Comparison of the virulence of community- and hospital- isolated Acinetobacter baumannii in HeLa cell line and insect model, Galleria mellonella

Acinetobacter baumannii is an important nosocomial pathogen causing high infections and morbidity among affected individuals, and most studies focus on nosocomial strains. However, A. baumannii can also be isolated from healthy community individuals. This study compared the pathogenicity of hospital and community A. baumannii isolates using Galleria mellonella and human cell cultures. The insect model, G. mellonella, and in vitro HeLa cell line were used with ten A. baumannii isolates (six community and four hospital isolates from Segamat, Malaysia). G. mellonella killing assays and HeLa cell adherence, invasion and cytotoxicity assays were performed to investigate the virulence and invasion potential of the isolates. Out of the ten isolates investigated, three community and two hospital isolates were found to be highly virulent in the G. mellonella infection model, killing 100% of larvae within 96 h. These strains were also found to be invasive and have significant cytotoxicity in HeLa cells. Our study revealed that community- and hospital-isolated A. baumannii could be equally virulent judged by both model systems. Undoubtedly, besides hospital settings, the presence of highly virulent A. baumannii in community reservoirs poses a significant public health risk and requires additional investigation.