Campylobacter jejuni is best described as which morphological form?

• A. Gram-positive rod
• B. Gram-negative coccobacillus
• C. Gram-negative spiral
• D. Gram-positive cocci

Answer: (B)

Campylobacter jejuni is a Gram-negative organism. On Gram stain its cells are slender and curved, which in lab reports are frequently described as short rods that may look coccoid. That combination—Gram-negative plus a small, oval/short-rod appearance—fits the term Gram-negative coccobacillus, making it the best choice among the options. It is not Gram-positive, and while many texts note its curved/spiral shape, the coccobacillus label effectively captures the typical short, somewhat oval appearance seen in routine staining. (For context, Campylobacter is also microaerophilic and motile with a polar flagellum, but the morphology-focused reasoning here centers on its Gram reaction and compact, curved-rod appearance.)