Campylobacter jejuni is the Most Likely Causative Agent
In a patient presenting with acute diarrhea containing blood and mucus, Campylobacter jejuni (Option C) is the responsible pathogen, as this clinical presentation defines inflammatory bacterial diarrhea, which is specifically caused by invasive bacterial pathogens rather than viral agents. 1
Why Campylobacter jejuni is the Answer
Bloody diarrhea with mucus is pathognomonic for invasive bacterial pathogens, not viral agents. The IDSA guidelines explicitly state that diseases diagnosed by stool culture (shigellosis, salmonellosis, and campylobacteriosis) share inflammatory features including bloody stools 1
Campylobacter causes bacterial hemorrhagic enterocolitis, characterized by bloody, purulent, and mucoid stool—exactly matching this patient's presentation 2, 3
The CDC specifically recommends considering Campylobacter infection in patients with proctocolitis and bloody diarrhea, identifying this as the most common presentation of Campylobacter infection 4
Why Rotavirus and Norovirus are Incorrect
Rotavirus (Option A) causes watery, non-bloody diarrhea. The IDSA guidelines classify viral gastroenteritis as causing "acute watery diarrhea," not bloody diarrhea 1
Norovirus (Option B) causes vomiting and nonbloody diarrhea lasting 2-3 days or less according to IDSA clinical presentations 1
Viral gastroenteritis does not produce bloody diarrhea under normal circumstances. While one case report documented norovirus with bloody diarrhea, this was due to concurrent ischemic colitis—a rare complication, not the typical presentation 5
The presence of blood and mucus indicates an inflammatory process with mucosal invasion, which is characteristic of bacterial pathogens, not viral agents 2, 3
Clinical Features Supporting Campylobacter
Fecal leukocytes are commonly present in Campylobacter infection, indicating inflammatory diarrhea 4
Associated symptoms typically include fever, abdominal cramping, and tenesmus—features of invasive bacterial infection 1
Abdominal pain tends to be particularly severe in Campylobacter enteritis and may even mimic appendicitis 1
Critical Diagnostic Approach
Stool culture and microscopy should be performed to definitively identify Campylobacter and differentiate it from other bacterial pathogens like Shigella, Salmonella, and enterohemorrhagic E. coli 4
Testing for fecal leukocytes supports the diagnosis of inflammatory bacterial diarrhea 4
The IDSA guidelines recommend restricting bacterial testing to patients with bloody stools, fever, or abdominal tenderness—all features that increase the likelihood of identifying a bacterial pathogen like Campylobacter 1
Management Implications
Azithromycin should be initiated immediately if Campylobacter is suspected, especially within 72 hours of symptom onset, with a 96% clinical cure rate 4
Fluoroquinolones should be avoided due to resistance rates exceeding 90% in many regions, with 33% clinical failure rates when the isolate is resistant 4
Monitor for severe complications including Guillain-Barré syndrome, which is specifically associated with Campylobacter infection 1, 4