This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Amsterdam, D. Articles by Wolfe, M. W. Search for Related Content PubMed Articles by Amsterdam, D. Articles by Wolfe, M. W. Agricola Articles by Amsterdam, D. Articles by Wolfe, M. W.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1968 October; 16(10): 1460-1464
Copyright © 1968 American Society for Microbiology. All Rights Reserved.

Comparison of Reagent-impregnated Paper Strips and Conventional Tests for Distinguishing Escherichia from Aerobacter: Correlation with Colonial Morphology

Department of Microbiology, Isaac Albert Research Institute, Kingsbrook Jewish Medical Center, Brooklyn, New York 11203

ABSTRACT

The means for distinguishing Escherichia from Aerobacter (Enterobacter) differ in laboratories and range from complete dependence on colonial reactions on typical gram-negative media to reliance on one or more of the classical indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters. Three colonial types (one prejudged as Escherichia) of lactose-positive rods were catalogued on each of the most commonly used selective media, MacConkey Agar, Endo Agar, and E M B Agar. Each cultural type was presumptively diagnosed and then compared with the expected outcome of individual IMViC tests. The distribution of preliminary identifications was similar from growth patterns on MacConkey Agar and E M B Agar, but it differed markedly from Endo Agar. When organisms initially diagnosed by cultural methods were compared by single IMViC tests, it was found that for each colonial type one of the biochemical parameters was best suited. Thus, for those types initially considered Escherichia, the methyl red or Voges-Proskauer test results agreed most consistently; for other types, the citrate reaction was most satisfactory. In addition, when newly formulated reagent-impregnated paper strip methods for indole, Voges-Proskauer, and citrate were evaluated and compared to the standard methods, agreement was 97% for indole, 90% for Voges-Proskauer, and 95% for Simmons' citrate.