Influence of sucrose on growth and sensitivity of <Emphasis Type="Italic">Candida albicans</Emphasis> alone and in combination with <Emphasis Type="Italic">Enterococcus faecalis</Emphasis> and <Emphasis Type="Italic">Streptococcus mutans</Emphasis> to photodynamic therapy

This study has evaluated the effects of photodynamic inactivation (PDI) using erythrosine as photosensitizer and green light-emitting diode (LED) on biofilms of Candida albicans alone and in combination with Enterococcus faecalis and Streptococcus mutans. We have also evaluated the effect of sucrose on biofilm formation and bacterial growth and sensitivity to PDI. Biofilms were formed in suspension of 10⁶ cells/ml on plates before being grown in broth culture with and without sucrose and incubated for 48 h. Next, the treatment was applied using erythrosine at a concentration of 400 μM for 5 min and green LED (532 ± 10 nm) for 3 min on biofilms alone and in combination. The plates were washed and sonicated to disperse the biofilms, and serial dilutions were carried and aliquots seeded in Sabouraud agar before incubation for 48 h. Next, the colony-forming units per milliliter (CFU/ml; log₁₀) were counted and analyzed statistically (ANOVA, Tukey test, P ≤ 0.05). Results show that S. mutans favors the growth of C. albicans in biofilms with sucrose, with treatment not being effective. However, when the biofilm was grown without sucrose, we found a reduction in biofilm formation and a significant decrease in the PDI treatment (P < 0.0001). In conclusion, both growth and sensitivity to PDI in biofilms of C. albicans are strongly influenced by bacterial combination, and the presence of sucrose affected directly the growth and sensitivity of the biofilm to PDI as sucrose is the substrate for construction of the exopolysaccharide matrix.     

Antimicrobial photodynamic therapy—a promising treatment for prosthetic joint infections

Periprosthetic joint infection (PJI) is associated with high patient morbidity and a large financial cost. This study investigated Photodynamic Therapy (PDT) as a means of eradicating bacteria that cause PJI, using a laser with a 665-nm wavelength and methylene blue (MB) as the photosensitizer. The effectiveness of MB concentration on the growth inhibition of methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa and Acinetobacter baumannii was investigated. The effect of laser dose was also investigated and the optimized PDT method was used to investigate its bactericidal effect on species within planktonic culture and following the formation of a biofilm on polished titanium and hydroxyapatite coated titanium discs. Results showed that Staphylococci were eradicated at the lowest concentration of 0.1 mM methylene blue (MB). With P. aeruginosa and A. baumannii, increasing the MB concentration improved the bactericidal effect. When the laser dose was increased, results showed that the higher the power of the laser the more bacteria were eradicated with a laser power?≥?35 J/cm² and an irradiance of 35 mW/cm², eradicating all S. epidermidis. The optimized PDT method had a significant bactericidal effect against planktonic MRSA and S. epidermidis compared to MB alone, laser alone, or control (no treatment). When biofilms were formed, PDT treatment had a significantly higher bactericidal effect than MB alone and laser alone for all species of bacteria investigated on the polished disc surfaces. P. aeruginosa grown in a biofilm was shown to be less sensitive to PDT when compared to Staphylococci, and a HA-coated surface reduced the effectiveness of PDT. This study demonstrated that PDT is effective for killing bacteria that cause PJI.     

Effects of photodynamic laser and violet-blue led irradiation on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilm and <Emphasis Type="Italic">Escherichia coli</Emphasis> lipopolysaccharide attached to moderately rough titanium surface: in vitro study

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This study investigates the in vitro efficacy of photodynamic treatment (PDT) with methylene blue (MB) photoactivated with λ 635 nm diode laser and of λ 405 nm violet-blue LED phototreatment for the reduction of bacterial biofilm and lipopolysaccharide (LPS) adherent to titanium surface mimicking the bone-implant interface. Staphylococcus aureus biofilm grown on titanium discs with a moderately rough surface was subjected to either PDT (0.1% MB and λ 635 nm diode laser) or λ 405 nm LED phototreatment for 1 and 5 min. Bactericidal effect was evaluated by vital staining and residual colony-forming unit count. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, discs coated with Escherichia coli LPS were treated as above before seeding with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Both PDT and LED phototreatment induced a statistically significant (p?<?0.05 or higher) reduction of viable bacteria, up to ?99 and ?98% (5 min), respectively. Moreover, besides bactericidal effect, PDT and LED phototreatment also inhibited LPS bioactivity, assayed as nitrite formation, up to ?42%, thereby blunting host inflammatory response. Non-invasive phototherapy emerges as an attractive alternative in the treatment of peri-implantitis to reduce bacteria and LPS adherent to titanium implant surface without causing damage of surface microstructure. Its efficacy in the clinical setting remains to be investigated.     

