Background Based on the analysis of infections and antibiotic usage in the years 2013 and 2014, an evidence-based antibiotic protocol was developed and implemented in our cardiac surgical intensive care unit (CSICU). This study intends to study the impact of this new protocol on the sensitivity profiles of common gram-negative bacteria in our CSICU. Methods The medical records of patients who underwent cardiac surgery at our center, between January 2017 and December 2018, were reviewed and the incidence of different hospital-acquired bacteria and their antibiotic sensitivity profiles were recorded. The antibiotic-sensitivity profiles of common gram-negative bacteria, for the years 2017 and 2018, were compared with the published data of 2013 and 2014 from our department. Results There was a significant decrease in the incidence of Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa resistant to carbapenems during 2017 and 2018. The incidence of colistin-resistant A. baumannii and P. aeruginosa also decreased significantly in 2017 and 2018. A significant increase in the proportion of amikacin resistant A. baumannii and E. coli and A. baumannii resistant to B lactam/B lactamase inhibitors also occurred. Conclusion Antibiotic stewardship can reverse the antibiotic resistance of common gram-negative bacteria in the ICU.