The occurrence of the trehalose fermenting, tetracycline and polymyxin resistant phenotype among the Enterobacteriaceae.

In Proteus morganii, P. mirabilis, and Providencia stuartii the ability to ferment trehalose and resistance to tetracycline were associated in 90%-97% of the strains. The same was true of at least 78% of the strains of Serratia marcescens. Proteus vulgaris showed a more quantitative association of the two traits. As the characters occur independently in 3-10% of the strains, the association is considered to be due to simultaneous selection in some natural niche. The trehalose fermenting, tetracycline and polymyxin resistant species ferment few other carbohydrates, fewer than the remainder of the Serratia species.