Antimicrobial Agents Used in the Treatment of Peri‐Implantitis Alter the Physicochemistry and Cytocompatibility of Titanium Surfaces

Background: Chemotherapeutic agents (ChAs) are considered an integral part of current treatment protocols for the decontamination of titanium implants with peri‐implantitis, based on their antimicrobial effect. Despite the proven antimicrobial effect of ChAs on titanium‐bound biofilms, previous studies have elucidated an unexpected disassociation between bacterial reduction and biologically acceptable treatment outcomes. In this study, the authors hypothesize that ChAs residues alter titanium physicochemistry and thus compromise cellular response to decontaminated surfaces. Methods: Grit‐blasted acid‐etched titanium disks were contaminated with multispecies microcosm biofilms grown from in vivo peri‐implant plaque samples. To simulate implant decontamination, the contaminated disks were burnished with 0.12% chlorhexidine, 20% citric acid, 24% EDTA/1.5% NaOCl, or sterile saline and assessed surface physicochemical properties. Sterile untreated surfaces were the controls. The biologic effects of decontamination were assessed via cell proliferation and differentiation assays. Results: Bacterial counts after decontamination confirmed that the ChAs were antimicrobial. X‐ray photoelectron spectroscopy invariably detected elemental contaminants associated with each ChA molecule or salt that significantly altered wettability compared with controls. Notably, all surfaces with ChA residues showed some cytotoxic effect compared with controls (P <0.05). Increased cell counts were consistently found in the saline‐treated group compared with chlorhexidine (P = 0.03). Interestingly, no association was found between antimicrobial effect and cell counts (P >0.05). Conclusions: ChA‐specific residues left on the titanium surfaces altered titanium physical properties and adversely affected the osteoblastic response irrespective of their observed antimicrobial effect. Chlorhexidine may compromise the biocompatibility of titanium surfaces, and its use is not recommended to detoxify implants. Sterile saline, citric acid, and NaOCl‐EDTA may be proposed for use in the treatment of peri‐implantitis. Contrary to previous studies that recommended the selection of ChAs for the decontamination of titanium implants according to their antimicrobial effects, the present study demonstrated that the restoration of the biocompatibility of contaminated titanium surfaces is also contingent on the preservation of titanium material properties.     

头孢他啶对早期和成熟期绿脓假单胞菌生物膜菌作用的差别

目的 观察头孢他啶对早期绿脓假单胞菌(PA)生物膜(BF)细菌和成熟期PABF细菌作用的差别。方法 通过恒化器结合改良的Robbins装置分别建立早期和成熟期PABF，用64μg／ml头孢他啶分别作用于两种生物膜细菌24h，扫描电镜观察结果，并分析生物膜内活菌数的变化。结果 头孢他啶作用24h后，扫描电镜观察显示早期PABF内的细菌已基本被清除，活菌清除率为99．62％，而成熟期PABF内仍有大量细菌存在，其活菌清除率仅为10．02％，两者差异有显著性。结论 成熟期PABF细菌比早期PABF细菌对头孢他啶具有更强的抵抗性。     

激光共聚焦显微镜观察铜绿假单胞菌生物膜的形成

目的采用激光共聚焦显微镜技术观察铜绿假单胞菌形成生物膜,进一步揭示了铜绿假单胞菌生物膜形成过程。方法使用盖玻片生物膜培养法,培养铜绿假单胞菌的生物膜,在培养2、4、8、12、16、24、48和72h后取出盖玻片,用异硫氰酸荧光素(FITC)标记的刀豆蛋白A(FITC-ConA)和碘化吡啶(PI)双重免疫荧光技术染色,用激光共聚焦显微镜(CLSM)观察铜绿假单胞菌生物膜形成过程与特点。结果获得生物膜形成过程不同时间点的CLSM图像,观察到铜绿假单胞菌一般在24h后开始逐渐形成生物膜,在72h形成稳定的生物膜。结论双重免疫荧光染色技术和CLSM是观察细菌生物膜形成过程的有效手段。     

Antimicrobial activity of silver-containing dressings on wound microorganisms using an in vitro biofilm model

Antimicrobial dressings such as those containing silver are now being used widely to control wound bioburden, and tests to demonstrate their efficacy predominantly involve in vitro models using free-living or planktonic bacteria. In this present study a wide range of antibiotic-sensitive and resistant bacteria were tested in their quasi-sessile state using a standard agar assay and a second method used a poloxamer gel (true biofilm state - poloxamer encourages microorganisms to exhibit a more clinically relevant biofilm phenotype) technique. The antimicrobial activity of two silver dressings, a silver-containing Hydrofiber (SCH) dressing and a nanocrystalline silver-containing dressing (NCS), were evaluated on a variety of microorganisms, using a zone-of-inhibition (ZOI) test. When grown on agar (presenting a quasi-sessile state of each organism), the antibiotic-susceptible microorganisms were generally more susceptible to the SCH dressing compared with the NCS. ZOIs associated with SCH dressing ranged between 5.7 and 17.5 mm; those for the NCS against the same group of organisms ranged between 1.9 and 8.6 mm. When grown on poloxamer gel, (presenting the biofilm state of each organism) the same group of microorganisms were less susceptible to both dressings. The SCH dressing was most effective against strains of Pseudomonas aeruginosa, Candida albicans and Staphylococcus aureus (ZOI range: 2.6-6 mm); the NCS was most effective against strains of Klebsiella pneumoniae, Enterococcus faecalis and Escherichia coli (i.e. ZOI range: 1-2.8 mm). Similarly to the antibiotic-susceptible microorganisms, nine of ten antibiotic-resistant bacterial strains when grown on agar were more susceptible to the SCH dressing compared with the NCS. Although the microorganisms tested were universally less susceptible to the silver dressings when in their biofilm state, in the majority of cases, the SCH dressing demonstrated greater biofilm-inhibiting activity than the NCS.     

