Isolation and identification of effective bacteriophages against Enterococcus faecalis bacteria from hospital wastewater

BACKGROUND AND OBJECTIVES Enterococcus is a family of gram-positive, non-spore-forming bacteria consisting of ۳۸ species. One of the most important of this family is Enterococcus faecalis, which lives in the human intestine. E. faecalis as a member of the mammalian gastrointestinal flora, is a major cause of nosocomial infections and a growing public health problem. Phage therapy is a viable alternative to antibiotics for treating microbial infections, particularly managing drug-resistant strains of bacteria. The aim of this study was to isolate and identify effective bacteriophages against E. faecalis isolated from hospitalized patients.MATERIALS AND METHODS Fifty-eight E. faecalis were isolated from urine, wound, abscess and blood samples from patients admitted to Resalat Hospital in Tehran, Iran, and identified by biochemical and molecular methods. The phage was isolated from hospital wastewater using the double layer agar method and was characterized using transmission electron microscopy (TEM). Phage host range was determined using spot test. The stability of isolated phage was tested at acidic and alkaline pH, at high temperatures, and in cold storage. Phage efficacy (MOI) was also investigated with regard to the bacterium/phage ratio. The effect of isolated bacteriophages against E. faecalis One, Three and five day old preformed biofilm was investigated using the microtitre plate method.RESULTS AND DISCUSSION According to Electron microscopy observations, the isolated phage belonged to the Siphoviridae family. Spot testing on the collected isolates indicated that bacteriophage was able to lyse ۴۰ out of ۵۸ isolates (۶۸%) of E. faecalis. Suitable pH spectra for phage survival was ۶–۱۰, at which the phage showed ۱۰۰% activity. The optimal temperature for phage growth was ۳۰–۴۵°C, with the highest growth at ۳۷°C. The results revealed that this isolated phage had low salt tolerance. The optimal MOI for isolated phage was ۰,۰۱. The results showed a ۱۰-۱۰۰-fold decrease in viable cells (CFU/biofilm) after phage treatment.CONCLUSION The characterization of bacteriophages with a diverse host range of E. faecalis could help in the development of effective therapeutic strategies for this pathogen.

کلیدواژه ها:

Bacteriophage ، Enterococcus faecalis ، Phage therapy