Figure 1.

Neonatal mice are highly susceptible to Escherichia coli K1 sepsis. Neonatal 4- to 6-day-old mice and adult 2- to 4-month-old mice were infected intraperitoneally with 1 × 10³ and 1 × 10⁴ colony-forming units (CFU), respectively, of E. coli. A, Survival for 72 hours following infection (n = 18 adults, n = 79 neonates). ****P < .0001, log-rank test. Bacterial burden in the peritoneal wash (B) and blood (C) of infected animals. Results are combined for 2 independent experiments. Bars represent median. *P < .05, **P < .01, ****P < .0001, Mann–Whitney test.