In Vitro and In Vivo Gastrointestinal Survival of Non-Encapsulated and Microencapsulated Salmonella Bacteriophages: Implications for Bacteriophage Therapy in Poultry

Abstract

The therapeutic use of bacteriophages is recognized as a viable method to control Salmonella. Microencapsulation of phages in oral dosage forms may protect phages from inherent challenges of the gastrointestinal tract in chickens. Therefore, the main objective of this study was to assess the survival of Salmonella BP FGS011 (non-encapsulated and microencapsulated) through the gastrointestinal tract under in vitro as well as in vivo conditions after oral administration to 1-day-old chicks. To this end, the phage FGS011 was encapsulated in two different pH-responsive formulations with polymers Eudragit® L100, and Eudragit® S100 using the process of spray drying. Phages encapsulated in either of the two formulations were able to survive exposure to the proventriculus-gizzard in vitro conditions whereas free phages did not. Moreover, phages formulated in polymer Eudragit® S100 would be better suited to deliver phage to the caeca in chickens. In the in vivo assay, no statistically significant differences were observed in the phage concentrations across the gastrointestinal tract for either the free phage or the encapsulated phage given to chicks. This suggested that the pH of the proventriculus/gizzard in young chicks is not sufficiently acidic to cause differential phage titre reductions, thereby allowing free phage survival in vivo.

In Vivo Recovery of Bacteriophages and Their Effects on Clostridium perfringens-Infected Broiler Chickens

“…The lack of stability upon exposure to acidic conditions (e.g., in the proventriculus/gizzard) and the relatively short residence times in the intestinal tract may limit the efficacy of orally delivered BPs [ 17 ]. To overcome these obstacles, encapsulation is proposed to provide protection from gastric acidity, releasing high doses of diet-origin BP distally [ 27 , 28 ]. In this study, we confirmed that encapsulated BP effectively delivered viable BP distally, suggesting that the encapsulation or coating of BPs may further increase their stability and viability during storage and upon ingestion.…”

Gastrointestinal Dynamics of Non-Encapsulated and Microencapsulated Salmonella Bacteriophages in Broiler Production

“…BP FGS011 used in this study was isolated by Sevilla-Navarro et al [ 26 ] and characterized by Lorenzo-Rebenaque et al [ 23 ]. BP FGS011 was propagated on Salmonella Senftenberg ( S. Senftenberg), obtained from poultry farms during the NSCP [ 27 ] in the Poultry Quality and Animal Nutrition Centre of the Valencia Region (CECAV).…”

“…During this study, the BP FGS011 was evaluated without encapsulation as free BP (FP) and micro-encapsulated with the polymer Eudragit ® L100 (L100) (Evonik Nutrition & Care GmbH, Darmstadt, Germany). Encapsulation was performed according to Malik [ 28 ] and Lorenzo-Rebenaque et al [ 23 ]. For this study, the anionic polymer Eudragit ® L100 was used for the BP encapsulation.…”

“…The possibility of BP administration via incorporation in feed or through drinking water would make phage therapy suitable for treatment en masse , overcoming a major limiting factor for large-scale poultry applications [ 20 ]. Nevertheless, changes in GIT conditions throughout the production cycle could compromise the efficacy of the orally administered BP, leading to variable efficacy outcomes [ 21 , 22 , 23 ]. In this sense, controlled-release formulation technology has gained interest due to the capability of delivering therapeutics at the target site where they are needed to control the pathogen [ 24 ].…”

“…In this sense, controlled-release formulation technology has gained interest due to the capability of delivering therapeutics at the target site where they are needed to control the pathogen [ 24 ]. Controlled release dosage forms could delay the release of the drug substance in the first stretch of the GIT (crop, proventriculus (PV) and gizzard), reaching the gut and the cecum [ 23 , 24 ]. This way, high doses of BP will reach the target site where Salmonella mainly colonizes (the caecum) improving the effectiveness of phage therapy.…”