Functional in vitro screening of probiotic strains for inoculation of piglets as a prophylactic measure towards Enterotoxigenic Escherichia coli infection.

Enterotoxigenic Escherichia coli (ETEC), being the major cause of post-weaning diarrhoea (PWD) in newly weaned piglets, induces poor performance and economic losses in pig production. This functional in vitro screening study investigated probiotic strains for use in suckling piglets as a prophylactic strategy towards PWD. Nine strains were evaluated based on their ability to: enhance intestinal epithelial barrier function, reduce adherence of ETEC F18 to intestinal cells, inhibit growth of ETEC F18, and grow on porcine milk oligosaccharides. Strains included in the screening were of the species Lactobacillus, Enterococcus, Bifidobacterium and Bacillus. Our in vitro screening demonstrated genus-, species and strain-specific differences in the mode of action of the tested probiotic strains. Some of the tested bifidobacteria were able to grow on the two porcine milk oligosaccharides, 3'-sialyllactose sodium salt (3'SL) and Lacto-N-neotetraose (LNnT), whereas most lactic acid bacteria strains and both Bacillus subtilis strains failed to do so. All probiotic strains inhibited growth of ETEC F18 on agar plates. All but the bifidobacteria reduced binding of ETEC F18 to Caco-2 cell monolayers, with the Enterococcus faecium strain having the most profound effect. All three lactic acid bacteria and Bifidobacterium animalis subsp. lactis counteracted the ETEC F18-induced permeability across Caco-2 cell monolayers with the E. faecium strain exhibiting the most pronounced protective effect. The findings from this in vitro screening study indicate that, when selecting probiotic strains for suckling piglets as a prophylactic strategy towards PWD, it would be advantageous to choose a multi-species product including strains with different modes of action in order to increase the likelihood of achieving beneficial effects in vivo.

Escherichia coli clonal group A causing bacteraemia of urinary tract origin.

Escherichia coli clonal group A (CgA) causes disease in humans. This is the first study investigating the prevalence of CgA among E. coli from non-urine, extraintestinal infections in a northern European country. E. coli blood (n = 196) and paired urine (n = 195) isolates from the same patients with bacteraemia of urinary tract origin were analysed. The isolates were collected from January 2003 through May 2005 at four hospitals in Copenhagen, Denmark. Pulsed-field gel electrophoresis (PFGE) patterns, antimicrobial resistance and patient characteristics were determined for all CgA isolates; presence of virulence-associated genes (VAGs) and serotypes were determined for the blood CgA isolates. Thirty blood isolates (15%) belonged to CgA. CgA blood isolates were associated with female patients and sulfamethoxazole-trimethoprim resistance and they harboured a distinctive VAG profile. The blood and urine isolates from each pair were found to be related in 26 of 27 CgA blood/urine pairs, confirming a urinary tract origin of infection. Furthermore, a relationship between the PFGE patterns of CgA blood/urine isolates and CgA isolates from UTI patients in general practice and a CgA isolate from a community-dwelling human reported previously, was found, suggesting a community origin of CgA. The finding of CgA strains in 15% of the E. coli bloodstream infections with a urinary tract origin in Denmark suggests that CgA constitutes an important clonal lineage among extraintestinal pathogenic E. coli. A reservoir of this pathogenic E. coli group in the community causing not only UTI but also more severe infections such as bacteraemia has implications for public health.