Infections in the Non-Transplanted Immunocompromised Host

Background: Discoveries regarding the basic mechanisms underlying malignant disease, rheumatologic disorders, and autoimmune diseases have led to the development of many new therapeutic modalities that target components of the immune system. Most of these are antibodies or fusion proteins that interfere with components of the immune response that are playing both pathological and protective roles, resulting in variable degrees of immune suppression and a higher risk of infectious complications. Methods: Review of the English-language literature. Results: As these modalities are often used in combination with more traditional methods of immune suppression (e.g., corticosteroids), an increasing spectrum of infection is being encountered by clinicians. Febrile neutropenia requires rapid assessment and initiation of empiric broad-spectrum antimicrobial therapy. Persistence despite this therapy should prompt further investigation for drug-resistant bacteria and invasive fungal disease. Important pathogens to consider in patients with neutropenia, chronic steroid exposure, or underlying gastrointestinal malignant diseases include fungi (Candida, Aspergillus) and atypical bacteria (Nocardia, Clostridium septicum). Conclusions: This review focuses on observations regarding the greater risk of infections associated with many of these new biological modalities, as well as some specific infectious complications that may be encountered more commonly by the surgical consultant.