Selective Synergy Between Phages and Antibiotics Improves Treatment Outcomes in Staphylococci Infections.

Abstract

An indiscriminate use of antibiotics in treatment of animal diseases has lead to emergence of antimicrobial resistance in Staphylococcus genus. Bacteriophages are a promising alternative, but it seems challenging to completely replace their use so the current study was undertaken to explore lytic bacteriophages against circulating Staphylococcus species obtained from animal farms and to assess their synergy with antibiotics. Five myophages (φBPA112-116) were isolated and assessed for their growth characteristics, host range, stability at varied physiological conditions of temperature and pH and for carriage of antibiotic resistance genes (ARGs). Only one isolate (φBPA116) was observed to be a broad range phage which was biologically active against (67.92%) of Staphylococcus isolates. Bacteriophages were found to show selective synergy with antibiotics as assessed by antibiotic-disc embedded double-layered agar method. The combined application of phages and cephalothin (0.5 µg/ml) lead to a significant inhibition of bacterial growth (p < 0.001) in liquid cultures compared with controls at all the multiplicity of infections (MOIs) tested and reduced the biofilm formation in a dose dependent manner in suboptimal antibiotic concentration supplemented media. These findings illustrate the potential therapeutic value of phages and support further clinical development of "Phage-Antibiotic synergy" as a treatment option for Staphylococcus infections prevailing in animal farms.

Supplementary information: The online version contains supplementary material available at https://doi.org/10.1007/s12088-026-01551-x.