Published online Jun 25, 2025. doi: 10.5501/wjv.v14.i2.95826
Revised: September 13, 2024
Accepted: October 23, 2024
Published online: June 25, 2025
Processing time: 429 Days and 22 Hours
The upsurge of antibiotic resistance is a significant challenge to public health, and the dry pipeline of new antibiotics has prompted the discovery of alternative treatment approaches. Enterococcus faecalis (E. faecalis) isolates are often multidrug-resistant, posing challenges to antibiotic therapy. Bacteriophage therapy is being explored as an alternative method to treat the growing population of antibiotic-resistant infections. Nevertheless, many inherent limitations of phages diminish their therapeutic utility, notably the restricted host range and quick development of mutants. The specific types and quantities of bacteriophages and antibiotics may be crucial in generating the optimal phage-antibiotic synergy.
To optimize the doses, order, and timing to optimize the synergy of phages and vancomycin on different bacteria states.
A volume of 180 μL of E. faecalis bacteria in the logarithmic growth phase, with a concentration of approximately 1 × 108 colony forming units (CFUs)/mL, was introduced onto a microtitre plate. Subsequently, 20 μL of phage suspension (1 × 106 PFUs/mL), vancomycin (16 µg/mL), or a combination of both was introduced into the designated wells in the specified sequence and incubated at 37 °C for 48 hours. The number of live bacteria was counted at different time points using standardized CFU counting protocols.
The biofilm model demonstrated that combining phages with vancomycin can eradicate the biofilm. Sequential therapy, involving phage application 8 hours before the antibiotic at a concentration of 108 PFUs/mL, proved the most efficient in eliminating the biofilms and killing the planktonic form of E. faecalis.
The combination of phage ɸEFP01 at a higher concentration with a subinhibitory concentration of vancomycin yields a synergistic antibacterial outcome on E. faecalis strain resistant to vancomycin.
Core Tip: Due to the potential limitations associated with either phages or antibiotics alone, extensive in-vitro and in-vivo investigations are required to evaluate the synergistic effect of phages and antibiotics in managing bacterial infection. The combination therapy offers significant advantages, including enhanced elimination of bacterial cells and decreased phage or antibiotic resistance development. Our study indicates that the combined treatment of phages and vancomycin with specified dose, order, and timing would yield better eradication of bacteria in a biofilm state than the application of either alone.