Antibiotic Classes: Sites of Action Flashcards
(111 cards)
1
Q
which antibiotics are cell wall inhibitors?
A
penicillins/cephalosporins, bacitracin, vancomycin
2
Q
penicillins & cephalosporins are what kind of antibiotics? what is its MOA?
A
β-lactam antibiotics
β-lactam ring incorporates into cell wall → prevents bacteria from building it → eventually killing bacteria
3
Q
what exists as part of the body’s own antibiotic system that break down cell wall bonds?
A
tear film lysozymes
4
Q
which antibiotic is predominantly useful for treating G+ & anaerobic infections?
A
penicillins
5
Q
PenG (IV, IM) & PenV (PO) belong to which class of penicillins?
A
PCNase sensitive
6
Q
methicillin (IV, IM), cloxacillin, dicloxacillin are what class of penicillins?
A
PCNase resistant
7
Q
ampicillin & amoxicillin are which class of penicillins?
A
aminopenicillins
8
Q
carboxypenicillins: carbencillin & ticarcillin are what class of penicillins?
A
anti-pseudomonal (G-) coverage
9
Q
Augmentin is composed of? how does it work?
A
amoxicillin + clavulanate → β-lactamase attacks clavulanate → amoxicillin left over & will be effective
10
Q
why are there no topical formulations for penicillins?
A
allergy risk is too high
11
Q
penicillins have a low but noticeable cross-sensitivity allergy risk with what antibiotic?
A
1st gen cephalosporins
12
Q
what are the hypersensitivity type reactions to penicillin?
A
- type I → anaphylaxis
- type II → hemolytic anemia
- type III → serum sickness
- type IV → Stevens-Johnson syndrome
13
Q
what is the structural difference between penicillins & cephalosporins?
A
cephalosporins have a β-lactam ring structure with 6 members
penicillins have a β-lactam ring structure with 5 members
14
Q
unlike penicillins, cephalosporins are?
A
less susceptible to PCNase
15
Q
which cephalosporin is used for most eyelid infections?
A
cephalexin (Keflex) 500mg BID PO x 7d
16
Q
newer generations of penicillins & cephalosporins have greater G+ or G- coverage
A
greater G- coverage
17
Q
is Bacitracin used for G+ or G- bacteria? where is its site of action
A
G+ → cell wall inhibitor
18
Q
why is Bacitracin only available as a topical ointment?
A
it has profound nephrotoxicity
19
Q
which Bacitracin ointment is well suited to staphylococcus blepharitis? Is it G+ or G-
A
AK-tracin ointment
20
Q
which Bacitracin ointment provides additional G- coverage including pseudomonas? what does it additionally contain & what are their sites of action?
A
Polysporin ointment - Bacitracin + Polymyxin B
- Bacitracin → cell wall inhibitor
- polymyxin-B → cell membrane toxin
21
Q
what antibiotic is the IV drug of choice for MRSA & MRSE infections & bacterial endophthalmitis? does it have G+ or G- coverage? where is its site of action?
A
vancomycin → G+ only → cell wall inhibitor
22
Q
what are the adverse effects of vancomycin?
A
- ototoxicity
- nephrotoxicity
- Red Man Syndrome
23
Q
what is Red Man Syndrome?
A
IV-induced mast cell degranulation → histamine released → vasodilation → pt appears red
24
Q
which antibiotics are cell membrane toxins?
A
polymyxin B & gramicidin
25
why are cell membrane toxins only available in topical form?
due to systemic toxicity
26
what is the mechanism of action of Polymyxin-B?
polymyxin incorporates into the cellular membrane → disrupts it → contents leak out
27
what is a cationic detergent/surfactant? does it work on G+ or G-?
polymyxin-B → G-
28
what antibiotic is only used topically, and never a stand-alone drug?
polymyxin-B
29
which cell membrane toxin has G+ coverage?
gramicidin
30
Polytrim solution, Polysporin ointment, Neosporin ointment & solution are all which antibiotic?
polymyxin-B combos
31
what are components in Polytrim solution? are their coverage G+ or G-? where is their site of action?
polymyxin-B + trimethroprim
- polymyxin-B (cell membrane toxin) → G-
- trimethoprim (folic acid inhibitors) → G+ & G-
32
what antibiotic combo is used for more common pediatric ocular infections? & from which organisms?
