Assessment of the risk of salmonellosis from internally contaminated shell eggs following initial storage at 18 °C (65 °F), compared with 7 °C (45 °F).

In the U.S., chicken-breeder farms that supply hatcheries typically store and transport eggs intended for broiler production at a temperature of 18.3 °C (65 °F). However, in case of surplus, some of these eggs may be diverted to human consumption. According to the U.S. Food and Drug Administration's 'Egg Safety Final Rule,' shell eggs intended for human consumption are required to be held or transported at or below 7.2 °C (45 °F) ambient temperature beginning 36 h after time of lay. We adapted a risk assessment model developed by the U.S. Department of Agriculture's Food Safety Inspection Service, to quantify human exposure to Salmonella Enteritidis and the risk of human salmonellosis if eggs are held and transported at 18.3 °C for up to 5.5 days after time of lay, as has been observed when hatchery eggs are diverted to human consumption, rather than held and transported at 7.2 °C within 36 h after time of lay. Storage at 18.3 °C leads to considerable bacterial growth in internally contaminated eggs. The model predicted that more than 10% of internally contaminated eggs would remain contaminated after in-shell pasteurization resulting in a 5-log10 reduction, and that some bacteria would survive after home-cooking. The model predicted that, alternatively, eggs stored at 7.2 °C after lay would have limited bacterial growth prior to pasteurization, and Salmonella would be very unlikely to be present after pasteurization. The predicted risk of salmonellosis from the consumption of eggs held and transported at 18.3 °C and subsequently diverted to human consumption is 25 times higher than the risk when eggs are held and transported at 7.2 °C.

Improved plating media for the detection of Salmonella species with typical and atypical hydrogen sulfide production.

The Salmonella detection ability of 2 surfactant-supplemental media, xylose-lysine-tergitol (Nia-proof) 4 (XLT4) and Miller-Mallinson (MM) agar, was compared against that of several commonly used plating media. XLT4 and MM appeared to be the most efficient in detecting Salmonella in meat products and food animal environments. MM was superior to XLT4 in detecting those increasingly more prevalent strains of Salmonella possessing weak to ultraweak H2S production characteristics.

Effect of d-mannose on fimbriae of bacterial isolates from chicken carcasses.

Pseudomonad-like microbial isolates were obtained from commercially processed broiler chicken carcasses for use in experiments to determine if d-mannose would interfere with their ability to form pellicles and rims and prevent agglutination of blood and yeast cells. Inhibition of agglutination, rim formation, and pellicle formation would provide evidence that d-mannose acts on the fimbriae to prevent attachment of microorganisms to surfaces. Presence of 4% d-mannose in the growth medium interfered with the formation and stability of the pellicle in some isolates. The pellicles affected by d-mannose did not cover the entire surface and were easily dispersed. Addition of d-mannose did not prevent the formation of rims to the same extent it prevented pellicle formation, and it was concluded that d-mannose did not completely prevent growth of fimbriae. The addition of d-mannose prevented the agglutination of 1% sheep blood, 1% horse blood, and yeast cells by interfering with the formation of fimbriae or the mechanism of attachment by fimbriae. These experiments provided evidence that d-mannose can be used to prevent attachment of isolates normally found on chicken carcasses to specific cell surfaces by occupying mannose-sensitive receptor sites on the cell.

Effect of D-mannose on motility, presence of flagella, and attachment of Pseudomonas aeruginosa to chicken skin cells.

Treatment of Pseudomonas aeruginosa with 1 to 3% d-mannose reduced cell activity indicating the flagella were affected by d-mannose but did not decrease attachment to chicken skin cells. Distance of migration of P. aeruginosa through a hollow tube filled with 1 to 4% d-mannose was reduced when compared with 0% d-mannose. This reduced movement through the tube indicated a possible affect on the flagella. Examination of P. aeruginosa with a light microscope showed that the addition of 1, 2, 3, and 4% d-mannose to a solution containing the organism removed the flagella from 27 to 40% of the cells.