Photodynamic therapy to control microbial biofilms

Microorganisms thrive in well-organized biofilm ecosystems. Biofilm-associated cells typically show increased resistance to antibiotics and contribute significantly to treatment failure. This has prompted investigations aimed at developing advanced and novel antimicrobial approaches that could effectively overcome the shortcomings associated with conventional antibiotic therapy. Studies are ongoing to develop effective curative strategies ranging from the use of peptides, small molecules, nanoparticles to bacteriophages, sonic waves, and light energy targeting various structural and physiological aspects of biofilms. In photodynamic therapy, a light source of a specific wavelength is used to irradiate non-toxic photosensitizers such as tetrapyrroles, synthetic dyes or, naturally occurring compounds to generate reactive oxygen species that can exert a lethal effect on the microbe especially by disrupting the biofilm. The photosensitizer preferentially binds to and accumulates in the microbial cells without causing any damage to the host tissue. Currently, photodynamic therapy is increasingly being used for the treatment of oral caries and dental plaque, chronic wound infections, infected diabetic foot ulcers, cystic fibrosis, chronic sinusitis, implant device-associated infections, etc. This approach is recognized as safe, as it is non-toxic and minimally invasive, making it a reliable, realistic, and promising therapeutic strategy for reducing the microbial burden and biofilm formation in chronic infections. In this review article, we discuss the current and future potential strategies of utilizing photodynamic therapy to extend our ability to impede and eliminate biofilms in various medical conditions.     

Differences in aerodynamic characteristics of new and dysfunctional Provox®2 voice prostheses in vivo

Tracheoesophageal voice prostheses need to be replaced due to increased airflow resistance or retrograde leakage of fluid into the trachea as a consequence of biofilm formation. Previous in vitro studies show a change of aerodynamic features of biofilm covered voice prostheses after removal of the prostheses out of the patient. To assess these changes in an in situ situation, aerodynamic characteristics were measured within 45 patients at the beginning and at the end of the wearing process of the Provox 2 voice prosthesis. As a consequence, the influence of biofilm formation on aerodynamic characteristics can be evaluated. In the majority of cases, leakage through the prosthesis was the reason for replacement. No differences were found in the total flow, volume range and intratracheal pressure (ITP) of the voice prostheses measured. The airflow resistance of biofilm covered prostheses was significantly reduced compared to new clean prostheses. However, no correlation was found between the extent of biofilm and the different aerodynamic features measured. Biofilm formation on the Provox 2 is responsible for both reduction in airflow resistance and leakage through the prosthesis by deterioration of the silicone rubber material.     

Gallstones Containing Bacteria are Biofilms: Bacterial Slime Production and Ability to Form Pigment Solids Determines Infection Severity and Bacteremia

Objective Gallstone bacteria provide a reservoir for biliary infections. Slime production facilitates adherence, whereas β-glucuronidase and phospholipase generate colonization surface. These factors facilitate gallstone formation, but their influence on infection severity is unknown. Methods Two hundred ninety-two patients were studied. Gallstones, bile, and blood (as applicable) were cultured. Bacteria were tested for β-glucuronidase/phospholipase production and quantitative slime production. Infection severity was correlated with bacterial factors. Results Bacteria were present in 43% of cases, 13% with bacteremia. Severe infections correlated directly with β-glucuronidase/phospholipase (55% with vs 13% without, P < 0.0001), but inversely with slime production (55 vs 8%, slime <75 or >75, P = 0.008). Low slime production and β-glucuronidase/phospholipase production were additive: Severe infections were present in 76% with both, but 10% with either or none (P < 0.0001). β-Glucuronidase/phospholipase production facilitated bactibilia (86% with vs 62% without, P = 0.03). Slime production was 19 (±8) vs 50 (±10) for bacteria that did or did not cause bacteremia (P = 0.004). No bacteria with slime >75 demonstrated bacteremia. Conclusions Bacteria-laden gallstones are biofilms whose characteristics influence illness severity. Factors creating colonization surface (β-glucuronidase/phospholipase) facilitated bacteremia and severe infections; but abundant slime production, while facilitating colonization, inhibited detachment and cholangiovenous reflux. This shows how properties of the gallstone biofilm determine the severity of the associated illness. Presented at the annual meeting of the Society for Surgery of the Alimentary Tract, held May 20–24, 2006 in Los Angeles, California.     

铜绿假单胞菌QS系统对大鼠皮肤溃疡面生物被膜形成的影响

目的 对比野生型铜绿假单胞菌及LasI和RhlI突变株铜绿假单胞菌感染大鼠皮肤溃疡创面后生物被膜形成的差异,探讨铜绿假单胞菌LasI及Rhll基凶在活体生物被膜形成中的作用.方法 制备大鼠皮肤溃疡模型,共60个创面,分成3组,前两组分别接种导人绿色荧光蛋白(GFP)质粒的野牛型铜绿假单胞菌及LasI和RhlI突变株铜绿假单胞菌,另一组不接种细菌作为空白对照组.分别于术后1、3 7 10 d切取标本,每个标本分成两等份,分别进行细菌学检测和光学显微镜及荧光显微镜观察二组上皮化及生物被膜形成情况.结果 除了第7天外,在第1、3、10天感染了野牛型铜绿假单胞菌创而组织内细菌数多于LasI及RhlI缺陷组的细菌数.空白对照组细菌数则更少,且野生组上皮化较慢,生物被膜较厚.结论 活体内LasI及RhlI基因缺损的铜绿假单胞菌生物被膜形成能力及组织感染能力均低于野生株.     

