What is the most common cause of neutropenic fever?

The most common cause of neutropenic fever is indeed associated with Gram-negative bacteria. Neutropenic fever occurs in patients with a significantly reduced level of neutrophils, which are crucial for fighting off infections. When the neutrophil count is low, patients are at heightened risk for infections, particularly from organisms that are most frequently found in the gastrointestinal tract and the environment, many of which are Gram-negative.

These types of bacteria, such as Escherichia coli and Pseudomonas aeruginosa, often lead to infections in neutropenic patients due to the breakdown of the mucosal barriers, especially when patients undergo chemotherapy or have hematologic malignancies. Gram-negative bacteria are often more virulent and can precipitate severe systemic infections rapidly, which aligns with the clinical presentation of neutropenic fever, characterized by fever due to these infections.

While Gram-positive bacteria, fungal infections, and viral infections can also cause fever in neutropenic patients, they are less common than Gram-negative bacterial infections. This reinforces the importance of prompt identification and treatment of suspected Gram-negative infections in neutropenic patients to mitigate the risk of severe complications.