Objectives To investigate the antimicrobial resistance patterns of multidrug-resistant Acinetobacter baumannii (MDRAB) in patients in pediatric intensive care units (PICU) in order to determine a guide for the empirical antibiotic treatment of MDRAB. Methods The authors retrospectively evaluated the medical records of patients with MDRAB infections in the PICU during a follow-up period, between January 2015 and January 2017. The identification of A. baumannii was performed using a BD Phoenix 100 Automated Microbiology System. A BD Phoenix NMIC/ID-400 commercial kit was used to test antibiotic susceptibility. All data was entered into Microsoft Excel, and the data was analyzed using SPSS version 23.0. Results The mean age of the patients was 8.1 +/- 6.2 y. In all, 46 isolates were obtained from 33 patients. The most effective antimicrobial agents were colistin, trimethoprim/sulfamethoxazole, and tigecycline. Nevertheless, with the exception of colistin, no antibiotic was associated with a susceptibility rate of >45% for the isolates. Low sensitivities in 2015 to tigecycline, aminoglycosides, levofloxacin, and carbapenems had been lost in 2016. Conclusions Many drugs that were previously effective against MDRAB, have lost their effectiveness. Currently, there is no effective drug to fight MDRAB, apart from colistin. Thus, it is clear that new drugs and treatment protocols should be developed urgently.