Survivability of Klebsiella aerogenes on Shell Egg Surfaces During Refrigerated Storage
Description
It is important to understand the survivability of microorganisms on egg surfaces for egg safety and for inoculation studies in antimicrobial investigations. It is also necessary to understand the coverage of cuticle (outermost protective layer) after preparing/treating eggs for inoculation study, as the cuticle may provide antimicrobial properties. A damaged cuticle can increase the risk of bacterial penetration inside the egg. In this study, the surface of egg was spot inoculated with nonpathogenic nalidixic acid resistant Klebsiella aerogenes B 199A on farm fresh egg (control) and after two treatments: eggs washed with tap water at 40 - 46 °C for 15 s and eggs washed with tap water at 40 - 46 °C for 15 s followed by soaking in ethanol for 60 s. The control and treated eggs were stored at 4 °C for 1 h, 24 h, and 48 h. No significant differences were found in K. aerogenes recovery (5.2 - 6.1 log cfu/egg) between all the treatments and control. The non-inoculated treated and control eggs also showed no significant difference from each other for cuticle coverage analyzed after each treatment using dye staining method. Our study showed that the attachment of bacteria on the surface of shell eggs was not affected by different treatments, and the cuticle may not have provided the antimicrobial properties to inactivate K. aerogenes. These results are useful for researchers in egg safety to determine post-inoculation attachment conditions. The data from this study can also be used in predictive growth models like ComBase.