Microbiology: Antibiotic Resistance

Question 1

How do patients come to acquire a resistant pathogen?

Answer 1

-by transmitting the bacteria that already have the resistance gene in place
-by having their bacteria acquire a gene that codes for resistance
(the first is more common)

Question 2

Define antimicrobial

Answer 2

A substance that inhibits or kills microbes

Question 3

What is an antibiotic

Answer 3

a type of antimicrobial synthesized by a living microorganism, usually a fungus

Question 4

How are most antimicrobials administered>

Answer 4

by intravenous route

Question 5

all antimicrobials are what? (hint: mechanisms of action)

Answer 5

bacteriostatic or fungostatic
bacteriocidal or fungicidal

Question 6

differentiate between cidal and static

Answer 6

cidal kills 99%> while static kills 90-99%

Question 7

static agents ___ growth

Answer 7

arrest

Question 8

Whether a drug exhibits cidal or static depends on what?

Answer 8

the concentration of drug an organism is exposed to or the mechanism by which a drug inhibits microbial growth

Question 9

list drugs that act on microorganisms by inhibiting cell wall synthesis

Answer 9

-B lactams
-glycopeptides
-echinocandins

Question 10

list cell membrane inhibitors

Answer 10

-daptomycin
-colithimethate
-imidazole antifungal agents

Question 11

list drugs that inhibt protein synthesis in the bacterial ribosome

Answer 11

-aminoglycosides
-macrolides
-tetracyclines
-oxazolidanones

Question 12

which drugs inhibit nucleic acid synthesis

Answer 12

-fluroquinalones
-the antifungal fluccytosine
-antivirals (acylcovir)

Question 13

Which drugs inhibit microbial growth by acting on the metabolic pathway?

Answer 13

-ethambutol
-trimethoprime sulfamthoxadole

Question 14

the effectiveness of antimicrobials is optimized by understanding what?

Answer 14

the minimal inhibitory concentration

Question 15

define minimal inhibitory concentration

Answer 15

the lowest concentration of a drug that can still inhibit microbial growth

Question 16

define half-life

Answer 16

quantifies how long the body takes to metabolize half of a drug

Question 17

What is concentration dependent activity?

Answer 17

achieving a higher concentration in the blood over a short time is most effective

Question 18

what is one characteristic of concentration dependent drugs?

Answer 18

they usually have a prolonged antibiotic effect (they continue to supress microbial growth long after drug concentration has declined). The goal is to maximize serum or tissue drug concentration

Question 19

Which drugs are concentration dependent?

Answer 19

aminoclycosides and fluroquinolines

Question 20

Which drugs depending on maintaining levels above the MIC?

Answer 20

B-lactams

Question 21

Define time-dependent drugs

Answer 21

lower doses at increased frequency over time

Question 22

What are the two major side effects of drug use?

Answer 22

allergic and gastrointestinal reactions

Question 23

True or false. Virtually all antimicrobials inhibit growth in the large intestine

Answer 23

True

Question 24

How are antimicrobials classified?

Answer 24

based on the broad category of microorganisms against which the drug possesses activity (i.e. antibacterial, antiviral, antifungal, antiparasitic)

Question 25

What are some antibacterials

Answer 25

-penicillin
-cephlasporins
-monobactams and carbapenems
-fluroquinalones
-macrolides, lincosamides, streptogramins
-aminoglycocides
-vancomycin

Question 26

The drug of choice for group A streptococcal pharyngitis is

Answer 26

Natural penicillins

Question 27

Penicillin G lacks activity against what?

Answer 27

gram negative bacteria. Aminopenicillins were developed because of this

Question 28

What are 3 indications for antimicrobial use?

Answer 28

1. Pathogen-directed
2. Empirical
3. Prophylactic