# Top 200 Drugs: Antimicrobials (Antibiotics, Antivirals, Antifungals & Antimycobacterials) > High-yield Top 200 antimicrobial medications covering beta-lactams, glycopeptides, lipopeptides, oxazolidinones, macrolides, tetracyclines, aminoglycosides, fluoroquinolones, RIPE antimycobacterials, antifungals, and HIV/HCV/herpes/influenza/SARS-CoV-2 antivirals. - **Canonical URL:** https://flashcards.world/flashcards/sets/d81290dd-9f6a-4042-a085-066953a61a0a/ - **Markdown URL:** https://flashcards.world/flashcards/sets/d81290dd-9f6a-4042-a085-066953a61a0a.md - **Level:** basic - **Languages:** en → en - **Total Cards:** 32 ## Flashcards (32 Cards) | # | Front (Term / Prompt) | Back (Definition / Answer) | Example | Multiple-Choice Options | | :--- | :--- | :--- | :--- | :--- | | 1 | What are the spectrum of activity and primary excretion pathway of the antistaphylococcal penicillins Nafcillin, Oxacillin, and Dicloxacillin? | Antistaphylococcal penicillins with bulky R-side chains that sterically block staphylococcal beta-lactamase. Active against MSSA and streptococci (no Gram-negative activity). Cleared predominantly via the biliary tract (no renal dose adjustment required). | | | | 2 | What is the antimicrobial spectrum of Meropenem, Imipenem-Cilastatin, and Ertapenem, and how do these carbapenems differ clinically? | Broad-spectrum beta-lactams resistant to ESBLs (cover Gram-positives, Gram-negatives, and anaerobes). Imipenem is co-formulated with cilastatin (inhibits renal dehydropeptidase-I) and lowers seizure threshold more than meropenem. Ertapenem lacks activity against Pseudomonas and Acinetobacter. | | | | 3 | What are the mechanism of action, VRE resistance mechanism, and infusion-related reaction of Vancomycin? | Glycopeptide that binds D-Ala-D-Ala of cell wall peptidoglycan precursors, inhibiting transglycosylation (Gram-positives only, including MRSA). VRE mutates D-Ala-D-Ala to D-Ala-D-Lac. Rapid infusion triggers direct mast-cell histamine release ('vancomycin flushing syndrome'), managed by slowing the infusion rate and giving antihistamines. | | | | 4 | What are the mechanism of action and oral clinical indication of Fosfomycin? | Inhibits cytosolic enolpyruvyl transferase (MurA), blocking the first step of bacterial cell wall peptidoglycan synthesis. Administered as a single 3-gram oral sachet for uncomplicated lower urinary tract infections (including ESBL-producing E. coli and VRE). | | | | 5 | What are the mechanism of action and primary bacterial resistance mechanisms for Penicillin G and Amoxicillin? | Bind penicillin-binding proteins (PBPs/transpeptidases) to block peptidoglycan cross-linking in the bacterial cell wall, activating autolysins. Resistance occurs via beta-lactamase cleavage of the beta-lactam ring (overcome by adding clavulanate, sulbactam, or tazobactam) or altered PBPs (e.g., mecA/PBP2a in MRSA). | | | | 6 | What are the mechanism of action, oxygen dependence, and major toxicities of Gentamicin, Tobramycin, and Amikacin? | Aminoglycosides are bactericidal 30S ribosomal inhibitors that cause mRNA misreading and require oxygen-dependent active transport to enter bacteria (strictly inactive against anaerobes). Exhibit concentration-dependent killing and post-antibiotic effect. Cause irreversible ototoxicity (vestibular/cochlear), reversible nephrotoxicity (ATN), and neuromuscular blockade. | | | | 7 | What is the mechanism of action of Abacavir, and what pharmacogenomic screening test is mandatory before initiation? | Guanosine analog NRTI. Requires mandatory screening for the HLA-B*57:01 allele prior to initiation; patients positive for HLA-B*57:01 must never receive abacavir due to risk of fatal multiorgan hypersensitivity reaction. | | | | 8 | What are the mechanism of action, Gram-positive spectrum, and three major toxicities of Linezolid? | Oxazolidinone that binds the 50S ribosomal subunit (23S rRNA) to prevent formation of the 70S initiation complex; active against MRSA and VRE with 100% oral bioavailability. Toxicities: