Antimicrobials Flashcards
(412 cards)
1
Q
Which 3 antimalarial agents can be administered to a patient with a life-threatening malaria infection?
A
Quinidine in the United States, quinine outside of the United States, or artesunate
2
Q
Why are fluoroquinolones contraindicated for women who are pregnant or breastfeeding and for children younger than 18 years of age?
A
Possibility of cartilage damage (fluoroquinolones hurt attachments to your bones)
3
Q
Which protein synthesis–inhibiting antibiotics are bacteriostatic?
A
Tetracyclines, chloramphenicol, clindamycin, erythromycin (linezolid is variable: bacteriostatic and bactericidal)
4
Q
Which of the 2 aminopenicillins (amoxicillin and ampicillin) has a greater oral bioavailability?
A
Amoxicillin (AmOxicillin has better Oral bioavailability)
5
Q
What is the mechanism of action of daptomycin?
A
Lipopeptide disrupts gram-positive cocci cell membranes by creating transmembrane channels
6
Q
A patient requests prophylaxis against Mycobacterium tuberculosis before travel. What is the one drug that can be used as solo prophylaxis?
A
Isoniazid
7
Q
What is the mechanism of action of the antipseudomonal penicillins (piperacillin and ticarcillin)?
A
Same as that of penicillin (they inhibit peptidoglycan cross-linking in bacterial cell walls)
8
Q
What are the common CNS adverse effects of fluoroquinolones?
A
Headaches, dizziness
9
Q
Name the 3 respiratory fluoroquinolones.
A
Levofloxacin, moxifloxacin, and gemifloxacin
10
Q
Name a skin condition that can be treated with tetracycline antibiotics.
A
Acne
11
Q
Anion gap metabolic acidosis develops in a patient being treated for HIV. What is the most likely cause?
A
Nucleoside reverse transcriptase inhibitor–induced lactic acidosis (nucleoside agents only)
12
Q
Which antifungal agent deposits into keratin-containing tissues, thus making it effective against dermatophyte infections?
A
Griseofulvin
13
Q
List the organisms that can be treated with metronidazole.
A
Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (Bacteroides, Clostridium difficile), Helicobacter pylori (GET GAP on the Metro with metronidazole!)
14
Q
What is the mechanism of action of nystatin?
A
It forms membrane pores on fungi, allowing electrolytes to leak
15
Q
What 5 medications can be given to a person traveling to an area in which malaria is endemic?
A
Atovaquone-proguanil, doxycycline, mefloquine, primaquine, or chloroquine (for areas with sensitive species)
16
Q
Why is daptomycin ineffective against pneumonia?
A
Daptomycin binds to and is inactivated by surfactant before acting on the lungs (“Dapto-myo-skin” is used for skin infections but can cause myopathy)
17
Q
What is the consequence of treating latent tuberculosis solely with rifamycins (eg, rifampin)?
A
Development of rapid resistance
18
Q
At what point during disease progression are carbapenem antibiotics considered?
A
Because of their significant adverse effects, they are used when other medications have failed or when an infection is life threatening
19
Q
What are the major adverse effects of dapsone?
A
Hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, methemoglobinemia, and agranulocytosis
20
Q
What are the adverse effects of trimethoprim?
A
Hyperkalemia (high doses), leukopenia, granulocytopenia, megaloblastic anemia (TMP Treats Marrow Poorly)
21
Q
Describe the mechanism of action for sulfonamide antibiotics.
A
They prevent folate synthesis by inhibiting dihydropteroate synthase, which prevents bacterial replication (bacteriostatic)
22
Q
What is the mechanism of action of amphotericin B?
A
Amphotericin B binds ergosterol (unique to fungi) and forms membrane pores (“tears” holes), allowing leakage of electrolytes
23
Q
A patient presents with peripheral neuropathy and sideroblastic anemia after being treated for tuberculosis. What medication is the most likely cause?
A
Isoniazid
24
Q
List the antibiotics that inhibit the 30S subunit of the bacterial ribosome.
A
Aminoglycosides, Tetracyclines (30S); “Buy AT 30, CCEL (sell) at 50”
25
Which drug is effective in treatment of both disseminated Lyme disease and gonorrhea?
Ceftriaxone
26
What is the mechanism of action of isoniazid?
Decreases the synthesis of mycolic acids
27
Why should griseofulvin be avoided in the treatment of pregnant patients with fungal infections ?
It is teratogenic
28
By what 3 mechanisms can bacteria develop resistance to a flouroquinolone antibiotic?
Chromosome-encoded mutation in the bacterial DNA gyrase, efflux pumps, or resistance mediated by plasmids
29
Why do patients require different dosages of isoniazid?
People are either fast or slow acetylators, and the half-life of isoniazid differs depending on the individual rate of acetylation
30
At what pH does pyrazinamide work best?
Acidic pH (eg, phagolysosomes)
31
A patient receiving antiretroviral therapy for HIV has nausea, diarrhea, lipodystrophy, and episodes of hyperglycemia. Which class of drug is the patient likely taking?
An HIV protease inhibitor
32
What are some adverse effects of penicillinase-resistant penicillins?
Interstitial nephritis and hypersensitivity reactions
33
Which 2 antimicrobials act by disrupting membrane integrity?
Daptomycin, polymyxins
34
Which 50S-inhibiting antibiotic inhibits peptidyl transferase activity?
Chloramphenicol
35
Cefepime (fourth-generation cephalosporin) has increased activity against which organisms?
Pseudomonas and gram-positive organisms
36
What is the major adverse effect of cidofovir and how can it be minimized?
Nephrotoxicity; coadministration with probenecid and intravenous saline solution
37
What are the 2 major indications for use of cidofovir?
Cytomegalovirus retinitis in immunocompromised patients and acyclovir-resistant herpes simplex virus infections
38
How does the microbial coverage of amoxicillin and ampicillin compare with that of penicillin?
Ampicillin and amoxicillin have a broader spectrum of coverage (AMinoPenicillins are AMPed-up penicillin)
39
Which bacterial enzyme is needed to activate isoniazid?
Catalase-peroxidase (encoded by KatG)
40
Which types of organisms are treated with vancomycin?
Gram ⊕ only: MRSA, Staphylococcus epidermidis, Enterococcus spp, Clostridium difficile (oral dosing for pseudomembranous colitis)
41
What is the 4-drug regimen commonly used to treat tuberculosis?
Rifampin, Isoniazid, Pyrazinamide, and Ethambutol (RIPE for treatment)
42
What generation of cephalosporins is used for severe gram-negative infections resistant to previously prescribed β-lactams (eg, amoxicillin)?
Third-generation cephalosporins (eg, ceftriaxone, cefotaxime, cefpodoxime, or ceftazidime)
43
What 2 common adverse effects of metronidazole are NOT associated with alcohol use?
Headache and metallic taste
44
Polymyxins are used to treat which types of infections?
Last resort treatment for multidrug-resistant gram ⊖ bacterial infections and topical treatment for superficial skin infections
45
In patients with HIV, what is the indication for use of fluconazole?
Long-term suppression of cryptococcal meningitis
46
What is the mechanism of action of dicloxacillin, nafcillin, and oxacillin?
Inhibition of peptidoglycan cross-linking in bacteria cell walls (same as penicillin)
47
Addition of a certain bactericidal antibiotic leads to misreading of the mRNA by inhibition of which ribosomal subunit?
30S ribosomal unit (blocked by aminoglycosides and can cause misreading of mRNA)
48
Which types of influenza are oseltamivir and zanamivir effective against?
Influenza A and B (for treatment and prevention)
49
What is the mechanism of action of elvitegravir?
As an integrase inhibitor, elvitegravir stops HIV genome integration into host cell DNA
50
Which class of HIV medication binds to the gp41 protein?
