Spectrum of Non-Typhoidal <i>Salmonella</i> Infections among Immunocompetent Individuals

Abstract

Non-typhoidal salmonellosis has emerged as an invasive infection in industrialized countries. Bacteremia and pleuropulmonary involvement usually occur in the setting of chronic illnesses such as diabetes, malignancies and HIV. We present three cases of non-typhoidal salmonellosis in immunocompetent patients presenting over a year period. A 66-year-old female presented with septic shock. She was started on vancomycin, doripenem and ciprofloxacin. Her blood cultures grew Salmonella enteridis that was also isolated from her urine and bronchoalveolar lavage fluid. Stool cultures were negative for Salmonella species. She had no epidemiologic risk factors for invasive Salmonella infection. Her immunodeficiency workup was negative. CT scan abdomen was unremarkable. She became hemodynamically stable and completed a two week course of Ceftriaxone without complications. A 58-year-old female presented with sub-acute onset of fever and dyspnea. CT chest showed bilateral pleural effusions. Left sided thoracentesis revealed purulent fluid consistent with empyema. Pleural fluid cultures grew Salmonella Group D. Blood, sputum and stool cultures remained negative. She denied consumption of raw eggs or exposure to pets, farm animals or reptiles. She was treated with Ceftriaxone for two weeks along with pigtail catheter drainage. Her immunodeficiency workup was negative. A 62-year-old man presented with acute left lower quadrant abdominal pain. CT Abdomen revealed a focal abnormality in abdominal aorta consistent with mycotic aneurysm. Blood cultures grew Salmonella Group D resistant to cephalosporins and bactrim, hence treatment with Meropenem was started. Subsequent blood, respiratory tract, urine and stool cultures remained negative. Due to high risk of perioperative complications, it was decided to follow the mycotic aneurysm expectantly. Antibiotics were deescalated to six weeks of Ertapenem followed by long term quinolone prophylaxis. He also did not have any epidemiologic risk factors for salmonellosis and his immunodeficiency workup was negative. These cases highlight the pathogenesis of this invasive organism that is transmitted though food borne route and causes bacteremic seeding of various sites such as lungs and pleura. It is extremely important to consider this organism in patients presenting with gram negative bacteremia leading to septic shock as well as endovascular infections.