OBJECTIVE To analyze the biological characteristics and genomic features of highly lytic bacteriophages isolated from sewage in tropical hospitals and provide references for the hospital-associated infection prevention and control of multidrug-resistant Acinetobacter baumannii (MDR-Ab).

METHODS With MDR-Ab as the host bacterium, bacteriophages were isolated from sewage. Transmission electron microscopy was employed to observe their morphology, and determine the optimal multiplicity of infection (MOI), one-step growth curve and environmental stability. Whole-genome sequencing and bioinformatics analysis were conducted to annotate functional genes and construct a phylogenetic tree.

RESULTS A virulent bacteriophage, HN_Aba_01, was isolated. Electron microscopy revealed that it belonged to the Myoviridae family, with a head diameter of 50 nm and a tail length of 90 nm. This bacteriophage exhibited strong lytic activity, with an optimal MOI of 0.000 000 1, a latent period of 5 minutes and a lysis yield of 15 PFU/cell. It remained stable at temperatures ranging from 4 ℃ to 60 ℃ and pH values from 3 to 10. Genomic analysis identified 85 ORFs, including lyase, perforin and depolymerase genes. It shared 98.12% identity with the bacteriophage AbP2 genome (reference genome) and was classified into the Obolenskvirus genus.

CONCLUSIONS The bacteriophage isolated from tropical hospital sewage, with high lytic activity and good environmental adaptability, can be used for the hospital-associated infection prevention and control of MDR-Ab.