APPLICATION OF SALMONELLA PHAGE COCKTAIL TO CONTROL SALMONELLA TYPHIMURIUM IN VITRO

Members of the genus Salmonella are among the microbial pathogens associated with dangerous infection. The increased of Salmonella spp. antibiotic resistance has propelled the need of alternate therapeutic methods or strategies. Bacteriophage forms one of these alternate strategies. Six lytic bacteriophages infecting Salmonella Typhimurium were isolated from sewage drain water. Phages were purified biologically by single plaque assay and concentrated using the ultracentrifugation. The phage isolates were named Ø SM, Ø SF, Ø SG, Ø SP, Ø SA and Ø SD. Morphological characters of Salmonella phages showed that all the phage isolates belong to family Myoviridae. All phage isolates were highly stable at room temperature, storage at refrigerator temperature and had thermal inactivation point ranged from 90 to 98 °C. Phages were stable at pH conditions ranging from pH 4 to 12. Phages did not lose their infectivity after exposure to UV for 90 min. at 35 cm and 53 cm distance. The host range of the isolated phages was found that the phages had narrow host range. Phage cocktail with different MOI was used to control Salmonella Typhimurium in vitro. Data revealed that addition of phage cocktail at MOI 10 reduced the Salmonella cells with rate 98.2 % after 4 hrs. from addition.   introduction   Salmonella spp. belong to family Enterobacteriaceae and widely distributed in nature and often found in the intestinal tract of warm-blooded animals and humans,where they asymptomatically colonize and multiply (Newell & Fearnley, 2003 and Doyle & Erickson, 2006). More than 2,500 serotypes of Salmonella exist and the most prevalent and important Salmonella enterica serotypes reported worldwide are Enteritidis and Typhimurium. These are responsible for 99 % of Salmonellosis in humans and warm-blooded animals. The most common symptoms of Salmonella infection is non-bloody diarrhea and abdominal cramps (Bell and Kyriakides, 2002). Due to foodborne infections by Salmonella are obtained through ingesting contaminated food or water, (Abd El-Aziz, 2013 ) detected high incidence of Salmonella Typhimurium , one of the most frequently isolated serovars from food borne outbreaks throughout the world, in retail raw chicken meat and giblets in Egypt. Bacteriophages are considered an effective weapon against pathogenic bacteria. As a result of development resistant bacteria against antibiotics because of their repeated usage,  bacteriophages are used as a safe alternative to control pathogenic bacteria (Abramia et al 2016). In addition, offer a great advantage over antibiotics. First, bacteriophages are specific and target only the pathogens of interest, so the normal gut microflora are not affected. Second, bacteriophages are self-replicating in the bacterial host and lyse bacteria. (Connerton and Connerton, 2005). This paper aims to investigate the incidence of lytic bacteriophages specific for Salmonella in sewage water and study the posibility of their application for controling the Salmonella in vitro.