Salmonella infects over 90 million people worldwide each year, with over 150,000 deaths resulting from the infection. Treatment of Salmonella infection is complicated by the spread of antibiotic-resistant Salmonella strains. This poses a problem for both sick people and farm birds and animals, which often transmit salmonellosis, become ill, and even die. Therefore, farmers, like doctors, need an effective alternative to traditional antimicrobials.

One promising approach to combating Salmonella infection is the use of bacteriophages (phages). Results from a trial of a phage cocktail against Salmonella on a broiler farm in Colombia were recently published. This is the first field trial of bacteriophages in poultry.

The use of bacteriophages in farm conditions is associated with several difficulties. First, phages are specific, meaning one bacteriophage strain may infect one or several Salmonella strains while sparing others. Therefore, when developing a phage preparation, it is necessary to select a combination of phages with the broadest possible bacterial host range. Second, birds receive bacteriophages orally through their drinking water, meaning the phage concentration in the water must be very high. Third, in farm conditions, phages easily spread and reach control birds, complicating the analysis of test results. At the same time, phage therapy is an inexpensive, safe, and relatively simple method for controlling bacterial infections in chickens.

At a broiler farm in Colombia, which had previously experienced salmonella outbreaks, scientists tested a commercial phage cocktail containing six bacteriophages specific to various salmonella strains. The cocktail's safety for chickens was proven in laboratory conditions.

Two trials were conducted on the farm, each involving approximately 30,000 chickens. Each trial consisted of an experimental group that received a phage preparation and a control group. The birds received three doses of the phage preparation in their drinking water on days 18, 27, and 35 of the cycle. Each dose consisted of 30-60 ml of water containing 108 CFU/ml of phages. The day before and the day after receiving the phage preparation, the chickens underwent cloacal swabs for Salmonella.

The use of a phage cocktail demonstrated 100% effectiveness in preventing Salmonella infection in chickens, the safety of the drug, and its lack of impact on production parameters (chicken weight, feed efficiency, mortality, etc.).

The value of the Colombian study lies not only in its demonstration of the effectiveness of phage prophylaxis against salmonellosis in poultry farming, but also in the fact that it will help phages gain the trust of private farmers and will facilitate new testing and the introduction of bacteriophage preparations into agricultural production.

* Clavijo V, Baquero D, Hernandez S, Farfan JC et al. Phage cocktail SalmoFREE® reduces Salmonella on a commercial broiler farm // Poultry Science, 09 May 2019, pez251.DOI: 10.3382/ps/pez251