The idea of using bacteriophages as a weapon against bacterial infections, including those resistant to antibiotics, has already captured the imagination of researchers studying rare animals. Australian scientists compared the efficacy and safety of bacteriophages and antibiotics in treating bacterial infections in rare marine reptiles—green turtles. *

Green turtles are marine animals that, by digesting vast amounts of plant matter, play a significant role in the marine ecosystem. Their populations are rapidly declining, so they are closely monitored by scientists. Sick turtles are placed in special turtle hospitals for treatment. The problem is that establishing an accurate diagnosis and identifying the pathogen is difficult, so the standard practice is to administer broad-spectrum antibiotics to turtles. This approach, however, damages the animals' intestinal microflora and, consequently, disrupts normal digestion.

To reduce the negative impact of antimicrobial therapy, scientists decided to study the effects of bacteriophages on both pathogenic target bacteria in the turtle gut and the microbiome of healthy animals. In the experiment, one group of healthy turtles received a cocktail of bacteriophages specific for various strains of Acinetobacter bacteria, while the other received the antibiotic enrofloxacin. The bacterial composition of the animals' fecal samples was analyzed by sequencing the V1-V3 regions of bacterial 16S rRNA.

Turtles treated with bacteriophages showed a significant reduction in the number of Acinetobacter bacteria while maintaining the composition and diversity of their intestinal microflora. Animals treated with antibiotics, from day 15 until the end of the trial, showed a significant reduction in the diversity of their intestinal microflora, specifically an increase in the number of gram-positive bacteria of the genus Firmicutes and a decrease in the number of gram-negative bacteria of the genus Bacteroidetes, Proteobacteria, and Verrucomicrobia.

The study's authors believe that the results obtained support the use of bacteriophages for the treatment of infectious diseases, as well as for the correction of the intestinal microbiome in sea turtles.

* Ahasan Md. Sh, Kinobe R, Elliott L et al. Bacteriophage versus antibiotic therapy on gut bacterial communities of juvenile green turtle, Chelonia mydas // Environmental Microbiology, 2019, First published: April 29, 2019. https://doi.org/10.1111/1462-2920.14644