Biofilm formation in clinical and laboratory strains of Escherichia Coli and Campylobacter Jejuni

Abstract

Biorilms are structured communities of bacterial cells enclosed in a self-produced polymeric matrix that are adherent to an inert or living surface. Their growth on the surface of catheter lines, artificial joints and other surgical implants is of major
medical concern. As many laboratory strains have become accustomed to standardised conditions, they are not necessarily representative of clinical strains. This study investigated the effect of horse blood, human blood and human blood
components on biofilm. formation by clinical and laboratory isolates of Escherichia coli and Campylobacter jejuni using a 96-well microtitre plate method, crystal violet staining and confocal laser scanning microscopy.
The results for the E. coli laboratory isolatesi ndicated a decreasein biofilm fonnation in Luria-Bertani (LB) broth supplemented with lysed horse blood, whole and lysed human blood, human plasma, human serum and whole and lysed human red blood cells. Conversely, the results for the E. coli clinical isolates showed an increase in biofilm formation in LB broth supplemented with either lysed horse blood or lysed human blood. Supplementation with human serum decreased biofilm formation by these clinical strains, whilst the addition of human plasma appeared to be inhibitory to biofilm formation. Of the clinical E. coli, only the urine derived strains showed a significant increase in biofilm formation in LB broth with added whole human red blood cells or whole human blood and produced haemolysin.
The results for the C. jejuni isolates used in this study indicated a large increase in biofilm formation when grown in Bolton Broth (BB) supplemented with lysed horse blood, lysed human blood or lysed human red blood cells. This increased biofilm
formation was not observed for cultures grown in BB supplemented with human serum, human plasma, whole human blood, iron or whole human red blood cells.