Abstract:

Objective To investigate the biological characteristics of phages of carbapenem-resistant Acinetobacter baumannii (CRAB), and provide new strategy for controlling CRAB infection. Methods Phages of CRAB isolated from raw sewage of a hospital were identified using the plaque method. The morphology of phages was observed by electron microscopy. The genome of phages was extracted for electrophoresis. The structural proteins of phages were analysed by SDS-PAGE. The optimal multiplicity of infection, resistant mutation rate and one-step growth curve of phages were determined. Results One CRAB-specific and tailless phage with double-stranded DNA was isolated, and was named as phage AB3. The size of phage AB3 genome was about 35 kb, and the relative molecular mass of major coat protein was 35×10³. The incubation and burst periods of phage AB3 were 20 min and 60 min respectively, the burst size was 350, and the mutation rate of phage resistance was 2.5×10^－10. The phage AB3 was stable to a wide range of pH and temperature. Conclusion Phage AB3 has relatively broad host range, shorter incubation period, apparent burst size, lower resistant mutation rate and good stability to physical and chemical factors, which leads to its promising prospect in clinical application.

Key words: Acinetobacter baumannii, phages, biological characteristics