Ticarcillin antimicrobial activity

The antimicrobial activity of carbenicillin, its indanyl ester (carbenicillin indanyl), and ticarcillin is extended to include Pseudomonas, Enterobacter, and Proteus spp. These agents are inferior to ampicillin against Gram-positive cocci and Listeria monocytogenes and are less active than piperacillin against Pseudomonas. 

The combination of piperacillin and tazobactam does not increase the activity of piperacillin against P. aeruginosa because there is resistance due to either chromosomal P-lactamases or decreased permeability of piperacillin into the periplasmic space. Because the currently recommended dose (3 g piperacillin per 375 mg tazobactam every 4 to 8 hours) is less than the recommended dose of piperacillin when used alone for serious infections (3 to 4 g every 4 to 6 hours), concern has been raised that piperacillin-tazobactam may prove ineffective in the treatment of some P. aeruginosa infections that would have responded to piperacillin. The combination of piperacillin plus tazobactam should be equivalent in antimicrobial spectrum to ticarcillin plus clavulanate. 

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