Pseudomonas stutzeri in pathological material.

Summary Six strains of Ps. stutzeri, recently isolated from pathological material obtained from human sources in this country, as well as two strains from the National Collection of Type Cultures, were compared with five strains of Ps. pseudomallei. The two species could readily be differentiated by means of the aerobic nitrate reduction test: Ps. stutzeri reduces nitrate rapidly and completely with the production of gas, whereas Ps. pseudomalZei reduces nitrate only to nitrite. Ps. stutzeri has a single polar flagellum, Ps. pseudomallei has several polar flagella. Ps. pseudomallei has heat-stable alkaline phosphatases and gives positive results in the tests for gelatin liquefaction, arginine desimidase, intracellular accumulation of poly-β-hydroxybutyrate, casein hydrolysis, KCN tolerance and opalescence on LV agar. Ps. stutzeri strains were negative in all these respects. At present it is not possible to say for certain whether Ps. stutzeri found in pathological material represents a secondary invader in a debilitated host or should be regarded as a contaminant.