Polymicrobial infection in patients with cancer: an underappreciated and underreported entity.

Polymicrobial infections account for ~15% of infections in immunocompromised patients with cancer. However, limited information exists regarding the spectrum and microbiology of these infections, even in severely neutropenic patients. Most studies describe only monomicrobial bloodstream infections in detail, and information regarding polymicrobial infections and nonbacteremic infections is often incomplete or not provided at all. The current lack of well-established definitions for various infections in the immunocompromised host, including pneumonia, neutropenic enterocolitis, and polymicrobial infections, probably plays an important role in the paucity of published information. In this review, we briefly describe the limited information available regarding polymicrobial infections in patients with cancer and address the need for establishing consensus definitions for site-specific polymicrobial infections in neutropenic and nonneutropenic patients. We anticipate that, as factual information regarding such infections becomes available, a more comprehensive understanding of the true scope and impact of these infections will emerge, leading to appropriate modifications in the diagnostic work-up and in the therapeutic approaches used in treating these patients.