Chemotherapy (Lec 11) Flashcards

1
Q

Chemo is unique how?

A

1) selective toxicity (more toxic to parasite than host)
2) selects for resistant strains
3) lowers microorg load so host defense can kill the rest

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2
Q

2 issues with Chemo

A

1) potential hypersensitivity

2) organ directed toxicity

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3
Q

Mechanisms of drug resistance (6)

A

1) drug not absorbed
2) drug is inactivated
3) drug pumped out
4) target is modified
5) inc production of targets
6) metabolic pathway bypasses target

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4
Q

Antimicrobial resistance mutation can be passed to other bacteria by what methods? (2)

A

vertically to daughter cells

horizontally to unrelated cells

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5
Q

3 methods of horizontal transfer of antimicrob resistance mutation?

A

1) transduction
2) transformation
3) conjugation

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6
Q

Transduction transfer occurs how?

Example of bacteria that uses transduction?

A

Bacteriophage (virus) transfers the resistant DNA from one bacteria to another.

S. aureus

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7
Q

Transformation transfer occurs how?

Example?

A

Incorporation of DNA found free in environment into bacteria.

penicillin-resistant pneumococci
neisseria

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8
Q

Conjugation transfer occurs how?

Example?

A

Direct cell-to-cell contact through pilus or bridge.
Allows trxn of resistance to multiple drugs.

Gram - bacilli

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9
Q

3 adverse effects of antimicrobial therapy?

A

1) over-extension of pharmacologic actions
2) organ-directed toxicity
3) hypersensitivity rxns

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10
Q

Chloramphenicol is bactericidal against? (3)

A

pneumococci
meningococci
h. flu

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11
Q

MIC is?

A

Minimum Inhibitory Concentration of drug needed to inhibit bacterial growth

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12
Q

MBC is?

A

Minimum Bactericidal Concentration of drug needed to kill bacteria

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13
Q

Concentration Dependent Killing

bactericidal agents

A

rate and extent of killing dependent on drug concentration

e.g. aminoglycosides, quinolones

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14
Q

Time Dependent Killing

bactericidal agents

A

Kill dependent on length of time exposed to drug.
Increase in drug does not increase kill.

e.g. beta-lactams, vancomycin

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15
Q

Postantibiotic Effect (PAE) is?

What enhances PAE?

A

Persistent suppression of bacterial growth after limited exposure to drug.

Postantibiotic leukocyte enhancement assists this effect

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16
Q

3 mechanisms of synergism

A

1) Block of sequential steps in metabolism (TMP-SMX)
2) Inhibition of enz inactivation (beta-lactamase inhibitors)
3) Enhancement of drug uptake (penicillin ↑uptake of aminoglycosides)

17
Q

2 mechanisms of antibiotic antagonism

A

1) bacteriostatic agent inhibits bacterialcide

2) drug induces enzyme inhibition towards itself

18
Q

Drug misuses that cause tx failure? (4)

A

1) antibiotics to treat viral infections
2) antibiotics to treat fevers of unknown origin
3) too low a dose
4) not treating for long enough time period

19
Q

Superinfections are?

Most frequently seen w/ which antibiotics?

A

new infection during tx of primary infection

broad spectrum antibiotics

20
Q

Intestinal candidiasis

A

fungal
most common superinfection
tx: continue antibiotics, add oral nystatin or amphotericin B

21
Q

Staph enterocolitis

A

life threatening superinfection

tx: stop antibiotic, start oral vancomycin

22
Q

Pseudomembranous colitis

A

life threatening superinfection
(U) post clindamycin
caused by c. difficile
tx: stop antibiotic, start oral metronidazole or vancomycin

23
Q

Antibacterial prophylaxis:

surgery

A

cefazolin

24
Q

Antibacterial prophylaxis:

HSV

A

acyclovir

25
Q

Antibacterial prophylaxis:

Group B strep

A

ampicillin or penicillin G

26
Q

Antibacterial prophylaxis:

h flu type B

A

rifampin

27
Q

Antibacterial prophylaxis:

malaria

A

chloroquine

28
Q

Antibacterial prophylaxis:

meningococci

A

rifampin

29
Q

Antibacterial prophylaxis:

pertussis

A

erythromycin

30
Q

Antibacterial prophylaxis:

pneomococcemia

A

penicillin G

31
Q

Antibacterial prophylaxis:

pneumocystis carinii

A

TMP-SMZ

trimethoprim-sulfamethoxazole

32
Q

Antibacterial prophylaxis:

tuberculosis

A

isoniazid

33
Q

Antibacterial prophylaxis:

UTI

A

TMP-SMZ

trimethoprim-sulfamethoxazole