Second most common cause of diarrhea?

• A. Escherichia coli O157:H7
• B. Salmonella enteritidis
• C. Campylobacter Jejuni enteritis
• D. Clostridioides difficile

Answer: (C)

Campylobacter jejuni enteritis is a leading cause of infectious gastroenteritis and is often cited as the second most frequent cause of diarrhea in many populations. It typically arises from eating undercooked poultry, unpasteurized milk, or contaminated water, and presents with fever, crampy abdominal pain, and often inflammatory, sometimes bloody stools. Diagnosis is usually by stool culture on selective media under microaerophilic conditions, though PCR is increasingly used.

Compared with E. coli O157:H7, which can cause hemorrhagic colitis and potential kidney injury, Campylobacter more commonly produces inflammatory diarrhea without that severe bleeding pattern in most cases. While Salmonella enteritidis is also a common bacterial cause, Campylobacter consistently ranks highly in surveillance data for sporadic diarrheal illness. Clostridioides difficile is a major cause of antibiotic-associated diarrhea, especially in healthcare settings, rather than a general second-most-common cause of diarrhea.