Entry inhibitors; this is enfuvirtide, which inhibits fusion
51
Against which organisms are dicloxacillin, nafcillin, and oxacillin useful?
Staphylococcus aureus (except MRSA); "Use naf (nafcillin) for staph"
52
What is the activity of acyclovir, famciclovir, or valacyclovir against latent varicella-zoster virus (VZV) and herpes simplex virus (HSV)?
None; there is no effect on the latent forms of VZV and HSV
53
Name 3 examples of macrolide antibiotics.
Erythromycin, azithromycin, and clarithromycin
54
What are the clinical uses of fluoroquinolones?
Treat gram ⊖ rods causing urinary and gastrointestinal tract infections (including Pseudomonas), some gram ⊕ organisms, and otitis externa
55
What is the mechanism of resistance of the rifamycins (eg, rifampin), particularly with monotherapy?
Mutations decrease the drug's ability to bind to the RNA polymerase
56
What is the mechanism of resistance for valacyclovir?
Mutation in viral thymidine kinase
57
What is the mechanism of action of aminoglycosides?
They are bactericidal antibiotics that irreversibly inhibit the initiation complex by binding 30S, blocking translocation, and causing misreading of mRNA
58
What is the mechanism of action of echinocandins (eg, anidulafungin, caspofungin, and micafungin)?
Inhibition of cell wall synthesis
59
What is the mechanism of action of sofosbuvir and dasabuvir?
Inhibition of NS5B, an RNA-dependent RNA polymerase that serves as a chain terminator, which prevents viral replication
60
Which macrolide antibiotics inhibit cytochrome P-450 enzymes?
Erythromycin, clarithromycin
61
What is the effect of ciprofloxacin on cytochrome P-450?
Inhibits cytochrome P-450
62
What is the mechanism of resistance of foscarnet?
DNA polymerase mutation
63
What is the mechanism by which bacteria develop resistance to macrolide antibiotics
By methylation of the 23S ribosomal RNA–binding site, which prevents the drug from binding to it
64
What are the 2 most common adverse effects of echinocandins?
Gastrointestinal upset and flushing (due to release of histamine)
65
What is the shared mechanism of action of oseltamivir and zanamivir?
Inhibition of viral neuraminidase, which blocks the release of viral progeny
66
What drug should not be taken with fluoroquinolones?
Antacids
67
What is the difference between disinfection and sterilization?
Disinfection reduces the number of pathogenic organisms to a safe level; sterilization inactivates all microbes (including spores)
68
Trimethoprim and sulfamethoxazole are used in combination to treat which types of infections?
Urinary tract infections, Shigella, Salmonella, and Pneumocystis jirovecii pneumonia
69
Which organisms would you consider using linezolid against?
Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE)
70
What are 2 potential adverse effects of daptomycin?
Rhabdomyolysis, myopathy
71
Which 6 disinfection and sterilization techniques are sporicidal?
Autoclaving, chlorine, ethylene oxide, hydrogen peroxide, iodine and iodophors (may be sporicidal)
72
Why are tetracyclines contraindicated in pregnancy?
Because they inhibit bone growth in children
73
An HIV ⊕ patient has a CD4+ count of \<100 cells/mm3 and must receive prophylactic therapy for Pneumocystis pneumonia and toxoplasmosis. Which medication is indicated?
Trimethoprim-sulfamethoxazole (TMP-SMX)
74
What is the mechanism of action of hydrogen peroxide in infection control?
Induction of free radical oxidation
75
A patient is found to have drug-induced systemic lupus erythematosus after completing prophylaxis for tuberculosis. Which drug is the most likely cause?
Isoniazid
76
Name 4 drugs that can be given with penicillin antibiotics to prevent degradation by β-lactamase (penicillinase).
Clavulanic acid, Avibactam, Sulbactam, Tazobactam (CAST); these are β-lactamase inhibitors
77
A patient develops orange urine after initiation of treatment for tuberculosis. What medication is the most likely cause?
A rifamycin (eg, rifampin)
78
An immunocompromised patient has cytomegalovirus retinitis that does not respond to ganciclovir. Which antiviral agent should be considered?
Foscarnet
79
What is the mechanism of resistance of isoniazid?
Mutations resulting in the underexpression of KatG, which encodes bacterial catalase-peroxidase
80
What is the mechanism of action of the echinocandins (eg, caspofungin)?
Inhibition of β-glucan synthesis, which disrupts cell wall synthesis
81
What drug is used for Mycobacterium tuberculosis prophylaxis?
Isoniazid
82
What are the musculoskeletal adverse effects of fluoroquinolones?
Leg cramps, myalgias, damage to cartilage in children, tendonitis and tendon rupture in patients older than 60 years or patients treated with prednisone
83
What organisms does tigecycline cover?
Anaerobic, gram-positive, gram-negative, and multidrug-resistant organisms (eg, VRE, MRSA)
84
What adverse effects are associated with cephalosporin use?
Disulfiram-like reaction, autoimmune hemolytic anemia, hypersensitivity reaction, vitamin K deficiency
85
Describe the mechanism of action of the bacteriostatic macrolide antibiotics.
They inhibit protein synthesis by binding to the 23S rRNA of the 50S subunit and preventing translocation ("macroslides")
86
Which 2 combinations of medications are indicated for a patient with malaria caused by Plasmodium falciparum?
Artemether/lumefantrine or atovaquone/proguanil
87
What is the mechanism of action of nucleoside reverse transcriptase inhibitors (NRTIs) (abacavir, emtricitabine, lamivudine, tenofovir, zidovudine)?
Inhibition of nucleotide binding to reverse transcriptase due to lack of 3′ OH group, thus stopping DNA synthesis (NRTIs must be phosphorylated to be activated)
88
What are the adverse effects of penicillin?
Hypersensitivity reactions, drug-induced interstitial nephritis, and direct Coombs ⊕ hemolytic anemia
89
When selecting appropriate treatment of hepatitis C infection in pregnant women, which medication should be avoided and why?
Ribavirin because of severe teratogenicity
90
What is the clinical use of baloxavir?
Decreases the duration of illness due to influenza virus if taken within 48 hours of symptom onset
91
What is the mechanism of action of ampicillin and amoxicillin?
They bind penicillin-binding proteins (transpeptidases) and block cross-linking of peptidoglycan in bacterial cell walls (same as penicillin)
92
Enfuvirtide blocks which genetic processes immediately downstream of penetration?
Uncoating and reverse transcription
93
Which 2 antibiotics would you prescribe as prophylaxis against Mycobacterium avium-intracellulare infection?
Azithromycin or rifabutin
94
Which antibiotic is administered prophylactically for women with recurrent urinary tract infections?
Trimethoprim-sulfamethoxazole (TMP-SMX)
95
To overcome bacterial resistance, what drug must be administered with extended-spectrum β-lactams (eg, piperacillin) for pseudomonal infection?
β-Lactamase inhibitor because of sensitivity of Pseudomonas spp to penicillinase
96
Name the 3 drugs that belong to the sulfonamide class.
Sulfamethoxazole (SMX), sulfadiazine, sulfisoxazole
97
Name the 2 antibiotics that belong to the polymyxin class.
Colistin (polymyxin E) and polymyxin B
98
Name 5 third-generation cephalosporins.
Ceftriaxone, cefotaxime, ceftazidime, cefpodoxime, cefixime
99
Name the antibiotics that inhibit peptidoglycan cross-linking and are penicillinase sensitive.
Penicillin G and V, ampicillin, amoxicillin
100
Lack of which enzyme is to blame for premature infants developing gray baby syndrome after receiving chloramphenicol?
