A 24-year-old man with no known past medical history presented with a one week history of nightly fevers to 38.8-39C. Two weeks prior to presentation, he spent the weekend at Fire Island in Long Island, NY at a log cabin where he had a BBQ dinner. One day later he experienced severe abdominal cramps and non-bloody diarrhea. The diarrhea resolved, but he developed recurrent fevers one week later. On initial presentation he was febrile to 38.3C. Physical examination was unrevealing. Laboratory studies revealed a normal white blood cell count of 5.6 k/ul with a normal differential. Chest x-ray and urinalysis were negative. Blood and urine cultures were collected and the patient was sent home with a five day prescription for oseltamivir. Anaerobic blood culture grew gram negative rods and the patient was recalled to the emergency room. Laboratory studies revealed a normal white blood cell count of 5.8 k/ul with bandemia (1.9%) and mildly elevated transaminases (AST:93, ALT:92). The patient was admitted to the hospital and started on intravenous ceftriaxone. One day after admission initial blood culture was positive for Salmonella group D (Salmonella Enterica serotype Muenster) susceptible to all tested antibiotics. Subsequent blood cultures drawn before and after the initiation of intravenous antibiotic were negative. Other lab tests were notable for mild microcytic anemia (11.3 g/dl), low iron (27), ferritin >1000, LDH > 1000, elevated procalcitonin (0.25). HIV antibody and viral load testing were negative. A right upper quadrant ultrasound revealed mild hepatomegaly with nonspecific signs of hepatitis. No focus of infection was identified. After two doses of ceftriaxone, the patient remained afebrile and was discharged home to complete a fourteen day course of amoxicillin/clavulanic acid.
It is estimated that one percent of enteric infections with nontyphoidal Salmonella (NTS) result in bacteremia, but the true rate is unknown, as many primary enteric infections are mild or not microbiologically diagnosed. Risk factors for invasive NTS include extremes of age, immunosuppressive conditions, diabetes mellitus, hemoglobinopathies and malignant neoplasms. Our patient had none of these conditions which is what made this case unique.
Invasive NTS is very rare in immunocompetent hosts. Although more commonly associated with immunocompromised states and hemoglobinopathies, the risk of iNTS is not restricted to these groups. Alteration of the GI tract can also predispose to progression from enteric to systemic salmonellosis. Most bloodstream infections in the United States are due to Salmonella serogroup D. Invasive uncomplicated infection with NTS should be treated with minimum two weeks of antimicrobial therapy in a normal host with removal of the focus if and when feasible.