When treating Pseudomonas aeruginosa infections, it's essential to understand that this bacterium has intrinsic resistance to many common antibiotics. The antibiotics tested in the image are potential treatment options for Escherichia coli infections, but the situation is different for P. aeruginosa.

P. aeruginosa exhibits intrinsic resistance to five of these antibiotics: ampicillin, amoxicillin/clavulanate, cefuroxime, trimethoprim/sulfamethoxazole, and nitrofurantoin. Resistance to ampicillin, amoxicillin/clavulanate, and cefuroxime (all beta-lactam antibiotics) is primarily due to the production of AmpC β-lactamase (present in nearly all strains of P.aeruginosa).

P. aeruginosa is also frequently resistant to fosfomycin, which is not commonly used to treat infections caused by this pathogen—especially in more severe or hospital-acquired cases.

Ciprofloxacin (and other fluoroquinolones) is often effective against P. aeruginosa, although resistance can develop, particularly with prolonged use or in the presence of specific mutations in the gyrA and parC genes, which encode enzymes that are the targets of fluoroquinolones.

Interpretation of the Results