Which test result is NOT associated with the identification of Enteroinvasive E. coli (EIEC)?

Enteroinvasive E. coli (EIEC) is characterized by specific microbiological properties that help in its identification. Non-lactose fermenting activity is a key trait of EIEC, making it lactose negative rather than positive. This aspect is crucial because many pathogenic strains of E. coli exhibit distinct biochemical behaviors that set them apart from other types.

Indole positivity can be associated with certain strains of E. coli, including some EIEC, as they can produce the enzyme tryptophanase. The Gram-negative rod shape is a general characteristic not exclusive to EIEC, as it applies broadly to many bacteria within the Enterobacteriaceae family, including several E. coli strains. Additionally, EIEC typically does not exhibit motility in standard laboratory conditions, as many pathogenic strains of E. coli are either non-motile or exhibit reduced motility.

Therefore, lactose positivity, which implies that the organism can ferment lactose—a characteristic of many strains of E. coli, particularly those classified as enterotoxigenic or enteropathogenic—is not a trait you would identify with EIEC. Instead, knowing that EIEC typically displays lactose negative results helps further differentiate it from other E. coli types that may have positive results in lactose fermentation tests