Antimicrobials

Question 1

Penicillin G

Answer 1

Prototype β-lactam antibiotic. IV.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Mostly used for gram-positive organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used for N. meningitidis, T. pallidum. BacteriCIDAL for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes. Penicillinase sensitive.
Hypersensitivity reactions, hemolytic anemia. Safe in pregnancy.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 2

Penicillin V

Answer 2

Prototype β-lactam antibiotic. Oral.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Mostly used for gram-positive organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used for N. meningitidis, T. pallidum. BacteriCIDAL for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes. Penicillinase sensitive.
Hypersensitivity reactions, hemolytic anemia. Safe in pregnancy.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 3

Ampicillin

Answer 3

Aminopenicillin, penicillinase-sensitive penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Extended spectrum. BacteriCIDAL for Haemophilus influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci. Penicillinase sensitive. Combine with clavulanic acid to protect against β-lactamase.
Hypersensitivity reactions, rash, pseudomembranous colitis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 4

Amoxicillin

Answer 4

Aminopenicillin, penicillinase-sensitive penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Extended spectrum. BacteriCIDAL for Haemophilus influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci. Penicillinase sensitive. Combine with clavulanic acid to protect against β-lactamase.
Hypersensitivity reactions, rash, pseudomembranous colitis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 5

Oxacillin

Answer 5

Penicillinase-resistant penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. Penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.
Narrow spectrum. BacteriCIDAL for S. aureus (except MRSA; resistant due to altered penicillin-binding protein target site).
Hypersensitivity reactions, interstitial nephritis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 6

Nafcillin

Answer 6

Penicillinase-resistant penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. Penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.
Narrow spectrum. BacteriCIDAL for S. aureus (except MRSA; resistant due to altered penicillin-binding protein target site).
Hypersensitivity reactions, interstitial nephritis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 7

Dicloxacillin

Answer 7

Penicillinase-resistant penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. Penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.
Narrow spectrum. BacteriCIDAL for S. aureus (except MRSA; resistant due to altered penicillin-binding protein target site).
Hypersensitivity reactions, interstitial nephritis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 8

Methicillin

Answer 8

Penicillinase-resistant penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. Penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.
Narrow spectrum. BacteriCIDAL for S. aureus (except MRSA; resistant due to altered penicillin-binding protein target site).
Hypersensitivity reactions, interstitial nephritis.
Resistance conveyed by penicillinase in bacteria (a type of β-lactamase), which cleaves the β-lactam ring.

Question 9

Ticaricillin

Answer 9

Anti-pseudomonal penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Extended spectrum. BacteriCIDAL for Pseudomonas species, gram-negative rods. Susceptible to penicillinase. Use with β-lactamase inhibitors.
Hypersensitivity reactions.

Question 10

Piperacillin

Answer 10

Anti-pseudomonal penicillin.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes.
Extended spectrum. BacteriCIDAL for Pseudomonas species, gram-negative rods. Susceptible to penicillinase. Use with β-lactamase inhibitors.
Hypersensitivity reactions.

Question 11

Clavulanic acid

Answer 11

β-lactamase inhibitor.

Added to penicillin antibiotics to protect the antibiotic from destruction by β-lactamase (a penicillinase)

Question 12

Sulbactam

Answer 12

β-lactamase inhibitor.

Added to penicillin antibiotics to protect the antibiotic from destruction by β-lactamase (a penicillinase)

Question 13

Tazobactam

Answer 13

β-lactamase inhibitor.

Added to penicillin antibiotics to protect the antibiotic from destruction by β-lactamase (a penicillinase)

Question 14

Cefazolin

Answer 14

First generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, Proteus mirabilis, E. coli, Klebsiella pneumoniae. Used prior to surgery to prevent S. aureus wound infections.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increase the nephrotoxicity of aminoglycosides. Safe in pregnancy.