Liver UDP-glucuronosyltransferase
101
Acyclovir and valacyclovir are not useful against which 2 viruses?
Epstein-Barr virus (weak activity), cytomegalovirus (no activity)
102
What are the 2 most common adverse effects of pyrazinamide?
Hepatotoxicity and hyperuricemia
103
How does isoniazid affect cytochrome P450?
It is an inhibitor of cytochrome P-450
104
Which 6 antibiotics can be used to treat methicillin-resistant Staphylococcus aureus (MRSA)?
Ceftaroline, daptomycin, doxycycline, linezolid, tigecycline, and vancomycin
105
Can aminoglycosides kill anaerobic bacteria?
No, because they require oxygen for uptake
106
Which process does rifampin block to exert antimicrobial effects?
The synthesis of bacterial messenger RNA via inhibiting RNA polymerase
107
What is the mechanism of resistance of Plasmodium falciparum to chloroquine?
Membrane pumps decrease intracellular concentrations of the drug
108
Is ritonavir a cytochrome P-450 inhibitor or inducer?
Inhibitor
109
What are the 4 most common adverse effects of terbinafine therapy?
Gastrointestinal upset, headache, taste disturbances, hepatotoxicity
110
What is the mechanism of action of ethambutol?
Blocks arabinosyltransferase, thus decreases carbohydrate polymerization in the mycobacterial cell wall
111
What is unique regarding seizures induced by isoniazid toxicity?
Seizures caused by isoniazid toxicity are refractory to benzodiazepines
112
What are the 3 different mechanisms by which bacteria develop resistance against sulfonamides?
Alteration in bacterial dihydropteroate synthase, decreased uptake, or increased synthesis of para-aminobenzoic acid
113
What are the 3 first-line antiviral agents used to treat herpes simplex virus and varicella-zoster virus infections?
Valacyclovir, famciclovir, and acyclovir
114
Which antiviral medication prevents HIV virions from attaching to host cells?
Maraviroc
115
Why are trimethoprim and sulfamethoxazole used in combination?
To synergistically inhibit folate metabolism and thus DNA synthesis (becoming bactericidal instead of bacteriostatic)
116
What antiprotozoal agent is used to treat Trypanosoma cruzi infection?
Nifurtimox
117
How would an organism become resistant to linezolid?
From a point mutation in the ribosomal RNA
118
What are 2 major adverse effects of acyclovir, famciclovir, and valacyclovir?
Acute kidney injury and obstructive crystalline nephropathy in association with inadequate hydration
119
In a pregnant patient taking an aminoglycoside, what adverse effect would be expected in the fetus?
Ototoxicity
120
Name the narrow-spectrum, penicillinase-resistant antibiotics.
Nafcillin, oxacillin, dicloxacillin
121
Name the drug that is a monobactam.
Aztreonam
122
What is the mechanism of action of terbinafine?
It inhibits squalene epoxidase (converts squalene into squalene epoxide), which inhibits synthesis of the cell membrane
123
Which antibiotics belong to the carbapenem group?
Doripenem, ertapenem, imipenem, meropenem
124
What are the 5 major adverse effects caused by macrolides?
MACRO: GI Motility issues, Arrhythmia (prolonged QT interval), acute Cholestatic hepatitis, Rash, eOsinophilia
125
Which antibiotics inhibit bacterial translocation?
Antibiotics that act on translocation such as the macrolides and clindamycin, which inhibit the 50S subunit
126
What are 2 common adverse effects of efavirenz?
CNS symptoms and vivid dreams
127
Compared with other β-lactams, cephalosporins are more resistant to what bacterial enzyme?
Penicillinase
128
Which 2 infections are the echinocandins used to treat?
Invasive aspergillosis, Candida infections
129
What are 2 clinical uses of griseofulvin?
Superficial infections (oral therapy) and dermatophytoses, such as tinea and ringworm.
130
Why should chlarithromycin not be prescribed for pregnant patients?
It is known to cause embryotoxicity
131
What types of infections is daptomycin used to treat?
Vancomycin-resistant enterococcus, bacteremia, endocarditis, and skin infections with Staphylococcus aureus (especially methicillin-resistant strains)
132
Which antimicrobials are used to treat anaerobic infections below and above the diaphragm?
Metronidazole treats anaerobic infections below the diaphragm; clindamycin treats anaerobic infections above the diaphragm
133
Which 2 classes of HIV antiviral drugs act by inhibiting reverse transcriptase?
Nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs)
134
Sulfonamides are active against which organisms?
Gram ⊕ and gram ⊖ organisms and Nocardia
135
What is the mechanism of action of chlorine in infection control?
Oxidizes and denatures proteins
136
Which 2 infection control techniques disrupt cell membranes?
Alcohols and chlorhexidine
137
What is the advantage of using valacyclovir over acyclovir?
Valacyclovir is a prodrug of acyclovir with better oral bioavailability
138
What is the mechanism of action of ethambutol?
Inhibition of arabinosyltransferase, which prevents carbohydrate polymerization of mycobacterial cell walls
139
Which antifungal agent is primarily used to treat dermatophytoses, especially onychomycosis?
Terbinafine
140
You want to prescribe a triple therapy regimen for a patient with Helicobacter pylori, but she has a penicillin allergy. How do you alter your treatment plan?
Replace amoxicillin with metronidazole (triple therapy also includes a proton pump inhibitor and clarithromycin)
141
Localized or less serious systemic mycoses are an indication for which class of antifungal agents?
Azoles
142
How can megaloblastic anemia seen with trimethoprim-sulfamethoxazole (TMP-SMX) be avoided?
By coadministration of leucovorin (folinic acid)
143
What viruses are targeted by the antiviral medications, acyclovir and ganciclovir?
Acyclovir targets herpes simplex virus and varicella zoster virus, while ganciclovir targets cytomegalovirus
144
What is a common suffix for the protease inhibitor class?
-navir: atazanavir, darunavir, fosamprenavir, indinavir, lopinavir, ritonavir, saquinavir
145
What is the clinical use for remdesivir?
Treatment of patients with COVID-19 who require hospitalization
146
What is the mechanism of action of the antibiotic linezolid?
Binds to the 50S subunit and blocks formation of the initiation complex, inhibiting protein synthesis
147
How do bacteria develop resistance to penicillin?
By producing a β-lactamase (such as penicillinase), which cleaves the β-lactam ring, or by mutations in the penicillin-binding proteins
148
Which antiviral medications are inhibitors of viral DNA polymerase?
Cidofovir and foscarnet
149
What is the mechanism of action of the antiviral medications acyclovir and ganciclovir?
They are guanosine analogs that inhibit DNA replication
150
What is the mechanism of action of metronidazole?
Forms free radical metabolites that damage bacterial DNA, leading to cell death (bactericidal)
151
A patient receiving single-agent therapy for latent tuberculosis has abnormal liver function test results. Which medication is the most likely cause?
Isoniazid
152
Name the 4 carbapenem antibiotics.
Doripenem, Imipenem, Meropenem, and Ertapenem (“Pens” (carbapenems) cost a DIME)
153
What is the most serious adverse effect of flucytosine?
Bone marrow suppression
154
A patient taking a cephalosporin develops a prolonged prothrombin time. Why?
Cephalosporin use can cause vitamin K deficiency, leading to ↓ clotting factors
155
Describe the mechanism of action of trimethoprim.
It blocks dihydrofolate reductase (like pyrimethamine), preventing bacterial replication (bacteriostatic)
156
A patient reports blurry vision after being treated for malaria. What is the most likely cause?
Chloroquine-induced retinopathy
157
A patient with chronic obstructive pulmonary disease being treated with inhaled steroids develops oral candidiasis. Which antifungal medication is indicated for this patient?
