Ch. 37 Principles of Antimicrobial Therapy

Question 1

prior to initiating treatment

Answer 1

obtain a sample culture of the organism

however if patient is critically ill: empiric therapy

Question 2

may be indicated when the organism is unkown or polymicrobial infections are likely

Answer 2

broad-spectrum therapy

Question 3

gram positive cocci in the spinal fluid of a neworn infant

Answer 3

streptococccus agalactiae (group B streptococcus)
-penicilin G sensitive

Question 4

gram (+) cocci in the spinal fluid of a 40 yr old pt is most likely to be

Answer 4

S. pneumoniae

Question 5

S. pneumonai is resistent and sensitive to

Answer 5

resistant to penicillin G and requires treatment with a high dose 3rd generation cephalosporin (ceftriaxone) or Vancomycin

Question 6

show unpredictable susceptibility patterns and require susceptibility testing to determine appropriate antimicrobial therapy?

Answer 6

gram(-) bacill, enteroccoci, and staphylococcal species

Question 7

have predictable susceptibility patterns to certain antibiotics

Answer 7

streptococcus pyogenes and Neisseria meningitidis

Question 8

antimicrobial drugs are classified as

Answer 8

bacteriostatic

bactericidal

Question 9

arrest the growth and replication of bacteria at serum (of urine) levels achievable in the patient , thus limiting the spread of infection until the immune system attchs, immobilizes, and eliminates the pathogen

Answer 9

bacteriostatic

Question 10

kill the bacteria at drug serum levels achievable in the patient

Answer 10

bactericidal

Question 11

drug of choice for the seriously ill and immunocompromised patients

Answer 11

bactercidal

Question 12

bacteriostatic agent against staphylococcus aureus and enterococci but is bactercidal against S. Pneumoniae

Answer 12

Linezolid

-antibiotic bacteriostatic for one organism and bactercidal for another

Question 13

the lowest antimicrobial concentration that prevents visible growth of an organism after 24 hours of incubation

Answer 13

minimum inhibitory concentration (MIC)

Question 14

quantitative measure of in vitro susceptibility and is commonly used in practice to streamline therapy

Answer 14

MIC

Question 15

lowest concentration of antimicrobial agent that results in a 99.9% decline in colony count after overnight broth dilution incubations

Answer 15

minimum bactercidal concentration (MBC)

Question 16

elipid solubility of a drug

Answer 16

penetrates into the brain

Question 17

chloramphenicol and metronidazole

Answer 17

significant penetration into the CNS

Question 18

b-lactam such as peniciliin

Answer 18

only penetrate the blood-brain barrier when there’s infection:
meningitis

Question 19

low molecular weight compounds

Answer 19

cross blood-brain barrier

Question 20

vancomycin is low molecular weight or high molecular weight?

Answer 20

high molecular weight, penetrates poorly even in the presence of meningial inflammation

Question 21

protein binding drugs

Answer 21

do not enter CSF

Question 22

patient factors

Answer 22

immune system
renal dysfunction
hepatic dysfunction
poor perfusion
age
pregnancy/lactation
multi-drug resistant organisms
safety of the agent
cost of therapy

Question 23

immune system requires

Answer 23

high doses of bactercidal agents

Question 24

renal dysfuntion

Answer 24

vanncomycn, aminglycosides

modification

Question 25

hepatic dysfunction

Answer 25

antibiotics concentrated or eliminated by liver erythromycin and doxycycline

Question 26

poor perfusion

Answer 26

lower limbs of a diabetic patient , reduces the amount of antibiotic that reaches that area

Question 27

age

Answer 27

newborns -renal and hepatic elimination is poor | same with elderly folk

Question 28

neonates vulnerable to the toxic effects of

Answer 28

chloramphenicol and sulfonamides

Question 29

contraindications for tetracyclines or quinolones

Answer 29

young children | -affect bone growth

Question 30

has less specificity an are reserved for life-threatening infections because of the potential serious toxicity to the patient

Answer 30

chloramphenicol

Question 31

methicillin-resistant Staphylococcus aureus (MRSA) treatment

Answer 31

vancomycin, clindamycin, daptomycin (most expensive), linezolid (expensive)

Question 32

vancomycin, aminoglycosides, and amphotercin B

Answer 32

parental route | -poorly absorbed via GIT

Question 33

show a significant increase in the rate of bacterial killiing as it is concentration dependent killing

