Influence of glucose on biodegradable waterborne polyurethane blend together with LL-37 in inhibiting ESBLs producing Escherichia coli biofilm in vitro

Abstract:

Objective：To investigate the influence of the change of glucose concentration on ‘LL-37 sustained-release BWPU mem－brane’ in inhibiting the formation of the BF of urinary pathogenic ESBLs producing E.coli. Methods：Urinary pathogenic ESBLs pro－ducing E.coli isolates（E44） and standard strains ATCC25922（E0） were collected. Dynamic simulated bladder BF model was adopted. ‘Two-step approach’ was adopted to prepare new LDI-BWPU emulsion PCLPU33. ‘Physical dissolution and air-drying’ loading technique was adopted to prepare LL-37 sustained-release BWPU membrane.H group：high peptide（LL-37，2000 ?滋g/mL），L group：low peptide group（LL-37，250 ?滋g/mL），P group：positive control（Imipenem，8 ?滋g/mL），and N group：negative control（without antibacterial drug） were set up to incubate under artificial urine environment for 48hours. The influence of different glucose concen－trations（0，11.1，33.3 mmol/L），control of glucose concentration（33.3→0 mmol/L） on LL-37 sustained-release BWPU membrane in inhibiting BF were observed. The detection methods included viable bacteria count method. Syto-9/P fluorescent staining，combined with laser scanning confocal microscope，was applied to construct a space diagram to measure the BF thickness. Scan－ning electron microscope was adopted to observe the microscopic view of BF structure. One-way analysis of variance（ANOVA） was adopted in viable bacteria count，BF thickness and comparison of means of multiple groups. Results：For the observation point of different glucose concentration under the constantly infected artificial urine environment，the viable bacteria count and BF thickness of P group，H group，and L group were significantly decreased than that of N group（aP=0.000）. The viable bacteria count of group H was significantly decreased than that of L group（bP=0.000）in the glucose-free environment（G0 mmol/L）,and there was no statistical dif－ference between the H and L group in the glucose-containing environment（G11.1，33.3 mmol/L）（P＞0.01）；The BF thickness of the H group was significantly decreased than that of L group at the observation point of different glucose concentration（bP=0.000）. With the increase of glucose concentration，the viable bacteria count and BF thickness of the H and L groups，increased significantly（cP=0.000）. When glucose concentration was controlled（33.3→0 mmol/L） in the H and L groups，the viable bacteria count and BF thickness were were significantly decreased（dP=0.000）. Conclusion：When the glucose concentration is different under the constantly infected artificial urine environment，LL-37 sustained-release BWPU membrane can inhibit BF growth，kill BF bacteria and signifi－cantly inhibit BF formation.