Question 15

Cephalexin

Answer 15

First generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, Proteus mirabilis, E. coli, Klebsiella pneumoniae.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increase the nephrotoxicity of aminoglycosides. Safe in pregnancy.

Question 16

Cefoxitin

Answer 16

Second generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria species, Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia marcescens.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increase the nephrotoxicity of aminoglycosides. Safe in pregnancy.

Question 17

Cefaclor

Answer 17

Second generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria species, Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia marcescens.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increase the nephrotoxicity of aminoglycosides. Safe in pregnancy.

Question 18

Cefuroxime

Answer 18

Second generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria species, Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia marcescens.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increase the nephrotoxicity of aminoglycosides. Safe in pregnancy.

Question 19

Ceftriaxone

Answer 19

Third generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Serious gram-negative infections resistant to other β-lactams. Meningitis, gonorrhea.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increases nephrotoxicity of ahminoglycosides. Safe in pregnancy.

Question 20

Cefotaxime

Answer 20

Third generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Serious gram-negative infections resistant to other β-lactams.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increases nephrotoxicity of ahminoglycosides. Safe in pregnancy.

Question 21

Ceftazidime

Answer 21

Third generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Serious gram-negative infections resistant to other β-lactams. Pseudomonas.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increases nephrotoxicity of ahminoglycosides. Safe in pregnancy.

Question 22

Cefipime

Answer 22

Fourth generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Increased activity against Pseudomonas and gram-positive organisms.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increases nephrotoxicity of ahminoglycosides. Safe in pregnancy.

Question 23

Ceftaroline

Answer 23

Fifth generation cephalosporin. β-lactam drug.
Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Broad gram-positive and gram-negative organism coverage, including MRSA. Does not cover Pseudomonas.
Hypersensitivity reactions, vitamin K deficiency, low cross-reactivity with penicillins, increases nephrotoxicity of ahminoglycosides. Safe in pregnancy.

Question 24

Aztreonam

Answer 24

Monobactam. Resistant to β-lactamases. Prevents peptidoglycan cross-linking by binding to penicillin-binding protein 3. Synergistic with aminoglycosides.
Gram-negative rods only. No activity against gram-positives or anaerobes. Useful in penicillin-allergic patients (no cross-allergenicity with penicillins) and those with renal insufficiency who cannot tolerate aminoglycosides.
Usually nontoxic. Occasional GI upset.

Question 25

Imipenem

Answer 25

Broad spectrum, β-lactamase-resistant carbapenem. Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL. Always administered with cilastatian (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules.
Gram-positive cocci, gram-negative rods, anaerobes. Wide spectrum, use is limited to life-threatening infections after other drugs have failed.
GI distress, skin rash, CNS toxicity (seizures) at high plasma levels.

Question 26

Meropenem

Answer 26

Broad spectrum, β-lactamase-resistant carbapenem. Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL.
Gram-positive cocci, gram-negative rods, anaerobes. Wide spectrum, use is limited to life-threatening infections after other drugs have failed.
GI distress, skin rash, decreased risk of seizures. Stable to dehydropeptidase I.

Question 27

Ertapenem

Answer 27

Broad spectrum, β-lactamase-resistant carbapenem. Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL. Always administered with cilastatian (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules.
Gram-positive cocci, gram-negative rods, anaerobes. Wide spectrum, use is limited to life-threatening infections after other drugs have failed. Limited Pseudomonas coverage.
GI distress, skin rash, CNS toxicity (seizures) at high plasma levels.

Question 28

Doripenem

Answer 28

Broad spectrum, β-lactamase-resistant carbapenem. Binds penicillin-binding proteins (transpeptidases), block transpeptidase cross-linking of peptidoglycan, activates autolytic enzymes. BacteriCIDAL. Always administered with cilastatian (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules.
Gram-positive cocci, gram-negative rods, anaerobes. Wide spectrum, use is limited to life-threatening infections after other drugs have failed.
GI distress, skin rash, CNS toxicity (seizures) at high plasma levels.

