Isolation and Characterization of a Phage to Control Vancomycin Resistant Enterococcus Faecium

Salmonella Enteritidis Bacteriophages Isolated from Kenyan Poultry Farms Demonstrate Time-Dependent Stability in Environments Mimicking the Chicken Gastrointestinal Tract

Multi-drug resistant (MDR) Salmonella enterica Enteritidis is one of the major causes of foodborne illnesses worldwide. This non-typhoidal Salmonella (NTS) serovar is mainly transmitted to humans through poultry products. Bacteriophages (phages) offer an alternative to antibiotics for reducing the incidence of MDR NTS in poultry farms. Phages that survive the harsh environment of the chicken gastrointestinal tract (cGIT), which have low pH, high temperatures, and several enzymes, may have a higher therapeutic or prophylactic potential. In this study, we analysed the stability of 10 different S. Enteritidis phages isolated from Kenyan poultry farms in different pH-adjusted media, incubation temperatures, as well as simulated gastric and intestinal fluids (SGF and SIF, respectively). Furthermore, their ability to persist in water sources available in Kenya, including river, borehole, rain and tap water, was assessed. All phages were relatively stable for 12 h at pHs ranging from 5 to 9 and at temperatures ranging from 25 °C to 42 °C. At pH 3, a loss in viral titre of up to three logs was observed after 3 h of incubation. In SGF, phages were stable for 20 min, after which they started losing infectivity. Phages were relatively stable in SIF for up to 2 h. The efficacy of phages to control Salmonella growth was highly reduced in pH 2- and pH 3-adjusted media and in SGF at pH 2.5, but less affected in SIF at pH 8. River water had the most significant detrimental effect on phages, while the other tested waters had a limited impact on the phages. Our data suggest that these phages may be administered to chickens through drinking water and may survive cGIT to prevent salmonellosis in poultry.

Novel lytic bacteriophage vB_GEC_EfS_9 against Enterococcus faecium

Enterococcus spp. is a common commensal microorganism, however, some strains can cause opportunistic infections in humans. Treatment of Enterococcus faecium-related endocarditis, urinary and genital tract infections, meningitis, septicemia, and even neonatal sepsis is often complicated by antibiotic resistance. The spread of multi-resistant bacterial strains has renewed interest in phage therapy, which has many advantages: Its advantages include a much lower frequency of resistance development compared to antibiotics and strict specificity, which allows affecting of only their target microbes without disturbing necessary microbiome. We isolated and characterized a virulent bacteriophage which is active against Enterococcus faecium clinical strains. The phage, which was designated as vB_GEC_EfS_9 was studied in terms of its growth pattern and adsorption rate, as well as its host range. The whole genome of the phage was sequenced and analyzed. Obtained results indicate that phage vB_GEC_EfS_9 is a virulent phage which has a very good potential for therapeutic use against strains of E. faecium.

Biological characteristics and anti-biofilm activity of a lytic phage against vancomycin-resistant Enterococcus faecium

BACKGROUND AND OBJECTIVES

An important leading cause of the emergence of vancomycin-resistant enterococci, especially Enterococcus faecium, is the inefficiency of antibiotics in the elimination of drug-resistant pathogens. Consequently, the need for alternative treatments is more necessary than ever.

MATERIALS AND METHODS

A highly effective bacteriophage against vancomycin-resistant E. faecium called vB-EfmS-S2 was isolated from hospital sewage. The biological properties of phage S2 and its effect on biofilm structures were determined.

RESULTS

Phage S2 was specifically capable of lysing a wide range of clinical E. faecium isolates. According to Electron microscopy observations, the phage S2 belonged to the Siphoviridea family. Suitable pH spectra for phage survival was 5-11, at which the phage showed 100% activity. The optimal temperature for phage growth was 30-45°C, with the highest growth at 37°C. Based on one-step growth curve results, the latent period of phage S2 was 14 min with a burst size of 200 PFU/ml. The phage S2 was also able to tolerate bile at concentrations of 1 and 2% and required Mg2+ for an effective infection cycle. Biofilms were significantly inhibited and disrupted in the presence of the phage.

CONCLUSION

According to the results, phage S2 could potentially be an alternative for the elimination and control of vancomycin-resistant E. faecium biofilm.

Isolation of a Novel Phage and Targeting Biofilms of Drug-Resistant Oral Enterococci

INTRODUCTION

Enterococci are now recognized as the second most cause of nosocomial infections worldwide. The emergence of multidrug-resistant strains in the organism has given rise to alternative strategies such as phage therapy. In this study, an Enterococcus faecalis infecting phage was isolated and its efficiency against biofilms formed by drug-resistant enterococci obtained from chronic periodontitis was evaluated.

MATERIALS AND METHODS

Bacteriophage against E. faecalis was isolated from sewage sample. The phage was propagated and identified using transmission electron microscope (TEM). In vitro biofilm formation was assessed.

RESULTS

TEM microscopy showed that the phage belonged to Siphoviridae family. In the presence of the novel phage, the metabolic activity of enterococci biofilm was reduced at 48 h of contact. A difference of at least 5 log CFU/ml was seen in the live cells of the control biofilm, and the phage treated biofilm of enterococci isolates.

CONCLUSION

The study shows that the novel phage inhibits biofilm production in oral enterococci isolates from periodontitis patients but has a narrow host range. The role of bacteriophages as strong biotechnological and natural therapeutic agents for E. faecalis in chronic periodontitis can be considered.