Locally isolated broad host-range bacteriophage kills methicillin-resistant Staphylococcus aureus in an in vivo skin excisional wound model in mice.

From the perspective of an ever-increasing multidrug resistance among bacterial pathogens, bacteriophages are receiving renewed interest as potential alternative to antibiotics. We investigated the potential of a locally isolated species-specific phage against Staphylococcus aureus infection in a skin excisional wound model in mice. A significant time-dependent increase (P < 0.05) in wound healing was observed in the phage-treated mice groups. The animals treated with the phage ΦDMSA-2 exhibited a faster re-epithelialization and faster tissue re-modelling. Bacterial load in the infected tissue in all phage-treated groups diminished. The mean ± SD CFU per ml decreased from 3.3 × 10 ± 3.5 × 10 at day 1-1.43 × 10 ± 8.48 × 10 at day 16 (P < 0.05). The highest reduction in the bacterial load was observed in G5 (povidine-iodine treated) and G6 (povidine iodine + phage 10 PFU) groups as no bacterial counts were detected by day 12 in both groups. Interestingly, group G3, which was treated with a lower phage concentration (5 × 10 PFU), resulted in total clearing of the inoculated bacteria by day 16; while bacterial counts were still detected by that time in group G4, which was treated with a higher phage concentration of 10 PFU. Animals from phage-treated group G3 survived 100%, while those from the infected wound control group survived at a rate of 34% at day 9 and reached 0% by the end of day 22 (P < 0.001). The data from this study convincingly showed that phage treatment of the S. aureus-infected wounds resulted in a faster wound healing and a 100% survival of the animals. The results emphasize the utility of locally isolated species-specific phages in treatment against multidrug-resistant MRSA infections.