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Flashcards in Chemotherapy Deck (62):
1

why is chemotherapy unique?

1. selective toxicity
2. selects for resistant strains
3. hypersensitivity and organ directed toxicity = problem
4. lowers microorganism load

2

define: selective toxicity

need greater toxicity to parasite than host
(if more toxic to host, then no benefit)

3

is maintenance of blood levels more important with bacteriostatic agents or bactericidal agents?

bacteriostatic

4

how does chemotherapy select for drug resistant strains?

1. natural/acquired
2. mechanisms
3. multiple drug resistance, usu transferred by plasmids

5

what are the MECHANISMS by which chemotherapy selects for drug resistant strains?

- pathogen/cell fails to absorb drug
- pathogen/cell inactivates drug
- pathogen/cell pumps drug out
- drug target is modified, thus resistant to drug
- increased production of target molecules
- altered metabolic pathway bypasses drug target

6

how is antimicrobial resistance acquired?

1. by a mutation & passed vertically by selection to daughter cells
2. by horizontal transfer of resistant determinants from donor cell (usu from bacterial species)
- by transduction
- by transformation
- by conjugation

7

"____________ resistant strains of pneumococci account for 50% + isolates in Europe and is rising in the US."

"PENICILLIN resistant strains of pneumococci account for 50% + isolates in Europe and is rising in the US."

8

"The worldwide emergence of Haemophilus & gonococci that produce ____________ is a major therapeutic problem."

"The worldwide emergence of Haemophilus & gonococci that produce BETA LACTAMASE is a major therapeutic problem."

9

"____________ is widely distributed among hospitals."

"MRSA is widely distributed among hospitals."

10

"There are strains of ________, _________, & ________ that are resistant to all known drugs."

"There are strains of ENTEROCOCCI, PSEUDOMONAS, & ENTEROBACTERS that are resistant to all known drugs."

11

"____________ is widely distributed among hospitals."

"MRSA is widely distributed among hospitals."

12

"There are strains of ________, _________, & ________ that are resistant to all known drugs."

"There are strains of ENTEROCOCCI, PSEUDOMONAS, & ENTEROBACTERS that are resistant to all known drugs."

13

"Epidemics of multiple drug resistant strains of _________ have been reported in the US."

"Epidemics of multiple drug resistant strains of M.TUBERCULOSIS have been reported in the US."

14

what are common categories of adverse effects of antimicrobial therapy?

1. overextension of pharmacologic actions
2. organ directed toxicity
3. hypersensitivity rxns

15

what drugs are known for hepatotoxicity?

- tetracyclines
- isoniazid
- erythromycin estolate
- clindamycin
- sulfonamides
- amphotericin B

16

what drugs are known for renal toxicity?

- cephalosporins
- vancomycin
- aminoglycosides
- sulfonamides
- amphotericin B

17

what drugs are known for ototoxicity?

- aminoglycosides
- vancomycin
- minocycline (vestibular only)

18

what drugs are known for visual toxicity?

- ethambutol
- isoniazid

19

what are idiosyncrasies that can occur in response to drugs?

- hemolytic anemia (sulfonamides, nitrofurantoin)
- photosensitivity (tetracyclines, flouroquinolones, sulfonamides)

20

what are allergies that can occur in response to drugs?

- anaphylactic shock
- skin rashes
- immune induced blood dyscrasias
- immune hemolytic anemias

21

what are idiosyncrasies that can occur in response to drugs?

- hemolytic anemia (sulfonamides, nitrofurantoin)
- photosensitivity (tetracyclines, flouroquinolones, sulfonamides)

22

what are microorganisms common to gram (+) cocci?

- strep pneum/viridans/pyogenes/agalactiae
- staph aureus
- enterococcus

23

what are microorganisms common to gram (+) bacilli?

- bacillus species
- listeria species
- nocardia species

24

what are microorganisms common to gram (-) cocci?

- moraxella catarrhalis
- neisseria gonorrhoeae
- meningitidis

25

what are microorganisms common to spirochetes?

- t. pallidum
- B. burgdorferi

26

what are anaerobic organisms for which we need meds?

- clostridia
- actinomyces
- c. diff
- bacteriodes fragillis

27

what are microorganisms common to spirochetes?

