Bacterial biofilms are associated with at least 80% of human bacterial infections. The clinical treatment of biofilm infection is still arduous, and therefore many new treatment options are under study, such as probiotics and their derivatives, quorum sensing inhibitors, antimicrobial peptides, phage therapy, organic acids, light therapy, and plant extracts. However, most of these schemes are not mature, and it is important to develop new research directions of anti-biofilms.
Between 1988 and 1994, 78 cases (183 tendons) of flexor tendon injuries of the hand were repaired by microsurgical techique. The patients were followed up from4 to 6 months. The results were assessed according to the grading method of TAM. In 36 cases, 78 tendons were repaired by microsurgical suture and the excellentgood rate reached 76.2 per cent and the other 42 cases, 105 tendons were repaired with biological memberane wrapped arround the anastomotic site following microsurgical suture, in which, 32 cases, 77 tendons were followed up and the excellentgood rate was 89.5 per cent. The curative effect between the two groups hadsignificant difference statistically (Plt;0.05). Those cases with a bad results were mainly those injuries occurred in Zone II which had very poor soft tissue condition of the palm and thoes old cases having extensive scar tissue formation surrounding the tendon bed.
Seventeen cases involving 18 fingers of acute rupture of flexor tendon within the Zone Ⅱ were repaired by microsurgical technique for reconstructing the digital sheath with biological membrane since 1989. The excellent/good rate based on Eaton grading was 89%. The main procedure of the operation. the early postoperative rehabilitation and active excercises were described.
Objective To explore the mechanism of antibiotic delivery system targeting bacterial biofilm with linezolid (LZD) based on ε-poly-L-lysine (ε-PLL) and cyclodextrin (CD) (ε-PLL-CD-LZD), aiming to enhance antibiotic bioavailability, effectively penetrate and disrupt biofilm structures, and thereby improve the treatment of bone and joint infections. Methods ε-PLL-CD-LZD was synthesized via chemical methods. The grafting rate of CD was characterized using nuclear magnetic resonance. In vitro biocompatibility was evaluated through live/dead cell staining after co-culturing with mouse embryonic osteoblast precursor cells (MC3T3-E1), human umbilical vein endothelial cells, and mouse embryonic fibroblast cells (3T3-L1). The biofilm-enrichment capacity of ε-PLL-CD-LZD was assessed using Staphylococcus aureus biofilms through enrichment studies. Its biofilm eradication efficacy was investigated via minimum inhibitory concentration (MIC) determination, scanning electron microscopy, and live/dead bacterial staining. A bone and joint infection model in male Sprague-Dawley rats was established to validate the antibacterial effects of ε-PLL-CD-LZD. Results In ε-PLL-CD-LZD, the average grafting rate of CD reached 9.88%. The cell viability exceeded 90% after co-culturing with three types cells. The strong biofilm enrichment capability was observed with a MIC of 2 mg/L. Scanning electron microscopy observations revealed the effective disruption of biofilm structure, indicating potent biofilm eradication capacity. In vivo rat experiments demonstrated that ε-PLL-CD-LZD significantly reduced bacterial load and infection positivity rate at the lesion site (P<0.05). ConclusionThe ε-PLL-CD antibiotic delivery system provides a treatment strategy for bone and joint infections with high clinical translational significance. By effectively enhancing antibiotic bioavailability, penetrating, and disrupting biofilms, it demonstrated significant anti-infection effects in animal models.
Liposomes with precisely controlled composition are usually used as membrane model systems to investigate the fundamental interactions of membrane components under well-defined conditions. Hydration method is the most common method for liposome formation which is found to be influenced by composition of the medium. In this paper, the effects of small alcohol (ethanol) on the hydration of lipid molecules and the formation of liposomes were investigated, as well as its coexistence with sodium chloride. It was found that ethanol showed the opposite effect to that of sodium chloride on the hydration of lipid molecules and the formation of liposomes. The presence of ethanol promoted the formation of liposomes within a certain range of ethanol content, but that of sodium chloride suppressed the liposome formation. By investigating the fluorescence intensity and continuity of the swelled membranes as a function of contents of ethanol and sodium chloride, it was found that sodium chloride and ethanol showed the additive effect on the hydration of lipid molecules when they coexisted in the medium. The results may provide some reference for the efficient preparation of liposomes.