Understanding the microbiome of diabetic foot osteomyelitis: insights from molecular and microscopic approaches

Objectives

Rigorous visual evidence on whether or not biofilms are involved in diabetic foot osteomyelitis (DFO) is lacking. We employed a suite of molecular and microscopic approaches to investigate the microbiome, and phenotypic state of microorganisms involved in DFO.

新型mucA基因突变的铜绿假单胞菌生物被膜的形成和藻酸盐相关基因表达的研究

目的 确定黏液型铜绿假单胞菌PA17的mum基因突变位点，研究藻酸盐合成相关基因在其生物被膜形成过程中的表达，并观察PAl7生物被膜形成过程和形态。方法 PCR方法扩增铜绿假单胞菌PA17的mueA基因全长并测序；改良平板培养法建立PA17的生物被膜模型，半定量RT-PCR测定生物被膜形成24h、3d．6d时藻酸盐合成相关基因,algD、algU和algR的表达，并进行统计学分析；扫描电镜观察不同时间点的生物被膜形态。结果 PA17的mucA基因第166～333位核苷酸片段缺失，第342位A→G；其藻酸盐相关基因algD和algU均在生物被膜形成过程的第6天表达水平最高，algR在24h表达最高，单因素方差分析显示，上述基因在生物被膜形成过程不同时间点表达的差异有统计学意义；PA17于第6天形成成熟生物被膜，形态为薄膜状。结论 PA17是一株含新型mucA突变基因的黏液型铜绿假单胞菌，其藻酸盐相关基因在生物被膜形成的不同时间点的表达差异具有统计学意义，其生物被膜形态为薄膜状。     

Anastomotic false aneurysms with aortic Dacron graft after twenty-five years

One of the early diamond crimped knitted polyester (Dacron) grafts was surgically excised after implantation for 25 years in the aorto-billiac position because of false aneurysm formation at the three anastomotic sites. The sutures were no longer visible. While the areas around the false aneurysm were poorly incorporated, the graft limbs were well encapsulated with some endothelial-like cells on the luminal surface. The integrity of the graft was well preserved despite mild fraying and the disruption of one stitch.     

Comparative study of the efficacy of Ionic Silver Solution and Super Oxidized Solution in the management of chronic wounds

BackgroundChronic wounds are of many etiologies and difficult to treat. Many commercial products to manage such wounds are available, which claim to have good outcomes. Aim of this study was to compare the efficacy of Ionic Silver Solution and Super Oxidized Solution in the management of chronic wounds.MethodsPatients with chronic wounds were randomly placed in two groups-Group A (Ionic Silver Solution) and Group B (Super Oxidized Solution) with 30 patients each. The dressings were continued until the wound healed completely or the wound was ready for a definitive procedure. Wound parameters were recorded as per Bates Jensen Wound Assessment Tool (BJWAT) Score.ResultsFIfty patients completed the study. The scores were compared at the initiation and endpoint of treatment. The pretreatment total for BJWAT was 916 and 924 in group A and group B respectively, which was not statistically significant. Post-treatment improvement was noticed in both the groups and the score decreased to 510 and 675 in group A and group B respectively (p = 0.001). Ionic Silver Solution and Super Oxidized Solution both were found to be effective in improving the overall wound condition. However, Ionic Silver Solution was found to be more effective than Super Oxidized Solution in the healing of chronic wounds. Complete healing was noticed in a small number (6%) of patients. These agents can therefore best prepare the wounds for early surgical intervention.ConclusionBoth the agents were found to be safe and useful in the management of chronic wounds. However, Ionic Silver Solution was found to be more effective than the super oxidized solution in this study.     

三种细菌生物被膜中超广谱β-内酰胺酶的检测

目的检测肺炎克雷伯氏菌、大肠埃希氏菌、铜绿假单胞菌三种细菌的生物被膜(biofilm,BF)中超广谱β-内酰胺酶(Extended-spectrumβ-lactamases,ESBLs)的产生。方法用改良平板培养法在硅胶膜上建立肺炎克雷伯氏菌、大肠埃希氏菌、铜绿假单胞菌BF的体外模型。用银染法及扫描电镜对BF进行鉴定。用双纸片试验检测ESBLs,等电聚焦电泳测定β-内酰胺酶的等电点。结果三种细菌的各30株中,BF肺炎克雷伯氏菌组(A2组)中ESBLs的产生率最高(14株,46.7%),其浮游菌组(A1组)检出8株(26.7%);BF大肠埃希氏菌组(B2组)有10株(33.3%)产生ESBLs,其浮游菌组(B1组)检出6株(20.0%);BF铜绿假单胞菌组(C2组)有3株(10%)产ESBLs,其浮游组(C1组)为2株(6.7%)。浮游菌组中ESBLs的产生率低于BF菌组,其中肺炎克雷伯氏菌及大肠埃希氏菌的BF组和浮游菌组的检出率之间有显著差异(P<0.05)。A2组共检出14株产生ESBLs,有4种ESBLs,等电点分别为8.2(4株)、7.6(8株)、6.3(1株)和5.6(1株),A1组检出8株产生ESBLs,为3种ESBLs,等电点分别为8.2(2株)、7.6(5株)和5.6(1株);B2、B1组检出2种相同等电点分别为7.6(B1组4株,B2组6株)、8.2(B1组2株,B2组4株)的ESBLs;C1、C2组检出一种等电点为6.4的ESBLs(C1组2株,C2组3株)。以pI为7.6的β-内酰胺酶的检出率最高,其