Three different lyric bacteriophages (BPs) were isolated from the sewage system of commercial chicken flocks and used to reduce Salmonella Enteritidis (SE) colonization from experimental chickens. Ten-day-old chickens were challenged with 9.6 x 10(5) colony-forming units (CFU)/ml of a SE strain and treated by coarse spray or drinking water with a cocktail of the three phages at a multiplicity of infection (MO1) of 10(3) plaque-forming units (PFU) 24 hr prior to SE challenge. Chickens were euthanatized at day 20 of age for individual SE detection, quantitative bacteriology, and phage isolation from the intestine and from a pool of organs. SE detection was performed by both bacteriologic culture and genome detection by polymerase chain reaction (PCR). Qualitative bacteriology showed that aerosol-spray delivery of BPs significantly reduced the incidence of SE infection in the chicken group (P = 0.0084) to 72.7% as compared with the control group (100%). In addition, SE counts showed that phage delivery both by coarse spray and drinking water reduced the intestinal SE colonization (P < 0.01; P < 0.05, respectively). BPs were isolated at 10 days postinfection from the intestine and from pools of organs from BP-treated chickens. We conclude that the phage treatment, either by aerosol spray or drinking water, may be a plausible alternative to antibiotics for the reduction of Salmonella infection in poultry.

A combination of three different Salmonella-specific bacteriophages (BPs) and one competitive exclusion (CE) product were used to reduce Salmonella Enteritidis (SE) colonization in experimentally infected chickens. Equal numbers of 7-day-old chickens were used in each of three groups: a CE group (treated with CE), a BP group (treated with BP), and a CE-plus-BP group (treated with both products). The CE product was administered via coarse spray at 1 day of age and the cocktail of three BPs was given via spray at 6 days of age using a multiplicity of infection of 10(3) plaque-forming units. All the experimental groups, except a healthy control group, were challenged orally with 2.95 x 10(5) colony-forming units (CFU)/ml of an SE strain at 7 days of age. Seven days postchallenge, the chickens were euthanatized for individual SE detection, quantitative bacteriology, and phage isolation from ceca and an internal organ pool. The qualitative bacteriology demonstrated that the use of the CE product diminished the incidence of SE to 75.7% and the mixture of BPs reduced it to 80%; when CE plus BP were used, the incidence dropped significantly to 38.7% (P < 0.0001), as compared with the infection control group (100%). A significant difference in the incidence was observed between the CE and the CE-plus-BP groups, and the BP and the CE-plus-BP groups (P = 0.0027 and P = 0.0010, respectively). The mean SE cecal count diminished with the use of CE plus BP (1.6 x 10(2) CFU/g, P = 0.0003) compared with the control group (1.56 x 10(5) CFU/g), the CE group (4.23 x 10(3) CFU/g), and the BP group (9.48 x 10(3) CFU/g). On the basis of the present study, it may be concluded that the use of both types of biocontrollers can be an effective method for reducing SE colonization in commercial chickens, but further basic and applied research is needed.

No abstract

COMUNICACIÓN Uso de bacteriófagos en gallinas de postura infectadas con SUMMARYSalmonella enterica serovar Enteritidis (SE) remains an important enteropathogen in the poultry industry and public health. Due to the limited effectiveness of control measures, lytic bacteriophages have shown a potential use as biocontrollers of SE in birds. The aim of this study was to determine the effectiveness of prophylactic therapy with phages to control intestinal and reproductive tract colonization of SE in laying hens. 22-week old HyLine Brown hens free of Salmonella, were treated with a mixture of three bacteriophages (10 11 PFU/dose/phage) and challenged with 2.4 x 10 8 CFU of SE, 24 hours post phage treatment. On day 10 post challenge, hens were euthanatized, and individual samples of cecum, ovary and oviduct, were analyzed using qualitative and quantitative bacteriology. Eggs laid during the experience were collected and processed to detect SE. The incidence of Salmonella in ceca was similar between positive control and treated groups (96.67%) and cecal bacterial counts did not present significant differences between them (P > 0.05). In reproductive tissues, phagetherapy was able to slightly reduce the SE count in the ovary (P < 0.05), but not in oviducts (P > 0.05). This lytic activity of phages observed in ovaric tissue, encourages further efforts to elucidate the real contribution of bacteriophages as SE biocontrollers in laying hens.Palabras clave: Salmonella, prevención, bacteriófagos, gallinas de postura, aves.

Prevención de la infección por SuMMaRyInfections caused by Salmonella enterica subspecies enterica serotype Enteritidis (Salmonella Enteritidis) are an important cause of foodborne diseases, epidemiologically associated with the consumption of poultry products. Since antibiotic treatments cause the appearance of multiresistant strains, phages can be used as an alternative method for controlling S. Enteritidis in the poultry industry. The aim of this study was to evaluate the effect of the bacteriophage f3αSE on the incidence of Salmonella Enteritidis in chickens. 15 broiler chickens of 10 days of age were arranged into 5 groups. Groups A and B received 1 ml of a phage suspension orally containing 10 6 and 10 7 PFU/dose, respectively. Two hours later, the birds were challenged orally with 1 ml of Salmonella Enteritidis (4 x 10 6 CFU/dose). The control group (C) only received the phage (10 7 PFU/dose) and the control group D was infected with Salmonella Enteritidis (4 x 10 6 CFU/dose); group E remained untreated and constituted the healthy control. Ten days post challenge, the chickens were euthanised by CO 2 inhalation and samples of intestine and organs were obtained for the re-isolation of the challenge strain and phage. The incidence of infection by Salmonella Enteritidis decreased (P = 0.028) in the group that received 10 7 PFU/dose (7/15 chickens) unlike the group that received a 10 6 PFU dose (8/15 chickens). The decrease in the incidence of Salmonella Enteritidis in chickens by using the phage f3αSE, indicates that it is possible to consider such phages as useful agents in the control of Salmonella Enteritidis infections.Palabras clave: Salmonella, pollos, bacteriófagos.