Thrombocytopenia/bone marrow suppression (>2 weeks), serotonin syndrome (weak MAOI activity), and optic/peripheral neuropathy. | | | | 9 | What are the mechanism of action, spectrum of activity, and beta-lactam allergy cross-reactivity profile of Aztreonam? | Monobactam that binds PBP3 solely in aerobic Gram-negative rods (including Pseudomonas aeruginosa), with zero activity against Gram-positives or anaerobes. Shows virtually no cross-allergenicity with penicillins or carbapenems, EXCEPT with ceftazidime and cefiderocol, which share an identical R1 side chain. | | | | 10 | What are the mechanism of action, anaerobic coverage rule ('above the diaphragm'), and toxin-suppressing role of Clindamycin? | Lincosamide that binds the 50S ribosomal subunit (blocks translocation). Covers Gram-positive cocci (strep, CA-MRSA) and anaerobes above the diaphragm (aspiration pneumonia, lung abscess) while suppressing bacterial toxin synthesis in necrotizing fasciitis/toxic shock syndrome. High risk of Clostridioides difficile colitis. | | | | 11 | What are the mechanism of action, clinical indication, and renal contraindication threshold of Nitrofurantoin (Macrobid)? | Reduced by bacterial flavoproteins into reactive intermediates that damage ribosomal proteins and DNA. Concentrates exclusively in the lower urinary tract (used only for uncomplicated cystitis, never pyelonephritis). Contraindicated when CrCl < 30 mL/min and in G6PD deficiency; chronic use causes pulmonary fibrosis. | | | | 12 | How do Amphotericin B and the Echinocandins (Caspofungin, Micafungin) compare in antifungal targets, spectrum, and toxicity profiles? | Amphotericin B binds ergosterol to form transmembrane pores (broadest spectrum; causes infusion fever/rigors, dose-limiting nephrotoxicity, hypokalemia, and hypomagnesemia—mitigated by liposomal formulation). Echinocandins (caspofungin, micafungin) inhibit beta-(1,3)-D-glucan synthase in the fungal cell wall (first-line for candidemia; ineffective against Cryptococcus). | | | | 13 | What are the mechanism of action, spectrum differences, and FDA boxed warnings for Ciprofloxacin, Levofloxacin, and Moxifloxacin? | Fluoroquinolones inhibit bacterial DNA gyrase (topoisomerase II) and topoisomerase IV. Ciprofloxacin/levofloxacin cover Pseudomonas and urinary infections; levofloxacin/moxifloxacin are 'respiratory fluoroquinolones' covering S. pneumoniae (moxifloxacin also covers anaerobes but has poor urine levels and no Pseudomonas coverage). Black Box Warnings: Tendinopathy/Achilles tendon rupture, aortic aneurysm dissection, peripheral neuropathy, CNS effects, and myasthenia gravis exacerbation. | | | | 14 | What are the mechanisms of action of Oseltamivir (Tamiflu) and Baloxavir Marboxil (Xofluza) against influenza? | Oseltamivir inhibits influenza A and B neuraminidase, preventing cleavage of sialic acid residues and release of progeny virions from infected cells (most effective within 48 hours of symptom onset). Baloxavir inhibits cap-dependent endonuclease of the viral polymerase complex in a single oral dose. | | | | 15 | What are the mechanism of action, spectrum differences, and signature adverse effects of Fluconazole, Voriconazole, and Posaconazole? | Inhibit fungal lanosterol 14-alpha-demethylase (CYP450), blocking ergosterol synthesis. All inhibit human CYP450 enzymes and prolong QTc. Fluconazole penetrates CSF (Candida, Cryptococcus maintenance) and lacks Aspergillus coverage. Voriconazole is first-line for invasive aspergillosis and causes reversible visual disturbances, hallucinations, and periostitis (fluoride excess). | | | | 16 | What are the antimalarial targets and G6PD deficiency precautions for Chloroquine, Hydroxychloroquine, and Primaquine? | Chloroquine/hydroxychloroquine block Plasmodium heme polymerase in the food vacuole (hydroxychloroquine is also a DMARD in SLE/RA; requires annual retinal exam for bull's-eye maculopathy). Primaquine eradicates dormant hepatic hypnozoites of P. vivax and P. ovale, but causes severe oxidative hemolysis