Antimicrobial Pharmacology Flashcards
1
Q
what does the mechanism of antimicrobial drug action identify
A
the drug target
2
Q
knowledge of the drug target gives you info about what 3 things
A
- selective toxicity
- drug resistance
- bactericidal vs bacteroistatic
3
Q
what are the gram positive cocci
A
strep pneumo
strep pyogenes
staph aureus (MSSA and MRSA)
enterococcus faecium
4
Q
what are the gram negative cocci
A
n. gonorrhea
n. meningitidis
m. catarrhalis
5
Q
what are the gram positive rods
A
bacillus anthracis
listeria monocytogenes
6
Q
what are the gram negative rods
A
h. flu
e. coli
pseudomonas
7
Q
what are the anaerobic gram positive rods
A
c. diff
tetani
botulinum
8
Q
what are the anaerobic gram negative rods
A
bacteroides fragilis
9
Q
what are the atypical bacteria
A
chlamydia
mycoplasma
rickettsia
10
Q
what abx target cell wall synthesis
A
vancomycin
bacitracin
penicillins
cephalosporins
monobactams
carbapenems
11
Q
which stage of cell wall synthesis does vancomycin target
A
2
12
Q
which abx target cell membranes
A
daptomycin
polymixin B
13
Q
which abx target nucleic acids
A
fluoroquinolones
rifampin
nitrofurantoin
14
Q
which abx target protein synthesis
A
aminoglycosides
tetracyclines
clindamycin
macrolides
chloramphenicol
streptogramins
muciporin
15
Q
which abx target intermediary metabolism (folate metabolism)
A
sulfonamides
trimethoprim
16
Q
what is selective toxicity
A
a feature of abx therapy that ensures abx selectively exert effects on microbe and not the host
17
Q
name 4 methods of selective toxicity
A
- inhibition of metabolic pathway → folate metabolism
- differences in enzyme structure → ribosomes and DNA gyrase
- macromolecular structure → cell wall synthesis
- macromolecular structure → fungal cell membrane
18
Q
what is the difference in folate metabolism between bacteria and humans
A
bacteria must synthesize folate
humans can take it up from the environment
19
Q
what are the 2 bacterial ribosomes
A
30s
50s
20
Q
what are the human ribosomes
A
40s
60s
21
Q
humans use __ for nucleic acid synthesis
bacteria use __ for nucleic acid synthesis
A
humans: topoisomerase
bacteria: DNA gyrase
22
Q
what do bacterial cell walls contain that eukaryotes do not contain
A
peptidoglycan
23
Q
what is the difference between fungal cell membranes and human cell membranes
A
humans: cholesterol
fungal: ergosterol
24
Q
what are the 4 mechanisms of abx resistance
A
- antibiotic target site alteration
- antibiotic inactivating or modifying enzyme
- reduced permeability → natural resistanve
- increased efflux → restricts abx access
25
what are the 4 methods of abx target site alteration
penicillin binding proteins
DNA gyrase
peptidoglycan side chain
50s ribosome methylation
26
what are the penicillin binding protein bacteria
MRSA
strep pneumo
enterococci
27
what bacteria use DNA gyrase for abx resistance
s. aureus
pseudomonas
28
what bacteria use peptidoglycan side chains for abx resistance
enterococci (VRE)
staphylococci (VRSA)
29
which bacteria use 50s ribosome methylation for resistance
strep
staph
enterococci
30
which bacteria use beta lactamase for abx modification or inactivation
s. aureus
p. aeruginosa
bacteroides
enterococci
31
which bacteria use acetyl-phospho-adenylyl transferases for resistance
enterococci
32
which bacteria use decreased entry (natural resistance)
pseudomonas
e.coli
33
which bacteria use increased efflux for abx resistance
streptococci
staphylococci
enterococci
pseudomonas
34
which type of abx resistance is this: microbes lack a susceptible target for drug action
natural (intrinsic) resistance
35
list 3 examples of natural (intrinsic) resistance
1. fungal cell walls do not have peptidoglycans
2. mycoplasma do not have cell walls at all
3. pseudomonas - drugs can not penetrate outer membrane
36
what type of resistance is this: microbes are sensitive and abx reaches target, but something prevents the drug form working
escape resistance
37
which type of resistance is important for surgical drainage
escape → abx tolerance
38
what is acquired abx resistance
selective pressure of abx administration produces successive generations of organisms with biochemical traits that minimize drug action
