Abstract
BackgroundAvian pathogenic Escherichia coli (APEC) strains cause infectious diseases in poultry. Resveratrol is extracted from Polygonum cuspidatum, Cassia tora Linn and Vitis vinifera, and displays good antimicrobial activity. The present study aimed to investigate the antibiofilm effect of resveratrol on APEC in vitro. The minimum inhibitory concentration (MIC) of resveratrol and the antibiotic florfenicol toward APEC were detected using the broth microdilution method. Then, the effect of resveratrol on swimming and swarming motility was investigated using a semisolid medium culture method. Subsequently, the minimum biofilm inhibitory concentration (MBIC) and the biofilm eradication rate were evaluated using crystal violet staining. Finally, the antibiofilm activity of resveratrol was observed using scanning electron microscopy (SEM). Meanwhile, the effects of florfenicol combined with resveratrol against biofilm formation by APEC were evaluated using optical microscopy (OM) and a confocal laser scanning microscopy (CLSM).ResultsThe MICs of resveratrol and florfenicol toward APEC were 128 μg/mL and 64 μg/mL, respectively. The swimming and swarming motility abilities of APEC were inhibited in a resveratrol dose-dependent manner. Furthermore, resveratrol showed a significant inhibitory activity against APEC biofilm formation at concentrations above 1 μg/mL (p < 0.01). Meanwhile, the inhibitory effect of resveratrol at 32 μg/mL on biofilm formation was observed using SEM. The APEC biofilm was eradicated at 32 μg/mL of resveratrol combined with 64 μg/mL of florfenicol, which was observed using CLSM and OM. Florfenicol had a slight eradication effect of biofilm formation, whereas resveratrol had a strong biofilm eradication effect toward APEC.ConclusionResveratrol displayed good antibiofilm activity against APEC in vitro, including inhibition of swimming and swarming motility, biofilm formation, and could eradicate the biofilm.
Highlights
Avian pathogenic Escherichia coli (APEC) strains cause infectious diseases in poultry
Resveratrol had little effect on APEC growth at the 1/32 minimum inhibitory concentration (MIC), 1/16 MIC, 1/8 MIC, 1/4 MIC, and 1/2 MIC, which corresponded to concentrations of 4, 8, 16, 32, and 64 μg/mL, respectively (Fig. 1)
The inhibitory effect of resveratrol on APEC motility occurred in a dose-dependent manner
Summary
MIC determination and growth curve construction The MICs of resveratrol and florfenicol against planktonic APEC were 128 μg/mL and 64 μg/mL, respectively. The inhibitory effect of resveratrol on APEC biofilm formation occurred in a dose-dependent manner (Fig. 4). The results of the present study showed that resveratrol inhibited the swimming and swarming motility of APEC in a dose-dependent manner. It was speculated that resveratrol decreased the adhesion of APEC cells by inhibiting their swimming and swarming motility abilities, which in turn would inhibit biofilm formation [53, 54]. We found that resveratrol inhibited the APEC swimming and swarming motility, which might represent the mechanism by which resveratrol inhibits APEC biofilm formation; this requires further study.
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