Abstract
Acinetobacter baumannii is one of the most influential pathogens causing nosocomial infections characterized by high resistance to antibacterial drugs. Thus, this study aimed to evaluate the dynamics of A. baumannii isolation and the level of antibiotic resistance in a multidisciplinary hospital for the period 2021-2025. For this reason, a comparative retrospective analysis was conducted on 13 221 clinical isolates obtained from various departments. The analysis was conducted using phenotypic identification and susceptibility testing methods. Susceptibility testing (antibiograma) was performed using the Vitek 2 automated system and the disk diffusion method for nine antimicrobial drugs. These antibiotics included carbapenems (imipenem, meropenem), aminoglycosides (gentamicin, amikacin, tobramycin), fluoroquinolones (ciprofloxacin, levofloxacin), colistin, and a trimethoprim/sulfamethoxazole combination. The results showed a decrease in the frequency of A. baumannii isolation over the observation period (χ² = 19.29, p = 0.0007), with the majority of isolates retaining multiple-drug resistance (MDR). The highest resistance was detected to fluoroquinolones and carbapenems, while susceptibility to colistin remained high throughout all years. The lack of molecular analysis limits the interpretation of the results; however, the resulting resistance profile suggested genes that could act as pathogenicity factors. These comparative retrospective analyses of resistance highlight the need for ongoing local monitoring of A. baumannii antibiotic resistance and the rational use of antimicrobials in hospital settings.