Background: The aim of our study was to evaluate the antimicrobial resistance rates among pathogen microorganisms especially colistin resistant rates of Acinetobacter baumannii in intensive care unit (ICU)-acquired infections and to determine infection-specific correct treatment strategies. Methods: The data of adult and newborn infant patients diagnosed with ICU-acquired infection in a tertiary education and research hospital in Bursa in 2014 and 2016 were analyzed, retrospectively. Results: Acinetobacter baumannii was the most frequent pathogen of ICU-acquired infections in 2014 and 2016. There was a significant increase in colistin (CO) resistance rates in A. baumanii (0.0%-6.8%). A significant increase in CO, cefepime (FEP), ciprofloxacin (CIP) resistance rates was established in all gram negative bacteria (0.0%-7.9%, 50.0%-91.9%, 54.7%-74.6%), respectively. A significant increase in the rate of detection of A. baumanii as the pathogen microorganism in respiratory tract infection (RTI) was established (53.9% -79.5%). In addition, the average ventilator-associated pneumonia (VIP) infection rate also increased in 2016 compared to 2014 (VIP rate 2014: 7.12, 2016: 7.45, per 1000 ventilator days). A significant decrease in the rate of detection of all gram negative microorganisms in the surgical site infection (SSI), and a significant increase in the rate of detection of all gram positive microorganisms in the SSI was determined. Conclusion: Increased antimicrobial resistance, especially increased colistin resistance rates in ICU-acquired infections, necessitates the creation of new strategies in empirical therapy. Detection of antimicrobial resistance profiles of local and infectious pathogen microorganisms in ICUs is a good guide for correct antimicrobial management.