Figure 1.

Resource allocation in bacterial sepsis explains the need for disease tolerance as a defense strategy in neonates. Bacterial infection requires a massive, sustained energy input in order to mount an inflammatory, disease resistance response. (A) Adults have substantial energy stores and a resting metabolic rate that is not near its max capacity, which allows for a burst of energy to be rapidly allocated toward fighting the infection. If the infection results in a prolonged state of sepsis, eventually the amount of energy required to maintain the inflammatory response necessitates a siphoning from other vital functions. Too much energy siphoned can result in organ failure and lead to mortality. (B) Neonates have much higher basal metabolic needs, lower energy stores than adults, and are unable to increase resting energy expenditure during infection. Allocating resources toward fighting infection therefore comes at a greater cost to neonates, which has resulted in an increased reliance on disease tolerance as a defense strategy. Mortality due to sepsis may be a result of the energetic demands of a sustained response, rather than a direct result uncontrolled inflammation.