Fighting biofilm: bacteriophages eliminate biofilm formed by multidrug-resistant Enterobacter hormaechei on urological catheters.

The Enterobacter cloacae complex (ECC) is a prevalent nosocomial pathogen associated with various human infections, which currently comprises several species, including Enterobacter cloacae and Enterobacter hormaechei. Strains capable of producing biofilm on various biotic and abiotic surfaces pose a particular threat. Therefore, we focused on three E. hormaechei strains in whose genomes the presence of the biofilm-related genes: fimA, csgA, csgD, and sdiA was confirmed. Kinetic of biofilm formation by these strains on urological catheters depended on the catheter material (silicon or latex), temperature (24 °C or 37 °C) and incubation time. The ability of phages to disrupt biofilm formation was assessed and found to be the most effective when phages were applied at an early stages of this process. Moreover, destruction of existing biofilm by bacteriophages and/or silver or copper nanoparticles was strain-dependent. Incubation with Enterobacter-specific bacteriophages enabled, in some cases, almost complete eradication of three-day biofilms attached to urological catheters. In genomes of two Enterobacter-specific bacteriophages the presence of regions encoding proteins with lytic activity were identified (6 regions in Entb_43 phage and 4 regions in Entb_45 phage genomes, respectively). These results highlight the threat of biofilm-related infections, but also indicate the multifaceted anti-biofilm activity of bacteriophages, which should be considered for useful in clinical practice.