A temperate phage 5W infecting multidrug-resistant Acinetobacter baumannii

Abstract We isolated 5W, a temperate phage that infects multidrug-resistant Acinetobacter baumannii from pond water, using an enrichment method that involves the addition of host bacteria. 5W is a long-tailed phage with a narrow host range lysed four of 19 A. baumannii clinical isolates tested, and complete lysis was observed for A. baumannii clinical isolate Ab1. 5W adsorbed rapidly to its Ab1 host and > 80% adsorption was observed after 2 min of mixing. The one-step growth curve showed that 5W has a 20 min latent period and a ~ 100 min rise period, with a burse size of ~ 180 PFU/cell. 5W contains a dsDNA genome 43,032 bp in length, with 61 open reading frames and a GC content of 39.85%. The genome lacks any known virulence and drug resistance genes, but encodes an N-acetyl-β-D-muramidase with numerous positively charged amino acids at its C-terminus that belongs to the GH_108 family. The M/S subunits of the restriction endonuclease are inserted in the lysogenic gene cluster. The first and second halves of the 5W genome are highly homologous with prophages phiABCR01-03 and phiABCR01-02 in the A. baumannii ABCR01 genome, respectively, which suggests that 5W may be a product of recombination between the two prophages.