Nonmotile among the Burkholderia species is
**Core Concept**
Burkholderia species are a group of Gram-negative bacteria that exhibit varying degrees of motility. Motility in bacteria is typically conferred by flagella, which are structures composed of flagellin proteins that provide the necessary force for movement. Nonmotile bacteria, on the other hand, lack these flagella or have defective flagellar structures.
**Why the Correct Answer is Right**
The correct answer is Burkholderia pseudomallei. Burkholderia pseudomallei is a nonmotile bacterium, which is an important characteristic in its identification and diagnosis. This is because the lack of motility helps to distinguish it from other Burkholderia species, such as Burkholderia mallei and Burkholderia cepacia, which are motile. The nonmotility of Burkholderia pseudomallei is due to the absence of flagella, which makes it unable to move.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Burkholderia mallei is actually a motile bacterium, not nonmotile. It has a single polar flagellum that provides its motility.
**Option B:** This option is incorrect because Burkholderia cepacia is a motile bacterium, not nonmotile. It has a single polar flagellum that provides its motility.
**Option D:** This option is incorrect because the other Burkholderia species mentioned, such as Burkholderia thailandensis and Burkholderia oklahomensis, are motile, not nonmotile.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the nonmotility of Burkholderia pseudomallei is a key characteristic in its identification and diagnosis. This is particularly important in the context of melioidosis, a disease caused by Burkholderia pseudomallei that can be severe and life-threatening.
**Correct Answer:** C.