Detection of Salmonella spp. reservoirs in lizards from Gran Canaria island.

Abstract

The giant lizard of Gran Canaria (Gallotia stehlini) is endemic to the island of Gran Canaria. It is currently threatened by a wide variety of invasive exotic species that have been introduced into the Canary Islands in recent years, which pose a problem in terms of the transmission of certain pathogens as they share the same environment. Furthermore, reptiles are known to play a role as asymptomatic carriers of certain zoonotic pathogens, such as Salmonella spp. Previous studies have shown that Gallotia stehlini is a carrier of this pathogen, however, these studies have been biased as they have been carried out with a low number of samples. Given the health importance that this could have, the aim of this study was to determine the real prevalence of Salmonella spp. in the endemic lizard of Gran Canaria. For this purpose, we have taken a total of 55 samples of lizard feces from different localities of the island. To develop this study, the ISO 6579-1:2017 Standard was used, using Hektoen enteric agar and a double concentration of MgCl2 as a second selective isolation medium. Our results showed a final prevalence of Salmonella spp. of 70.90% (39/55) in the giant lizard of Gran Canaria. Our results using a concentration of 36 g/L of MgCl2, higher than that indicated by the ISO standard (13.58 g/L), detected 17 (39.53%) Salmonella spp. isolates that would have gone undetected if we had followed the concentrations recommended by the Standard. Hektoen enteric agar was shown to be an efficient medium to isolate Salmonella spp.