Which genus is typically nonmotile among common gram-negative enteric bacteria?

Which genus is typically nonmotile among common gram-negative enteric bacteria?

• A. Enterobacter cloacae
• B. Klebsiella oxytoca
• C. Morganella morganii
• D. Providencia stuartii

Answer: (B)

Motility varies among gram-negative enteric bacteria, with many possessing flagella and being motile. Klebsiella species, including Klebsiella oxytoca, are typically nonmotile because they lack flagella. In the lab, they show no movement in motility tests and often form smooth, sometimes mucoid colonies due to a thick capsule. This nonmotile trait helps distinguish them from other common enteric genera like Enterobacter, Morganella, and Providencia, which are motile. So, Klebsiella oxytoca is the genus typically nonmotile.

Motility varies among gram-negative enteric bacteria, with many possessing flagella and being motile. Klebsiella species, including Klebsiella oxytoca, are typically nonmotile because they lack flagella. In the lab, they show no movement in motility tests and often form smooth, sometimes mucoid colonies due to a thick capsule. This nonmotile trait helps distinguish them from other common enteric genera like Enterobacter, Morganella, and Providencia, which are motile. So, Klebsiella oxytoca is the genus typically nonmotile.