Nystatin (swish and swallow)
158
What antiprotozoal agent is used to treat toxoplasmosis?
Pyrimethamine
159
What is the mechanism of action of non-nucleoside reverse transcriptase inhibitors (NNRTIs)?
Binding of reverse transcriptase at different locations than NRTIs; NNRTIs do not require phosphorylation or completion with nucleotides to be activated (unlike NRTIs)
160
Why should ribavarin be avoided in the treatment of pregnant patients with hepatitis C?
It is teratogenic
161
What organisms do ampicillin and amoxicillin cover that penicillin does not?
Haemophilus influenzae, Helicobacter pylori, Escherichia coli, Enterococci, Listeria monocytogenes, Proteus mirabilis, Salmonella, and Shigella (HHEELPSS kill enterococci)
162
What is the most common electrical cardiac abnormality seen with erythromycin?
Prolonged QT interval
163
A patient with herpes simplex virus has a strain resistant to acyclovir. Which antiviral agent should be considered?
Foscarnet
164
Does ganciclovir or valganciclovir have better oral bioavailability?
Valganciclovir, because it is a prodrug of ganciclovir
165
Ganciclovir inhibits which viral enzyme?
Viral DNA polymerase
166
What is the treatment for tuberculoid leprosy?
Long-term regimen of dapsone and rifampin
167
Through inhibition of which enzyme do fluoroquinolones and quinolones exert their antibacterial effects?
DNA gyrase inhibition
168
What neurologic injury can sulfonamides cause in infants?
Kernicterus
169
Are patients with penicillin allergies likely to be allergic to cephalosporins?
No; cephalosporins have a low rate of cross-reactivity even in patients with penicillin allergy
170
Name the bacterial infections that can be treated with tetracycline antibiotics.
Mycoplasma pneumoniae, Chlamydia, Borrelia burgdorferi, Rickettsia, community-acquired methicillin-resistant Staphylococcus aureus (doxyclycline)
171
What is the mechanism of action of streptomycin?
Blocks the 30S subunit of the bacterial ribosome
172
A patient is given a triple antibiotic ointment for a superficial skin infection. Which antibiotic in the topical therapy is a cationic polypeptide?
Polymyxin B
173
What are the major adverse effects of ampicillin and amoxicillin?
Rash, hypersensitivity reaction, pseudomembranous colitis
174
What are the 4 R's of Rifampin?
RNA polymerase inhibitor Ramps up microsomal cytochrome P-450 Red/orange body fluids Rapid resistance when used alone
175
Which azole antifungal medication is indicated for Aspergillus and some Candida infections?
Voriconazole
176
Name 3 antibiotics that belong to the tetracycline class of antibiotics.
Doxycycline, minocycline, and tetracycline
177
What are the possible adverse effects of the carbapenem class of antibiotics?
Skin rashes, gastrointestinal distress, and central nervous system toxicity (seizures)
178
A patient being treated for HIV is receiving a nucleoside reverse transcriptase inhibitor (NRTI) that does not require intracellular phosphorylation. What drug is this?
Tenofovir, which is already a nucleoTide; all other NRTIs require phosphorylation
179
Ribavarin is used to treat infection with which 2 viruses?
Respiratory syncytial virus, hepatitis C virus
180
What antiprotozoal agent is used to treat leishmaniasis?
Sodium stibogluconate
181
Why should fluoroquinolones be avoided in patients older than 60 years of age?
Fluoroquinolones may cause tendinitis/tendon rupture in people older than 60 years of age (fluoroquinolones hurt attachments to your bones)
182
A young female presents for treatment of tinea corporis. What do you need to remember when considering the antifungal griseofulvin for her?
It is teratogenic and contraindicated in pregnancy; perform a pregnancy test before starting therapy
183
Aminoglycosides are synergistic with which class of antibiotics?
β-Lactams
184
Itraconazole is indicated for which 4 fungal infections?
Histoplasma, Blastomyces, Coccidioides, Sporothrix schenckii
185
What is the mechanism of action of fluoroquinolones?
Bactericidal; inhibition of prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV
186
A patient presents with low hemoglobin soon after initiation of treatment with sulfadiazine. Which underlying enzyme deficiency does this patient likely have?
Glucose-6-phosphate-dehydrogenase (G6PD) deficiency, causing hemolytic anemia
187
A patient with HIV develops leukopenia, neutropenia, and thrombocytopenia after starting treatment for cytomegalovirus esophagitis. What is the most likely cause?
He most likely began taking ganciclovir, which has an adverse effect on bone marrow suppression
188
What is the mechanism of action of an integrase inhibitor (eg, raltegravir)?
Reversibly blocks viral DNA integration into host cell genome for transcription
189
What is a common suffix for nucleoside reverse transcriptase inhibitors (NRTIs)?
-ine: emtricitabine, lamivudine, zidovudine; others are abacavir and tenofovir
190
What is a common dermatologic adverse effect of fluoroquinolones?
Rash
191
What infectious processes are commonly treated using clindamycin?
Aspiration pneumonia, lung abscesses, and oral infections involving anaerobic organisms
192
What antibiotic do you prescribe as prophylaxis against streptococcal pharyngitis for a child with a history of rheumatic fever?
Oral penicillin V or benzathine penicillin G
193
What are the major adverse effects of amphotericin B?
Anemia, arrhythmias, fevers, chills, nephrotoxicity, hypotension, and intravenous phlebitis
194
A patient develops an anion gap metabolic acidosis after being treated for tuberculosis. What is the most likely causal medication?
Isoniazid
195
Acyclovir, famciclovir, and valacyclovir are guanosine analogs that inhibit which viral enzyme?
Viral DNA polymerase through chain termination
196
Neuraminidase inhibitors are used to treat which viral infections?
Influenza A and B infections (the 2 neuraminidase inhibitors are oseltamivir and zanamivir)
197
A patient with HIV contracts tuberculosis. Why would rifabutin be favored over rifampin for this patient?
Less P-450 stimulation (rifampin ramps up cytochrome P-450, but rifabutin does not)
198
What is the treatment for lepromatous leprosy?
Long-term regimen of dapsone, rifampin, and clofazimine
199
What are 2 indications for topical nystatin?
Vaginal candidiasis and diaper rash
200
A patient being treated for HIV infection develops anemia. Which drug is responsible?
Zidovudine (ZDV)
201
While prescribing antiretroviral therapy (ART), you discover that your patient has an HLA-B\*5701 mutation. What drug is contraindicated?
Abacavir (nucleoside reverse transcriptase inhibitor) because of increased risk of hypersensitivity
202
Vancomycin is bactericidal except against which bacteria?
Clostridium difficile (bacteriostatic)
203
Which 5 medications can be used in the treatment of vancomycin-resistant enterococcus (VRE)?
Daptomycin, tigecycline, linezolid, and streptogramins (quinupristin, dalfopristin)
204
A patient develops minor hepatotoxicity after starting treatment for tuberculosis. What class of medications is the most likely cause?
Rifamycins
205
What is the mechanism by which echinocandins (eg, anidulafungin) cause flushing?
Release of histamine
206
In a pregnant patient taking a sulfonamide, what adverse effect would be expected in the fetus?
Kernicterus
207
What biochemical variation in methicillin-resistant Staphylococcus aureus (MRSA) makes nafcillin ineffective?
Alteration of the penicillin-binding protein target site
208
Which 3 anti-mite/louse agents may be used to treat an infection with scabies (Sarcoptes scabiei) or lice (Pediculus and Pthirus)?
Permethrin, malathion, ivermectin
209
What is the mechanism of action of azoles?
They block fungal synthesis of sterols (ergosterol) by inhibiting cytochrome P-450 enzymes from converting lanosterol to ergosterol
210
Pancytopenia develops in a patient being treated for HIV. Which drugs should be considered to counteract this adverse effect?
