Antibacterials

Question 1

gram + has a 1 wall of peptidoglycan

gram - has a 2 wall of peptidoglycan

Answer 1

1. thick

2. thin

Question 2

Lipopolyaccharide makes up the outer membrane structure of gram 1 bacteria cell wall and consists of 2 and 3

Answer 2

1. negative
2. phospholipid
3. polysaccharides

Question 3

what bacteria is teichoic and teichuronic acid found in?

how does it effect the use of antibiotics

Answer 3

gram +

strong anionic character - affect rate of penetration (antibiotics with positive charge would be more attracted to the acid)

Question 4

how do nutrient transport protiens of cytoplasmic membrane effect antibiotics?

Answer 4

Facilitate rapid penetration of agents similar in structure

Question 5

how does LPS on gram - bacteria effect antibiotcs

Answer 5

prevents penetration of bulking, high MW antibiotics (e.g. erythromycin)

Question 6

What on gram - bacteria allows penetration of water soluble molecules up to 650 daltons (e.g sulfonamides)

Answer 6

hydrophilic pores

Question 7

What are extended spectrum antibiotcs effect against?

Answer 7

gram + primarily, but also gram -

Question 8

tx of high-risk pts that have become infected but are asymptomatic

Answer 8

pre-emptive therapy

Question 9

tx of symptomatic pt without further testing or confirmation of organism

Answer 9

empirical therapy

Question 10

how will bacteria develop resistance

Answer 10

through acquisition of new genetic material

mutation in the existing genome that is selected for under clinical/antibiotic pressure

Question 11

name the drug resistant bacteria

Answer 11

ESKAPE

Enterococcus faecium

Staph. aureus

Klebsiella pneumoniae

Acinetobacter baumanni

Psuedomonas aeruginosa

Enterobacter specieies

Question 12

therapeutic use of daptomycin

Answer 12

tx of complicated skin infections, bacteremia, endocarditis

Question 13

how does bacteria develop resistance to daptomycin

Answer 13

Reduced drug entry

gene mutation (mprF) - membrane changes to more positive charge and antibiotics are repelled with cationic properties

Question 14

how has bacteria developed resistance to tetracycline

Answer 14

Expression of efflux pump

common organisms: N. gonorrhoeae, E. coli, S. pneumoniae, P. aeruginosa

Question 15

how have bacteria developed resistance to metronidazole

Answer 15

Changs in expression enzymes that activate the pro-drug

Metronidazole needs to be reduced to generate ROS. Mutation in rdxA gene alters/decreases activated of drug

Question 16

how do bacteria develop resistance against aminoglycosides such as streptomycin?

Answer 16

Expression of enzymes by the organism that destroy the drug

• Aminoglycoside-modifying enzymes chemically modify the antibiotic and alter binding of the drug to its target

Question 17

How do bacteria develop resistance against amoxicillin

Answer 17

Expression of enzymes by the organism that destroys the drug

• Expression of the enzyme beta-lacatamase which can hydrolyze the lactam ring of amoxicillin and make compound ineffective

Question 18

how do bacteria develop resistance against trimethoprim and sulfonamides?

Answer 18

Impaired drug binding to the original target:

• expression of the drug-insensitive enzymes dihydropteroate synthase and dihydrofolate reductase

Question 19

how do bacteria develop resistance to vancomycin

Answer 19

Development of new or different pathways that are not inhibited by the drug

Substitution on the peptidoglycan stem so that the agent can no longer bind to the target

Question 20

Mechanism of resistance for what drug class?

1. expression of beta lactamase
2. alteration in PBP binding to drug
3. Alteration in porin function

Answer 20

Penicillins

Cephalosporins

Question 21

Mechanism of resistance for what drug class?

Expression of enzymes that alter chemical structure of the drug

Answer 21

Aminoglycosides

Question 22

Mechanism of resistance for what drug class?

1. Transport of drug out of cell (drug efflux)
2. Alterations of drug binding to the 50S ribosomal unit

Answer 22

Macrolides

Question 23

Mechanism of resistance for what drug class?

Transport of drug of of cell (drug efflux)

Answer 23

Tetracyclines

Question 24

Mechanism of resistance for what drug class?

1. Less sensitive drug target
2. Increased synthesis of PABA
3. Scavenge or use other sources of folic acid

Answer 24

Sulfonamides

Question 25

Mechanism of resistance for what drug class?

1. Less sensitive drug target
2. Transport of drug out of cell (drug efflux)

Answer 25

Fluoroquinolones

Question 26

Mechanism of resistance for what drug class?

1. expression of inactivating enzymes

Answer 26

Chloramphenicol

Question 27

All antibiotics cross the ____

Answer 27

placenta (can go into breast milk too)

Question 28

1 doses and 2 treatment regimens will likely be needed for immune compromised pts

Answer 28

1. higher

2. longer

Question 29

what patient consideration should you make when giving antibiotics to someone with renal disease

Answer 29

reduce doses for agents eliminated by the kidney - risk of drug accumulation

Question 30

what patient consideration should you make when giving antibiotics to someone with hepatic disease

Answer 30

reduce doses for agents eliminated by the liver- risk of drug accumulation

Question 31

what patient consideration should you make when giving antibiotics to geriatric patients and infants

Answer 31

Geriatrics may have decreased renal function

Infants may have underdeveloped detox mechanisms