Penetration time of Salmonella Heidelberg through shells of white and brown commercial eggs

Abstract

This study aimed at determining the minimum time required for the penetration of Salmonella Heidelberg inside the eggs after contact with contaminated material. Recently-collected brown and white eggs from laying hens between 45-50 weeks of age, reared in a commercial poultry house, were artificially contaminated by contact with wood shavings moistened with liquid inoculum of Salmonella Heidelberg in stationary-growth phase (10³-10(4) CFU g-1). According to type (white or brown), eggs were distributed into three different groups, with four replicates each: negative control group (no artificial contamination), positive control group (analyzed externally immediately after contamination and internally after the maximum storage period of the test group) and test group. Eggs were stored at controlled environmental temperature varying from 25ºC to 30ºC. In the test group, eggs contents (yolk and albumen) were pooled and analyzed after 1:00, 1:30, 2:00, 2:30, 3:00, 3:30, and 4:00 hours after contamination for the presence of Salmonella Heidelberg in 25g of this pool. The experimental unit consisted of five eggs in each test. The analysis protocol included pre-enrichment, selective enrichment, plating on selective agar, and biochemical and serological tests. The results obtained were submitted to logistic regression, which indicated that the presence of Salmonella Heidelberg was verified after 2:16 h and 2:44 h of contact with white and brown eggs, respectively

Comparative study of egg contamination with <i>Salmonella</i> Heidelberg and <i>Salmonella</i> Typhimurium

“…After 4 h of incubation, it was possible to observe contamination in the eggs by Salmonella.This finding demonstrates that contamination may occur within few hours after exposure to a contaminated environment such as chicken farms with poor or inadequate biosecurity measures. Similar results were observed by Raghiante et al (2010). These authors detected Salmonella 4 h after the egg was in contact with a contaminated substrate.…”

Antimicrobial resistance of potential pathogenic strains isolated from eggs produced by informal farms and sold in Abidjan, Ivory Coast

“…In addition, the level of eggs-laying surfaces cleanliness could affect the bacterial load of these eggs (Mallet et al, 2005). Attention should be paid during the manipulations of eggs as it was established that the bacterial load of egg shell influences the penetration of potentially harmful pathogens in egg through the shell (Schoeni et al, 1995;Braun et al, 1999;Raghiante et al, 2010).…”