ObjectiveTo investigate the effect of accessory gene regulator C (agr C) specific binding peptides (named N1) on the biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride (PVC) materials in vitro.MethodsFirstly, the two strains (ATCC35984, ATCC12228) were cultured with N1 at concentrations of 100, 200, 400, 800, and 1 600 μg/mL, respectively. The control group was cultured with agrC specific binding unrelated peptides (named N0) at the same concentrations and the absorbance (A) value was measured after 24 hours to determine the optimal bacteriostatic concentration of N1. The two strains were cultured with N1 and N0 of the optimal concentration, respectively. The A values were measured at 6, 12, 18, 24, 30, and 48 hours to observe the effect of N1 on the biofilm formation ability of Staphylococcus epidermidis. On this basis, the surface structure of the biofilm on the surface of PVC material was observed by scanning electron microscopy after 6, 12, 18, 24, and 30 hours of incubation with PVC material sheet. The thickness of the biofilm was observed by laser confocal microscopy after 6, 12, 18, and 24 hours of incubation with ATCC35984 strain.ResultsThe optimal bacteriostatic concentration of N1 was 800 μg/mL. ATCC 12228 strain did not form obvious biofilm after being cultured with N1 and N0. When ATCC35984 strain was cultured with N1 and N0 for 12 hours, the difference in biofilm formation ability between groups N1 and N0 was statistically significant (P<0.05), but there was no significant difference at 6, 18, 24, 30, and 48 hours (P>0.05). Scanning electron microscopy examination showed that mature biofilm structure was observed in ATCC35984 strain and was not observed in ATCC12228 strain. Laser confocal microscopy observation showed that the number of bacteria in the group N1 was significantly lower than that in the group N0 at 12 hours, and the most of bacteria were dead bacteria. There was no significant difference in the number of bacteria at 6, 18, and 24 hours, and the most of them were live bacteria. The biofilm thickness of group N1 was significantly lower than that of group N0 at 12 and 18 hours (P<0.05).ConclusionThe intensity of N1 inhibiting the formation of Staphylococcus epidermidis biofilm is dose-dependent. During the aggregation period, N1 can inhibit the biofilm formation by hindering the bacterial growth and aggregation. The inhibition effect on mature biofilm is not obvious.
ObjectiveTo observe the bladder regeneration by collagen membrane scaffolds for bladder construction to find a new alternative scaffold material. MethodsTwelve healthy adult male Sprague Dawley rats, weighing 300-350 g, were randomly divided into collagen membrane scaffold group (experimental group, n=6), and sham operated group (control group, n=6). Upper hemicystectomy was performed and collagen scaffold was used for reconstruction in experimental group, while the bladder was turned over without bladder resection in control group. At 30 days after operation, the animals were sacrificed and grafts were harvested;HE staining and Masson staining were used to evaluate the bladder regeneration, immunohistochemical staining was performed with α-smooth muscleactin (α-SMA) and von Willebrand factor (vWF) markers to evaluate the percentage of α-SMA positive area and capillary number. ResultsThe rats of 2 groups survived to the end of the experiment, and no urine leakage or infection was observed in experimental group. Histologically, control group presented a pattern of normal bladder structure, experimental group presented a pattern of almost normal urothelium with a small amount of smooth muscle cells and a thin layer of undegraded collagen fibers. Immunohistochemically, experimental group showed ingrowth of smooth muscle fibers and new capillary formation along the collagen membrane scaffolds. The percentage of α-SMA positive area and capillary number in experimental group were significantly lower than those in control group (6.49%±2.14% vs. 52.42%±1.78% and 4.83±0.75 vs. 14.83±1.17, respectively)(t=40.40, P=0.00; t=17.62, P=0.00). ConclusionThe collagen membrane scaffolds could be an effective scaffold material for bladder reconstruction.
Objective To observe the inhibitory characteristics of silver nanoparticles (AgNP) on bacterial biofilms and investigate their inhibitory effect on biofilm formation on three common orthopedic biomaterials. Methods The minimal inhibitory concentration (MIC) and minimal biofilm inhibitory concentration (MBIC) of AgNP were determined by microplate dilution assay. Biofilms of Staphylococcus aureus (ATCC 25923) were cultured on three orthopedic biomaterials (titanium alloy, titanium oxide, and stainless steel) and intervened with AgNP at concentrations of 32, 16, 8, 4, 2 and 0 μg/mL to determine the MBICs on the three materials. The effects of AgNP on biofilm formation were analyzed by scanning electron microscopy and measuring optical density. Results The MIC and MBIC of AgNP in the microplate assay were both 16 µg/mL. The MBICs of AgNP on biofilm formation in titanium oxide, titanium alloy, and stainless steel were 16 μg/mL, 32 μg/mL, and 32 μg/mL, respectively. Among the three materials, the lowest optical density was observed on titanium oxide, while the highest was on titanium alloy. Conclusions AgNP has strong antibacterial biofilm characteristics and can prevent the formation of Staphylococcus aureus biofilm in vitro. Biofilm formation is most pronounced on titanium alloy, least on titanium oxide, and intermediate on stainless steel.
