Assessing the growth and recovery of Salmonella Enteritidis SE86 after sodium dichloroisocyanurate exposure

Abstract

The objective of the present study was to assess the growth and the recovery of Salmonella (S.) Enteritidis SE86 in different diluents, culture media and using different plating methods after the exposure to 200 mg/kg sodium dichloroisocyanurate (NaDCC). Before and after NaDCC exposure, SE86 was cultured at 30 °C and 7 °C in the following diluents: Peptone water (P), Saline solution (SaS), Peptone water+Saline solution (P+SaS), Peptone water+Tween 80+Lecithin+Sodium thiosulfate (P+N) and Saline solution+Tween 80+Lecithin+Sodium thiosulfate (SaS+N). The SaS diluent was chosen because it was able to maintain cells viable without growth and was further used for plating SE86 on non selective medium (Tryptic Soy Agar-TSA) and on selective media (Mannitol Lysine Crystal Violet Brilliant Green Agar-MLCB; Brilliant Green Agar-BGA; Salmonella Shigella Agar-SS and Xylose Lysine Dextrose–XLD). The Thin Agar Layer method (TAL) i.e., selective media overlayed with non selective TSA was also evaluated. Results indicated that SE86 not exposed to NaDCC was able to grow in P, P+N, SaS+N and P+SaS, but not in SaS, that was able to maintain cells viable. SE86 exposed to NaDCC demonstrated similar counts after dilution in SaS and the plating on non selective TSA, selective media MLCB, BGA, SS and XLD and on TAL media. SE86, S. Typhimurium and S. Bredeney, exposed or not exposed to NaDCC, showed no significant differences in counts on TSA, XLD and XLD overlayed with TSA, suggesting that all those media may be used to quantify NaDCC-exposed Salmonella by plating method.

Selenite Cystine Agar for Enumeration of Inoculated Salmonella Serovars Recovered from Stressful Conditions during Antimicrobial Validation Studies

“…Strantz and Zottola [55] were only able to improve recovery with XLD and HE media by plating cells on TSA, allowing them to sit for 4 hrs of recuperation, and then overlaying with XLD or HE agar. Subsequent work by various investigators led to several modifications of the selective overlay technique, including the agar underlay [21] and thin agar layer [19,20,56,57] methods.…”

Survival assessment of Salmonella enterica in inoculated pork salami

“…In fact, the use of TAL agar enabled a higher mean recovery of S. enterica cells, at approximately 0.14 log CFU g -1 , than that with XLD agar (p <0.05). In contrast, Ferreira, Horvath and Tondo (2013) found no significant difference in the recovery of injured cells from S. Enteritidis, S. Typhimurium and S. Bredeney when XLD and TAL agar were compared. Other studies, however, reported results that corroborate the greater recovery of injured S. Typhimurium in associated culture media such as TAL (Chang et al, 2003;Kang & Siragusa, 1999;Kang & Fung, 2000;Wu et al, 2001).…”