SELECTIVE DECOLONIZATION OF ENTEROCOCCI IN MICE GUT USING SPECIFIC LYTIC BACTERIOPHAGES

RAMÍREZ BENJAMÍN , BOSCARO GABRIELA, CENTRÓN DANIELA, PÉREZ PABLO, LOPARDO HORACIO

Porto Heli, Grecia

Simposio; XVIIth Lancefield International Symposium on Streptococci and Streptococcal Disease; 2008

Lancefield Society

Selective Decolonization of Enterococci in Mice Gut Using  Specific Lytic Bacteriophages                                    Benjamín Ramírez1, Gabriela Boscaro1, , Daniela Centrón2 Pablo Pérez2, Horacio Lopardo1                                                                                                                                                                                                                                              (1)Hospital de Pediatría Prof. Dr. Juan P Garrahan, Buenos Aires, Argentina; (2) Departamento de Microbiología, Facultad de Medicina UBA Buenos Aires, Argentina; (3) Facultad de Ciencias Exactas U.N. de La Plata, Argentina.  Vancomycin-resistant enterococci, especially E .faecium and E. faecalis, are a global threat to public health. Colonization precedes most infections in susceptible hosts. VRE can colonize the bowel of patients and can persist during long periods of time. Decolonization, if possible, would be a cost-effective practice taking into account the difficulties of the management of VRE infections and the expensiveness of the isolation or cohortization of patients. OBJECTIVE: The objective of this study was to isolate and characterize specific lytic  phages for using in in vitro and in vivo assays of selective decolonization of  enterococci. METHODS: Pools of stool samples were filtrated by Millipore 0.22 μm and tested on possible bacterial hosts for bacteriophage isolation. A total of  5 enterococcal bacteriophages were isolated. These were characterized further by electron microscopy, lytic activity in vitro and host range. We designed a model of Caco2 cells for decolonization studies by phages. One of them was administered (1 week) in drinking water to 42-days-old mice naturally colonized with specific host strains. Mice were killed and upper and lower intestines were firstly separated  and then removed by sterile dissection; the fecal contents were collected for Enterococcus and bacteriophage isolation. Colonization levels were recorded as the log10 CFU per gram of intestinal contents. RESULTS: The number of viable enterococci in fecal matter and in the gastrointestinal tract was significantly lower (about 3 log) in phage-treated mice than in the saline-treated control mice, but complete decolonization was not accomplished. Same results were found by the culture cell model. CONCLUSION: This study suggested that bacteriophages can be used to reduce the colonization of gut by enterococci. The results are promising, although further work needs to be undertaken to determine the optimal timing and delivery of bacteriophages.