USMLE Antibiotics Flashcards
1
Q
Penicillin mechanism
A
Blocks cell wall synthesis by inhibiting peptidoglycan cross-linking
- Binds to penicillin binding proteins in peptidoglycan
- activates autolytic enzymes
2
Q
penicillin use
A
Gram + organisms:
- S. pneumoniae, S. pyogenes, Actinomyces
Also:
- Neisseria meningitidis, Treponema pallidum, & Syphilis
3
Q
penicillin toxicity
A
hypersensitivity reactions, hemolytic anemia
4
Q
penicillinase resistant penicillins
A
methicillin, nafcillin, dicloxacillin
5
Q
penicillinase resistant penicillin use
A
Staph aureus
6
Q
penicillinase resistant penicillin toxicity
A
hypersensitivity; methicillin: interstitial nephritis
7
Q
aminopenicillins
A
ampicillin, amoxacillin
amOxicillin has greater Oral bioavailability
8
Q
aminopenicillin mechanism
A
- Same as penicillin but wider spectrum
- Penicillinase sensitive
- Combine w/ Clavulanic acid to protect against B-lactams
9
Q
aminopenicillin use
A
Same as Penicillin, but wider spectrum
–H. influenza, E coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, Klebsiella, Enterococci
(Aminopenicillin HELPSS Kill Enterococci)
10
Q
aminopenicillin toxicity
A
hypersensitivity, ampicillin rash, pseudomembranous colitis
11
Q
antipseudomonal drugs
A
ticarcillin, piperacillin, carbenicillin
12
Q
antipseudomonal mechanism
A
same as penicillin; wider spectrum
13
Q
antipseudomonal use
A
Pseudomonas and gram negative rods
14
Q
antipsuedomonal toxicity
A
hypersensitivity reaction
15
Q
beta lactamase inhibitor mechanism
A
inhibit beta lactamase (protects penicillins from destruction)
16
Q
beta lacatamase drugs
A
clavulanic acid, sulbactam, tazobactam
17
Q
bacteriostatic antibiotics
A
Macrolides (Azithromycin, Clarithromycin, Erythromycin)
- Tetracyclines (Tetracycline, Doxycycline, Demeclocycline, Minocycline)
- Clindamycin
- Sulfonamides (Sulfamethoxazole, Sulfisoxazole, Sulfadiazine)
- Trimethoprim
- Chloramphenicol
18
Q
bactericidal antibiotics
A
vancomycin, fluoroquinolones, penicillin, aminoglycosides, cephalosporins, metronidazole
19
Q
1st generation cephalosporins
A
Cefazolin, Cephalexin
20
Q
1st generation cephalosporin coverage
A
Gram + Cocci: Proteus, E. coli, Klebsiella
“PEcK”
21
Q
cephalosporin mechanism
A
beta lactams; inhibit cell wall synthesis but less susceptible to penicillinases
22
Q
2nd generation cephalosporins
A
Cefoxitin, Cefaclor, Cefuroxime
23
Q
2nd generation cephalosporin coverage
A
Gram + Cocci:
H. influenzae, Enterobacter aerogenes, Neisseria, Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia marcescens
“HEN PEcKS”
24
Q
3rd generation cephalosporins
A
ceftriaxone, ceftazidime, cefotaxime
25
3rd generation cephalosporin coverage
Serious gram negative infections, resistant to other B-lactams:
Ceftriaxone: Neisseria meningitidis & Gonorrhea
Ceftazidime: Pseudomonas
26
4th generation cephalosporins
Cefepime
| - inc'd activity against Pseudomonas & gram + organisms
27
cephalosporin toxicity
hypersensitivity, vitamin K deficiency, cross-hypersensitivity with penicillins, increase nephrotoxicity of aminoglycosides, reaction with alcohol
28
aztreonam mechanism
beta lactamase resistant monobactam; binds penicillin binding protein
29
aztreonam use
gram negative rods only
30
aztreonam toxicity
occasional GI upset
31
imipenem/cilastin mechanism
beta-lactamase resistant carbapenem; cilastin is a renal dihydropeptidase 1 (to decrease renal inactivation)
32
imipenem use
broad spectrum; gram + cocci, gram - rods and anaerobes
| use limited to life-threatening or refractory infections because of side effects
33
imipenem toxicity
GI distress, skin rash, CNS toxicity (seizures) at high plasma levels
34
vancomycin mechanism
inhibits cell wall mucopeptide formation by binding D ala D ala portion of cell wall precursors