in G6PD deficiency. | | | | 17 | What viral proteins are targeted by Direct-Acting HCV Antivirals (Sofosbuvir/Velpatasvir and Glecaprevir/Pibrentasvir), and what pre-treatment viral screening is required? | Pangenotypic Hepatitis C cures: NS5B RNA-dependent RNA polymerase inhibitors (-buvir: sofosbuvir), NS5A replication complex inhibitors (-asvir: velpatasvir, pibrentasvir), and NS3/4A protease inhibitors (-previr: glecaprevir). Require HBV serology screening before starting due to risk of HBV reactivation. | | | | 18 | What are the mechanism of action, antimicrobial spectrum, and cardiac/CYP450 risks of Azithromycin and Clarithromycin? | Macrolides that bind the 23S rRNA of the 50S ribosomal subunit to block translocation. Cover atypical respiratory pathogens (Legionella, Mycoplasma, Chlamydia), Bordetella pertussis, and MAC. Prolong the QTc interval and cause GI motility cramps (motilin agonists); clarithromycin/erythromycin strongly inhibit CYP3A4 (azithromycin does not). | | | | 19 | What are the antiretroviral classes and mechanisms in Bictegravir/Tenofovir Alafenamide/Emtricitabine (Biktarvy), and how does TAF compare with TDF? | Single-tablet HIV regimen combining an Integrase Strand Transfer Inhibitor (INSTI: bictegravir, blocks viral DNA integration) with two NRTIs (emtricitabine + tenofovir alafenamide). Tenofovir alafenamide (TAF) has much lower renal proximal tubular toxicity (Fanconi syndrome) and bone mineral density loss than tenofovir disoproxil fumarate (TDF). | | | | 20 | How does Trimethoprim-Sulfamethoxazole (TMP-SMX / Bactrim) sequentially block folate synthesis, and what are its major adverse effects? | Sulfamethoxazole inhibits dihydropteroate synthase; trimethoprim inhibits dihydrofolate reductase (sequential blockade of tetrahydrofolate synthesis). Covers MRSA, UTIs, Nocardia, and Pneumocystis jirovecii (PCP prophylaxis/treatment). Adverse effects: Hyperkalemia (TMP blocks ENaC), pseudo-elevation of serum creatinine, megaloblastic anemia, hemolysis in G6PD deficiency, and SJS/TEN. | | | | 21 | What are the mechanism of action and primary clinical indications of Terbinafine in dermatophytosis? | Allylamine antifungal that inhibits fungal squalene epoxidase, causing toxic intracellular squalene accumulation. Oral drug of choice for onychomycosis and tinea capitis; requires baseline liver function testing due to hepatotoxicity risk. | | | | 22 | What is the mechanism of action of Nirmatrelvir/Ritonavir (Paxlovid), and why does it cause critical CYP3A4 drug interactions? | Nirmatrelvir inhibits the SARS-CoV-2 main protease (Mpro / 3CLpro), preventing viral polyprotein cleavage. Ritonavir is a potent irreversible CYP3A4 inhibitor used purely as a pharmacokinetic booster; requires holding or dose-reducing statins, tacrolimus, amiodarone, rivaroxaban, and many other CYP3A4 substrates. | | | | 23 | How are Acyclovir, Valacyclovir, and Ganciclovir activated by viral kinases, and what are their dose-limiting toxicities? | Guanosine analogs phosphorylated first by viral thymidine kinase (HSV/VZV for acyclovir) or UL97 kinase (CMV for ganciclovir), then inhibit viral DNA polymerase via chain termination. IV acyclovir causes obstructive crystalline nephropathy without adequate IV hydration; ganciclovir/valganciclovir cause severe dose-limiting myelosuppression (neutropenia). | | | | 24 | What are the mechanism of action, last-resort MDR Gram-negative indications, and major toxicities of Colistin (Polymyxin E)? | Cationic polypeptide that binds lipopolysaccharide (LPS) and phospholipids in the outer cell membrane of multidrug-resistant Gram-negative bacilli (Pseudomonas, Acinetobacter, CRE), disrupting membrane integrity. Intrinsically inactive against Proteus, Providencia, Serratia, and Gram-positives; causes severe nephrotoxicity and neurotoxicity. | | | | 25 | What are the mechanisms of action and signature toxicities of the first-line RIPE tuberculosis drugs (Rifampin, Isoniazid, Pyrazinamide, and Ethambutol)? | Rifampin (inhibits RNA polymerase; potent