Consideration of Occult Infection and Sepsis Mimics in the Sick Patient Without an Apparent Infectious Source

Background: Evaluation and treatment of the acutely ill patient is typically complicated by multiple comorbidities and incomplete medical histories. This is exemplified by patients with sepsis, whose care is complicated by variable presentations, shifting definitions, and a variety of potential sources. Many practitioners fail to consider and recognize less-common sources of infection in a timely manner. Additionally, multiple noninfectious conditions can present with the fever and tachycardia typical of the septic patient. The errors of anchoring and premature closure may lead to delay in, or failure of, diagnosis of these conditions. Objective: This review addresses the evaluation of the acutely ill-appearing patient without an apparent source, focusing on occult sources of infection and conditions that mimic sepsis. Discussion: Musculoskeletal, cardiac, neuraxial, and abdominal sources of sepsis should be considered in the acutely ill patient. Indwelling devices should be carefully examined for signs of infection. Consideration for sepsis mimics, such as neuroleptic malignant syndrome, malignant hyperthermia, medication toxicity, and thyroid storm, in patients who fail to respond to standard therapies for sepsis, may lead the physician to potentially reversible life-threatening diagnoses and management. Conclusion: In the seemingly septic patient who does not respond to antimicrobials and fluids, the differential should be broadened to include acutely life-threatening conditions that can mimic sepsis. A review of the patient's medical history, medications, and recent exposures can assist in identifying the source of the patient's elevated body temperature and tachycardia. Consideration of potential sources and other mimics of sepsis is needed in the emergency department.