35
vancomycin use
gram + only; use reserved for resistant infections--Staph aureus, enterococci, C diff
36
vancomycin toxicity
nephrotoxicity, ototoxicity, thrombophlebitis, red man syndrome, but well-tolerated in general
37
resistance to vancomycin
amino acid change from D-ala D-ala to D-ala D-lac
38
30s ribosomal inhibitors
tetracyclins, aminoglycosides
39
50s ribosomal inhibitors
clindamycin, chloramphenicol, erythromycin, linezolid, lincomycin
40
aminoglycoside drugs
gentamicin, neomycin, amikacin, tobramycin, streptomycin
41
aminoglycoside mechanism
inhibit initiation of protein synthesis by binding to & distorting the structure of prokaryotic 30S ribosomal unit
- this causes misreading of mRNA
- require O2 for uptake
42
aminoglycoside use
no anaerobe coverage; severe gram - rod infections; synergistic with beta lactams; neomycin for bowel surgery
43
aminoglycoside toxicity
nephrotoxicity (esp with cephalosporins), ototoxicity (esp with loop diuretics), teratogen
44
aminoglycoside resistance
drug modification via transferases
45
tetracycline mechanism
binds to 30s and prevents attachment of amino-acyl tRNA; limited CNS penetration
46
tetracycline use
borrelia burgdorferi, H. pylori, Mycoplasma. Rickettsia, Chlamydia (accumulates intercellularly); demeclocycline is ADH antagonist so used in SIADH
47
tetracycline administration consideration
absorption inhibited by milk, antacids, iron preparations; can be used in patients with renal failure because fecally eliminated
48
tetracycline toxicity
GI distress, teeth discoloration, inhibition of bone growth in children, photosensitivity
49
tetracycline resistance
decreased uptake or increased efflux
50
macrolide drugs
erythromycin, azithromycin, clarithromycin
51
macrolide mechanism
binds to 50s subunit and blocks translocation (binds to 23s RNA)
52
macrolide use
atypical pneumonias (mycoplasma, chlamydia, legionella), URIs, STDs, gram positive cocci (in pts allergic to penicillin), Neisseria
53
macrolide toxicity
prolonged QT, GI discomfort, acute cholestatic hepatitis, eosinophilia, skin rashes, increases serum concentration of theophyllines and oral anticoagulants
54
macrolide resistance
methylation of 23s binding site
55
chloramphenicol mechanism
binds to 50s ribosome, inhibits peptidyltransferase activity
56
chloramphenicol use
meningitis (H flu, Neisseria meningitis, Strep pneumo)
57
clindamycin mechanism
binds to the 50 S ribosome, blocks peptide bond formation (bacteriostatic)
(blocks translocation step)
58
clindamycin use
anaerobic infections in aspiration pneumonia or lung abscesses
59
clindamycin toxicity
psuedomembranous colitis, fever, diarrhea
60
sulfonamide mechanism
Blocks nucleotide synthesis by inhibiting folic acid synthesis (involved in methylation)
- PABA antimetabolites (compete w/ PABA to) inhibit dihydropteroate synthetase; inhibit bacterial folic acid production (bacteriostatic)
61
sulfonamide use
gram positive, gram negative, Nocardia, chlamydia, simple UTI, also opportunistic infection prophylaxis in HIV patients
62
sulfonamide toxicity
hypersensitivity reactions, hemolysis in G6PD deficiency, nephrotoxicity, photosensitivity, kernicterus in infants, displaces warfarin and other drugs from albumin binding
63
sulfonamide resistance
altered bacterial dihydropteroate synthetase, decreased uptake or increased PABA synthesis
64
trimethoprim mechanism
Blocks nucleotide synthesis by inhibiting folic acid synthesis (involved in methylation)
- Inhibits bacterial dihydrofolate reductase (bacteriostatic)
65
trimethoprim use
used in combo with sulfamethoxazole for recurrent UTI's, Shigella. Salmonella, pneumocystis
66
trimethoprim toxicity
megaloblastic anemia, leukopenia, granulocytopenia; lurcovorin rescue to supplement with folinic acid
