Observations on the bacterial flora of the hen's egg, with a description of new species ofProteusandPseudomonascausing rots in eggs

Abstract

1. Examination of several hundred eggs suggests that a high proportion (98%) of the whites of fresh eggs, and a slightly smaller proportion of the yolks (93%), are sterile.2. The shell of the egg is heavily infected with a heterogeneous flora, includingProteusandPseudomonasbacteria capable of producing rotting.3. The rots found in imported New Zealand and Australian eggs, and in English stored eggs, may be grouped into black rot, red rot, green rot, and a miscellaneous group.4. Black rot is brought about chiefly by strains ofProteus, but some species ofPseudomonascause some blackening. Red and green rots are due to infection with particular strains ofPseudomonas.5. A “fishy” odour is developed during the multiplication of certain atypical coliform organisms in the white, and a strong “cabbage-water” smell is often found after the growth ofPseudomonasspecies.6. Washing eggs under clean conditions has no effect on immediate bacterial penetration. Washing removes a protective coating so that if the eggs are subsequently soaked in a bacterial suspension, much more penetration of bacteria occurs than with untreated controls.7. Detailed descriptions of the coliform andProteusorganisms isolated are given. It is shown that the strains ofProteusfrom the eggs here investigated are antigenically not related toP. melanovogenesfound by Miles and Hainan to be the cause of black rot in South African eggs.8. It does not at present seem possible to assign specific names to the organisms isolated. The utilization of carbon sources by the species ofPseudomonasobtained from eggs, and by certain stock strains, and the possibility of a grouping on that basis, is discussed.