Abstract

Aims: To compare in vitro the inhibitory activity of four bacteriocin producing E. coli to a well-characterized panel of Salmonella strains, recently isolated from clinical cases in Switzerland.
Methods and Results: A panel of 68 non-typhoidal Salmonella strains was characterized by PFGE analysis and susceptibility to antibiotics. The majority of tested strains were genetically different, with 40% resistant to at least one antibiotic. E. coli Mcc24 showed highest in vitro activity against Salmonella (100%, microcin 24), followed by E. coli L1000 (94%, microcin B17), E. coli 53 (49%, colicin H) and E. coli 52 (21%, colicin G) as revealed using a cross-streak activity assay.
Conclusion: E. coli Mcc24, a genetically modified organism producing microcin 24, and E. coli L1000, a natural strain isolated from human feces carrying the mcb-operon for microcin B17-production, were the most effective strains in inhibiting in vitro both antibiotic resistant and sensitive Salmonella isolates.
Significance and Impact of the Study: Due to an increasing prevalence of antibiotic resistant Salmonella strains, alternative strategies to fight these foodborne pathogens are needed. E. coli L1000 appears to be a promising candidate in view of developing biotechnological alternatives to antibiotics against Salmonella infections.