Objectives: To determine the effect of bovine lactoferrin (BLF) in the formation of biofilms in clinical enteroaggregative Escherichia coli (EAEC) strains and whether this effect is independent of iron.
Materials and methods: Two methods were used: (a) qualitative, by direct observation of optical microscopy, and (b) quantitative readings of the absorbance values using ELISA reader in the presence of bLf in concentrations of 0.01 mg mL and 1 mg/mL, with and without iron and no bLf (control). Analysis occurred in 122 strains of EAEC (60 strains from children with diarrhea and 62 healthy children) previously collected in a previous study of passive surveillance of diarrhea in the Southern Cone Lima. 31 strains of the same method were used for the qualitative study.
Results: (A) Qualitative method: 31 strains were evaluated with and without iron. Without iron biofi formation was 77% (24/31) in the control group versus 58% (14/31) with bLf of 0.01 mg/mL and 4% (1/31) with 1 mg/ml. Iron biofilm formation was 90% (28/31) in the control group versus 55% (17/31) with bLf of 0.01 mg/mL and 4% (1/31) with 1 mg/mL. (B) Quantitative method: without iron absorbance measured at OD 560 nm of the control group was 0.7 ± 0.5 versus 0.4 ± 0.3 with bLf 0.01 mg/mL and 0.3 ± 0.2 with bLf of 1 mg/mL (p<0.0001). This decrease in the presence of bLf included iron.
Conclusions: bLf tends to decrease the formation of biofilms, showing an inhibitory effect in clinical isolates of EAEC; this effect is not iron-dependent.