- t. pallidum
- B. burgdorferi

28

define: bactericidal

cell death

29

define: bacteriostatic

growth inhibition

30

define: MIC

minimum inhibitory concentration - need certain concentration to do job

31

define: time dependent killing

killing not increased w/ increasing concentrations above MCB (beta lactams, vancomycin), but dependent on time of exposure to antibiotic

32

define: concentration dependent killing

rate/extent of killing dependent upon drug concentration
(aminoglycosides, quinolones)

33

define: time dependent killing

killing not increased w/ increasing concentrations above MCB (beta lactams, vancomycin), but dependent on time of exposure to antibiotic

34

define: PAE

post antibiotic effect = persistent suppression of bacterial growth after limited exposure to antimicrobial agent (amino glycosides, quinolones)
- in vivo longer due to postantibiotic leukocyte enhancement

35

example of synergism mechanism:
enhancement of antimicrobial agent uptake?

penicillins increase uptake of amino glycosides & amphotericin B increases uptake of flu cytosine by fungi

36

example of synergism mechanism:
inhibition of enzymatic inactivation?

beta-lactamase inhibitors

37

example of synergism mechanism:
enhancement of antimicrobial agent uptake?

penicillins increase uptake of amino glycosides & amphotericin B increases uptake of flu cytosine by fungi

38

example for improved therapeutic effects:
enterococcal endocarditis?

penicillin + aminoglycoside

39

example for improved therapeutic effects:
Pseudomonas infections

penicillin + aminoglycoside

40

example for improved therapeutic effects:
Brucellosis

doxycycline + rifampin or aminoglycoside

41

example for improved therapeutic effects:
Helicobacter pylori

bismuth + metronidazole + tetracycline

42

example for improved therapeutic effects:
listeria

ampillin + aminoglycoside

43

what are the two mechanisms of antagonism?

1. inhibition of bactericidal activity by bacteriostatic agents
2. induction of enzymatic inactivation (some gram neg bacilli contain inducible beta lactamases)

44

example for improved therapeutic effects:
P. aeruginosa

gentamycin + carbenicillin

45

what are the two mechanisms of antagonism?

1. inhibition of bactericidal activity by bacteriostatic agents
2. induction of enzymatic inactivation (some gram neg bacilli contain inducible beta lactamases)

46

what are common misuses of drugs/failures of therapy?

- attempts to treat untreatable infections
- therapy of FUO
- improper dosage
- improper dosage
- improper duration

47

how do super infections develop?

- usu w/ broad spectrum antibiotics, usu during chemotherapy of infection (usu evidence of new infection)

48

most common superinfection & characteristics?

INTESTINAL CANDIDIASIS:
- fungal superinfection
- usu antibiotic therapy continued, fungal superinfection treated w/ oral nystatin or amphotericin B

49

superinfection staphylococcal enterocolitis?

- LIFE THREATENING
- discontinue antibiotic therapy
- treat w/ oral vancomycin

50

superinfection pseudomembranous colitis?

- life threatening (first seem after clindamycin)
- caused by C-diff
- discontinue therapy, treat w/ oral metronidazole or vancomycin
- severe cases must be treated for symptoms w/ fluids, electrolytes, corticosteroids

51

when do you use antibacterial prophylaxis?

when efficacy has been demonstrated and benefits outweigh risk of prophylaxis

52

antibacterial prophylaxis:
surgical procedures

cefazolin (usu drug of choice)

53

antibacterial prophylaxis:
genital herpes

acyclovir

54

antibacterial prophylaxis:
group B strep

ampicillin or pen G

55

antibacterial prophylaxis:
Haemophilus influenza type B

rifampin

56

antibacterial prophylaxis:
malaria

chloroquine

57

antibacterial prophylaxis:
meningococcal infection

rifampin

58

antibacterial prophylaxis:
pertussis

erythromycin

59

antibacterial prophylaxis:
pneumococcemia

pen G

60

antibacterial prophylaxis:
pneumocystis carinii

trimethoprim sulfamethoxazole

61

antibacterial prophylaxis:
TB

isoniazid

62

antibacterial prophylaxis:
UTIs

trimethoprim sulfamethoxazole