A Tale of Two Infections: A Rare Synchronous Infection of Herpes Simplex Virus Oesophagitis and Clostridium difficile in an Immunocompetent Host.

Herpes simplex virus (HSV) is a common cause of infectious oesophagitis, predominantly affecting immunocompromised populations. Clostridium difficile (C. difficile), while prevalent in this population, is also a frequently encountered cause of nosocomial diarrhoea associated with antibiotic exposure, prolonged hospitalisation, or residence in long-term care facilities. A simultaneous HSV oesophagitis and C. difficile infection (CDI), despite the absence of the typical risk factors, is rare but possible, as illustrated by the following case.  A 95-year-old female patient presented with acute confusion, abdominal pain, diarrhoea, odynophagia, and dysphagia. The stool sample detected toxigenic C. difficile, and a course of fidaxomicin was completed. Oesophagogastroduodenoscopy (OGD) observed mucosal changes consistent with HSV oesophagitis, but treatment was initially withheld due to pending histopathology. She was readmitted due to the recurrence of her symptoms. HSV was confirmed, and the patient started on dual antimicrobial therapy with marked improvement and resolution.  This case study prompts us to consider non-traditional risk factors such as immunosenescence, frailty, proton pump inhibitors (PPIs), and nutritional deficiencies in addition to the lack of primary prevention measures.