Analysis of Genetic Characteristics, Biofilm Formation Ability, and Mortality Risk Factors in Patients Infected with Carbapenem-Resistant Acinetobacter baumannii

Purpose: , in order to provide guidance for rational clinical prevention and control. Methods: This study included 244 patients with CRAB infections admitted to a tertiary hospital in Zhangjiakou, China, between June 2021 and December 2024. Statistical analysis was performed using SPSS 27.0 software to investigate potential risk factors for mortality associated with CRAB. Conventional PCR amplification was used to qualitatively detect resistance genes, efflux pump genes, and biofilm-related genes in isolated CRAB strains. Biofilm formation capacity was assessed using the crystal violet staining method. The study analyzed the association between the aforementioned genetic and phenotypic characteristics, biofilm formation capacity, and antibiotic resistance. Results: (223/244, 91.4%); the detection rates of the remaining genes ranged between 84.8% and 90.6%. Of the 244 CRAB strains tested in this study, the vast majority (97.95%) possessed biofilm-forming ability. The OD values of the strains were determined using the crystal violet method, with weak biofilm-forming strains (47.54%) and moderate biofilm-forming strains (44.26%) predominating; strong biofilm-forming strains accounted for 6.15%, while strains incapable of biofilm formation accounted for only 2.05%. Antimicrobial susceptibility testing revealed that 99.58% of the 244 CRAB strains were resistant to piperacillin/tazobactam, and 99.15% were resistant to imipenem and meropenem. Resistance rates for amoxicillin/clavulanate, cefepime, ceftazidime, ceftiofur, ciprofloxacin, and levofloxacin, all exceeded 95%, while 3.08% were resistant to tigecycline. No resistance to polymyxin was observed. Results of multivariate logistic regression analysis showed that age (OR = 1.044, 95% CI: 1.009-1.079, P < 0.05) and white blood cell count (OR = 1.106, 95% CI: 1.029-1.188, P < 0.05) were independent risk factors for mortality in CRAB infections. Conclusion: OXA-51 resistance genes and commonly carry efflux pump and biofilm formation genes, suggesting that their resistance may be closely associated with carbapenemases, efflux pump systems, and biofilm formation.