Polytrim solution
- H. influenzae → polymyxin-B (G-)
- S. pneumoniae → trimethoprim (G+ & G-, uses G- in this case)
33
why is Polytrim solution a good option for MRSA & MRSE?
because of the trimethoprim component (G+ & G- coverage)
34
what are the components in Polysporin ointment? what is the coverage & site of action?
polymyxin-B + Bacitracin
- polymyxin-B → G- (cell membrane toxin)
- Bacitracin → G+ (cell wall inhibitor)
35
what are the components in Polysporin ointment & what are their site of action & coverages?
- polymyxin-B → G- (cell membrane toxin)
| - Bacitracin → G+ (cell wall inhibitor)
36
what are the components in Neosporin ointment? what is their site of action & their coverages?
- polymyxin-B → G- (cell membrane toxin)
- neomycin → G- > G+ (protein synthesis inhibitor)
- bacitracin → G+ (cell wall inhibitor)
37
what are the components in Neosporin solution? where are their sites of action & what is their coverage?
- polymyxin-B → G- (cell membrane toxin)
- neomycin → G- > G+ (protein synthesis inhibitor)
- gramicidin → G+ (cell membrane toxin)
38
how do protein synthesis inhibitor antibiotics work?
bind to & inhibit 30S/50S ribosomal subunits of prokaryotes (bacteria)
39
which protein synthesis inhibitors inhibit 30S subunit? what is their coverage?
- aminoglycosides (G- > G+)
| - tetracyclines (G+ & G-) broad-spectrum
40
which protein synthesis inhibitor does not have any oral formulations?
aminoglycosides
41
neomycin, gentamicin & tobramycin are all what class of antibiotics? where is their site of action?
aminoglycosides → 30S protein synthesis inhibitors
42
which aminoglycoside is the oldest & is never used as a stand-alone? what is its coverage?
neomycin → G+ & G- (broad-spectrum, no pseudomonas)
43
which aminoglycoside is used for severe infections & why? what is its coverage?
gentamicin → G- > G+
| - only used for severe infections bc too much toxicity
44
which aminoglycoside is the 2nd most effective against MRSA, following trimethroprim? what is its coverage?
tobramycin → (G- > G+)
45
which antibiotic is one of the few in pregnancy category B? where is its site of action?
tobramycin → 30S protein synthesis inhibitor
46
why are aminoglycosides not typically administered orally? what do you do when you need to use it systemically?
they are poorly distributed from GI tract
| when used systemically → given parenterally (injections)
47
aminoglycosides can cause which type hypersensitivity reaction?
type IV
48
SPK & delayed re-epithelialization, neurotoxicity, nephrotoxicity, & type IV hypersensitivity reaction are adverse effects of what class of antibiotics?
aminoglycosides
49
corneal toxicity is most pronounced adverse effect of which aminoglycoside?
gentamicin
50
routine use of neomycin can cause what adverse effect?
5-10% contact dermatitis risk
51
tetracycline, doxycycline & minocycline are what class of antibiotics & what is their site of action & Gram covereage?
tetracyclines → 30S protein synthesis inhibitors
| G+ & G-, broad spectrum
52
what are tetracyclines used more for & how?
more used for their anti-inflammatory benefits
| - inhibition of MMP's neovascularization & bacterial lipases
53
which tetracycline(s) are short-acting?
tetracycline
54
which tetracycline(s) are long-acting?
doxycycline & minocycline
55
what is minocycline indicated for? what class of antibiotics does it belong to & what is its site of action? what is its Gram coverage?
