Pharm: Antibiotics

Question 0

Aminopenicillins (ampicillin, amoxicillin)

Answer 0

Mechanism: binding of PBPs blocks peptidoglycan cross-linking
Use: penicillin coverage + gram- rods (HELPSS: H flu, E coli, Listeria, Proteus, Salmonella, Shigella)
SE: allergic rxn, rash, pseudomembranous colitis (C diff)

Question 1

Penicillin

Answer 1

Mechanism: binding of PBPs blocks peptidoglycan cross-linking
Use: gram+ cocci, gram- cocci, N meningitidis, T pallidum
SE: allergic rxn, hemolytic anemia

Question 2

Methicillin, naficillin, oxacillin, dicloxacillin

Answer 2

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; β-lactamase resistant
Use: S aureus (except MRSA)
SE: interstitial nephritis (methicillin)

Question 3

Piperacillin, ticarcillim, carbenicillin

Answer 3

Mechanism: binding of PBPs blocks peptidoglycan cross-linking
Use: Pseudomonas, gram- rods
SE: allergic rxn

Question 4

Clavulanic acid, sulbactam, tazobactam

Answer 4

β lactamase inhibitors

Question 5

Aztreonam

Answer 5

Mechanism: binding of PBPs blocks peptidoglycan cross-linking
Use: gram- rods; used in pts with penicillin allergy or renal insufficiency
SE: GI upset

Question 6

Carbapenems (imipenem, meropenem)

Answer 6

Mechanism: binding of PBPs blocks peptidoglycan cross-linking
Use: wide spectrum, used with serious infxn; must administer with cilastatin (renal dihydropeptidase I inhibitor)
SE: seizures, GI upset, rash

Question 7

1st gen cephalosporins (cefazolin, cephalexin)

Answer 7

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; more β-lactamase resistant
Use: UTIs from Proteus, E coli, Klebsiella (PEK) + gram+ cocci
SE: allergic rxn, disulfiram-like rxn, nephrotoxicity

Question 8

2nd gen cephalosporins (cefoxitin, cefaclor, cefuroxime)

Answer 8

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; more β-lactamase resistant
Use: H flu, Enterobacter, Neisseria, Proteus, E coli, Klebsiella, Serratia (HEN PEKS) + gram+ cocci
SE: allergic rxn, disulfiram-like rxn, nephrotoxicity

Question 9

3rd gen cephalosporins (ceftriaxone, cefdinir, cefotaxime, ceftazidime)

Answer 9

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; more β-lactamase resistant
Use: serious gram- infections (including pseudomonas)
SE: allergic rxn, disulfiram-like rxn, nephrotoxicity

Question 10

4th gen cephalosporins (cefepime)

Answer 10

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; more β-lactamase resistant
Use: gram- + increased activity against pseudomonas, gram+
SE: allergic rxn, disulfiram-like rxn, nephrotoxicity

Question 11

5th gen cephalosporins (ceftaroline)

Answer 11

Mechanism: binding of PBPs blocks peptidoglycan cross-linking; more β-lactamase resistant
Use: broad spectrum coverage + MRSA (doesn’t cover pseudomonas)
SE: allergic rxn, disulfiram-like rxn, nephrotoxicity

Question 12

Aminoglycosides (gentamicin, neomycin, amikacin, tobramycin, streptomycin - GNATS)

Answer 12

Mechanism: bind 30s subunit > inhibit formation of initiation complex and cause mRNA misreading
Use: severe gram- rod infections; synergistic with β-lactam antibiotics
SE: nephrotoxicity, ototoxicity, teratogenic

Question 13

Clindamycin

Answer 13

Mechanism: bind 50s subunit, block peptide transfer (translocation)
Use: anaerobic infections above the diaphragm, invasive GAS infxn
SE: pseudomembranous colitis (C diff), fever, diarrhea

Question 14

Chloramphenicol

Answer 14

Mechanism: binds to 50s subunit, blocks peptidyltransferase
Use: meningitis and Rocky Mountain spotted fever
SE: anemia (dose-dependent), aplastic anemia (dose-independent), gray baby syndrome

Question 15

Macrolides (erythromycin, azithromycin, clarithromycin)

Answer 15

Mechanism: binds 50s subunit, inhibits formation of initiation complex and translocation
Use: atypical Pneumonia, URIs (GAS), STDs (Chlamydia) (PUS); MAC prophylaxis in AIDS pts
SE: GI upset, long QT arrhythmia, acute cholestatic hepatitis, rash, eosinophilia; P-450 inhibitor

Question 16

Tetracyclines (tetracycline, doxycycline, minocycline)

Answer 16

Mechanism: binds 30s subunit, blocks aminoacyl-tRNA from binding
Use: Vibrio, acne, Chlamydia, Ureaplasma, M pneumoniae, Tularemia, H pylori, B burgdorferi, R riskettsii (VACUM TH BR)
SE: GI upset, teeth discoloration and bone deformity in children, photosensitivity

Question 17

Trimethoprim-Sulfamethoxazole (TMP-SMX/Bactram)

Answer 17

Mechanism: TMP inhibits dihydrofolate reductase; SMX is a PABA analogue that inhibits dihydropteroate synthase
Use: UTIs, Shigella, Salmonella, and Pneumocystis treatment and prophylaxis, toxoplasmosis prophylaxis in AIDS pts
SE: SJS, hemolytic anemia, granulocytopenia, kernicterus in newborns

Question 18

Fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin, levofloxacin)

Answer 18

Mechanism: inhibit DNA topoisomerase II, causing DNA strand breakage
Use: gram- UTIs and GI infxns, Neisseria gonorrhea
SE: tendonitis, tendon rupture, damage growing cartilage, GI upset, rash, headache, dizziness

Question 19

Vancomycin

Answer 19

Mechanism: binds D-ala D-ala terminus of cell wall precursors
Use: gram+ only, reserved for drug-resistant infxns (MRSA, C diff)
SE: nephrotoxicity, ototoxicity, thrombophlebitis, red man syndrome

Question 20

Metronidazole

Answer 20

Mechanism: forms free radical toxic metabolites to damage DNA
Use: Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes, H Pylori (GET GAP)
SE: disulfiram-like rxn, headache, metallic taste

Question 21

Rifampin

Answer 21

Mechanism: inhibits bacterial DNA-dependent RNA polymerase
Use: tuberculosis, leprosy, prophylaxis for meningococcal meningitis and H flu type B
SE: red-orange secretions, hepatotoxicity, induces P-450

Question 22

Isoniazid

Answer 22

Mechanism: decreases synthesis of mycolic acids
Use: tuberculosis treatment and prophylaxis
SE: hepatotoxicity, give pyridoxine (B6) to prevent neurotoxicity, drug-induced lupus

Question 23

Pyrazinamide

Answer 23

Mechanism: uncertain; requires activation in acidic pH (phagolysosomes)
Use: tuberculosis
SE: hepatotoxicity, hyperuricemia

Question 25

Ethambutol

Answer 25

Mechanism: inhibits arabinosyl transferase, blocks synthesis of mycobacterial cell wall
Use: tuberculosis
SE: retrobulbar neuritis > red-green color blindness

Question 26

What three categories of PBP-binding drugs are resistant to the activity of beta-lactamase?

Answer 26

Cephalosporins, carbapenems, and methicillin/nafcillin