The use of a salmonella bacteriophage in bearded dragons: application, passage time and reisolation

Abstract

Objective This study determined the passage time and phage propagation time of a salmonella specific phage, Felix O1, in bearded dragons, based on reisolation from cloacal swabs and faecal samples following oral administration, as a possible tool for reducing the zoonotic risk of salmonella from pet reptiles. An application scheme for this phage in bearded dragons was developed. Material and methods Ten healthy bearded dragons (Pogona vitticeps) were used in the study. The pH tolerance of the phage was tested and drugs were used to evaluate their influence on the gastric pH of the reptiles. After pH adjustment, the phage was administered orally for 12 consecutive days. Over 60 days, swabs were taken from the cloaca and examined for the presence of phages using culture and PCR. Furthermore, faecal samples were collected for phage quantification. Results Felix O1 displayed no activity at pH below 2.8. A calcium- and magnesium carbonate buffer induced an appropriate gastric pH increase for 30 minutes. Phages were reisolated for up to 24 days (mean shedding: 19 days) after last administration. Titres between 105 and 107 plaque forming units/g faeces were detected. The animals did not show any clinical signs related to phage application. Conclusion and clinical relevance The study provides first results on oral administration, passage time, and reisolation of a phage in reptiles. It could be shown that the phage was able to replicate in the intestine, and was shed for a prolonged period and therefore could potentially contribute to a reduction of salmonella shedding.

Bacteriophage as an alternative to prevent reptile‐associated Salmonella transmission

“…In this study, we focused on RAS and its contact transmission. In a previous study with the same goal, phages were administered through the reptile gut to prevent Salmonella excretion through the cloaca (Renfert et al., 2019). Here, we targeted the eradication of excreted Salmonella and its formed biofilms with a phage designated as pSal‐SNUABM‐02.…”

Influence of Salmonella specific bacteriophages (O1; S16) on the shedding of naturally occurring Salmonella and an orally applied Salmonella Eastbourne strain in bearded dragons (Pogona vitticeps)

“…Study 2 was then conducted to detect the influence of a phage cocktail (Felix O1, S16) on shedding of a Salmonella serovar administered with the phage cocktail. Parts of the results of Study 1 (phage administration, phage detection in swabs and faeces) have been described previously (Renfert et al., 2019). The animal studies were performed with the approval of the responsible authorities (Reg.‐Nr.…”

“…For qualitative reisolation of the phages , swabs were placed in nutrient broth (Oxoid) containing a Salmonella reference strain (Anderson et al., 1977) and incubated at 37°C for six hours (Renfert et al., 2019). 10 µl of the broth were then plated onto a prepared “Blue Plate” (Rabsch, 2007) and evaluated as described.…”

“…Plaques were then counted and the phages were quantified ( Salmonella and phages after adapting DIN ISO 18593:2009). Each sample was confirmed as phage Felix O1 by PCR (Renfert et al., 2019).…”

“…Phages have been described as a potential tool for Salmonella reduction and previous studies have demonstrated that they can be administered to bearded dragons and are then shed in the faeces (Renfert et al., 2019). This study therefore aimed to further investigate phage passage and shedding, as well as the impact of phage administration on the quality and quantity of Salmonella shedding in bearded dragons.…”