In a long-term care facility, thirteen residents present with watery diarrhea, abdominal pain, fever, and nausea. Which organism is the most likely cause?

• A. Clostridioides difficile
• B. Escherichia coli
• C. Staphylococcus aureus
• D. Salmonella enterica

Answer: (A)

A cluster of watery diarrhea in an elderly population within a long-term care facility strongly points to Clostridioides difficile infection. Antibiotic exposure common in such settings disrupts normal gut flora, allowing C. difficile to overgrow. The bacteria produce toxins that inflame and damage the colon, leading to profuse watery diarrhea, abdominal pain, and sometimes fever or nausea. The healthcare setting also facilitates transmission because C. difficile forms durable spores that survive routine cleaning, making infection control crucial.

While other organisms can cause diarrheal illness, the combination of a healthcare setting, many residents affected, and a likely history of antibiotic use makes C. difficile the most plausible cause. Diagnosis is through detecting the toxin or organism in stool, and management includes stopping the inciting antibiotic if possible and starting targeted therapy (such as oral vancomycin or fidaxomicin). Strict infection-control practices, including handwashing with soap and water, contact precautions, and spore-cleaning measures, are essential to stop spread.