ObjectiveTo study the current situation and influencing factors of biofilm formation of digestive endoscopy in Zhongshan Hospital, Fudan University.MethodsFrom September 1st to 13th, 2020, ATP fluorescence assay and membrane filtration method were carried out on 130 endoscopes from the Endoscopy Center of Zhongshan Hospital, Fudan University. The type, number, source, duration of use and disinfection times in the past week were collected. Positive culture samples were identified by matrix-assisted laser desorption / ionization time of flight mass spectrometry. Logistic regression analysis was used to explore the factors affecting the formation of biofilms.ResultsThe total qualified rate of ATP assay and bacterial culture was 94.62% and 92.31% respectively. The 10 positive culuture samples were mainly composed of Pseudomonas aeruginosa, Moraxella osloensis, Stenotrophomonas maltophilia, Pseudomonas putida and Micrococcus luteus. Multivariate logistic regression analysis showed that the frequency of disinfection in the past week was associated with positive biofilm culture (P=0.001). The odds ratio of disinfection frequency more than 30 times in past week compared with disinfection frequency less than 15 times was 0.040, and 95% confidence interval was (0.005, 0.295).ConclusionsThe biofilm of digestive endoscopy in the Endoscopy Center of Zhongshan Hospital, Fudan University is mainly formed by aquatic bacteria. The formation biofilm can decrease by increasing disinfection frequency, and attention should be paid to the monitoring of endoscopic biofilm in the future.
ObjectiveTo study the effect of intercellular adhesion (ica) operon of Staphylococcus epidermidis on the inflammation associated with mixed biofilm of Staphylococcus epidermidis and Candida albicans on endotracheal tube material in rabbits. MethodsThe standard strains of Staphylococcus epidermidis RP62A (ica operon positive, positive group) and ATCC12228 (ica operon negative, negative group) were taken to prepare a bacterial solution with a concentration of 1×106 CFU/mL, respectively. Then, the two bacterial solutions were mixed with the standard strain of Candida albicans ATCC10231 of the same concentration to prepare a mixed culture solution at a ratio of 1∶1, respectively. The mixed culture solution was incubated with endotracheal tube material for 24 hours. The formation of mixed biofilm on the surface of the material was observed by scanning electron microscope. Thirty New Zealand rabbits, aged 4-6 months, were divided into two groups (n=15), and the endotracheal tube materials of the positive group and the negative group that were incubated for 24 hours were implanted beside the trachea. The body mass of rabbits in the two groups was measured before operation and at 1, 3, and 7 days after operation. At 1, 3, and 7 days after operation, the levels of interleukin 1β (IL-1β), IL-6, tumor necrosis factor α (TNF-α), and monocytechemotactic protein 1 (MCP-1) were detected by using an ELISA test kit. At 7 days after operation, the formation of mixed biofilm on the surface of the endotracheal tube materials was observed by scanning electron microscope, the inflammation and infiltration of tissues around the materials were observed by HE staining, and the bacterial infections in heart, lung, liver, and kidney were observed by plate colony counting method.ResultsScanning electron microscope observation showed that the mixed biofilm structure was obvious in the positive group after 24 hours in vitro incubation, but no mixed biofilm formation was observed in the negative group. In vivo studies showed that there was no significant difference in body mass between the two groups before operation and at 1, 3, and 7 days after operation (P>0.05). Compared with the negative group, the levels of MCP-1 and IL-1β at 1 day, and the levels of IL-1β, MCP-1, IL-6, and TNF-α at 3 and 7 days in the positive group all increased, with significant differences (P<0.05). Scanning electron microscope observation showed that a large amount of Staphylococcus epidermis and mixed biofilm structure were observed in the positive group, and a very small amount of bacteria was observed in the negative group with no mixed biofilm structure. HE staining of surrounding tissue showed inflammatory cell infiltration in both groups, and neutrophils and lymphocytes were more in the positive group than in the negative group. There was no significant difference in the number of bacterial infections in heart and liver between the two groups (P>0.05). The number of bacterial infections in lung and kidney in the positive group was higher than that in negative group (P<0.05).ConclusionIn the mixed infection of Staphylococcus epidermidis and Candida albicans, the ica operon may strengthen the structure of the biofilm and the spread of the biofilm in vivo, leading to increased inflammatory factors, and the bacteria are difficult to remove and persist.