Anti-infective Therapy

Question 0

Antibiotics

Answer 0

Compound of natural origin that has antimicrobial activity. Source is often soil microorganisms.

Question 1

Antimicrobial agent

Answer 1

A substance that interferes with the proliferation of microorganisms

Question 2

Should bacteriostatic and bacteriocidal agents be used in combination?

Answer 2

NO!

They antagonize each other

Question 3

Bacteriostatic

Answer 3

Inhibits growth but does not kill

Question 4

Bacteriocidal

Answer 4

Kills the pathogen

Esp needed in immunodeficienct Pt.s

Question 5

Broad spectrum

Answer 5

Both gram + and gram -

Question 6

Kirby Bauer disc diffusion

Answer 6

A qualitative measure of antibiotic susceptibility that determines either sensitivity or resistance of the microbial isolate to the antimicrobial agent

Question 7

Minimum inhibitory Concentration

Answer 7

is a quantitative measure of the amount required to prevent bacterial growth.

Can not determine if the conc is bacteriostatic or bacteriocidal though. :(

Question 8

MIC is always __________ or _________ MBC

Answer 8

Equal to or less than MBC

Question 9

What measurement is essential to know for infections such as endocarditis, bacterial meningitis, & osteomyelitis?

Answer 9

The MBC (mean bacterial conc.)

Question 10

Antimicrobial serumucidal conc.

Answer 10

Min conc. of an antimicrobial agent required to kill a pt.s bacterial isolate in the presence of the Pt.s serum.

Question 11

Antibiogram

Answer 11

Mgmt of antibiotic usage in a clinical setting - antibiotic resistance trends, and susceptibility reports
–> aids in reducing the occurrence of antibiotic resistant bacteria by restricting the use of certain antibiotics.

Question 12

Poor selective Toxicity

Answer 12

An agent that is harmful to both the Pt. and the microbe exhibits poor selective toxicity.

Question 13

The more similar the target on the pathogen is to human host cell, the ________the selective toxicity.

Answer 13

Poorer

Ex. Agents that attack membranes

Question 14

Good selective toxicity

Answer 14

An agent that is well tolerated by the human host but is harmful to microbe.

-> the less similar, the better the selective toxicity

( eg human cells lack peptidoglycan, a target)

Question 15

Don’t give tetracycline to immunosuppressed Pt.

Answer 15

.

Question 16

An _______________________ must be present for complete clearance of a pathogen

Answer 16

intact functioning immune system

Question 17

Limitations to effective chemotherapy

Answer 17

Abscess formation
Foreign bodies
Immunosuppression
Superinfection
Location of infection- drug penetration
Antimicrobial drug interactions

Question 18

Characteristics of abscess formation

Answer 18

Low O2 levels & blood flow
Drug is unable to penetrate
-Tissue breakdown products decrease effectiveness of sulfonamides (d/t abundant exogenous folic acid)
- effectiveness of aminoglycosides is depressed d/t low pH in abscess
—-> effective tx requires drainage, & removal of necrotic tissue!!!!!

Question 19

Justified chemoprophylaxis

Answer 19

Crede procedure
Prevention of malaria in travelers
Rheumatic heart Dz pts to prevent group A streptococcal Dz
Prophylaxis against bacterial endocarditis in pts w/ valve abnormalities
Surgeries involving mucosal surfaces
Immunocompromised pts 
Rcurrent UTIs
Bite wounds
Post exposure

Question 20

Post exposure prophylaxis

Answer 20

Meningococcal meningitis Dz outbreaks
Persons w/ tuberculosis.
HIV

Question 21

Synergism

Answer 21

1+1=16
Combo of drugs are Cidal at concs lower than that of either drug used individually.
Less amounts of toxic drugs can be used :)
Ex. Aminoglycoside + penicillin

Question 22

Additive

Answer 22

1+1=2
When 1 or both drugs are toxic, can dec conc of each by 50%
Effectiveness not lost

Question 23

Antagonism of drugs

Answer 23

Reduction in efficacy of one or both drugs when combined
D/t:
1. Competition for binding site - erythromycin & chloramphenicol

2. Drug-drug interaction- opposing effects - tetracycline & penicillin