Which genus among Enterobacteriaceae is nonmotile?

Which genus among Enterobacteriaceae is nonmotile?

• A. Escherichia coli
• B. Klebsiella oxytoca
• C. Morganella morganii
• D. Providencia stuartii

Answer: (B)

Motility varies within Enterobacteriaceae, and some members move with flagella while others do not. Klebsiella species are classic nonmotile, lacking flagella. Among the options, an iconic motile organism is Escherichia coli, which has peritrichous flagella and can move. Providencia stuartii and Morganella morganii also have flagella and are motile. Therefore, Klebsiella oxytoca fits as the nonmotile genus in this group. This distinction helps in identification alongside other traits like capsule presence and lactose fermentation (Klebsiella typically ferments lactose and forms mucoid colonies).

Motility varies within Enterobacteriaceae, and some members move with flagella while others do not. Klebsiella species are classic nonmotile, lacking flagella. Among the options, an iconic motile organism is Escherichia coli, which has peritrichous flagella and can move. Providencia stuartii and Morganella morganii also have flagella and are motile. Therefore, Klebsiella oxytoca fits as the nonmotile genus in this group. This distinction helps in identification alongside other traits like capsule presence and lactose fermentation (Klebsiella typically ferments lactose and forms mucoid colonies).