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| Question | Answer |
| Amoxicillin, ampicillin (aminopenicillins, penicillinase-sensitive penicillins)- Mechanisms | Same as penicillin. Wider spectrum; penicillinase sensitive. Also combine with clavulanic acid to protect against destruction by β-lactamase. AMinoPenicillins are AMPed-up penicillin. AmOxicillin has greater Oral bioavailabilitythan ampicillin. |
| Amoxicillin, ampicillin (aminopenicillins, penicillinase-sensitive penicillins)- Clinical use | Extended-spectrum penicillin—H. influenzae, H. pylori, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci. |
| Amoxicillin, ampicillin (aminopenicillins, penicillinase-sensitive penicillins)- Toxicity | Hypersensitivity reactions; rash; pseudomembranous colitis. |
| Dicloxacillin, nafcillin, oxacillin (penicillinase-resistant penicillins)- Mechanisems | Same as penicillin. Narrow spectrum; penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring. |
| Dicloxacillin, nafcillin, oxacillin (penicillinase-resistant penicillins)- Clinical use | S. aureus (except MRSA; resistant because of altered penicillin-binding protein target site). “Use naf (nafcillin) for staph.” |
| Dicloxacillin, nafcillin, oxacillin (penicillinase-resistant penicillins)- Toxicity | Hypersensitivity reactions, interstitial nephritis |
| Carbapenems- Imipenem, meropenem, ertapenem, doripenem. -Mechanism | Imipenem is a broad-spectrum, β-lactamase– resistant carbapenem. Always administered with cilastatin (inhibitor of renal dehydropeptidase I) to diminished inactivation of drug in renal tubules. With imipenem, “the kill is lastin’ with cilastatin.” Newer carbapenems include ertapenem (limited Pseudomonas coverage) and doripenem. |
| Carbapenemes- Clinical use | Gram-positive cocci, gram-negative rods, and anaerobes. Wide spectrum, but significant side effects limit use to life-threatening infections or after other drugs have failed. Meropenem has a lower risk of seizures and is stable to dehydropeptidase I. |
| Carbapenems- Toxicity | GI distress, skin rash, and CNS toxicity (seizures) at high plasma levels. |
| Monobactams- Aztreonam Mechanisms | Less susceptible to β-lactamases. Prevents peptidoglycan cross-linking by binding to penicillinbinding protein 3. Synergistic with aminoglycosides. No cross-allergenicity with penicillins. |
| Monobactams- Aztreonam- Clinical use | Gram-negative rods only—no activity against gram-positives or anaerobes. For penicillin-allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides. |
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