CYP450 inducer, orange body fluids, hepatotoxicity). Isoniazid (inhibits mycolic acid synthesis; requires prodrug activation by KatG; causes hepatotoxicity, drug-induced lupus, and B6-deficient peripheral neuropathy—prevent with pyridoxine). Pyrazinamide (hyperuricemia/gout, hepatotoxicity). Ethambutol (inhibits arabinosyltransferase; causes optic neuritis/red-green color blindness). | | | | 26 | What are the antiparasitic mechanisms of Albendazole/Mebendazole, Praziquantel, and Ivermectin? | Albendazole/mebendazole inhibit helminth beta-tubulin polymerization (nematodes/cestodes). Praziquantel increases Ca2+ permeability, causing spastic paralysis of trematodes (Schistosoma) and cestodes. Ivermectin activates glutamate-gated Cl- channels, causing flaccid paralysis (Strongyloides, Onchocerca, scabies). | | | | 27 | What are the mechanism of action, antimicrobial spectrum ('GET GAP on the Metro'), and alcohol interaction of Metronidazole (Flagyl)? | Forms toxic free-radical intermediates that damage bacterial/protozoal DNA. Covers Giardia, Entamoeba, Trichomonas, Gardnerella, and strict Anaerobes below the diaphragm (Bacteroides, C. difficile). Causes a disulfiram-like reaction with ethanol, metallic taste, and peripheral neuropathy/cerebellar ataxia with prolonged use. | | | | 28 | Why are Oral Vancomycin and Fidaxomicin the first-line treatments for Clostridioides difficile infection, and how do they compare? | Fidaxomicin (200 mg PO BID for 10 days; narrow-spectrum macrocyclic RNA polymerase inhibitor with minimal systemic absorption and lower recurrence rate) is the IDSA/SHEA preferred first-line therapy for initial and recurrent C. difficile infection, with oral vancomycin (125 mg PO QID for 10 days; not absorbed systemically) as an effective first-line alternative. | | | | 29 | What are the mechanism of action and clinical indications of Daptomycin, and why is it ineffective for pneumonia? | Cyclic lipopeptide that inserts into Gram-positive cell membranes in a Ca2+-dependent manner, causing rapid depolarization. Used for MRSA/VRE bacteremia and endocarditis. Inactivated by pulmonary surfactant (cannot be used for pneumonia); requires weekly CPK monitoring for myopathy/rhabdomyolysis. | | | | 30 | How does antimicrobial coverage progress across Cefazolin (1st gen), Ceftriaxone (3rd gen), Cefepime (4th gen), and Ceftaroline (5th gen)? | Cefazolin: MSSA, strep, PEcK (surgical prophylaxis). Ceftriaxone: CNS penetration, Neisseria, strep, Gram-negatives (no Pseudomonas; biliary clearance). Cefepime: Covers Pseudomonas and AmpC producers. Ceftaroline: Binds PBP2a to cover MRSA (does not cover Pseudomonas). | | | | 31 | What is the extended spectrum of activity of Piperacillin-Tazobactam (Zosyn), and what is the clinical significance of co-administering it with Vancomycin? | Antipseudomonal ureidopenicillin combined with a beta-lactamase inhibitor. Covers Gram-positives (MSSA, streptococci, Enterococcus faecalis), Gram-negatives (including Pseudomonas aeruginosa), and anaerobes. Co-administration with vancomycin increases the incidence of measured serum creatinine elevation compared with cefepime + vancomycin (reflecting both competitive inhibition of renal tubular OAT1/OAT3 creatinine secretion ['pseudo-nephrotoxicity'] and potential synergistic tubular stress, as evaluated in the ACORN trial). | | | | 32 | What are the mechanism of action, atypical/tick-borne pathogen coverage, and classic adverse effects of Doxycycline? | Tetracycline that binds the 30S ribosomal subunit to block aminoacyl-tRNA attachment. Covers Rickettsia, Borrelia, Chlamydia, Mycoplasma, and CA-MRSA. Adverse effects: Tooth enamel discoloration/bone growth inhibition in young children, photosensitivity, pill esophagitis, and chelation with divalent cations (Ca2+, Mg2+, Fe2+). | | | --- Study this deck interactively with FSRS-6 spaced repetition, audio review, and multiple-choice mode at [Flashcards World](https://flashcards.world/flashcards/sets/d81290dd-9f6a-4042-a085-066953a61a0a/).