- used for acne rosacea (from bacterial lipases/demodex)
- tetracycline 30S protein synthesis inhibitor
- G+ & G- (broad spectrum)
56
what are the indications for doxycycline? what class of antibiotics does it belong to & where is its site of action? what Gram coverage does it have?
- meibomian gland stasis, recurrent corneal erosions, acne roseacea
- tetracycline 30S protein synthesis inhibitor
- G+ & G- (broad-spectrum)
57
doxycycline 50mg QD is used for what?
anti-inflammatory
58
doxycycline 100mg QD is used for what?
kills bacteria
59
what is the dosage of doxycycline for chlamydia +/- involvemenet (eg, trachoma)?
100mg BID x 7d
60
what is the dosage of doxycyline for treating syphilis?
100mg BID x 14d
61
which tetracycline can cause vestibular toxicity within 2-3d of therapy?
minocycline
62
which tetracycline exhibits the least divalent chelation and has a risk of erosive esophagitis?
doxycycline
63
which tetracycline is an excellent option for MRSE?
doxycycline
64
what are the contraindications for use of tetracyclines?
- pregnancy
- nursing mothers
- children under 8 yrs
- renal failure
65
which tetracycline can be used in patients with renal failure & why?
doxycycline → eliminated fecally
66
erythromycin, clarithromycin & azithromycin belong to which class of antibiotics & where is their site of action? what is their Gram coverage?
macrolides → 50S protein synthesis inhibitor
| G+ > G-
67
which macrolide replaced silver nitrate prophylaxis for neonatal gonorrhea?
erythromycin
68
which macrolide is unstable in gastric acid?
erythromycin
69
which macrolide has reduced dosing because it has greater stability in the GI tract?
clarithromycin
70
which macrolide is the only one available in drop formulation? what is that solution called?
azithromycin → Azasite solution w/ Durasite
71
what permits azithromycin to have minimal dosing?
extended half-life
72
which macrolide is contraindicated in pregnancy?
clarithromycin
73
which macrolide can be used to treat bacterial conjunctivitis, bacterial infections, inclusion conjunctivitis & syphilis?
azithromycin
74
what is the site of action for chloramphenicol & what is its Gram coverage?
50S protein synthesis inhibitors
| G+ & G- (broad-spectrum)
75
why is chloramphenicol limited to topical use only in the US?
high oral toxicity
76
which protein synthesis inhibitor is a first-line therapy for bacterial conjunctivitis?
chloramphenicol
77
what are the adverse effects of chloramphenicol when used orally?
- blood dyscrasia risk
- optic neuritis with prolonged therapy
- gray baby syndrome
78
what is the cell metabolism pathway?
PABA → dihydropteroate synthase → DHF acid → DHF reductase → tetrahydrofolic acid → nucleotides
79
sulfonamides, trimethoprim & pyrimethamine are what class of antibiotics & where is its site of action? what Gram coverage do they have?
folic acid inhibitors → cell metabolism pathway
- sulfonamides → G+ & G- (broad spectrum)
- trimethoprim → G+ > G- (broad spectrum)
- pyrimethamine → G+ & G- (broad spectrum)
80
which folic acid inhibitor is a PABA analog & what is its MOA?
sulfonamides → mimics PABA & uses up dihydropteroate synthase → inhibits synthesis of dihydrofolic acid
81
sulfonamides are commonly combined with which antibiotic? what is the ratio? why is it combined with this antibiotic?
commonly combined with trimethoprim in a 5:1 ratio
| → gives better effect because you disrupt two parts of the cell metabolism pathway
82
which folic acid inhibitor is a DHF analog? what is its MOA?
trimethoprim → attacks DHF reductase → inhibiting synthesis of tetrahydrofolic acid
83
pyrimethamine inhibits which part of the cell metabolism pathway?
