Characterization of 29 newly isolated bacteriophages as a potential therapeutic agent against IMP-6-producing Klebsiella pneumoniae from clinical specimens

Kohei Kondoa ,  Satoshi Nakanoa ,  Junzo Hisatsunea ,  Yo Sugawara ,  Michiyo Kataokab ,  Shizuo Kayamaa ,  Motoyuki Sugaia ,  Mitsuoki Kawano

Carbapenemase-producing Enterobacteriaceae (CPE) are one of the most detrimental species of antibiotic-resistant bacteria globally. Phage therapy has emerged as an effective strategy for the treatment of CPE infections. In western Japan, the rise of Klebsiella pneumoniae strains harboring the pKPI-6 plasmid encoding blaIMP-6 is of increasing concern. To address this challenge, we isolated 29 phages from Japanese sewage, specifically targeting 31 K . pneumoniae strains and one Escherichia coli strain harboring the pKPI-6 plasmid. Electron microscopy analysis revealed that among the 29 isolated phages, 21 (72.4%), 5 (17.2%), and 3 (10.3%) phages belonged to myovirus, siphovirus, and podovirus morphotypes, respectively. Host range analysis showed that 18 Slopekvirus strains within the isolated phages infected 25–26 K . pneumoniae strains, indicating that most of the isolated phages have a broad host range. Notably, K. pneumoniae strain Kp21 was exclusively susceptible to phage øKp_21, whereas Kp22 exhibited susceptibility to over 20 phages. Upon administering a phage cocktail composed of 10 phages, we observed delayed emergence of phage-resistant bacteria in Kp21 but not in Kp22. Intriguingly, phage-resistant Kp21 exhibited heightened sensitivity to other bacteriophages, indicating a “trade-off” for resistance to phage øKp_21. Our proposed phage set has an adequate number of phages to combat the K. pneumoniae strain prevalent in Japan, underscoring the potential of a well-designed phage cocktail in mitigating the occurrence of phage-resistant bacteria.

Microbiology Spectrum

American Society for Microbiology

2165-0497

10.1128/spectrum.04761-22