Isolation, characterization, and antibacterial activity of lytic bacteriophage against methicillin-resistant Staphylococcus aureus causing bedsore and diabetic wounds

Iran J Microbiol. 2022 Oct;14(5):712-720. doi: 10.18502/ijm.v14i5.10967.

Abstract

Background and objectives: Phage therapy has gained interest as an alternative treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections. The purpose of this study was to isolate and characterize an effective bacteriophage against isolates of MRSA.

Materials and methods: Bacteriophage was isolated from hospital sewage. Lytic activity and the titers of phage lysates were measured using spot test and double-layer plaque assay. The phage characterization was determined through transmission electron microscopy. Adsorption rate, host range and stability tests were investigated. The latent period and burst size were estimated from a one-step growth curve. The effect of bacteriophage against MRSA biofilms was determined and Real-time PCR was used to assess the effects of the bacteriophage on the expression of the biofilm-associated genes.

Results: TEM results showed that the phage resembled the Cystoviridae family. Its latent period was 30 min, corresponding to about 71/43 phage particles per infected cell. The phage had a broad host range and it was most stable at 37°C and pH 7. It was sensitive to NaCl concentrations. The expressions of the biofilm-associated genes were significantly reduced in the presence of the phage.

Conclusion: The isolated phage was effective against MRSA strains and it can be an optional strategy of controlling biofilm development.

Keywords: Bacteriophage; Methicillin-resistant Staphylococcus aureus; Phage therapy; Wounds.