Objective:To study the synergistic antibacterial effect of honeysuckle active components isochlorogenic acid combined with voriconazole+ ceftazidime on the early polymicrobial biofilms of Pseudomonas aeruginosa and Aspergillus fumigatus. Methods:The polymicrobial biofilm models in the early stages were established in vitro under static condition and then treated with isochlorogenic acid at different concentrations (250, 500, 1 000 μg/ml) and antibiotics (1 μg/ml of voriconazole+ 16 μg/ml of ceftazidime) alone or in combination for 24 h in vitro. Morphological changes in the polymicrobial biofilm structure were observed under scanning electron microscope (SEM). Crystal violet staining assay was used for polymicrobial biofilm quantitation. The total metabolic activity of Pseudomonas aeruginosa and Aspergillus fumigatus in formed polymicrobial biofilms were calculated with 2, 3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. Results:Under the SEM, it was observed that isochlorogenic acid could destroy the structure of early polymicrobial biofilms and reduce the extracellular matrix. The inhibitory effect of isochlorogenic acid combined with antibiotics against the polymicrobial biofilms was stronger than that of the antibiotics alone, and the amount of biofilms on the carrier was significantly reduced. Crystal violet staining assay showed that the total amount of biofilms in isochlorogenic acid (250, 500, 1 000 μg/ml) groups was significantly different from that in isochlorogenic acid (250, 500, 1 000 μg/ml) combined with antibiotics groups, antibiotics group and blank control group (all P<0.05). Moreover, there were significant differences between different concentration groups ( P<0.05). XTT assay suggested that the metabolic activity in the isochlorogenic acid combined with antibiotics group was significantly lower than that in the blank group and isochlorogenic acid group (the inhibition rate reached 50%). Conclusions:Isochlorogenic acid could not kill the Aspergillus fumigatus and Pseudomonas aeruginosa in polymicrobial biofilms in vitro, but exhibit destructive effect on the polymicrobial biofilms in the early stages. Isochlorogenic acid combined with voriconazole and ceftazidime had inhibitory effects against the early stages of polymicrobial biofilms of Aspergillus fumigatus and Pseudomonas aeruginosa in a concentration-dependent manner and was stronger than voriconazole combined with ceftazidime.