Figure 1.
Dynamics of colonization and infection of neonatal rats following an oral dose of E. coli K1. (a) Survival, colonization and bacteraemic status of neonatal rats dosed orally with 4–8 × 106 CFU E. coli A192PP at P2. Colonized animals were fed vehicle buffer (no phage) or 109 PFU K1E bacteriophage 12, 36 or 50 h after receiving colonizing bacteria. n = 12 for each group; data from at least two independent experiments. For bacterial quantification, 2 cm segments of proximal (PSI), mid- (MSI) and distal (DSI) small intestine and colon were excised from P2 and P9 neonatal rat pups. Colonization of small intestinal regions 24 and 48 h after oral dosing of neonatal rats with E. coli A192PP at P2 or P9 was determined by culture-dependent enumeration of E. coli K1 bacteria (b); n = 4–12 animals; line is median, *P < 0.05. (c) Total bacterial load in small intestinal and colonic tissue segments as determined by qPCR of 16S rRNA genes; median ± range, *P < 0.05 (Tukey’s multiple comparison).