De Reu K, Grijspeerdt K, Messens W, Heyndrickx M, Uyttendaele M, Debevere J, Herman L
Department of Animal Product Quality and Transformation Technology, Agricultural Research Centre-Ghent, Ministry of the Flemish Community, Brusselsesteenweg 370, 9090 Melle, Belgium.
Int J Food Microbiol. 2006 Dec 1;112(3):253-60. doi: 10.1016/j.ijfoodmicro.2006.04.011. Epub 2006 Jul 5.
Trans-shell infection routes and whole egg contamination of 7 selected bacterial strains; Staphylococcus warneri, Acinetobacter baumannii, Alcaligenes sp., Serratia marcescens, Carnobacterium sp., Pseudomonas sp. and Salmonella enteritidis, recovered from egg contents, were studied. The first objective was to correlate bacterial eggshell penetration with various eggshell characteristics and bacterial strains. An agar approach was used to assess the eggshell penetration. The second objective was to assess the contamination of whole eggs with the bacterial strains; whole intact eggs were used in this case. The intact shells of agar-filled and whole eggs were inoculated with 10(3) -10(4) cfu of the selected strains. During 3 weeks storage at 20 degrees C and 60% relative humidity, the bacterial eggshell penetration was regularly monitored. The whole egg contamination was only analyzed after 3 weeks. The eggshell characteristics such as area eggshell, shell thickness and number of pores did not influence the bacterial eggshell penetration. For each individual bacterial strain the mean cuticle deposition was lower for penetrated compared to non-penetrated eggshells. For the individual strain Carnobacterium sp. and for the global results of all strains this difference was statistical significantly. The whole egg contamination was not influenced by neither the area of the eggshell nor the porosity of the eggshell. The results of the agar approach indicate that the Gram-negative, motile and non-clustering bacteria penetrated the eggshell most frequently; Pseudomonas sp. (60%) and Alcaligenes sp. (58%) were primary invaders followed by S. enteritidis (43%). All selected strains were able to penetrate; penetration was observed most frequently after ca. 4-5 days. Particularly S. enteritidis was a primary invader of whole eggs: the membranes and/or the content of 32% of the whole eggs was contaminated. The remaining bacterial eggshell contamination with the selected strain was determined after 3 weeks storage. Penetrated eggshells and contaminated whole eggs showed a significantly higher bacterial contamination on the eggshell compared to non-penetrated eggshells and non-contaminated whole eggs respectively (global results of all strains). The influence of hen age on bacterial eggshell penetration and egg content contamination was not significant. While the agar approach is suitable to study the influence of the eggshell characteristics on the bacterial eggshell penetration, the intact egg approach gives an estimation of the penetration of the shell followed by the probability of survival and migration in whole eggs.
研究了从鸡蛋内容物中分离出的7种特定细菌菌株，即沃氏葡萄球菌、鲍曼不动杆菌、产碱菌属、粘质沙雷氏菌、肉杆菌属、假单胞菌属和肠炎沙门氏菌的跨蛋壳感染途径及全蛋污染情况。第一个目标是将细菌穿透蛋壳的情况与各种蛋壳特性及细菌菌株相关联。采用琼脂法评估蛋壳穿透情况。第二个目标是评估这些细菌菌株对全蛋的污染；在此情况下使用完整的全蛋。用10³ - 10⁴ cfu的选定菌株接种琼脂填充蛋和全蛋的完整蛋壳。在20℃和60%相对湿度下储存3周期间，定期监测细菌对蛋壳的穿透情况。全蛋污染情况仅在3周后进行分析。蛋壳特性如蛋壳面积、蛋壳厚度和气孔数量并未影响细菌对蛋壳的穿透。对于每种单独的细菌菌株，与未穿透的蛋壳相比，穿透的蛋壳上平均角质层沉积较低。对于单独的肉杆菌属菌株以及所有菌株的总体结果，这种差异具有统计学意义。全蛋污染情况既不受蛋壳面积也不受蛋壳孔隙率的影响。琼脂法的结果表明，革兰氏阴性、运动性和非聚集性细菌最常穿透蛋壳；假单胞菌属（60%）和产碱菌属（58%）是主要入侵者，其次是肠炎沙门氏菌（43%）。所有选定菌株都能够穿透；大约在4 - 5天后最常观察到穿透。特别是肠炎沙门氏菌是全蛋的主要入侵者：32%的全蛋的膜和/或内容物被污染。在储存3周后测定选定菌株对蛋壳的其余污染情况。与未穿透的蛋壳和未受污染的全蛋相比，穿透的蛋壳和受污染的全蛋在蛋壳上的细菌污染分别显著更高（所有菌株的总体结果）。母鸡年龄对细菌穿透蛋壳及蛋内容物污染的影响不显著。虽然琼脂法适用于研究蛋壳特性对细菌穿透蛋壳的影响，但完整蛋法可估计蛋壳的穿透情况以及随后在全蛋中存活和迁移的可能性。
