The intestinal microbiota and susceptibility to infection in immunocompromised patients

PURPOSE OF REVIEW: Many infections of immunocompromised patients originate from the gastrointestinal tract. The pathogenesis of these infections often begins with alteration of the intestinal microbiota. Understanding the microbiota and how it can either cause or prevent infection is vital for the development of more effective prevention and treatment of these infections. This article reviews and discusses recent work providing insight into the intestinal microbiota of these at-risk immunocompromised patients. RECENT FINDINGS: Studies continue to support the premise that commensal bacteria, largely anaerobic, serve to maintain microbial stability and colonization resistance by preventing overgrowth or domination with more pathogenic bacteria, through interactions within the microbial community and with the host. In patients with immune suppression due to high-dose chemotherapy or hematopoietic stem cell transplantation, disruption of the microbiota through antibiotics as well as impairment of host immunity gives rise to perturbations favoring intestinal domination by pathogenic species, leading to increased bacterial translocation and susceptibility to systemic infection. SUMMARY: An understanding of the intestinal microbiota and the impact of antibiotics will help to guide our treatment of these gut-originating infections.