Superinfection: another look.

Superinfection in the compromised host often poses a diagnostic and therapeutic dilemma for the physician who is concerned that a perplexing array of microorganisms might be involved. We believe that the differential diagnosis list can often be narrowed considerably by separating superinfection in the compromised host into five convenient categories: (1) infections due to the underlying disease itself; (2) infections due to the underlying disease plus therapy for that disease; (3) infections due solely to medicaments, operations, or procedures; (4) infections increased in severity but probably not in incidence; and (5) societally related infections. Use of this or a similar categorization should result in a more rational approach to differential diagnosis, should encourage a more focused diagnostic work-up, whould reduce the necessity for invasive procedures, should provide the microbiology laboratory information about specific organisms that should be sought sedulously, and should permit the selection of a more rational antimicrobial regimen prior to the availability of definitive microbiologic information.