The carboxypenicillins exhibit activity against Gram negative organisms including Pseudomonas aeruginosa and Proteus species. They are inactive against certain Gram positive pathogens such as Staphylococcus aureus, Enterococcus faecalis, and L. monocytogenes. The carboxypenicillins are beta-lactamase sensitive.
- "Mayo Clinic Proceedings". Retrieved 2015-12-08.