Evaluation of the Simultaneous E ects of Lactobacillus delbrueckii and L. lactis on Biofilms of Isolates from Chronic Ulcer Infections with Multiple-drug Resistance

Background: Bacterial biofilm is a major barrier to chronic wound healing. Therefore, the prevention of biofilm formation has an e ective role in accelerating the healing of these wounds. Today, probiotics’ anti-biofilm and antibacterial activity have been proven, and bacteriotherapy by probiotics is a new strategy for treating chronic ulcer infections. Objectives: The present study aimed to investigate the synergistic e ects of L. delbrueckii and L. lactis on biofilms of bacterial agents isolated from these ulcers in the human plasma biofilm model (hpBIOM). Methods: This study examined 82 specimens of chronic ulcer biofilms and identified bacterial isolates using phenotypic and molec-ular methods. After preparing the hpBIOM, 50 µL of each probiotic (109 CFU/mL) was added in two doses separately and simultane-ously. After 24 hours, 1 mL of bromelain (0.1 g/mL) was added to the complex and incubated at 37°C for two hours. Then, the surviving bacterial cells were counted by serial dilutions. Results: Among 119 bacterial isolates, Staphylococcus aureus (19%), Escherichia coli (17.0%), and Pseudomonas aeruginosa (14%) were the most common bacterial isolates. Lactobacillus delbrueckii showed anti-biofilm activity against multiple-drug resistance pathogens, Staphylococcus, P. aeruginosa, and Klebsiella pneumoniae. Although L. lactis had anti-biofilm activity against these three pathogens, its e ect was less than that of L. delbrueckii. The two probiotics did not have any synergistic e ect on the biofilms of the isolates. Conclusions: The results of the present study emphasized the potential of probiotics in destroying biofilms of isolates with multiple-drug resistance; however, their simultaneous use for this purpose requires further investigation.