Why is Yersinia enterocolitica often mistaken for appendicitis in children, and what growth characteristic aids detection?

• A. Causes gallbladder infection; grows in high salt
• B. Mimics appendicitis; grows only in anaerobic conditions
• C. Causes mesenteric adenitis mimicking appendicitis; grows well at cold temperatures (cold enrichment)
• D. Causes appendicitis-like diarrhea; grows best at body temperature

Answer: (A)

Yersinia enterocolitica often causes mesenteric adenitis, an inflammation and enlargement of the lymph nodes in the ileocecal region. That inflammation can produce right lower quadrant pain and clinical signs that resemble appendicitis in children, leading to confusion with true appendicitis even though the underlying cause is lymphoid inflammation rather than an inflamed appendix.

A helpful growth characteristic is its ability to grow well at cold temperatures, around 4°C. This psychrotrophic property enables cold enrichment, a technique used to isolate Y. enterocolitica from stool or other specimens when routine incubation at body temperature may miss it. Cold enrichment enhances detection because the organism can thrive in the cold while many other enterics do not, making it easier to identify in suspected cases.

Other options don’t fit because the organism is not primarily a gallbladder pathogen, it is not strictly anaerobic (it is facultatively anaerobic), its usual presentation is RLQ pain from mesenteric adenitis rather than diarrhea-dominant disease, and its diagnostic growth advantage is not at body temperature but at cold temperatures.