Bovine lactoferrin maintains antibacterial effect against neonatal Escherichia coli septicaemia isolates despite the presence of iron acquisition genes

Introduction. Escherichia coli is a dominant cause of neonatal sepsis for which no prevention measures currently exist. Lactoferrin (LF) is an iron-sequestering antibacterial protein that has been noticed to decrease neonatal late-onset sepsis. Hypothesis/Gap Statement. LF’s effect on in vitro growth of neonatal E. coli clinical isolates causing septicaemia is unknown. The prevalence of iron acquisition virulence genes which contribute to pathogenicity outcomes in these strains has also not been described in detail. Aim. To evaluate bovine lactoferrin’s (bLF) effects on the in vitro growth of neonatal septicaemia E. coli isolates, and to determine the presence of iron acquisition virulence genes in these isolates. Methodology. E. coli clinical strains isolated from blood of septic neonates, including the archetypal RS218 strain, all representing prevalent phylogroups and multi-locus sequence types among neonatal invasive strains were studied. Strains were grown in batch growth with 0, 0.1, 1.0 and 10 mg ml −1 bLF. OD measurements over time were used to generate growth curves, and the area under these curves was statistically compared using ANOVA or Kruskal–Wallis tests. Whole-genome sequencing (WGS) data were used to identify iron acquisition genes. Results. For all strains, growth decrease with 10 mg ml −1 bLF compared to zero was highly significant ( P