Photodynamic inactivation of <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> biofilms and planktonic cells by 5-aminolevulinic acid and 5-aminolevulinic acid methyl ester

The treatment of Klebsiella pneumoniae, particularly extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae, is currently a great challenge. Photodynamic antimicrobial chemotherapy is a promising approach for killing antibiotic-resistant bacteria. The aim of this study was to evaluate the capacity of 5-aminolevulinic acid (5-ALA) and its derivative 5-ALA methyl ester (MAL) in the presence of white light to cause photodynamic inactivation (PDI) of K. pneumoniae planktonic and biofilm cells. In the presence of white light, 5-ALA and MAL inactivated planktonic cells in a concentration-dependent manner. Biofilms were also sensitive to 5-ALA and MAL-mediated PDI. The mechanisms by which 5-ALA and MAL caused PDI of ESBL-producing K. pneumonia were also investigated. Exposure of K. pneumonia to light in the presence of either 5-ALA or MAL induced cleavage of genomic DNA and the rapid release of intracellular biopolymers. Intensely denatured cytoplasmic contents and aggregated ribosomes were also detected by transmission electron microscopy. Scanning electron microscopy showed that PDI of biofilms caused aggregated bacteria to detach and that the bacterial cell envelope was damaged. This study provides insights into 5-ALA and MAL-mediated PDI of ESBL-producing K. pneumoniae.     

The effects of diode laser on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilm and <Emphasis Type="Italic">Escherichia coli</Emphasis> lipopolysaccharide adherent to titanium oxide surface of dental implants. An in vitro study

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This in vitro study aims at providing the experimental basis for possible use of diode laser (λ 808 nm) in the treatment of peri-implantitis. Staphylococcus aureus biofilm was grown for 48 h on titanium discs with porous surface corresponding to the bone-implant interface and then irradiated with a diode laser (λ 808 nm) in noncontact mode with airflow cooling for 1 min using a Ø 600-μm fiber. Setting parameters were 2 W (400 J/cm²) for continuous wave mode; 22 μJ, 20 kHz, 7 μs (88 J/cm²) for pulsed wave mode. Bactericidal effect was evaluated using fluorescence microscopy and counting the residual colony-forming units. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, the titanium discs were coated with Escherichia coli lipopolysaccharide (LPS), laser-irradiated and seeded with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Diode laser irradiation in both continuous and pulsed modes induced a statistically significant reduction of viable bacteria and nitrite levels. These results indicate that in addition to its bactericidal effect laser irradiation can also inhibit LPS-induced macrophage activation and thus blunt the inflammatory response. The λ 808-nm diode laser emerges as a valuable tool for decontamination/detoxification of the titanium implant surface and may be used in the treatment of peri-implantitis.     

Sustained effects of blue light on <Emphasis Type="Italic">Streptococcus mutans</Emphasis> in regrown biofilm

In prior studies, exposure of Streptococcus mutans in biofilm to blue light using high fluences of up to 680 J/cm² did not interfere with bacterial capability to reform an initial biofilm; however, a delayed antibacterial effect was observed. Our aim was to determine the sustained effecttts of blue light-emitting diode (LED) curing light on the pathogenicity of the newly formed biofilm. S. mutans were grown to form biofilm that was exposed to blue light (wavelengths, 460–480 nm) for 1, 3, and 7 min (equivalent to 37, 112, and 262 J/cm², respectively). Then, bacteria were suspended and allowed to regrow into new biofilms. The regrown biofilms were assessed for bacterial quantification by optical density (OD) measurement and quantitative polymerase chain reaction (qPCR), bacterial viability and extracellular polysaccharide production by fluorescent staining using confocal scanning laser microscopy, acid production by bacteria (acidogenicity), and bacterial survival at low pH (aciduricity) using qPCR. Bacterial growth in the regrown biofilms was increased when samples were previously exposed to light; however, under the confocal microscopy, a higher proportion of dead bacteria and a reduction in polysaccharide production were observed. The acidogenicity from the regrown biofilm was lowered as fluences of light increased. The aciduricity of the regrown biofilm was decreased, meaning less growth of bacteria into biofilm in low pH with increasing fluences. Blue light has sustained effects on S. mutans bacteria grown into new biofilm. Although bacterial growth in biofilm increased, bacterial viability and virulence characteristics were impaired. The cariogenic potential over time of S. mutans previously exposed to blue light when grown on tooth surfaces is yet to be determined.     

