Rapid identification of Escherichia coli colonies from clinical sample inoculated on CHROMagar Orientation media (Becton Dickinson).

ABSTRACT

CHROMmagar Orientation media (Becton Dickinson) was developed and validated for the culture of urinary samples. It allows a direct identification of E. coli colonies without additional tests. As CHROMmagar Orientation media is superior to non-chromogenic media for the distinction of enterobacterial colonies, it is used for the inoculation of a large variety of samples in clinical laboratories. Direct identification of E. coli colonies cultured from these samples is not validated by the manufacturer. The difference in microbial ecology and the nature of the sample may impact CHROMagar Orientation performances for this use. We evaluated these media for the direct identification of E. coli colonies from 410 samples (excluding urine). Its sensitivity of 99% allows a direct identification of E. coli colonies cultured from a wide variety of samples. On-site testing using a large number of representative samples, allows laboratories to assess agar media performance and adapt their uses. Suppliers who are aware of frequent and non-recommended use of their culture media should perform tests and if conclusive, adapt their technical instructions.