Infectious disease · USMLE Step 1 and Step 2

Carbapenems & Monobactams song

Carbapenems & Monobactams - Coverage & Uses, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Carbapenems & Monobactams

Full song on YouTube ↗Spotify ↗

Key points in this song10

Carbapenems (imipenem, meropenem, ertapenem, doripenem) are beta-lactams with the broadest antibacterial spectrum, covering gram-positives, gram-negatives, and anaerobes, but NOT MRSA or Enterococcus faecium.
Imipenem is always co-administered with cilastatin, a renal dehydropeptidase inhibitor that prevents tubular inactivation of the drug and reduces nephrotoxicity.
Imipenem carries the highest seizure risk among carbapenems due to inhibition of GABA receptors; meropenem has lower seizure potential and is preferred for CNS infections.
Carbapenems are the drug of choice for extended-spectrum beta-lactamase (ESBL)-producing organisms and carbapenem-susceptible Klebsiella and Enterobacter species.
Carbapenem resistance is mediated by carbapenemases (e.g., KPC, NDM-1, OXA-48), which are encoded on transferable plasmids, making them a major public health threat.
Ertapenem lacks activity against Pseudomonas aeruginosa and Acinetobacter, distinguishing it from imipenem, meropenem, and doripenem, which do cover these organisms.
Aztreonam is the only monobactam in clinical use; it targets penicillin-binding protein 3 (PBP3) and is active exclusively against aerobic gram-negative rods, including Pseudomonas.
Aztreonam is safe in patients with penicillin allergy because its side chain does not cross-react with other beta-lactams, except ceftazidime, which shares an identical side chain.
Aztreonam is the preferred agent for serious gram-negative infections in patients with severe penicillin or carbapenem allergy, particularly in renal or pulmonary Pseudomonal infections.
Both carbapenems and aztreonam are beta-lactams that inhibit cell wall synthesis by binding penicillin-binding proteins, but they are resistant to most beta-lactamases due to their unique ring structures.