39
what prevents acquired abx resistance
proper dosing and duration of abx therapy
40
which mode of acquired resistance is an important source of multiple drug resistance
plasmid mediated resistance
41
bacteria develop resistance to beta lactam abx by what mechanism
target site alteration
42
bacteria develop resistance to fluoroquinolones by what mechanism
abx target site alteration
43
bacteria develop resistance to vancomycin by what mechanism
target site alteration
44
bacteria develop resistance to erythromycin and clindamycin by what mechanism
target site alteration
45
what are the 5 drugs to which bacteria develop resistance using target site alteration
1. beta lactams
2. fluoroquinolones
3. vancomycin
4. erythromycin
5. clindamycin
46
bacteria develop resistance to aminoglycosides and beta lactams via what mechanism
antibiotic modification or inactivation
47
bacteria develop resistance to beta lactams, fluoroquinolones, and aminoglycosides via what mechanism
decreased entry → natural resistance
48
bacteria develop resistance to tetracyclines, macrolides, and fluoroquinolones using what mechanism
increased efflux
49
MRSA, strep pneumo, and enterococci have developed resistance to what abx via target site alteration
beta lactams
50
s. aureus and pseudomonas species have developed resistance to what abx via target site alteration
fluoroquinolones
51
enterococci (VRE), and staphylococci (VRE) have developed resistance to what drug via target site alteration
vancomycin
52
streptococci, staphylococci, and enterococci have developed resistance to what 2 drugs via target site alteration
erythromycin
clindamycin
53
s.aureus, p.aeruginosa, bacteroides, and enterococci have developed resistance to what drug via abx modification or inactivation
beta lactams
54
enterococci have developed resistance to what drug via abx modification or inactivation
aminoglycosides
55
pseudomonas have developed resistance to what drug via decreased entry (natural resistance)
beta lactams
56
pseudomonas species have developed resistance to what drug via decreased entry (natural resistance)
fluoroquinolones
57
e.coli and pseudomonas have developed resistance to what drug via decreased entry (natural resistance)
aminoglycosides
58
streptococci, staphylococci, and enterococci have developed resistance to what 2 drugs via increased efflux
tetracyclines
macrolides
59
pseudomonas species have developed resistance to what drug via increased efflux
fluoroquinolones
60
what are 3 methods to minimize abx resistance
1. only use abx when need is established
2. select abx on basis of susceptibility tests
3. use adequate concentration and duration
61
what is bactericidal action
organisms are killed
62
what is bacteriostatic action
organisms are prevented from growing
63
what determines whether an abx is -cidal or -static (3)
1. mechanism of action → target
2. concentration achieved in vivo
3. specific microorganism
64
what are the 3 bactericidal mechanisms
1. inhibition of cell wall synthesis
2. disruption of cell membrane fxn
3. interference w. DNA fxn or synthesis
65
what are the 2 bacteriostatic mechanisms
1. inhibition of protein synthesis
2. inhibition of intermediary metabolic pathways
66
are aminoglycocides -static or -cidal
-cidal
67
are -cidal or -static abx preferred in severe infxns
-cidal
68
which abx class acts quickly and irreversibly with sustained effect
-cidal
69
which class of bacteria is preferred in CNS and endocarditis infxns (immune sanctuaries)
-cidal
70
what are the 4 categories of bacteria
1. cocci
2. rods
3. anaerobes
4. atypical
71
in the op setting, when C&S is infrequently available, what 4 factors should you consider in selecting abx
1. symptoms
2. anatomic site
3. local patterns of infxn
4. patient demographics
72
what are the 3 classes of abx spectrum
1. narrow
2. extended
3. broad
73
narrow spectrum abx cover
either gram (+)
OR
gram (-)
74
extended abx cover
gram (+)
AND
gram (-)
75
broad spectrum abx cover
gram (+)
AND
gram (-)
AND
atypical
76
which spectrum of abx have the least disturbance of host flora → less diarrhea
