Isolation and characterization of a bacteriophage targeting Proteus mirabilis for use in culture media

Proteus mirabilis is an important opportunistic bacterium that affects both animal and human health. One of the key characteristics of this bacterium is its distinctive zonal spreading on solid media. This movement, known as swarming, complicates the isolation and identification of pathogenic agents present alongside P. mirabilis in clinical samples. The aim of this study was to isolate a lytic bacteriophage targeting P. mirabilis to prevent its growth and evaluate the use of these phages in cultures of clinical samples contaminated with Proteus. A phage designated as P5663 was isolated using general phage isolation and purification methods. Genomic and electron microscopic analyses suggested that the phage belongs to the class Caudoviricetes, and genome-based comparisons supported its close relatedness to bacteriophages within the family Casjensviridae. The isolated phage was analyzed for its lytic activity against 16 P. mirabilis, one P. vulgaris, and 19 different non-Proteus bacterial species. The growth of P. mirabilis on Tryptic Soy Agar (TSA) medium prepared with the isolated phage was evaluated. All Proteus isolates analyzed in the study were lysed by P5663 Φ, while the other bacterial species were not affected. It was observed that while P. mirabilis suspensions of varying concentrations exhibited growth in the inoculation area on TSA containing P5663 Φ, the zonal spreading (swarming) was inhibited. In conclusion, this study presents a novel perspective on the use of bacteriophages, which have a wide range of applications. It was concluded that phages could be used to inhibit the swarming behavior of P. mirabilis in culture media without affecting the growth of non-target bacteria.