Introduction: Hippocampal formation is involved in memory function, so that damage to the hippocampus in humans and animals leads to amnesia. In addition to preventing the growth of bacteria and causing disease, antibiotics reduce the development of ATP, increase oxidative stress, and induce cell death, leading to the progression of neurodegenerative diseases. Bacteriophages, on the other hand, can kill bacteria but have no effect on eukaryotic cells. In the present study, the therapeutic effect of colistin antibiotic and lytic bacteriophage against Pseudomonas aeruginosa on the number of hippocampal neurons was compared. Methods: In this experimental study, adult male Wistar rats were divided into sham, control (burn), phage lytic treatment (100 μl), colistin antibiotic treatment (3000000 IU). After anesthesia the animals had third-degree burns on their backs and 100 μl of a half-McFarland suspension of Pseudomonas aeruginosa was applied to the burn site. Treated were done with phage or antibiotics for 6 consecutive days. At the end of which the brain was perfused and the hippocampal neurons were counted. Results: In the colistin group compared to the sham and control groups, the number of healthy neurons in CA1 (P <0.001), CA2 (P <0.001) and CA3 (P <0.05) significantly decreased. There was no significant difference in the number of healthy neurons in the phage group compared to the sham and control groups (P> 0.05). Conclusion: Phage treatment while treating infection has less adverse effects on the number of neurons in the hippocampus than antibiotics. Recommendations: Measurement of apoptosis and electron imaging of mitochondria of these cells.
