Which organism is not covered by ertapenem?

Which organism is not covered by ertapenem?

• A. Pseudomonas
• B. Bacteroides fragilis
• C. Escherichia coli
• D. Streptococcus pneumoniae

Answer: (A)

Ertapenem has a broad spectrum that includes many Gram-positive bacteria and anaerobes, as well as Enterobacterales, but it does not cover Pseudomonas aeruginosa. That makes it distinct from some other carbapenems, like imipenem or meropenem, which do have anti-pseudomonal activity. Clinically, this matters when choosing therapy for suspected Pseudomonas infections—you’d pick a drug with activity against Pseudomonas rather than ertapenem. The other organisms listed are typically covered by ertapenem: Bacteroides fragilis (an anaerobe), Escherichia coli (an Enterobacterale), and Streptococcus pneumoniae (a Gram-positive cocci).

Ertapenem has a broad spectrum that includes many Gram-positive bacteria and anaerobes, as well as Enterobacterales, but it does not cover Pseudomonas aeruginosa. That makes it distinct from some other carbapenems, like imipenem or meropenem, which do have anti-pseudomonal activity. Clinically, this matters when choosing therapy for suspected Pseudomonas infections—you’d pick a drug with activity against Pseudomonas rather than ertapenem.

The other organisms listed are typically covered by ertapenem: Bacteroides fragilis (an anaerobe), Escherichia coli (an Enterobacterale), and Streptococcus pneumoniae (a Gram-positive cocci).