Question 29

Vancomycin

Answer 29

Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors. BacteriCIDAL.
Gram positive only. Serious, MDR organisms, including MRSA, enterococci, Clostridium difficile (oral dose for pseudomembranous colitis).
Well tolerated in general. Risk of nephrotoxicity, ototoxicity, thrombophlebitis, diffuse flushing (red man syndrome - prevent with antihistamines, slow infusion rate).
Resistance conveyed by modification of D-ala D-ala to D-ala D-lac.

Question 30

Gentamicin

Answer 30

Aminoglycoside
Protein synthesis inhibitor at 30S ribosomal subunit. Inhibits formation of initiation complex and causes misreading of mRNA. Also blocks translocation. BacteriCIDAL.
Severe gram negative rod infections. Synergistic with β-lactam antibiotics. Requires O2 for uptake into cell, therefore ineffective against anaerobes.
Nephrotoxicity (especially when used with cephalosporins), neuromuscular blockade, ototoxicity (especially when used with loop diuretics), teratogen.
Resistance conveyed by bacterial transferase enzymes, which inactivate the drug by acetylation, phosphorylation, or adenylation.

Question 31

Neomycin

Answer 31

Aminoglycoside
Protein synthesis inhibitor at 30S ribosomal subunit. Inhibits formation of initiation complex and causes misreading of mRNA. Also blocks translocation. BacteriCIDAL.
Severe gram negative rod infections. Synergistic with β-lactam antibiotics. Requires O2 for uptake into cell, therefore ineffective against anaerobes. Prophylactic for bowel surgery.
Nephrotoxicity (especially when used with cephalosporins), neuromuscular blockade, ototoxicity (especially when used with loop diuretics), teratogen.
Resistance conveyed by bacterial transferase enzymes, which inactivate the drug by acetylation, phosphorylation, or adenylation.

Question 32

Amikacin

Answer 32

Aminoglycoside
Protein synthesis inhibitor at 30S ribosomal subunit. Inhibits formation of initiation complex and causes misreading of mRNA. Also blocks translocation. BacteriCIDAL.
Severe gram negative rod infections. Synergistic with β-lactam antibiotics. Requires O2 for uptake into cell, therefore ineffective against anaerobes.
Nephrotoxicity (especially when used with cephalosporins), neuromuscular blockade, ototoxicity (especially when used with loop diuretics), teratogen.
Resistance conveyed by bacterial transferase enzymes, which inactivate the drug by acetylation, phosphorylation, or adenylation.

Question 33

Tobramycin

Answer 33

Aminoglycoside
Protein synthesis inhibitor at 30S ribosomal subunit. Inhibits formation of initiation complex and causes misreading of mRNA. Also blocks translocation. BacteriCIDAL.
Severe gram negative rod infections. Synergistic with β-lactam antibiotics. Requires O2 for uptake into cell, therefore ineffective against anaerobes.
Nephrotoxicity (especially when used with cephalosporins), neuromuscular blockade, ototoxicity (especially when used with loop diuretics), teratogen.
Resistance conveyed by bacterial transferase enzymes, which inactivate the drug by acetylation, phosphorylation, or adenylation.

Question 34

Streptomycin

Answer 34

Aminoglycoside
Protein synthesis inhibitor at 30S ribosomal subunit. Inhibits formation of initiation complex and causes misreading of mRNA. Also blocks translocation. BacteriCIDAL.
Severe gram negative rod infections. Synergistic with β-lactam antibiotics. Requires O2 for uptake into cell, therefore ineffective against anaerobes.
Nephrotoxicity (especially when used with cephalosporins), neuromuscular blockade, ototoxicity (especially when used with loop diuretics), teratogen.
Resistance conveyed by bacterial transferase enzymes, which inactivate the drug by acetylation, phosphorylation, or adenylation.