67
fluoroquinolone mechanism
inhibit bacterial DNA gyrase (bactericidal)
68
sulfonamide drugs
sulfamethoxazole, sulfisoxazole, sulfadiazine
69
fluoroquinolone drugs
ciprofloxacin, norfloxacin, ofloxacin, sparfloxacin, moxifloxacin, gatifloxacin, enxoxacin, nalidixic acid (a quinolone)
70
fluoroquinolone use
gram negative rods of urinary and GI tracts, Neisseria, some gram positive, also has action vs. psuedomonas
71
fluoroquinolone toxicity
GI upset, rash, superinfection, headache, dizziness; contraindicated in pregnant women because of risk or cartilage damage, tendonitis and tendon rupture in adults, legs cramps and myalgias in kids; do not take with antacids
72
fluoroquinolone resistance
chromosomal DNA gyrase mutation
73
metronidazole mechanism
forms free radical toxic metabolites in bacterial cell that damages DNA; bactericidal and anti-protozoal
74
metronidazole use
anaerobes, giardia, entamoeba histolytica, trichomonas, gardnerella vaginalis; used in H. pylori triple therapy
75
metronidazole toxicity
disulfuram like reaction with alcohol; headache; metallic taste
76
polymixin drugs
polymixin B, colistimethate
77
polymixin mechanism
bind to cell membranes of bacteria and disrupt osmotic properties; catatonic and basic proteins that act as detergents
78
polymixin toxicity
neurotoxicity, acute renal tubular necrosis
79
polymixin use
resistant gram - infections
80
TB treatments
rifampin, isoniazide, ethambutol, pyrazinamide (isoniazid is prophylaxis)
81
Mycobacterium avium treatment
azithromycin, rifampin, ethambutol, streptomycin
82
mycobacterium leprae treatment
rifampin, dapsone, clofazimine
83
ethambutol toxicity
optic neuropathy
84
pyrazinamide toxicity
hepatotoxicity
85
ethambutol mechanism
blocks arabinosyltransferase to decrease carbohydrate polymerization of cell wall
86
isoniazid mechanism
decreases synthesis of mycolic acids; need bacterial catalase peroxidase to convert isoniazid to active metabolite
87
clinical use of isoniazid
TB
88
isoniazid toxicity
neurotoxicity, hepatotoxicity, lupus, pyradoxime (B6) deficiency--supplementation can prevent neurotoxicity and maybe lupus
89
rifampin mechanism
inhibits DNA-dependent RNA polymerase
90
rifampin use
TB, delays dapsone resistance in leprosy, Neisseria and H.flu prophylaxis
91
rifampin toxicity
minor hepatotoxicity, P450 inducer, orange body fluids
92
rifampin resistance
mutation in RNA polymerase
93
meningococcal prophylaxis
rifampin, minocycline
94
gonorrhea prophylaxis
ceftriaxone
95
syphylis prophylaxis
penicillin G
96
recurrent UTI prophylaxis
TMP-SMX
97
pneumocystis prophylaxis
TMP-SMX, aerosolized pentamidine
98
endocarditis prophylaxis in surgical/dental procedures
penicillins
99
mycobacterium avium prophylaxis
azithromycin
100
amphotericin B mechanism
binds ergosterol in fungal membrane and forms pores that allow leakage of electrolytes; does not cross BBB
101
amphotericin B use
serious systemic mycoses (crypococcus, blastomyces, coccidiodes, aspergillus, histoplasma, candida)
102
amphotericin B toxicity
fever/chills, hypotension, nephrotoxicity, arrhythmias, anemia, IV phlebitis; liposomal amphotericin reduces toxicity
103
nystatin mechanism
binds ergosterol in fungal membrane and forms pores that allow leakage of electrolytes
104
nystatin use
topical only because too toxic for systemic use; "swish and swallow" for oral thrush, topical for diaper rash or vaginal candidiasis
105
nystatin toxicity
too toxic for systemic use but not absorbed in GI tract
106
azole drugs
fluconazole, ketoconazole, clotrimazole, miconazole, itraconazole, voriconazole
107
azole mechanism
inhibit ergosterol synthesis by inhibiting the P450 enzyme that converts lanosterol to ergosterol
108
azole use
systemic mycoses
109
