Thermoresponsive oligomers reduceEscherichia coliO157:H7 biofouling and virulence

Abstract

Thermoresponsive polymers have potential biomedical applications for drug delivery and tissue engineering. Here, two thermoresponsive oligomers were synthesized, viz. oligo(N-isopropylacrylamide) (ONIPAM) and oligo(N-vinylcaprolactam) (OVCL), and their anti-biofouling abilities investigated against enterohemorrhagic E. coli O157:H7, which produces Shiga-like toxins and forms biofilms. Biofilm formation (biofouling) is closely related to E. coli O157:H7 infection and constitutes a major mechanism of antimicrobial resistance. The synthetic OVCL (MW 679) and three commercial OVCLs (up to MW 54,000) at 30 μg ml(-1) were found to inhibit biofouling by E. coli O157:H7 at 37 °C by more than 80% without adversely affecting bacterial growth. The anti-biofouling activity of ONIPAM was weaker than that of OVCL. However, at 25 °C, ONIPAM and OVCL did not affect E. coli O157:H7 biofouling. Transcriptional analysis showed that OVCL temperature-dependently downregulated curli genes in E. coli O157:H7, and this finding was in line with observed reductions in fimbriae production and biofouling. In addition, OVCL downregulated the Shiga-like toxin genes stx1 and stx2 in E. coli O157:H7 and attenuated its in vivo virulence in the nematode Caenorhabditis elegans. These results suggest that OVCL has potential use in antivirulence strategies against persistent E. coli O157:H7 infection.

Inhibition of Candida albicans biofilm and hyphae formation by biocompatible oligomers

“…These results concur with a previously reported result that OVCL exhibited antibiofilm activity in a temperature‐dependent manner in E. coli O157:H7 (Lee et al . ) and in S. aureus strains (Lee et al . ).…”

“…Previously, it was reported that the antibiofilm effects of OVCLs on E. coli O157:H7 and S. aureus are due to the down‐regulation of fimbriae production (Lee et al . ) and to the controlling of cell‐surface hydrophilicity and haemolytic activity (Lee et al . ), respectively.…”

“…A thermoresponsive OVCL was synthesized as previously reported (Lee et al . ). 1 H‐NMR and MALDI‐TOF analysis showed that the molecular weight (MW) of the synthesized OVCL was 679 (Lee et al .…”

“…Furthermore, biocompatible oligomers of N ‐vinylcaprolactam (OVCLs) have been reported to display antibiofilm and antivirulence activities against pathogenic Escherichia coli O157:H7 (Lee et al . ) and Staphylococcus aureus strains (Lee et al . ).…”

Temperature‐dependent control of Staphylococcus aureus biofilms and virulence by thermoresponsive oligo(N‐vinylcaprolactam)

“…Previously, we reported that OVCL has antibiofilm effects on E. coli O157:H7 via the down‐regulation of fimbriae production (Lee et al, ). The present study is the first to report that OVCL temperature‐dependently controls biofilm formation by three S. aureus strains, including a MRSA strain.…”