Bacteriophage Therapy Rescues Mice Bacteremic from a Clinical Isolate of Vancomycin-Resistant Enterococcus faecium

Abstract

Colonization of the gastrointestinal tract with vancomycin-resistant Enterococcus faecium (VRE) has become endemic in many hospitals and nursing homes in the United States. Such colonization predisposes the individual to VRE bacteremia and/or endocarditis, and immunocompromised patients are at particular risk for these conditions. The emergence of antibiotic-resistant bacterial strains requires the exploration of alternative antibacterial therapies, which led our group to study the ability of bacterial viruses (bacteriophages, or phages) to rescue mice with VRE bacteremia. The phage strain used in this study has lytic activity against a wide range of clinical isolates of VRE. One of these VRE strains was used to induce bacteremia in mice by intraperitoneal (i.p.) injection of 10 9 CFU. The resulting bacteremia was fatal within 48 h. A single i.p. injection of 3 ؋ 10 8 PFU of the phage strain, administered 45 min after the bacterial challenge, was sufficient to rescue 100% of the animals. Even when treatment was delayed to the point where all animals were moribund, approximately 50% of them were rescued by a single injection of this phage preparation. The ability of this phage to rescue bacteremic mice was demonstrated to be due to the functional capabilities of the phage and not to a nonspecific immune effect. The rescue of bacteremic mice could be effected only by phage strains able to grow in vitro on the bacterial host used to infect the animals, and when such strains are heat inactivated they lose their ability to rescue the infected mice.Isolates of vancomycin-resistant Enterococcus faecium (VRE) from patients in the United States, France, and England were first reported in 1989 (9, 19). By 1998, the U.S. National Nosocomial Infections Surveillance System had reported that 20% of nosocomial isolates of enterococci were resistant to vancomycin (12). Individuals with compromised immune systems, such as AIDS patients, cancer patients undergoing chemotherapy, postsurgical patients, transplant recipients, and the elderly in general, are particularly prone to develop VRE infections. While the antibiotic quinupristindalfopristin (Synercid; Rhone-Poulenc Rorer, Collegeville, Pa.) has recently been licensed for clinical use, its efficacy for VRE infections may be limited because (i) it is bacteriostatic, and (ii) one of its two components is an analog of virginiamycin, which has been used as an additive in hog and poultry feed for the past 2 decades. Quinupristin-dalfopristin-resistant bacteria have been isolated from turkeys fed virginiamycin, suggesting that the use of virginiamycin has created a reservoir of enterococci resistant to the analog in quinupristin-dalfopristin (5). Linezolid (Zyvox; Pharmacia and Upjohn), another recently introduced antibiotic, is also described as bacteriostatic for VRE, and resistance to it appeared during clinical trials even though it is the first member of a new class of agents (the oxazolodinones).Early applications of antibacterial phage therapy (1920s to 1950s) were impeded by...

Efficacy of Bacteriophage Therapy against Gut-Derived Sepsis Caused by Pseudomonas aeruginosa in Mice

“…Reports have revealed that a single treatment with phage leads to recovery in mice with infections caused by E. coli (34), P. aeruginosa (12), methicillin-resistant Staphylococcus aureus (24), and vancomycin-resistant Enterococcus faecium (6). In the present study, we also found that a single treatment with phage strain KPP10 prevented the death of mice after gutderived sepsis and intraperitoneal infection with P. aeruginosa.…”

“…The therapeutic efficacy of phage therapy against infectious diseases caused by P. aeruginosa (12), Staphylococcus aureus (including methicillin-resistant S. aureus) (24), Escherichia coli (3), Enterococcus faecium (including vancomycin-resistant Enterococcus) (6), and Streptococcus pneumoniae (16) has been shown in experimental animal models. However, the models used in those studies were simple models of infection that did not closely resemble the pathophysiologies of diseases in humans.…”

CpG Motif in Phage Genome DNA Enhanced the Efficacy of Phage Therapy by Immunostimulation

“…This means the protection level and also adaptive immunity might be enhanced by CpG contained Ф DNA administration. Our findings are consistent with similar studies [17] has proved activation of innate immunity by exposing mice to the single dose of CpG DNA provide long-term protection (for two weeks) against multiple pathogens, including Listeria monocytogenes, Francisells tubarsis, Anthrax, ebola, malaria, Leshmania, and Schisoma [18,[22][23]. In the current study, we were unable to determine the prolonged (more than six weeks) protective effect of immunized animals due to scarification of them for antisera.…”

A comparative study of different strategies for removal of endotoxins from bacteriophage preparations

“…Therefore, labor intensive endotoxin removal strategies should not be necessary for therapeutic phage preparations, knowing that the dilution of high titer phage preparations would be sufficient. Unfortunately, dilution of the phage preparations is not always possible when performing phage biology studies such as evaluating the immunological properties of phages on the mammalian immune system, where high phage titers might be advised (Biswas et al, 2002;Miernikiewicz et al, 2013).…”