CRISPR-Cas1 attenuates antibiotic resistance and virulence of Acinetobacter baumannii

Abstract:

The antibiotic resistance and virulence of Acinetobacter baumannii are increasingly serious. Studies have shown that the CRISPR-Cas system in A. baumannii attenuates the antibiotic resistance and virulence, while the effects of CRISPR-Cas system components on A. baumannii remain unclear.Objective Investigation of the role of components of the CRISPR-Cas system in the modulation of bacterial drug resistance and virulence in A. baumannii.Methods The impact of cas1 overexpression on bacterial growth, serum resistance, bacterial drug resistance, biofilm formation ability, and survival rate of mice in a mouse model of bacterial infection was investigated by constructing cas1 overexpression strains and corresponding with them to detect the aforementioned changes.Results The resistance of the bacterial strain AB26::cas1 to 22 commonly used antibiotics was determined using the paper diffusion method. Of these antibiotics, six were found to have an effect on the strain, causing it to change from resistant to sensitive. The capacity of the bacterial strain AB26::cas1 to form biofilms was evaluated through the use of crystal violet staining, which revealed a reduction in biofilm formation ability when compared to the AB26 strain. The intraperitoneal injection of the infected mice model demonstrated that no mortality occurred in the AB26::cas1 strain in vivo infected group in comparison to the AB26 strain in vivo infected group. The fluorescence quantitative PCR assay demonstrated a reduction in mRNA expression of the majority of resistance and toxicity genes. The survival assay, which involved incubating normal human serum with inactivated serum, revealed no statistically significant difference in serum resistance between the wild strains and the overexpression strains.Conclusion The cas1 gene, derived from strain AB43, was observed to exert an inhibitory effect on the drug resistance and biofilm-forming ability of A. baumannii, as well as the pathogenicity of the bacteria in mice.