inhibits DHF reductase
84
which folic acid inhibitor is combined with another antibiotic & is the drug of choice for pediatric bacterial conjunctivitis? what are the sites of action & Gram coverage?
trimethoprim (folic acid inhibitor) + polymyxin-B (cell membrane toxin) → Polytrim solution
- trimethoprim → broad spectrum (slightly more G+)
- polymyxin-B → G-
85
what folic acid inhibitor combination is used to treat toxoplasmosis?
sulfadiazine + pyrimethamine
86
which folic acid inhibitor combination is the oral drug of choice for MRSA?
sulfamethoxazole + trimethroprim (Bactrim)
87
which folic acid inhibitor is contraindicated in pregnancy?
sulfonamides
88
cross-reactivity is common within with folic acid inhibitor group?
sulfonamides
89
which folic acid inhibitor can cause bone marrow suppression?
trimethoprim
90
which folic acid inhibitor can cause contact dermatitis or Stevens-Johnson syndrome
sulfonamides
91
what class of antibiotics are fluoroquinolones & where is their site of action? what is their MOA? what is their Gram coverage?
DNA synthesis inhibitors → nucleid acid synthesis
- inhibits DNA gyrase & topoisomerase IV
- G- > G+
92
ciprofloxacin & ofloxacin are which generation of fluoroquinolones?
2nd gen
93
levofloxacin is which generation of fluoroquinolones?
3rd gen
94
moxifloxacin & gatifloxacin are which generation of fluoroquinolones?
4th gen
95
besifloxacin w/ Durasite is which generation of fluoroquinolones?
"5th" gen
96
which class of antibiotics are most commonly used & why?
fluoroquinolones because of their great coverage
97
in fluoroquinolones, the newer the generation...
the greater the G+ coverage (along with G- coverage)
98
using fluoroquinolones to treat what is FDA approved?
bacterial conjunctivitis
99
using fluoroquinolones to treat what is off-label use?
bacterial keratitis
100
which fluoroquinolone is 1st gen & can cause intracranial hypertension?
nalidixic acid (NegGram)
101
which fluoroquinolone is the only topical antibiotic that lacks a preservative? what generation is it?
moxifloxacin → 4th gen
102
which fluoroquinolone is concentration dependent? what does that mean? what generation is it?
gatifloxacin → 4th gen
| the more the patient uses it → the better it does its job
103
which fluoroquinolones are 100% effective when used for most common pediatric ocular infections?
levofloxacin, moxifloxacin, gatifloxacin
104
which fluoroquinolone is only available as a topical suspension? what is it combined with & why? what generation is it?
besifloxacin → 5th gen
| - uses Durasite as a viscous agent
105
besifloxacin demonstrates promising MRSA sensitivity, but ineffective for what?
coagulase negative staph
106
what G+ bacteria are antibiotic resistant?
- enterococcus (VRE)
| - staph aureus (MRSA)
107
what G- bacteria are antibiotic resistant?
- klebsiella
- acinetobacter
- pseudomonas
- extended spectrum beta lactamase (ESBL): e. coli, enterobacter
108
what are the 3 most common topical steroid/ABX combos?
blephamide, maxitrol, tobradex
109
what are the contents in Blephamide? what is the Gram coverage and what class of antibiotic is in it?
sulfacetamide + prednisolone acetate
- sulfacetamide → sulfonamides (folic acid inhibitor - inhibits dihydropteroate synthase)
- sulfacetamide → broad-spectrum
110
what are the contents in Maxitrol? what Gram coverage does it have? what antibiotic class is it & where is the site of action?
- neomycin (aminoglycoside - 30S protein synthesis inhibitor) G- > G+
- polymyxin-B (cell membrane toxin) G-
- dexmethasone (steroid)
111
what are the contents in TobraDex? what Gram coverage does it have? what class of antibiotics is in it? where is its site of action?
- tobramycin (aminoglycoside - 30S protein synthesis inhibitor) G- > G+
- dexamethasone (steroid)