fluconazole use
cryptococcal meningitis in AIDS patients (can cross BBB), candidal infections
110
ketoconazole use
blastomyces, histoplasma, coccidiodes, candida, hypercortisolism
111
clotrimazole, miconazole use
for topical fungal infections
112
azole toxicity
hormone synthesis inhibition (gynecomastia) liver dysfunction, CYP 450 inhibitor, fever, chills
113
flucytosine mechanism
inhibits DNA synthesis by conversion to 5-FU
114
flucytosine use
systemic fungal infections in combo with amphotericin B (candida, crypto)
115
flucytosine toxicity
nausea, vomiting, diarrhea, bone marrow suppression
116
caspofungin mechanism
inhibits cell wall synthesis by inhibiting synthesis of beta glucan
117
caspofungin use
invasive aspergillosis
118
caspofungin toxicity
GI upset, flushing
119
terbinafine mechanism
inhibits fungal squalene epoxidase
120
terbinafine use
dermatophytoses (especially onychomycosis)
121
griseofulvin mechanism
interferes with microtubule function; disrupts mitosis; deposits in keratin-containing tissues
122
griseofulvin use
oral treatment of superficial infections; dermatophytes (tinea, ringworm)
123
griseofulvin toxicity
P450 inducer (increases warfarin metabolism), teratogenic, carcinogenic, confusion, headaches
124
pyrimethamine mechanism
selectively inhibits plasmodial dihydrofolate reductase (best for . falciparum)
125
pyrimethamine use
for toxoplasmosis with sulfadiazine
126
suramin mechanism
inhibits enzymes involved in energy metabolism; no CNS involvement
127
suramin use
anti-protozoal; blood-borne trypanosoma brucei
128
melarsoprol mechanism
inhibits sulfhydryl groups in parasite enzymes; CNS involvement
129
melarsoprol use
anti-protozoal, CNS penetration of trypanosoma brucei
130
nifurtimox mechanism
forms intracellular oxygen radical that are toxic to the organism
131
sodium stibogluconate mechanism
inhibits glycolysis at PFK reaction
132
nifurtimox use
anti-protozoal, trypanosoma cruzi
133
sodium stibogluconate use
anti-protozoal; leishmania
134
chloroquine mechanism
blocks plasmodium heme polymerase, leading to accumulation of hemoglobin breakdown products that destroy the organism
135
mefloquine mechanism
unknown
136
chloroquine use
malaria
137
mefloquine use
chloroquine resistant malaria
138
quinine mechanism
unknown, maybe blocks protozoal protein/nuclei acid synthesis
139
quinine use
chloroquine resistant malaria when use in combination with pyrimethamine, sulfonamide, babesia
140
mebendazole mechanism
inhibits glucose uptake and microtubule synthesis
141
mebendazole use
anti-helminthic
142
pyrantel pamoate mechanism
stimulates nicotinic receptors at neuromuscular junction; depolarization-induced paralysis; no effect on tapeworms or flukes
143
pyrantel pamoate use
anti-helminthic
144
ivermectin mechanism
intensifies GABA-mediated neurotransmission and causes immobilization; doesn't cross BBB (so no effect on humans)
145
ivermectin use
anti-helminthic
146
diethylcarbamazine mechanism
unknown
147
diethycarbamazine use
anti-helminthic
148
praziquantel mechanism
increases membrane permeablility to Ca, causing contraction and paralysis in flukes and tapeworms
149
praziquantel use
anti-helminthic
150
primaquine use
plasmodium vivax and ovale
151
amantadine mechanism
blocks viral penetration/uncoating (M2 protein); causes release of dopamine from intact nerve terminals
152
amantidine use
Parkinson's; prophylaxis and treatment for Influenza A (only A!)
153
amantidine toxicity
ataxia, dizziness, slurred speech
154
amantidine resistance
mutated M2 protein (most Influenza A strains are resistant)
155
zanamivir and oseltamivir mechanism
inhibit influenza neuraminidase, decreases progeny release
156
zanamivir and oseltamivir use
influenza A and B (give early or as prophylaxis!)
