Epidemiological characteristics of multidrug-resistant Acinetobacter baumannii ST369 in Anhui, China

Acinetobacter baumannii is of growing concern for global health owing to its ability to evade the immune system and develop resistance to antibiotics. We analyzed A. baumannii using the National Center for Biotechnology Information (https://www.ncbi.nlm.nih.gov/pathogens) database and observed that the ST369 strain isolated in China constituted over 50% of the globally prevalent ST369 clones. This finding highlights the significant impact of ST369 on public health in China. In this study, we examined eight strains of multidrug-resistant A. baumannii ST369 isolated from a provincial hospital in China. We conducted whole-genome sequencing, comparative genomic analysis, and phenotypic experiments, and used the Galleria mellonella infection model to achieve a comprehensive understanding of the organism. In our study, we identified two mutations, G540A and G667D, on the wzc gene of A. baumannii ST369 that can potentially affect bacterial virulence and viscosity. We also verified the impact of these mutations on virulence and resistance. In addition, we examined two proteins, AB46_0125 and AB152_03903, which may play a role in virulence. These findings establish a foundation for future studies on clinical ST369 isolates harboring such mutations. IMPORTANCE: Acinetobacter baumannii is a major health threat due to its antibiotic resistance and ability to cause nosocomial infections. Epidemiological studies indicated that the majority of globally prevalent ST369 clones originated from China, indicating a significant impact on public health in the country. In this study, we conducted whole-genome sequencing, comparative genomics, and Galleria mellonella infection model on eight A. baumannii ST369 isolates collected from a provincial hospital in China to comprehensively understand the organism. We identified two mutations (G540A and G667D) on the wzc gene that can affect bacterial virulence and viscosity. We confirmed their impact on resistance and virulence. We also investigated the potential involvement of AB46_0125 and AB152_03903 proteins in virulence. This finding provides a theoretical reference for further research on A. baumannii ST369 clinical isolates with similar mutations.