN, creatinine, ALT/AST

Question 13

Disadvantages of Combination Drugs

Answer 13

increased risk for toxic and allergic reactions
antagonism of antimicrobial effects
risk for superinfection
selection of drug-resistant bacteria
increased cost

Question 14

Prophylaxis approved uses

Answer 14

surgery (decreased incidence of infection in certain surgeries)
bacterial endocarditis (in patients with congenital or valvular heart disease)
neutropenia (patients are high risk for infections)
for women with recurrent UTIs
prophylxasis against type A influenza
following exposure to organisms responsible for STDs

Question 15

Nursing Considerations

Answer 15

obtain culture before starting antibiotics
know timing of peak and trough levels for antibiotic levels
Patient education: importance of taking whole perscription
antibiotics must not be discontinued prematurely
how do we know an antibiotic was effective in treating a client’s pneumonia

Question 16

Important clinical indications of success

Answer 16

reduction of fever
resolution of signs and symptoms related to the affected organ system (e.g. improvement of breathing in patients with pneumonia)