Complete genome analysis of two new bacteriophages isolated from impetigo strains of Staphylococcus aureus

Exfoliative toxin A (ETA)-coding temperate bacteriophages are leading contributors to the toxic phenotype of impetigo strains of Staphylococcus aureus. Two distinct eta gene-positive bacteriophages isolated from S. aureus strains which recently caused massive outbreaks of pemphigus neonatorum in Czech maternity hospitals were characterized. The phages, designated phi B166 and phi B236, were able to transfer the eta gene into a prophageless S. aureus strain which afterwards converted into an ETA producer. Complete phage genome sequences were determined, and a comparative analysis of five designed genomic regions revealed major variances between them. They differed in the genome size, number of open reading frames, genome architecture, and virion protein patterns. Their high mutual sequence similarity was detected only in the terminal regions of the genome. When compared with the so far described eta phage genomes, noticeable differences were found. Thus, both phages represent two new lineages of as yet not characterized bacteriophages of the Siphoviridae family having impact on pathogenicity of impetigo strains of S. aureus.