Granulocyte colony-stimulating factor (G-CSF) and erythropoietin (EPO) to combat bone marrow suppression
211
What is the mechanism of action of ledipasvir, ombitasvir, and velpatasvir?
NS5A inhibition, preventing RNA replication (the exact mechanism by which they inhibit NS5A is unknown)
212
What drug regimen can you use to treat a Mycobacterium avium-intracellulare infection?
Azithromycin or clarithromycin plus ethambutol; rifabutin or ciprofloxacin can be added
213
What is the effect of griseofulvin on warfarin metabolism?
It increases warfarin metabolism because it is a cytochrome P-450 inducer
214
What are the 2 most common adverse effects of grazoprevir (NS3/4A inhibitor)?
Headache and fatigue
215
Which bacterial species are targeted by ticarcillin and piperacillin?
Pseudomonas spp and gram-negative rods
216
Does cidofovir have a long or short half-life?
A long half-life
217
Name the penicillin-type antibiotics that are sensitive to penicillinase.
Amoxicillin and ampicillin (aminopenicillins)
218
The use of azoles in treatment of fungal infections targets which fungal cell structure?
The cell membrane (due to inhibition of intracellular 14-α-demethylase, which reduces ergosterol synthesis)
219
Name the carbapenem that is resistant to β-lactamase and is prescribed with cilastatin to prevent inactivation by the kidneys.
Imipenem, a broad-spectrum antibiotic (“the kill is lastin' with cilastatin")
220
Name 4 combinations of penicillin antibiotics with β-lactamase inhibitors commonly used to treat bacterial infections.
Amoxicillin-clavulanate, ampicillin-sulbactam, ceftazidime-avibactam, piperacillin-tazobactam
221
Which antibiotic ointment is applied to prevent gonococcal conjunctivitis in newborns?
Ophthalmic erythromycin
222
Aztreonam is synergistic with which class of antibiotics?
Aminoglycosides
223
A patient with renal failure needs a tetracycline for treatment of a Mycoplasma pneumoniae infection. What do you prescribe and why?
Doxycycline; it is fecally eliminated and can be administered to patients with renal failure
224
What is the mechanism of action of metronidazole for its antimicrobial effect?
Free radical–induced damage to DNA integrity
225
How does adjusting the dose of the antibiotic chloramphenicol influence its risk of causing anemia?
Lowering the dose will lower the risk of anemia because chloramphenicol-induced anemia is a dose-dependent adverse effect of the drug
226
Why do antibiotics that inhibit protein synthesis generally not affect human cells?
They target bacterial ribosome 70S, which is smaller than the 80S of humans; thus, human ribosomes are left unaffected
227
Why are tetracycline antibiotics not a good choice for infections of the central nervous system (CNS)?
They have limited CNS penetration
228
How does adjusting the dose of the antibiotic chloramphenicol influence its risk of causing pancytopenia?
It has no effect because aplastic anemia is a dose-independent adverse effect of chloramphenicol
229
What are the 2 most common adverse effects of the NS5B inhibitors, sofosbuvir and dasabuvir?
Headache and fatigue
230
Against which classes of bacteria do penicillins exhibit bactericidal activity?
Gram ⊕ cocci, gram ⊖ cocci, gram ⊕ rods, spirochetes
231
Which antibiotic targeting bacterial protein synthesis can be given prophylactically before bowel surgery?
Neomycin (an aminoglycoside)
232
A pregnant woman is found to be HIV positive. Which nucleoside reverse transcriptase inhibitor (NRTI) is indicated?
Zidovudine (ZDV) can reduce the risk of vertical transmission and is also used for general prophylaxis
233
Which processes do sulfonamides and trimethoprim (TMP) affect to exert their antibacterial effects?
Folic acid synthesis and reduction (DNA methylation); sulfonamides inhibit conversion of PABA to dihydrofolate; TMP inhibits conversion of DHF to tetrahydrofolate
234
Name 5 antibiotics that belong to the aminoglycoside class of antibiotics.
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin; "Mean" (aminoglycosides) GNATS caNNOT kill anaerobes"
235
Which organisms are covered by the first-generation cephalosporins?
Gram ⊕ cocci (such as Staphylococcus auerus), Proteus mirabilis, Eschericia coli, Klebsiella pneumoniae (⊕ PEcK)
236
What is the mechanism by which bacteria develop resistance to aminoglycosides?
Transferase enzymes in bacteria cause inactivation of the drug via acetylation, phosphorylation, or adenylation
237
Name 2 examples of first-generation cephalosporins
Cefazolin and cephalexin
238
What 2 antiprotozoal agents are used to treat Trypanosoma brucei infection?
Suramin, melarsoprol
239
What is the mechanism of resistance against tetracyclines?
Decreased uptake into bacterial cells or increased efflux out of cells by plasmid-encoded transport pumps
240
What are the current guidelines for initiation of antiretroviral therapy (ART)?
ART is commonly started at diagnosis of HIV; high viral load, CD4 count \<500, or presence of AIDS-defining illness are strong indications for starting treatment
241
Use of aminoglycoside antibiotics is absolutely contraindicated for patients with what neuromuscular disorder?
Myasthenia gravis
242
Compare the modes of administration for penicillin G and penicillin V.
Penicillin G: intravenous or intramuscular; penicillin V: oral
243
Name 3 classes of antibiotics that work by binding to the bacterial 30S ribosomal subunit.
Aminoglycosides (eg, gentamicin), glycylcycline (eg, tigecycline), tetracyclines (eg, doxycycline)
244
Which antibiotic is most commonly used preoperatively to protect against Staphylococcus aureus wound infections?
Cefazolin
245
Which 2 systemic reactions accompanied by diffuse rash can be seen with vancomycin toxicity?
Red man syndrome (diffuse flushing) and DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome
246
Which drug class (1) stops viral particle budding and release in HIV-infected cells and (2) allows HIV proteins to remain within cells?
Protease inhibitors (eg, atazanavir), which block proteolytic processing
247
Isavuconazole is indicated for which 2 fungal infections?
Serious Mucor or Aspergillus infections
248
What is the mechanism of action of remdesivir?
It decreases production of viral RNA by inhibiting viral RNA-dependent RNA polymerase and evading proofreading by viral exoribonuclease
249
What is the mechanism of action of the anti-hepatitis C virus drugs simeprevir and grazoprevir?
Inhibition of HCV protease (NS3/4A), thereby preventing viral replication
250
Carbapenems are used to treat infections with which 3 types of organisms?
Anaerobes, gram-positive cocci, and gram-negative rods (wide spectrum)
251
What abnormality might be seen on an ECG in a patient being treated with a fluoroquinolone?
Prolonged QT interval
252
Which adverse effects are associated with aminoglycosides?
Nephrotoxicity, Neuromuscular blockade, Ototoxicity, Teratogenicity; "mean" (aminoglycoside) GNATS caNNOT kill anaerobes
253
Which 2 azoles are commonly used to treat topical fungal infections?
Miconazole and clotrimazole
254
Which medication is indicated in the treatment of plasmodia malaria (not including Plasmodium falciparum)?
Cholorquine
255
Most antiretroviral drugs are effective against both HIV-1 and HIV-2. Which of these medications are not?
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) and enfuviritide are only effective against HIV-1
256
Sulfonamides are bacteriostatic when used alone, but addition of which antibiotic can cause sulfonamides to be bactericidal?
Trimethoprim, a dihydrofolate reductase inhibitor
257
What is the mechanism of action of praziquantel?
It increases Ca2+ permeability and vacuolization
258
Nearly all carbapenem antibiotics are inactivated in the renal tubules by renal dehydropeptidase I. Which of the carbapenem antibiotics is not affected by this enzyme?
