Molecular characteristics of phages located in Carbapenemase-Producing Escherichia coli clinical isolates: New Phage-Like Plasmids

Abstract

Escherichia coli normally inhabits the gastrointestinal tract of humans and animals. Most E. coli bacteria do not cause problems, but the acquisition of different resistance and virulence genes encoded by mobile plasmids or phages by different bacterial isolates has been associated with the appearance of successful high-risk clones of multidrug-resistant (MDR) E. coli such as ST131 or ST405. In the present study, 50 temperate bacteriophages present in 21 clinical isolates of carbapenemase-producing E. coli of sequence types (STs) ST38, ST131, ST167, ST405 and ST410 were analysed. These phages were classified in the three families of the order Caudovirales: 24 within the family Siphoviridae, 23 in Myoviridae and 3 in Podoviridae. The size of the phages studied ranged from 11 to 95 Kb. Phylogenetic analysis of the terminase large subunit allowed us to classify these phages into different groups showing similarity with the phage sequences deposited in the Microbe Versus Phage (MVP) database and which belonged to clusters 229, 604, 2503 and 2725. On the other hand, bioinformatic study revealed that most of the identified proteins exerted a structural function (26.73%) but also functions involved in lysis/lysogeny (6.70%) or regulation (5.20%) among others. In addition, the ParA-ParB partitioning system and the type II toxin-antitoxin Phd-Doc system were also found in two of the phages studied, which could indicate the presence of plasmid-prophages. Host range testing revealed that two isolates were more susceptible to infection than the other isolates. IMPORTANCEEscherichia coli is one of the pathogens that causes most problems in human health, as it presents multiple resistances to different antibiotics. The study of bacteriophages located in different isolates of this species is important for the development of new anti-infective therapies. Currently, antibiotic resistance is a major problem, but more and more studies are pointing to experimental treatments with bacteriophages as a possible solution.