Optimization of ferrioxamine E concentration as effective supplementation for selective isolation of Salmonella enteritidis in egg white

• Published in: Journal of food protection 2006-03, Vol.69 (3), p.634-638
• Main Authors: Thammasuvimol, G, Seo, K.H, Song, K.Y, Holt, P.S, Brackett, R.E
• Format: Article
• Language: English
• Subjects: Animals; bacterial contamination; Biological and medical sciences; Chickens; Colony Count, Microbial; Consumer Product Safety; Dose-Response Relationship, Drug; egg albumen; Egg White - microbiology; Escherichia coli; Escherichia coli K12 - drug effects; Escherichia coli K12 - growth & development; Feeding. Feeding behavior; Ferric Compounds - pharmacology; food contamination; Food industries; Food microbiology; food pathogens; Fundamental and applied biological sciences. Psychology; iron; Iron - metabolism; isolation; Peptides, Cyclic - pharmacology; plate count; Salmonella enteritidis; Salmonella enteritidis - drug effects; Salmonella enteritidis - growth & development; Salmonella enteritidis - isolation & purification; selective media; Time Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-69.3.634

Utilization of ferrioxamine E (FE) as a sole source of iron distinguishes Salmonella from a number of related species, including Escherichia coli. FE is not able to serve as a source of iron for E. coli or the Proteus-Providencia-Morganella group. This confers a selective advantage on Salmonella Enteritidis in egg white supplemented with FE. The optimum concentration of FE that promoted a selective advantage for Salmonella in egg white was determined. Four supplementation concentrations were evaluated (25, 50, 200, and 500 microgram/ml) in egg white artificially inoculated with proportionally mixed cultures of a rifampin-resistant strain of Salmonella Enteritidis (0.1 ml of 10(2) CFU/ml) and E. coli K-12 (0.1 ml of 10(1) through 10(8) CFU/ml). After a 24-h incubation at 37 degrees C, Salmonella and E. coli populations were enumerated. At higher concentrations of FE (>50 microgram/ml), both Salmonella and E. coli were able to use the iron supplement (1 to 8.5 log CFU/ml and 1.8 to 8 log CFU/ml, respectively); however, lower FE concentrations (less than or equal to 50 microgram/ml) exclusively promoted Salmonella growth. Salmonella was unrecoverable without supplementation. This study indicates that optimum levels of FE supplementation in egg can improve the selective detection for Salmonella Enteritidis among other competitive organisms.