Master of Science / Food Science Institute / Daniel Y.C. Fung / ECA Check® Easygel® Plus (ECA) is a pectin-based gelling system that reacts with calcium ions bound to a pre-treated Petri dish, eliminating autoclaving prior to use. It can chromogenically and/or fluorogenically distinguish three organisms: Escherichia coli, Salmonella spp., and coliforms. This study compared the recovery of these organisms to conventional media using stock culture, inoculated, and non-inoculated ground beef and ground turkey. ECA was compared to Violet Red Bile Agar (VRB), Violet Red Bile Agar with 4-methylumbelliferyl-β-D-glucuronide (VRB-MUG), Xylose Lysine Desoxycholate Agar (XLD), Escherichia coli/Coliform (ECC) Count Plate Petrifilm™, and Tryptic Soy Agar (TSA). The stock culture recovery of Salmonella Typhimurium for ECA, TSA, and XLD were 8.62, 8.69, and 6.82 log CFU/ml, respectively. There was very little difference between the media in the recovery of Escherichia coli and Cronobacter spp., formerly referred to as Enterobacter sakazakii. Mean counts of presumptive E. coli in ground beef were 7.24 and 7.41 logs for ECA and VRB-MUG. Total coliform mean counts were 7.43, 7.63, and 7.37 logs for ECA, Petrifilm™, and VRB. Presumptive Salmonella means were 6.68 and 6.21 logs on ECA and XLD, while total aerobic counts were 7.84 and 6.51 logs on ECA and TSA. At 6.72 logs, ECA recovered considerably more Salmonella than XLD (5.71 logs) from the inoculated ground turkey; ECA recovered 7.62 logs total aerobic count which was significantly more than TSA at 6.89 logs. Total counts for both non-inoculated ground meats resulted in significant differences between TSA recovery and all other media. ECA also recovered significantly more than Petrifilm™ from both non-inoculated foods. The randomly selected organisms recovered from ECA were identified using BBL™ Crystal™ Enteric/Nonfermenter ID or Gram-Positive kits, and correlated precisely to the chromogenic reaction of the colonies. ECA Check® Easygel® was efficient, less labor-intensive, comparable to, and, in some instances, better than conventional media at recovering target organisms.

Urinvägsinfektion är en av de mest förekommande infektionerna hos människan. För att visualisera urinvägspatogener kan det kromogena mediet UriSelectTM4 användas för diagnostik. Det primära syftet med studien var att utvärdera om det är möjligt att inkubera det kromogena mediet UriSelectTM4 i 5 % koldioxid istället för aerob miljö utan att totalväxt och morfologi påverkas. Vidare utvärderades totalväxt och antal fria kolonier vid odling på en halv UriSelectTM4-agarplatta med två odlingstekniker för att undersöka om fortsatt diagnostik är möjligt. Urinprover inkuberades i aerob miljö och i 5 % koldioxid och jämfördes visuellt utifrån totalväxt, antal fria kolonier, morfologi samt färgförändring på kolonier och agarn. Resultatet visade att totalväxt och antal fria kolonier endast skiljer i liten grad mellan inkubationsmiljöerna. Däremot förekom skillnader i morfologi och färg. Vidare kunde en halv agarplatta användas vid odling och fortsatt diagnostik. Studien visar därmed att UriSelectTM4 kan inkuberas i 5 % koldioxid utan att totalväxt, fria kolonier och agarn påverkas. / Urinary tract infection is one of the most common infections among humans. For diagnostics, the chromogenic media UriSelectTM4 can be used to visualize the urinary tract pathogens. The primary purpose of the study was to evaluate if the chromogenic media UriSelectTM4 could be incubated in 5% carbon dioxide instead of aerobic environment without impacting total growth and morphology. Furthermore, total growth and number of free colonies was evaluated when cultivating on a half UriSelectTM4 agar media with two streak patterns to examine if further diagnostics is possible. Urine samples were incubated in aerobic environment and in 5% carbon dioxide and visually compared for total growth, number of free colonies, morphology and color change of bacterial colonies and the agar media. The results showed that total growth and free colonies only had slight differences between the incubation environments. On the other hand, morphology and color of the colonies may vary. Further a half agar media could be used for cultivation and further diagnostics. Consequently, the study shows that UriSelectTM4 can be incubated in 5% carbon dioxide without any impact on total growth, free colonies or of the chromogenic media.