Which carbapenem does NOT cover Pseudomonas?

Which carbapenem does NOT cover Pseudomonas?

• A. Ertapenem
• B. Imipenem
• C. Meropenem
• D. Doripenem

Answer: (A)

Pseudomonas coverage is the key difference among these carbapenems. Ertapenem has a narrower spectrum and does not reliably cover Pseudomonas aeruginosa (nor Acinetobacter). It can handle many Enterobacteriaceae and anaerobes, making it useful for community- and intraabdominal-type infections where Pseudomonas isn’t a concern. In contrast, imipenem, meropenem, and doripenem retain activity against Pseudomonas aeruginosa, which is why they’re chosen when Pseudomonas is suspected or when broader Gram-negative coverage is needed. Susceptibility can vary with local resistant strains, but these three are the carbapenems classically active against Pseudomonas, unlike ertapenem.

Pseudomonas coverage is the key difference among these carbapenems. Ertapenem has a narrower spectrum and does not reliably cover Pseudomonas aeruginosa (nor Acinetobacter). It can handle many Enterobacteriaceae and anaerobes, making it useful for community- and intraabdominal-type infections where Pseudomonas isn’t a concern.

In contrast, imipenem, meropenem, and doripenem retain activity against Pseudomonas aeruginosa, which is why they’re chosen when Pseudomonas is suspected or when broader Gram-negative coverage is needed. Susceptibility can vary with local resistant strains, but these three are the carbapenems classically active against Pseudomonas, unlike ertapenem.