Reassessing the forgotten cure: Efficacy of bacteriophage as a therapeutic agent against MRSA in diabetic rats

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of increased amputation, morbidity and mortality among patients with diabetic foot infections. These infections are refractory to antibiotics. Therefore, alternative therapy using phages has re-emerged as a promising option to treat such infections. The present study was conducted to evaluate the efficacy of phage in treating diabetic wound infection caused by MRSA 43300 in rats. Phages were isolated against MRSA 43300 and purified as per standard procedures. Diabetes was induced in healthy albino rats using streptozotocin. The minimum lethal dose (MLD) of MRSA and minimum protective dose (MPD) of phage was identified. A full-size excision wound was created on the back of rats. The rats were divided into five groups (Group I – Non-infected and untreated, Group II- Infected and untreated, Group III - Infected and phage challenged, Group IV- Infected and antibiotic treated, Group V – Non-infected and phage treated). Groups II, III and IV were infected with MLD of MRSA 43300. After 48 h of infection, Group III was treated with a single dose of MPD of phage and group IV was treated with mupirocin on all days. The wound were sampled on designated days, Gram stain was done to detect for the presence of pus cells and Gram positive cocci. Standard culture methods were used to confirm the presence of phage and MRSA 43300 and estimate their titre on different days among different groups. Wound contraction rate was recorded to compare the duration of wound healing between all the groups. Group II served as bacterial control in which all the rats died after 72h. The phage treated group III showed the presence of Gram positive cocci and pus cells in Gram stain till 6 days. Viable MRSA was isolated till 4 days post treatment and more than 50% of the wound contracted by day 12 of infection. Phage-treated group showed better wound contraction rate and faster bacterial clearance compared to antibiotic-treated group. The results of the present study help to reconsider phage therapy for treatment of drug-resistant infection.