Abstract
Phage therapy is an alternative approach to overcome the problem of multidrug resistance in bacteria. In this study, a bacteriophage named PZL-Ah152, which infects
Aeromonas hydrophila
, was isolated from sewage, and its biological characteristics and genome were studied. The genome contained 54 putative coding sequences and lacked known putative virulence factors, so it could be applied to phage therapy. Therefore, we performed a study to (i) investigate the efficacy of PZL-Ah152 in reducing the abundance of pathogenic
A. hydrophila
strain 152 in experimentally infected crucian carps, (ii) evaluate the safety of 12 consecutive days of intraperitoneal phage injection in crucian carps, and (iii) determine how bacteriophages impact the normal gut microbiota. The
in vivo
and
in vitro
results indicated that the phage could effectively eliminate
A. hydrophila
. Administering PZL-Ah152 (2 × 10
9
PFU) could effectively protect the fish (2 × 10
8
CFU/carp). Furthermore, a 12-day consecutive injection of PZL-Ah152 did not cause significant adverse effects in the main organs of the treated animals. We also found that members of the genus
Aeromonas
could enter and colonize the gut. The phage PZL-Ah152 reduced the number of colonies of the genus
Aeromonas.
However, no significant changes were observed in α-diversity and β-diversity parameters, which suggested that the consumed phage had little effect on the gut microbiota. All the results illustrated that PZL-Ah152 could be a new therapeutic method for infections caused by
A. hydrophila.