USMLE Step 1 Antimicrobials Quiz with complete solutions | Latest 2023/2024

USMLE Step 1 Antimicrobials Quiz with complete solutions | Latest 2023/2024 What antibacterials block cell wall synthesis by inhibition of peptidoglycan cross-linking? -- Penicillin, Ampicillina, Ticarcillin, Piperacillin, Imipnem, Aztreoname, Cephalosporins What is to MOA of Bacitracin and Vancomycin? -- block peptidoglycan synthesis What is the MOA of polymixins (used in resistant pseudomonas? -- Disrupt bacterial cell membranes What is the MOA of sulfonamides and trimethoprim? -- block nucleotide synthesis What is the MOA of fluroroquinolones? -- Block DNA topoisomerases What is the MOA of Rifampin? -- Block mRNA synthesis What is the MOA of chloramphenicol, Clindamycin, Macrolides (e.g Ezythromycin), Linezolid? -- Block Protein Synthesis at 50S subunit What is the MOA of Aminoglycosides and Tetracyclines? -- Block protein synthesis and the 30S subunit Which antibiotics are bactericidal? -- Vacomycin, Fluoroquinolones, Penicillin, Aminoglycosides, Cephalosporins, Metronidazole ("Very Finely Proficient At Cell Murder") Penicillin -- Use: Syphillis; gram-pos/ MOA: block penicillin-binding-proteins, block transpeptidase cross-linking of cell wall, activate autolytic enzymes/ Resistance: Penicillinase(B-lactamase)-sensitive aka drug broken down by enzyme in periplasmic space/ Tox: Hypersensitivity Methicillin -- MOA: Penicillanase-resistant penicillin--blocks transpeptidase and is reisstant to B-lactamase due to bulkier R group/ Use: MSSA/ Tox: interstitial nephritis; hypersensitivty Naficillin -- MOA: Penicillanase-resistant penicillin--blocks transpeptidase and is reisstant to B-lactamase due to bulkier R group/ Use: MSSA/ Tox: hypersensitivty Dicloxacillin -- MOA: Penicillanase-resistant penicillin--blocks transpeptidase and is reisstant to B-lactamase due to bulkier R group/ Use: MSSA/ Tox: hypersensitivty Ampicillin -- MOA: same as penicillin but has extended coverage/ Use: to inlcude gram negative rods, but is penicillinase-SENSITIVE so typically add a B-lactamase inhibitor