Answer 33

aminoglycosides and daptomycin

Question 34

b-lactams, macrolides, clindamycin , and linezolid

Answer 34

time-dependent killing

Question 35

persistent suppression of microbial growth that occurs after levels of antibiotic have fallen below the MIC

Answer 35

PAE | post antibiotic effect

Question 36

antimicrobial drugs exhibiting long PAE

Answer 36

aminoglycosides and fluoroquinolones | 1 dose per day against gram(-) bacteria

Question 37

chemotherapuetic spectra

Answer 37

narrow-spectrum antibiotics extended-spectrum antibiotic broad-spectrum antibiotics

Question 38

niazid is considered

Answer 38

narrow-spectrum antibiotic | only against Mycobacterium tuberculosis

Question 39

ampicillin is considered

Answer 39

extended-spectrum antibiotics | acts against gram(+) and gram (-)

Question 40

tetracycline, fluoroquinolones, and carbapenems are considered

Answer 40

broad-spectrum antibiotics | wide variety of microbial species

Question 41

can alter the nature of the normal bacterial flora and precipitate a superinfection due to organisms such as clostridium difficile

Answer 41

broad-spectrum antibiotics

Question 42

treatment of tuberculosis benefits from

Answer 42

drug combinations

Question 43

this combination shows synergism -treatment for enterococcal endocardititis

Answer 43

b-lactams and aminoglycosides

Question 44

interferes with the bactercidal effects of penicillins and cephalosporins

Answer 44

bacteriostatic tetracycline

Question 45

gram(-) organisms are inherently resistant to

Answer 45

vancomycin

Question 46

drug resistance

Answer 46

``` genetic alterations altered expression of proteins in drug resistant organism -modification of target sites -decreased accumulation -enzymatic inactivation ```

Question 47

involves alterations in one or more of the major bacterial penicillin-binding proteins, resulting in decreased binding of the antibiotic to its target

Answer 47

S. pneumoniae resistant to b-lactam antibiotics

Question 48

gram (-) bacteria can limit the penetration of certain agents , including b-lactam antibiotics as a result

Answer 48

alteration in the number and structure of porins (channels) in the outer membrane -decreased accumulation

Question 49

antibiotic-inactivating enzymes include

Answer 49

b-lactamases , acetyltransferases, esterases

Question 50

b-lactamases perform:

Answer 50

hydrolytic inactivation of the b-lactam ring of penicilins, cephalosporins

Question 51

acetyltransferases perform:

Answer 51

transfer an acetyl group to the antibiotic | -inactivating chloramphenicol or aminoglycosides

Question 52

esterases perform:

Answer 52

hydrolyze the lactone rings of macrolides

Question 53

prophylactic use of antibiotics

Answer 53

dental procedures and surgeries. for prevention purposes rather than treatment of infections

Question 54

complications of antibiotic therapy

Answer 54

hypersensitivity direct toxicity superinfections

Question 55

urticaria (hives) to anaphylactic shock, stevens-johnson syndrom (SJS) or toxic epidermal necrolysis

Answer 55

examples caused by antibiotic hypersensitivity

Question 56

ototoxicity caused by aminoglycosides is an example of

Answer 56

direct toxicity

Question 57

broad-spectrum antibiotics can lead to

Answer 57

superinfections

Question 58

inhibitors of cell membrane function

Answer 58

isoniazid, amphotericin B, polymyxins

Question 59

inhibitors of bacterial cell metabolism

Answer 59

sulfonamides | trimethoprim

Question 60

inhibitors of cell wall synthesis

Answer 60

b-lactams | vancomycins, daptomycins, telavancin, fosfomycin

Question 61

inhibitors of protein synthesis in the bacterial cell

Answer 61

tetracyclines, aminoglycocides, macrolides, clindamycin, chloramphenicol, linezolid

Question 62

inhibitors of nucleic acid function of synthesis of a bacterial cell

Answer 62

fluroquinolones | rifampin

Question 63

factors that influence concentration and penetration of cerebro spinal fluid

Answer 63

lipid solubility molecular weight (small) protein binding of the drug

Question 64

antibiotic that exhibits a long post antibiotc effect that permits once-daily dosing

Answer 64

gentamicin