['Antibiotic rotation has been proposed as a way to potentially reduce the development of antimicrobial resistant bacteria in intensive care units. We assessed the effect of an antibiotic rotation protocol on the antibiotic susceptibility profiles of three clinically relevant gram-negative microorganisms within our surgical intensive care unit (SICU).', 'Our SICU implemented an antibiotic rotation protocol in 2003. Four antibiotics (piperacillin/tazobactam, imipenem/cilastin, ceftazidime, and ciprofloxacin) were rotated as the primary antibiotic used to treat suspected gram-negative infections every month, with the four-drug cycle being repeated every 4 months. Antibiotic susceptibility data for three microorganisms (Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae) were collected for the year before (2002) and the year after (2004) the implementation of the rotation protocol. Changes in antimicrobial susceptibility rates were analyzed for the three microorganisms. As a comparison, a similar analysis was conducted for microorganisms isolated from our medical intensive care unit, where no antibiotic rotation protocol was implemented.', 'Implementation of an antibiotic rotation protocol in our SICU resulted in a significant increase in the percentage of P. aeruginosa isolates sensitive to ceftazidime (67% in 2002 vs. 92% in 2004, p = 0.002) and piperacillin/tazobactam (78% in 2002 vs. 92% in 2004, p = 0.043). Isolates from the medical intensive care unit did not demonstrate an increase in antimicrobial susceptibility. In fact, the susceptibility of E. coli to piperacillin/tazobactam decreased during this time period (p = 0.047).'] Does implementation of antibiotic rotation protocol improve antibiotic susceptibility profile in a surgical intensive care unit?