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This 1977 image depicts two analytical profile index strips, or API test strips, which had originally been manufactured in the United States, by Pierre Janin of Analytab Products, Inc., but is now manufactured by bioMérieux. These particular strips had been inoculated with inocula of unknown anaerobic bacteria. Though in a pragmatic sense, both the former strips, and the modern-made counterparts, are microbiologically similar, the newer versions reveal a different labeling format. In this example, the top strip produced a negative result, while the bottom revealed a positive outcome. The API strip consists of twenty small reaction tubes, known as cupules, each containing a unique reagent, which based upon the metabolic characteristics of the sample bacterium, will produce a color change in the tube. These tests provide for the identification of a limited number of Gram-negative, Enterobacteriaceae, or non-Enterobacteriaceae bacteria.
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CDC/ Dr. Theo Hawkins
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