Comparative in vitro investigation of the cariogenic potential of bifidobacteria

ObjectiveThis study aimed to assess the in vitro cariogenic potential of some Bifidobacterium species in comparison with caries-associated bacteria.DesignBifidobacterium lactis, Bifidobacterium longum, Bifidobacterium animalis, Bifidobacterium dentium, Lactobacillus acidophilus, Lactobacillus casei, Actinomyces israelii, Streptococcus sobrinus and Streptococcus mutans were tested for acidogenicity and aciduricity by measuring the pH of the cultures after growth in glucose and bacterial growth after exposure to acid solutions. Biofilm biomass was determined for each species either alone or associated with S. mutans or S. mutans/S. sobrinus. Enamel hardness was analyzed before and after 7-days biofilm formation using bacterial combinations.ResultsB. animalis and B. longum were the most acidogenic and aciduric strains, comparable to caries-associated bacteria, such as S. mutans and L. casei. All species had a significantly increased biofilm when combined either with S. mutans or with S. mutans/S. sobrinus. The greatest enamel surface loss was produced when B. longum or B. animalis were inoculated with S. mutans, similar to L. casei and S. sobrinus. All strains induced similar enamel demineralization when combined with S. mutans/S. sobrinus, except by B. lactis.ConclusionThe ability to produce acidic environments and to enhance biofilm formation leading to increased demineralization may mean that Bifidobacterium species, especially B. animalis and B. longum, are potentially cariogenic.     

Bacterial biofilm in adenoids of children with chronic otitis media. Part I: a case control study of prevalence of biofilms in adenoids,risk factors and middle ear biofilms

Background: Biofilms are communities of bacteria embedded in a self-produced glycocalyx matrix. Adenoids have been shown to harbor bacterial biofilms.

Aim/objectives: To compare the prevalence of biofilms in adenoid of children with chronic otitis media (COM) (group1) versus a control group without any COM (group 2) having adenoids removed because of hypertrophy.

Material and methods: One hundred and three children were prospectively enrolled in this case-control study, group 1 (n?=?52) and group 2 (n?=?51). The main outcome measurement was the prevalence of biofilm in adenoidectomy specimens analyzed using confocal laser scanning microscopy. Children in group 1 who had middle ear (ME) effusion and requiring the insertion of a tympanostomy tube underwent biopsy of the ME mucosa and effusion sampling.

Results: Biofilms were found in adenoids’ specimens of both groups and in the ME biopsy and effusion. The biofilm prevalence in adenoids was 63.5% (33/52) in group 1 and 47.1% (24/51) in group 2. Day nursery and previous antibiotics intake were significantly more frequent in group 1 than in group 2.

Conclusions and significance: This case-control study demonstrates that adenoid tissue in children with COM contains more mucosal biofilms than adenoid tissue removed for hypertrophy. Biofilm was seen in ME biopsies and effusion.     

Biofilms and bacterial imbalances in chronic wounds: anti‐Koch

Microbial imbalances and synergistic relationships between bacteria in medically important biofilms are poorly researched. Consequently, little is known about how synergy between bacteria may increase the net pathogenic effect of a biofilm in many diseases and infections, including chronic wounds. Microbial synergy in chronic wounds may increase virulence and pathogenicity, leading to enhanced tissue degradation, malodour and in some cases, an impairment of the host immune response. Microbial synergy and growth within a biofilm provide a competitive advantage to the microorganisms cohabiting in a wound, thereby promoting their survival and tolerance and resistance to antimicrobial agents. The aim of this article was to provide greater insight into microbial imbalances found within wound biofilms and the significance they may have on non healing and infected wounds. We also present two possible hypotheses which could explain the role microorganisms play in non healing chronic wounds and offer possible strategies for combating harmful and detrimental biofilms.     

In vitro bactericidal efficacy of a new sun- and heat burn gel

We assessed the in vitro bactericidal efficacy of a new sunburn gel (Rescudermtrade mark; RESC) against planktonic and sessile Pseudomonas aeruginosa (PSEUD) and Staphylococcus epidermidis (STAPH). While PSEUD levels were 4log(10) lower than those of STAPH within 24h of adding RESC to contaminated nutrient broths, all bacterial counts were comparable by 48h. PSEUD and STAPH levels were then measured after applying either a single or three consecutive aliquots of RESC to polyurethane sponges. Gel was removed after 5 or 20min, or left on for 72h. Bacterial counts in placebo-treated sponges had plateaued by 24h to values above 9log(10)CFU/mL. In contrast, six out of seven of the RESC application modalities reduced bacterial levels below 4log(10)CFU/mL for 72h. RESC remained effective against STAPH despite up to a 24h treatment delay, irrespective of the number of applications. Repeated RESC applications were required to maintain PSEUD below 4log(10)CFU/mL when the delay exceeded 7h. These data demonstrate the differential susceptibility of planktonic and sessile bacteria to RescuDermtrade mark. This product might be a good candidate for reducing the opportunity for wound infection, especially in burns.