157
ribavirin mechanism
inhibits synthesis of guanine nucleosides by competitively inhibiting IMP dephydrogenase
158
ribavirin use
RSV, chronic Hep C
159
ribavirin toxicity
hemolytic anemia; severe teratogen
160
acyclovir mechanism
monophosphorylated by HSV/VZV thymidine kinase; guanosine analog; chain termination of DNA polymerase
161
acyclovir use
HSV (mucocutaneous lesions and encephalitis), VZV, EBV; not effective for latent virus; prophylaxis in immunocompromised patients
162
acyclovir toxicity
generally well-tolerated
163
acyclovir resistance
lack of viral thymidine kinase
164
ganciclovir mechanism
Guanosine analog
| - Preferentially inhibits viral DNA polymerase (also interferes with human DNA polymerase)
165
ganciclovir use
CMV (esp. in immunocompromised patients -- HIV)
166
ganciclovir toxicity
leukopenia, neutropenia, thrombocytopenia, renal toxicity
(general --> anemia)
(more toxic to host enzymes than Acyclovir)
167
ganciclovir resistance
mutated DNA polymerase or lack of viral kinase
168
foscarnet mechanism
viral DNA polymerase inhibitor that binds to pyrophosphate binding site of enzyme; doesn't need activation
169
foscarnet use
CMV retinitis when ganciclovir fails; also acyclovir resistant HSV
170
foscarnet toxicity
nephrotoxicity
171
foscarnet resistance
mutated DNA polymerase
172
saquinavir class
protease inhibitor
173
ritonavir class
protease inhibitor
174
indinavir class
protease inhibitor
175
nelfinavir class
protease inhibitor
176
amprenavir class
protease inhibitor
177
protease inhibitor mechanism
prevent maturation of new viruses (protease cleaves the polypeptide products of HIV mRNA into functional parts)
178
protease inhibitor toxicity
hyperglycemia, GI intolerance, lipodystrophy, thrombocytopenia
179
zidovudine class
NRTI (nucleoside reverse transcriptase inhibitor)
180
didanosine class
NRTI (nucleoside reverse transcriptase inhibitor)
181
zalcitabine class
NRTI
182
stavudine class
NRTI
183
NRTI mechanism
Competitively inhibit nucleotide binding to reverse transcriptase and terminated DNA chain (lack a 3'OH group)
- must be phosphorylated by thymidine kinase (except Tenofovir, which is a nucleoTide analog)
184
zidovudine use
HIV general prophylaxis and during pregnancy to reduce risk of fetal transmission
185
NRTI toxicity
bone marrow suppression (give EPO and G-CSF), peripheral neuropathy, lactic acidosis, rash, megaloblastic anemia
186
nevirapine class
NNRTI
187
efavirenz class
NNRTI
188
delaviridine class
NNRTI
189
NNRTI mechanism
bind to reverse transcriptase at site different from NRTIs; do not need to be phosphorylated for activation
190
NNRTI toxicity
bone marrow suppression (give EPO and G-CSF), peripheral neuropathy, lactic acidosis, rash, megaloblastic anemia
191
enfuviritide class
fusion inhibitor
192
fusion inhibitor mechanism
bind viral gp41 subunit; inhibit conformational change for fusion with CD4 cells; blocks entry and replication
193
enfuvirtide toxicity
hypersensitivity reactions, injection site reaction, increased risk of bacterial pneumonia
194
interferon mechanism
glycoproteins synthesized by virus-infected cells that blocks replication of viruses
195
interferon use
alpha: HBV and HCV, Kaposi's sarcoma; beta: MS; gamma: NADPH oxidase deficiency
196
interferon toxicity
neuropenia
197
antibiotics to avoid in pregnancy
fluoroquinolones, sulfonamides, aminoglycosides, metronidazole, tetracyclines, ribavirin, griseofulvin, chloramphenicol
198
HAART therapy
2 NRTIs and 1 protease inhibitor or 2 NRTIs and 1 NNRTI
199
Didanosine - toxicity?
Pancreatitis
200
Cutaneous drug hypersensitivity such as SJS & TEN are associated w/ what 2 antiretroviral medications?
Nevirapine & Efavirenz
