Clinical studies on a transformation test for identification of Acinetobacter (Mima and Herellea)

Abstract

Deoxyribonucleic acid (DNA) from 250 strains of aerobic, nonfermentative, gram-negative coccobacilli and rods were tested for the ability to transform a stable competent auxotroph of Acinetobacter (strain trp E 27) to prototrophy by using the method established by Juni. Several modifications of Juni's original procedure were made to adapt it for use in a clinical diagnostic laboratory. These modifications were directed primarily towards shortening the procedure to allow completion in a time framework consistent with current procedures. The modifications included changes in sterilization temperature, incubation time and temperature of the competent auxotroph and DNA preparation, overnight incubation temperature, and variations in the age of the auxotroph culture when used. Under these conditions, the transformation can easily be performed in 24 h, the final 16 to 18 h being an overnight uninterrupted incubation period. When used in conjunction with the glucose oxidative fermentative basal metabolism test, it provided a rapid highly efficient means for grouping and identifying acinetobacters which is far superior to a biochemical schema. Without exception, the 141 strains of DNA from Acinetobacter species were able to transform the auxotroph to prototrophy. None of the 105 oxidase-positive nonfermenters possessed DNA which was able to transform the Acinetobacter auxotroph to prototrophy.