Comparing the Efficacy of Bacteriophages and Antibiotics in Treating Salmonella enterica Serovar Typhimurium on Streptomycin-pretreated Mice

The misuse of antibiotics had contributed significantly to the development of antibiotic resistance, hence decreasing its efficacy. Non-typhoidal Salmonella is a global problem causing gastroenteritis in humans. Since there are various antibiotics in treating Salmonella infections, its potential to become multidrug-resistant remains a considerable problem. The use of host-specific bacteriophages as a biocontrol is one possible intervention by which Salmonella colonization could be reduced. Isolated and purified from sewage water, a dose of 4.30 x 1010 PFU (plaque-forming units) Salmonella phages were used to treat gastroenteritis on streptomycin-mouse models. Lack of treatment yielded 2.06 x 106 CFU (colony-forming units)/g of Salmonella 24 h post-infection, which exponentially dropped to 3.80 x 103 CFU/g 24 h post-infection in bacteriophage treatment before gradually decreasing. However, the antibiotic treatment inhibited growth with 3.58 x 102 CFU/g 24 h post-infection, but it did not retain the decrease of the pathogen. Results also showed that the microflora of the gut was preserved with the appearance of various colonies in phage treatment, which aided recovery in a phenomenon known as “microbial interference.” In contrast, antibiotic treatment depleted the normal microflora, allowing colonization of Salmonella and resurgence of pathogenic growth in the gut. Bacteriophage therapy demonstrated a significant decrease in bacterial load when compared to the antibiotic ciprofloxacin. The high specificity of the treatment also allowed the phages to synergize with the gut microbiota, thereby inhibiting colonization and further increase in bacterial growth.