A STUDY OF METHODS TO ENUMERATE THE MICROBIAL FLORA OF THE AVIAN EGG SHELL

Abstract

Experiments were done to compare results from three different methods used to enumerate the microbial flora of avian egg shells. The methods compared were: (a) swabbing the shell surface, (b) rinsing the shell surface, and (c) blending the entire shell and membranes after removal of the contents. Sanitized eggs held at 25 C were inoculated with a 24-hr old culture of Pseudomonas fluorescens by immersion for 5 min at 25 C. In the swab method, the entire surface of the inoculated egg was swabbed by rolling the swab in either direction twice as each area was swabbed. For the rinse method, the inoculated egg was held using a metal holder and rinsed with 100 ml of 0.1% peptone solution. With the blender method, the entire emptied inoculated egg shell and shell membranes were blended using a Sorvall Omni-Mixer to which a presterilized Mason jar was attached. As expected, the blender method gave significantly higher counts (P<0.05) than either the swab or rinse methods. There was no significant difference (P<0.05) between counts obtained by the swab and rinse methods.