Susceptibility of P.aeruginosa to some other commonly used antibiotics.

• Chloramphenicol does have some activity against a variety of Gram-negative bacteria, but it is not reliable against P.aeruginosa. The organism typically exhibits intrinsic resistance due to efflux pumps and the presence of enzymes that can degrade chloramphenicol.
• Penicillin P. aeruginosa exhibits intrinsic resistance to penicillin primarily due to the production of AmpC β-lactamase (present in nearly all strains of P.aeruginosa)
• Erythromycin is a macrolide antibiotic, and Pseudomonas aeruginosa is typically resistant to macrolides (intrinsic resistance)
• Clindamycin is a lincosamide antibiotic that is mainly effective against Gram-positive bacteria and some anaerobes. P.aeruginosa is resistant to clindamycin (intrinsic resistance)
• Tetracycline while tetracycline can have activity against some Gram-negative organisms, P.aeruginosa is typically resistant due to efflux pumps and impermeability of the outer membrane
• Trimethoprim/Sulfamethoxazole (TMP/SMX) P.aeruginosa has intrinsic resistance to many common antibiotics, including trimethoprim/sulfamethoxazole (Co-trimoxazole).

Interpretation of the Results