Cm0669

Isolation and identification of Salmonella spp. were performed using procedures previously described by Addo et al. (18 (link)). 1 ml aliquots stock homogenate prepared earlier were transferred into 10 ml Rappaport–Vassiliadis Broth for enrichment. Samples in Rappaport–Vassiliadis Broth (Oxoid, CM0669) were incubated at 37°C for 24 h. 0.1 ml of the enriched samples were then streaked onto Salmonella–Shigella Agar (SSA) (Oxoid, CM0099) and incubated at 37°C for 24 h. Cream colonies with black centers on the SSA presumed to be Salmonella spp. were purified on nutrient agar and confirmed using Gram staining, analytical profile index (API) (20E, Biomérieux, France), and Salmonella latex agglutination.

Twenty-five g/ml portions of each sample and 10 ml of sponge eluates were homogenized, respectively, in 225 ml and 90 ml (1:10 (W/W)) of buffer peptone water (BPW, CM0509, Oxoid) and incubated at 37°C for 18-h. Subsequently, 0.1 and 1.0 ml of the incubated homogenates were transferred into Rappaport Vassiliadis broth (RVS, CM0669, Oxoid) and Muller Kaufman broth (MK, CM1048, Oxoid) and incubated at 41.5°C for 24-h and 37°C for 24-h, respectively. Then the enrichments were streaked into xylose-lysinedesoxycholate agar (XLD, CM0469, Oxoid) and Salmonella chromogenic agar base (CM1007, Oxoid) with salmonella selective supplement (SR0194, Oxoid) and incubated at 37°C for 24-h. Presumptive Salmonella colonies were biochemically identified through API 20 E. Afterwards, the isolates were serotyped at the Campania Region Salmonella Typing Center (Department of Food Microbiology, Istituto Zooprofilattico Sperimentale del Mezzogiorno, Portici, NA, Italy) following the Kaufmann–White scheme.