Use of Bacteriophages in Combination with Competitive Exclusion to Reduce Salmonella from Infected Chickens

Abstract

Salmonella-spedfic bacteriophages (BP) and competitive exclusion (CE) were used to reduce Salmonella colonization in experimentally infected chickens. A "cocktail" of distinct phage (i.e., phage showing different host ranges and inducing different types of plaques on Salmonella Typhimurium [ST] cultures) was developed. The killing activity of the selected BPs on ST cultures differed significantly, as determined in in vitro killing assays. BPs were administered orally to the chickens several days prior and after ST challenge but not simultaneously. BPs were readily isolated from the feces of the BP-treated chickens approximately 48 hr after administration. A CE product consisting of a defined culture of seven different microbial species was used either alone or in combination with BP treatment. CE was administered orally at hatch. Salmonella counts in intestine, ceca, and a pool of liver/spleen were evaluated in Salmonella-challenged chickens treated with BP or with BP and CE. In both trials 1 and 2, a beneficial effect of the phage treatment on weight gain performance was evident. A reduction in Salmonella counts was detected in cecum and ileum of BP-, CE-, and BP+CE-treated chickens as compared with nontreated birds. In trial 1, BP treatment reduced ST counts to marginal levels in the ileum and reduced counts sixfold in the ceca. A reduction of Salmonella counts with BP, CE, and BP+CE treatments was evident in chickens from trial 2. Both CE and BP treatments showed differences in the reduction of Salmonella counts after challenge between spedmens obtained at days 4 and 14 postchallenge in ceca, liver/spleen, and ileum. The preliminary data presented in this report show that isolation and characterization of Salmonella-specific BP is uncomplicated and feasible on a larger scale. Results indicate a protective effect of both Salmonella-specific BPs and a defined competitive exclusion product against Salmonella colonization of experimentally infected chickens. These results are encouraging for further work on the use of BP as an effective alternative to antibiotics to reduce Salmonella infections in poultry.

Phages as Therapeutic Tools to Control Major Foodborne Pathogens: Campylobacter and Salmonella

“…Moreover, there was a marginally improved weight gain in the treated animals. Although both approaches were able to reduce the Salmonella counts, unlike the previous study (Borie et al, 2009) a synergistic effect was not observed (Toro et al, 2005).…”

“…Moreover, they showed that phage treatment coupled with competitive exclusion resulted in even better Salmonella r e d u c t i o n s t h a n e a c h o f t h e treatments alone (Borie et al, 2009). Toro et al (2005) and coworkers also tested the association of phage therapy and competitive exclusion in the treatment of chickens infected experimentally with Salmonella. Phage treatment was given orally and included a cocktail of three different phages with different host ranges.…”

Phage-based biocontrol strategies to reduce foodborne pathogens in foods

“…Phage therapy has shown promise as an effective pre-harvest intervention by controlling foodborne pathogens in animals before they enter processing plants, [2][3][4] with several studies indicating that phage therapy is effective against a broad range of foodborne pathogens belonging to the genera Salmonella, Campylobacter, Listeria and Escherichia. [5][6][7][8][9] Phage therapy has been investigated for efficacy in red meat producing animals (cattle, sheep, swine) and white meat producing animals (poultry).…”

“…[2][3][4]10 Generally, the use of only one phage in some experiments has led to resistance, 2,10 while the use of multiple phages in a cocktail has decreased the chance of developing resistance to a single phage. 4,7,11 Ruminants. Phage based interventions have been aimed at controlling Escherichia coli (E. coli) serotype O157:H7 in cattle and other ruminants.…”

“…Toro et al 4 used a mixture of three Salmonella-specific phages in combination with competitive exclusion bacteria to reduce Salmonella colonization in experimentally infected chickens. The phages were administered orally to the chickens several days prior and after Salmonella challenge.…”