Meropenem
259
In combination with amphotericin B, flucytosine is indicated in the treatment of what condition?
Systemic fungal infections, especially meningitis caused by Cryptococcus
260
A patient being treated for HIV is noted to have an elevateed creatine kinase level. What is the most likely cause?
An integrase inhibitor (eg, elvitegravir, dolutegravir, bictegravir, raltegravir)
261
How can you prevent peripheral neuropathy in a patient being treated for tuberculosis with isoniazid?
By coadministering pyridoxine (vitamin B6) to prevent vitamin B6 deficiency induced by isoniazid
262
What aspect of nafcillin, dicloxacillin, and oxacillin makes them resistant to degradation by the bacterial enzyme β-lactamase?
Bulky R group in these drugs blocks access of β-lactamase to β-lactam ring
263
What are 3 indications for acyclovir, famciclovir, and valacyclovir?
Herpes simplex virus (HSV)–induced oral and genital lesions, HSV-induced encephalitis, and prophylaxis against HSV for immunocompromised individuals
264
A patient receiving a new HIV drug regimen has had several skin reactions at the site of injection. What drug was she prescribed?
Enfuvirtide
265
Which 2 disinfection and sterilization techniques are not sporicidal?
Alcohols and quaternary amines
266
What is the common renal manifestation of sulfonamide toxicity?
Tubulointerstitial nephritis
267
Which 2 electrolytes must be supplemented when amphotericin B is prescribed? Why?
Potassium and magnesium (due to altered renal tubule permeability)
268
Name the fourth-generation cephalosporin.
Cefepime
269
What is the mechanism of action of malathion?
It inhibits mite/louse acetylcholinesterases
270
What is the mechanism of action of griseofulvin?
Inhibition of microtubule function, thereby disrupting mitosis
271
Intrathecal administration of amphotericin B is indicated for treatment of which fungal meningitis?
Meningitis caused by Coccidioides
272
How are sulfonamides and dapsone similar in mechanism?
They both inhibit folate synthesis by blocking dihydropteroate synthase
273
Why does acyclovir interfere with viral DNA synthesis and not human DNA synthesis?
It requires monophosphorylation by the thymidine kinase of herpes simplex virus/varicella-zoster virus and is inactive in uninfected cells.
274
You prescribe metronidazole and advise the patient to avoid alcohol use. Why?
Metronidazole with alcohol causes a disulfiram-like reaction (severe flushing, hypotension, tachycardia)
275
What is the mechanism of action of cidofovir?
Inhibits viral DNA polymerase
276
What are 4 major adverse effects of streptomycin in the treatment of tuberculosis?
Ataxia, nephrotoxicity, tinnitus, and vertigo
277
Which feature of tetracyclines makes them effective against Rickettsia and Chlamydia infections?
Their ability to accumulate intracellularly
278
Amphotericin B is used to treat which serious, systemic fungal infections? (Hint: There are 6.)
Blastomyces, Candida, Coccidioides, Cryptococcus, Histoplasma, Mucor
279
What are the 2 most common adverse effects of NS5A inhibitors (ledipasvir, ombitasvir, velpatasvir)?
Diarrhea, headache
280
A patient receiving warfarin therapy begins taking a sulfonamide for an infection and soon notes easy bruising and dark tarry stools. What mechanism causes this adverse effect?
The sulfonamide increases the plasma concentration of warfarin by displacing it from albumin
281
Which antiviral medication is indicated for an immunocompromised patient with a cytomegalovirus infection?
Ganciclovir
282
An HIV ⊕ patient has a CD4+ count of \<200 cells/mm3 and must be treated with prophylaxis for Pneumocystis pneumonia. Which medication is indicated?
Trimethoprim-sulfamethoxazole (TMP-SMX)
283
What is the mechanism of action of mebendazole?
Inhibition of microtubules
284
A patient with active tuberculosis is found to be HIV positive. How must the treatment regimen for either diagnosis be modified?
Rifampin causes potent CYP/UGT induction that ↓ protease inhibitor levels; it should be replaced with rifabutin
285
What is autoclaving?
An infection control technique that involves the use of pressurized steam at temperatures \>120 °C
286
A patient with COPD and a recent episode of pneumonia has ↑ serum levels of theophylline. Which antibiotic is this patient likely taking?
A macrolide
287
Which carbapenem has limited Pseudomonas coverage?
Ertapenem
288
What organisms are targeted by clindamycin?
Organisms causing anaerobic lung infections (eg, Clostridium perfringens, Bacteroides spp) and group A streptococcal infections
289
What are the adverse effects of foscarnet therapy?
Electrolyte abnormalities (hypo- or hypercalcemia, hypo- or hyperphosphatemia, hypomagnesemia, hypokalemia), seizures, nephrotoxicity
290
What is the mechanism of action of the rifamycins, rifabutin and rifampin?
They block mRNA synthesis via inhibition of DNA-dependent RNA polymerase
291
What is the mechanism of action of terbinafine?
Inhibits squalene epoxidase in fungal cells
292
What is the benefit of utilizing rifampin in the treatment of Mycobacterium leprae?
It delays resistance to dapsone
293
Name 5 antibiotics that work by binding to the bacterial 50S ribosomal subunits and blocking protein synthesis.
Chloramphenicol, clindamycin, linezolid; quinupristin, dalfopristin (streptogramins); azithromycin, clarithromycin, erythromycin (macrolides)
294
Which 3 medications belong to the rifamycin class of antibiotics?
Rifampin, rifapentine, and rifabutin
295
In a pregnant patient taking a fluoroquinolone, what adverse effect would be expected in the fetus?
Cartilage damage
296
A patient being treated with clindamycin for pneumonia develops fever and loose stools. What is the bacterial culprit?
Clostridium difficile overgrowth in the colon, causing pseudomembranous colitis
297
What are 2 dermatologic manifestations of sulfonamide toxicity?
Photosensitivity amd Stevens-Johnson syndrome
298
Which 3 antibiotics can be administered prophylactically for meningococcal meningitis exposure?
Rifampin, ceftriaxone, ciprofloxacin
299
A patient develops renal toxicity after being treated for cytomegalovirus. What is the most likely cause?
Ganciclovir
300
What are the 3 non-nucleoside reverse transcriptase inhibitors (NNRTIs) available to treat HIV?
Efavirenz, delavirdine, nevirapine
301
What is the mechanism of action of dapsone?
It inhibits dihydropteroate synthase (sulfonamides inhibit the same enzyme), impairing bacterial folate synthesis
302
Which protein synthesis–inhibiting antibiotics are bactericidal?
Aminoglycosides (note that linezolid is variable: bacteriostatic and bactericidal)
303
What is the mechanism of action of ethylene oxide in infection control?
Alkylation
304
What are the 3 medications classified as echinocandins?
Anidulafungin, caspofungin, and micafungin
305
List the antibiotics that inhibit the 50S subunit of the bacterial ribosome.
Chloramphenicol, Clindamycin, Erythromycin (macrolides), Linezold; "Buy AT 30, CCEL (sell) at 50"
306
What is the mechanism of action of polymyxin antibiotics?
Cation polypeptides bind to phospholipids on cell membranes of gram ⊝ bacteria, which disrupts cell membrane integrity, leading to leakage of cellular components and cell death.
307
A patient taking prednisone has been recently prescribed a fluoroquinolone antibiotic. What complication may arise from a drug interaction?
Tendon rupture; risk is increased when fluoroquinolones are combined with prednisone
308
What is the mechanism of action of tigecycline?
It binds the 30S ribosome to inhibit bacterial protein synthesis; bacteriostatic (tetracycline derivative)
309
Which organisms are typically not covered by the first 4 generations of cephalosporins?