Question 35

Tetracycline

Answer 35

Tetracycline
Protein synthesis inhibitor at 30S ribosomal subunit, prevents attachment of ammoniacal-tRNA. BacterioSTATIC.
Borrelia burgdorferi, M. pneumoniae. Ability to accumulate intracellularly makes it very effective against Rickettsia and Chlamydia. Also used to treat acne. Limited CNS penetration. Do not take with milk, antacids, or iron-containing preparations because divalent cations inhibit its absorption in the gut.
GI distress, discoloration of teeth, inhibition of bone growth in children. Photosensitivity. Contraindicated in pregnancy.
Resistance conveyed by decreased uptake or increased efflux out of bacterial cells by plasmid-encoded transport pumps.

Question 36

Doxycycline

Answer 36

Tetracycline
Protein synthesis inhibitor at 30S ribosomal subunit, prevents attachment of ammoniacal-tRNA. BacterioSTATIC.
Borrelia burgdorferi, M. pneumoniae. Ability to accumulate intracellularly makes it very effective against Rickettsia and Chlamydia. Also used to treat acne. Limited CNS penetration. Do not take with milk, antacids, or iron-containing preparations because divalent cations inhibit its absorption in the gut. Fecally eliminated, so safe in renal failure.
GI distress, discoloration of teeth, inhibition of bone growth in children. Photosensitivity. Contraindicated in pregnancy.
Resistance conveyed by decreased uptake or increased efflux out of bacterial cells by plasmid-encoded transport pumps.

Question 37

Minocycline

Answer 37

Tetracycline
Protein synthesis inhibitor at 30S ribosomal subunit, prevents attachment of ammoniacal-tRNA. BacterioSTATIC.
Borrelia burgdorferi, M. pneumoniae. Ability to accumulate intracellularly makes it very effective against Rickettsia and Chlamydia. Also used to treat acne. Limited CNS penetration. Do not take with milk, antacids, or iron-containing preparations because divalent cations inhibit its absorption in the gut.
GI distress, discoloration of teeth, inhibition of bone growth in children. Photosensitivity. Contraindicated in pregnancy.
Resistance conveyed by decreased uptake or increased efflux out of bacterial cells by plasmid-encoded transport pumps.

Question 38

Azithromycin

Answer 38

Macrolide
Inhibits protein synthesis by blocking translocation. Binds to 23S rRNA of the 50S ribosomal subunit. BacterioSTATIC.
Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STDs (Chlamydia) and gram positive cocci (streptococcal infections in patients allergic to penicillin).
GI motility issues, arrhythmia (prolonged QT), acute cholestatic hepatitis, rash, eosinophilia. Increases serum concentration of theophylline and anticoagulants.
Resistance conveyed by methylation of 23S rRNA-binding site, which prevents binding of drug.

Question 39

Clarithromycin

Answer 39

Macrolide
Inhibits protein synthesis by blocking translocation. Binds to 23S rRNA of the 50S ribosomal subunit. BacterioSTATIC.
Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STDs (Chlamydia) and gram positive cocci (streptococcal infections in patients allergic to penicillin).
GI motility issues, arrhythmia (prolonged QT), acute cholestatic hepatitis, rash, eosinophilia. Increases serum concentration of theophylline and anticoagulants.
Resistance conveyed by methylation of 23S rRNA-binding site, which prevents binding of drug.

Question 40

Erythromycin

Answer 40

Macrolide
Inhibits protein synthesis by blocking translocation. Binds to 23S rRNA of the 50S ribosomal subunit. BacterioSTATIC.
Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STDs (Chlamydia) and gram positive cocci (streptococcal infections in patients allergic to penicillin).
GI motility issues, arrhythmia (prolonged QT), acute cholestatic hepatitis, rash, eosinophilia. Increases serum concentration of theophylline and anticoagulants.
Resistance conveyed by methylation of 23S rRNA-binding site, which prevents binding of drug.