narrow
77
which spectrum of abx are most effective on susceptible organism
narrow
78
which spectrum of abx are more likely to cause superinfections
broad
79
which spectrum of abx sacrifices efficacy for greater scope and is used for initial tx
broad
80
which spectrum of abx should be used for severe infxns of unknown etiology
empiric
81
what are mixed infxns
oral or intraabdominal
82
what is an ex of a synergistic abx effect
penicillin plus an aminoglycocide against enterococci
83
what are 3 advantages of oral routes of administration
1. ease of administration
2. patient acceptance
3. lower cost
84
what are 3 cons of oral routes of administration
1. GI upset
2. lack of absorption for some drugs
3. unsuitable for npo
85
taking a drug on an empty stomach is recommended when
the abx is unstable dt increased gastric acidity when food is in the stomach
86
taking a drug with food is recommended when
the drug is acid stable but may be irritating to stomach
87
taking a drug on an empty stomach protects
the drug
88
taking a drug with food protects
the stomach
89
when are IV drugs indicated
1. when rapid and predictable plasma levels are needed
2. pt w. life threatening infxns
90
what are cons of IV administration (3)
1. greater training needed
2. greater expense
3. requires strict aseptic conditions
91
abx vary greatly in ability to cross
bbb
92
which class of drugs is excellent at crossing bbb
ceftriaxone → 3rd gen cephalosporins
93
what is accumulation
a characteristic of certain drugs that can result in beneficial and harmful effects
94
which drug has a beneficial accumulation effect in bone
clindamycin
95
which drug has a beneficial accumulation effect in pulmonary cells
macrolides
96
which drug has a beneficial accumulation effect in gingival crevicular fluid and sebum (peridontitis and acne)
tetracyclines
97
which drug has a beneficial accumulation effect into urine (UTIs)
nitrofurantoin
98
which drug can cause ototoxicity and nephrotoxicity via accumulation
aminoglycocides
99
which drug can cause abnormal bone growth and tooth discoloration via accumulation
tetracyclines
100
renal status is monitored via
SCr
CrCl
101
how do you monitor hepatotoxicity with abx
you can't! → must avoid hepatotoxic drugs if liver dysfxn
102
what does DCRIMES mean
hepatotoxic abx
103
what does DCRIMES stand for
Doxycycline
Clindamycin
Rifampin
Isoniazid
Metronidazole
Erythromycin-like (Macrolides)
Sulfonamides
104
what class of drugs can cause urea crystalluria
sulfonamides
105
what are 2 consequences if abx therapy is too short
1. resistance develops
2. recurrence possible
106
what are 2 consequences if abx duration is too long
1. superinfxn more likely via alteration of normal flora
2. dose-related toxicities more likely
107
what 2 abx can be dosed less frequently dt high initial cp levels (concentration dependent killing)
aminoglycosides
fluoroquinolones
108
what 3 abx kill best when cp is above MIC for longer durations (time dependent killing)
1. beta-lactams
2. vancomycin
3. macrolides
109
what is direct toxicity
when abx effect on microbes affects host cellular processes → lack of selective toxicity
110
what 5 systems does direct toxicity usually involve
1. GI tract
2. liver
3. kidney
4. nervous system
5. blood and blood forming systems
111
what are 3 examples of indirect toxicity
1. allergic rxns and hypersensitivity
2. salt effects → dt salt administered w. abx **not abx itself**
3. drug-drug interactions → ex alteration of CYP450 metabolizing enzyme
112
disturbances of host microflora (superinfection) usually occurs with what spectrum of abx
broad
113
what is an example of superinfection related to disturbance of host microflora
pseudomembranous colitis dt c.diff overgrowth
114
what 3 host factors can increase risk for toxicity
1. age → very old and very young
2. pregnancy/nursing → consider harm to fetus
3. drug hypersensitivity → pt allergies
115
what is post antibiotic effect
the persistent suppression of bacterial growth that may occur after limited exposure to some abx
116
what side effects should you know w. abx
1. most common
2. most severe