LAME: Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, Enterococci
310
Fluconazole is indicated for treatment of which common fungal infection?
Candidal infections of all types (can also be used for suppression of crytococcal meningitis in patients with HIV)
311
How soon after onset of influenza symptoms should treatment with oseltamivir or zanamivir be initiated?
Within 48 hours of symptom onset
312
How does chlorhexidine affect the intracellular components of pathologic agents in infection control?
Coagulates intracellular components
313
Which 2 antibiotics can be used against multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii?
Polymyxins B and E (colistin)
314
Name 2 antibiotics that work by blocking peptidoglycan synthesis.
Bacitracin and vancomycin (glycopeptides)
315
What is the mechanism of action of ribavirin?
Competitive inhibition of inosine monophosphate dehydrogenase, thereby inhibiting synthesis of guanine nucleotides
316
Which 2 antibiotics can be administered prophylactically for pregnant women with group B streptococcal colonization?
Ampicillin, penicillin G
317
What organisms are aminoglycosides used against?
Gram-negative rods, particularly in cases of severe infection
318
What is the mechanism of action of isoniazid?
Decreases mycolic acid synthesis
319
What is the mechanism of action that leads to liver dysfunction when azoles (eg, clotrimazole) are used in the treatment of fungal infections?
Inhibition of cytochrome P-450
320
What are the 2 most common dermatologic adverse effects of the simeprevir (NS3/4A inhibitor)?
Photosensitivity and rash
321
What is the mechanism of action of cephalosporin antibiotics?
They are bactericidal β-lactams that inhibit cell wall synthesis
322
Name 4 examples of second-generation cephalosporins.
Cefaclor, cefoxitin, cefuroxime, and cefotetan (2nd graders wear fake fox fur to tea parties)
323
Which third-generation cephalosporin is effective against Pseudomonas spp?
Ceftazidime
324
What are 2 methods for reducing amphotericin B toxicity?
Use the liposomal formulation of the drug and hydrate the patient to prevent nephrotoxicity
325
What is the mechanism of action of ganciclovir?
It is a guanosine analog, first phosphorylated by cytomegalovirus viral kinase and then phosphorylated by cellular kinases to produce ganciclovir triphosphate
326
What is the mechanism of action of the antibiotic chloramphenicol?
Inhibits peptidyltransferase activity in the 50S subunit of the ribosome
327
What is the mechanism of action of the antibiotic chloramphenicol?
Inhibits peptidyltransferase activity in the 50S subunit of the ribosome
328
A patient is taking warfarin because of a recent pulmonary embolism. What complication could arise if a macrolide is prescribed for newly diagnosed pneumonia?
Increased risk of bleeding due to increased serum concentration of warfarin (an oral anticoagulant) as a result of interaction with a macrolide antibiotic
329
What are some of the adverse reactions associated with vancomycin?
Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome; Nephrotoxicity, Ototoxicity, Thrombophlebitis, diffuse Flushing (red man syndrome) (NOT trouble Free)
330
What is the mechanism of action of the polyenes (amphotericin B and nystatin)?
Create membrane pores to disrupt cell membrane integrity
331
Name 2 antipseudomonal antibiotics that interfere with peptidoglycan cross-linking.
Ticarcillin, piperacillin
332
Which antibiotics should be avoided in pregnancy?
Sulfonamides, Aminoglycosides, Fluoroquinolones, Clarithromycin, Tetracyclines, Ribavirin, Griseofulvin, Chloramphenicol (SAFe Children Take Really Good Care)
333
What are the most common uses for chloramphenicol?
Treatment of rickettsial diseases (eg, Rocky Mountain spotted fever) and meningitis (Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae)
334
What adverse effect is more commonly seen in dark-skinned individuals taking chloroquine?
Pruritus
335
Which component of the cell wall is targeted by antibiotics acting at the level of cell wall?
Peptidoglycans
336
Which organisms do second-generation cephalosporins cover?
Gram ⊕ cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria spp, Serratia marcescens, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae (HENS PEcK)
337
Which antifungal agent inhibits nucleic acid synthesis?
Flucytosine
338
What dermatologic adverse effect results from use of tetracyclines?
Photosensitivity
339
What are 3 well-known adverse effects of linezolid?
Peripheral neuropathy, bone marrow suppression (especially thrombocytopenia), and serotonin syndrome (due to partial monoamine oxidase inhibition)
340
What is the mechanism of action of quaternary amines on microbes?
Impairment of cell membrane permeability
341
Why should chloramphenicol not be prescribed for pregnant patients?
It can cause gray baby syndrome
342
What is the mechanism of action of baloxavir?
It decreases viral replication by inhibiting the "cap snatching" endonuclease activity of influenza virus RNA polymerase
343
What types of infections are macrolides used to treat?
Sexually transmitted diseases (Chlamydia), atypical pneumonias (eg, Mycoplasma), gram ⊕ cocci (streptococcal infections in patients allergic to penicillin), Bordetella pertussis
344
Which agent, when given with amoxicillin, protects against β-lactamases?
Clavulanic acid
345
Name a fifth-generation cephalosporin.
Ceftaroline
346
A patient being treated for HIV experiences paresthesia and decreased sensation in both legs. What is the most likely cause?
Nucleoside reverse transcriptase inhibitor–induced peripheral neuropathy
347
What is the mechanism of action of pyrazinamide?
Unclear; it acts via an unknown mechanism intracellularly
348
What is the recommended combination of antiretroviral therapy (ART) medication classes in HIV therapy?
2 nucleoside reverse transcriptase inhibitors (NRTIs) and a third agent (integrase inhibitors are preferred)
349
A patient with a severe bacterial infection is allergic to penicillin. Is aztreonam a good treatment option?
Yes; aztreonam has no cross-sensitivity to penicillins
350
What is the mechanism by which bacteria develop resistance to carbapenems?
Via carbapenemases, which inactivate the drug (typically produced by Eshcerichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes)
351
Which individuals should receive prophylactic amoxicillin?
Patients at high risk for endocarditis who are undergoing surgical or dental procedures
352
Dapsone is used for prophylaxis against infection with which organism?
Pneumocystis jirovecii
353
Which 2 enzymes does foscarnet inhibit?
Viral DNA/RNA polymerase and HIV reverse transcriptase
354
A patient being treated for systemic mycoses develops gynecomastia. What is the most likely causal agent?
Ketoconazole (most likely azole) secondary to inhibition of testosterone synthesis
355
How do penicillins, antipseudomonals, cephalosporins, carbapenems, and monobactams work?
They block cell wall synthesis by inhibiting cross-linking of peptidoglycans
356
What 2 diseases is dapsone indicated to treat?
Leprosy (both lepromatous and tuberculoid forms), Pneumocystis jirovecii (if used with trimethoprim)
357
What is the function of the HIV-1 protease from the pol gene?
Cleaves polypeptides made from HIV mRNA into functional components; therefore, protease inhibitors prevent the maturation of new viruses
358
Which antiviral medication is most appropriate for treating herpes zoster?
Famciclovir
359
What is the mechanism of action of clindamycin?
It is a bacteriostatic antibiotic that inhibits peptide transfer (translocation) at the 50S ribosomal subunit
360
Which antifungal agent acts like amphotericin B but is only available in topical formulations because of systemic toxicity?
Nystatin (same mechanism as amphotericin B)
361
What is the mechanism of resistance of ganciclovir?
Mutation of viral kinase
362
Hemolysis may occur as an adverse effect in which patients taking dapsone?
Patients who are glucose-6-phosphate dehydrogenase (G6PD) deficient
363
A patient being treated for ringworm experiences flushing, tachycardia, and hypotension after a bachelor party. What drug interaction occurred?
