Isolation of Salmonella strains from reptile faeces and comparison of different culture media

Aims: To provide information on epidemiology and isolation of Salmonella strains from reptiles. Methods and Results: Ninety-one samples collected from reptiles of the zoo of Rome or belonging to private owners were analysed using a standard protocol for isolation of Salmonella from food. Salmonella strains were tested for susceptibility to 15 antimicrobics by a disc-agar diffusion method. Forty-six samples (50.5%) were positive for Salmonella. Of the 22 strains serotyped, 17 belonged to Salmonella enterica subsp. I, four to the subsp. IIIa and one strain resulted untypeable. Rappaport-Vassiliadis broth (RVB) allowed to recover more Salmonella strains when bacterial growth in buffered peptone water (BPW) was scarce, while selenite cystine broth (SCB) was more efficient, whereas growth in BPW was abundant. The maximum isolation score was obtained by plating onto xylose lysine desoxycholate agar (XLD). The strains exhibited resistance at high percentages to colistin sulphate (58.7%), sulphamethoxazole (55.5%), streptomycin (32.6%), tetracycline (19.6%), ampicillin (17.4%) and nalidixic acid (13.1%). Conclusions: A high prevalence of Salmonella in reptiles was observed. For isolation, the choice of the enrichment broth depending on the degree of growth in BPW followed by plating onto XLD may be suggested. Significance and Impact of the Study: This paper provides epidemiological data on the prevalence of Salmonella and laboratory protocols useful for isolation of Salmonella from faeces of reptiles.