TABLE 1

Host- and microbe-centric views of outcomes of host-microbe interaction, in comparison with DRF view

StateMicrobe-centricHost-centricDamage-response framework
DiseaseMicrobes that cause disease have traits that allow them to cause disease. Such microbes are called pathogens. Pathogens are different from nonpathogens.Host susceptibility allows some microbes to cause disease. The capacity of a microbe to be a pathogen depends on host immunity.There are only microbes and hosts: disease is one state resulting from the host-microbe interaction where there is sufficient damage to affect host homeostasis.
CommensalismCommensal microbes have traits that allow them to adapt to host niches.Host defenses regulate and maintain microbial flora in host niches.There are only microbes and hosts: commensalism is one state of the host-microbe interaction where there is no damage to the host but there could be a benefit. When mutual benefit results from the interaction, a state of mutualism results.
Colonization (or carriage)Colonizing microbes are identified based on their propensity to reside in host tissues/niches. In most instances, the microbe is linked to a particular niche, e.g., Staphylococcus aureus in nares. In most/many instances, colonization is transient, rather than permanent/ongoing.Colonizing microbes are characterized as such based on host immunity. Thus, some microbes could colonize host tissues, whereas others cannot. In transient colonization, the microbe persists until the immune system responds. In persistent colonization, the host is unable to eradicate the state.There are only microbes and hosts: colonization is a state where the amount of damage incurred by the host is not sufficient to affect homeostasis. Host damage can trigger an immune response that eradicates the microbe. The interaction can also progress to disease. When damage is minimal, this state is indistinguishable from commensalism.