Alcohol and griseofulvin caused a disulfiram-like reaction
364
What is the clinical use of streptomycin?
Second-line treatment for Mycobacterium tuberculosis
365
What is the mechanism of action of azoles?
Decreased ergosterol synthesis from lanosterol via the inhibition of 14-α-demethylase
366
How do bacteria develop resistance to vancomycin?
Conversion of D-Ala-D-Ala to D-Ala-D-Lac; (If you Lack a D-Ala [dollar], you can’t ride the van [vancomycin])
367
How do iodine and iodophors work to control infection?
Halogenation of proteins, RNA, and DNA
368
What is the mechanism by which bacteria develop resistance to chloramphenicol?
By acquiring a plasmid-encoded acetyltransferase that inactivates the drug
369
Which of the carbapenem antibiotics has a lower risk of seizures?
Meropenem
370
A patient taking an antidepressant is prescribed linezolid for MRSA pneumonia. Which serious adverse effect might you worry about?
Serotonin syndrome; more likely to occur if a patient is also taking a selective serotonin reuptake inhibitor (due to partial monoamine oxidase inhibition)
371
What is the mechanism of action of tetracyclines?
They are bacteriostatic, binding to 30S and preventing the attachment of aminoacyl-tRNA
372
Name the 4 nonrespiratory fluoroquinolones.
Ciprofloxacin, norfloxacin, ofloxacin, and enoxacin
373
Which cephalosporins work particularly well in the treatment of meningitis and why?
Third-generation cephalosporins because they can cross the blood-brain barrier
374
Aztreonam is active against which organisms?
Gram-negative rods only
375
What second agent can be administered with amphotericin B to treat cryptococcal meningitis?
Flucytosine
376
What is the mechanism of action of chloroquine?
Stops the detoxification of heme into hemozoin, causing an accumulation of heme, which is toxic to plasmodia
377
What is the mechanism of resistance to ampicillin and amoxicillin?
Bacterial penicillinase (a type of β-lactamase) cleaves the β-lactam ring (avoid this by coprescribing clavulanic acid, which inhibits penicillinases)
378
What is the mechanism of action of flucytosine?
Flucytosine is converted to 5-fluorouracil by cytosine deaminase; 5-fluorouracil inhibits DNA and RNA synthesis
379
Which 2 antibiotics can be used as prophylaxis against postsurgical Staphylococcus aureus infection?
Cefazolin; vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) infections
380
What is the core structure of penicillin and penicillin derivatives?
β-Lactam ring
381
Where does foscarnet bind on viruses (eg, cytomegalovirus)?
The pyrophosphate-binding site of either viral DNA/RNA polymerase or HIV reverse transcriptase (foscarnet = pyrofosphate analog)
382
What is the major toxicity associated with ethambutol?
Optic neuropathy (think "eyethambutol"), which commonly manifests as red-green color blindness and is usually reversible
383
Name the antibiotics that inhibit peptidoglycan cross-linking and are penicillinase resistant.
Oxacillin, nafcillin, dicloxacillin
384
Ethambutol is used to treat which bacterial infection?
Mycobacterium tuberculosis
385
What is the mechanism of action of oseltamivir and zanamivir?
They inhibit neuraminidase, thus blocking the release of progeny virus from the cell
386
A child presents with discolored teeth, inhibited bone growth, and gastrointestinal distress secondary to antibiotic treatment. What antibiotic was used?
A tetracycline, which should be avoided in children because of these adverse effects
387
What is a major hematologic adverse effect of ribavirin?
Hemolytic anemia
388
What is the mechanism of action of maraviroc?
Inhibits viral attachment by binding to CCR-5 on T cells/monocytes; this prevents CCR-5 interaction with gp120 (maraviroc inhibits docking)
389
What is the mechanism of action of vancomycin?
It binds the D-Ala D-Ala part of cell wall precursors, inhibiting the formation of peptidoglycan cell wall (bactericidal against most bacteria)
390
How does cilastatin work to decrease inactivation of carbapenem antibiotics?
Inhibitor of renal dehydropeptidase I, which decreases the inactivation of carbapenem antibiotics
391
You add a bacteriostatic antibiotic to bacteria and notice that the A-site tRNA binding is reduced. Which ribosomal subunit is inhibited?
30S (this is caused by tetracycline antibiotics)
392
A patient with hepatitis C refractory to newer therapies is in need of which medication adjunct?
Ribavirin
393
When would you consider using clindamycin over metronidazole to treat an anaerobic infection?
Clindamycin is useful for anaerobic infections above the diaphragm; metronidazole, for those below it
394
Ceftaroline (fifth-generation cephalosporin) is active against which organisms?
Gram-positive and gram-negative organisms, including MRSA and Enterococcus faecalis (note: no coverage of Pseudomonas spp)
395
A patient with sepsis receiving an aminoglycoside is also prescribed a cephalosporin. What adverse effect could occur?
When combined with aminoglycosides, cephalosporins increase the potential for nephrotoxicity
396
What is the mechanism of action of protease inhibitors?
They stop viral maturation by preventing the formation of polypeptide products (Navir [never] tease a protease)
397
What is the mechanism of action of penicillin?
As a D-Ala-D-Ala structural analog, it binds transpeptidases (penicillin-binding proteins) and inhibits transpeptidase cross-linking of peptidoglycan in cell walls
398
β-Lactamase inhibitors are used to protect antibiotics from bacterial penicillinases. Would you use these with vancomycin?
No, because vancomycin is resistant to β-lactamases
399
What are 2 common adverse effects of all non-nucleoside reverse transcriptase inhibitors (NNRTIs)?
Rash and hepatotoxicity
400
What diet modifications must a patient taking a tetracycline follow?
Avoid milk (Ca2+), antacids (eg, Ca2+ or Mg2+), and iron-containing preparations because divalent cations inhibit tetracycline absorption in the gut
401
The autoclave is not reliably successful against what pathologic agents?
Prions
402
Besides treatment of mycobacterial infections, what are 2 other uses for rifamycins (eg, rifampin)?
Meningococcal prophylaxis and chemoprophylaxis for contacts of children with Haemophilus influenzae type b
403
What are the 3 major adverse effects of the drugs belonging to the polymyxin class?
Nephrotoxicity, neurotoxicity (slurred speech, paresthesias, weakness), and respiratory failure
404
What is the mechanism of resistance to cephalosporins?
Inactivation of the drug by cephalosporinases (a type of β-lactamase) or by structural changes in the penicillin-binding proteins (transpeptidases)
405
Combinations of which 3 drug classes can be used to treat chronic hepatitis C infections?
NS5A inhibitors, NS5B inhibitors, NS3/4A inhibitors (alternative drugs include ribavirin)
406
What is the major reason for the limited use of chloramphenicol in the United States?
High level of toxicity (although still widely used in some countries because of its low cost)
407
In a pregnant patient taking a tetracycline, what adverse effect would be expected in the fetus?
Discolored teeth, inhibited bone growth
408
A Cushing-like syndrome can be an adverse effect of which class of HIV medications?
Protease inhibitors
409
Aztreonam inhibits peptidoglycan cross-linking by binding to which protein?
Penicillin-binding protein 3
410
What is the mechanism of action of the rifamycin class?
Inhibition of DNA-dependent RNA polymerase
411
Which 5 agents can be used to treat helminthic infections?
Pyrantel pamoate, Ivermectin, Mebendazole, Praziquantel, Diethylcarbamazine (helminths get PIMP’D)
412
A patient treated with vancomycin develops diffuse flushing (image). How could this have been prevented?
Pretreatment with antihistamines and a slow infusion rate can prevent red man syndrome, which is seen in vancomycin toxicity