Curcumin-mediated anti-microbial photodynamic therapy against <Emphasis Type="Italic">Candida dubliniensis</Emphasis> biofilms

The purpose of this study was to evaluate the effectiveness of anti-microbial photodynamic therapy (aPDT) mediated by curcumin (Cur) associated with LED light against biofilms of Candida dubliniensis, and further, investigate cellular uptake and drug penetration through the biofilms under confocal laser scanning microscopy (CLSM). Four C. dubliniensis strains were tested: three clinical isolates from HIV-positive patients and one reference strain (CBS 7987). Biofilms were treated with three Cur concentrations (20.0, 30.0, and 40.0 μM). All samples were incubated in the dark for 20 min and exposed to a 5.28 J/cm² of LED light fluence. Additional samples of each strain were treated either with Cur or LED light only. Control samples had neither Cur nor light. After aPDT, results were read using the XTT salt reduction method. The data were statistically analyzed by two-way ANOVA followed by Games-Howell post-hoc test (α?=?0.05). Confocal laser scanning microscopy was used to verify both the uptake of Cur by yeast cells and its penetration through the biofilm. The results showed that aPDT promoted significant reduction on the metabolism of the biofilm-organized cells of C. dubliniensis. Further, while Cur was rapidly taken up by C. dubliniensis cells, a longer time interval was required to allow Cur penetration into biofilm cells. Based on these results, aPDT associating LED and Cur presents promising potential on fungal control of biofilms of C. dubliniensis.     

Repeated applications of photodynamic therapy on <Emphasis Type="Italic">Candida glabrata</Emphasis> biofilms formed in acrylic resin polymerized

Previous studies have been suggested that photodynamic therapy (PDT) can be used as an adjuvant treatment for denture stomatitis. In this study, we evaluated the effects of multiple sessions of PDT on Candida glabrata biofilms in specimens of polymerized acrylic resin formed after 5 days. Subsequently, four applications of PDT were performed on biofilms in 24-h intervals (days 6–9). Also, we evaluated two types of PDT, including application of laser and methylene blue or light-emitting diode (LED) and erythrosine. The control groups were treated with physiological solution. The effects of PDT on biofilm were evaluated after the first and fourth application of PDT. The biofilm analysis was performed by counting the colony-forming units. The results showed that between the days 6 and 9, the biofilms not treated by PDT had an increase of 5.53 to 6.05 log (p?=?0.0271). Regarding the treatments, after one application of PDT, the biofilms decreased from 5.53 to 0.89 log. When it was done four applications, the microbial reduction ranged from 6.05 log to 0.11 log. We observed that one application of PDT with laser or LED caused a reduction of 3.36 and 4.64 compared to the control groups, respectively (p?=?0.1708). When it was done four applications of PDT, the reductions achieved were 1.57 for laser and 5.94 for LED (p?=?0.0001). It was concluded that repeated applications of PDT on C. glabrata biofilms showed higher antimicrobial activity compared to single application. PDT mediated by LED and erythrosine was more efficient than the PDT mediated by laser and methylene blue.     

Influence of pre-irradiation time employed in antimicrobial photodynamic therapy with diode laser

The aim of the present study was to evaluate, in vitro, the effect of different pre-irradiation times of the photosensitizer in photodynamic therapy in biofilms formed by Streptococcus mutans and Candida albicans, through the evaluation of the microbial load. The factors under study were as follows: times of pre-irradiation of the photosensitizer in three levels (1, 2, or 5 min). For the control of the cariogenic dental biofilm with antimicrobial photodynamic therapy (aPDT), methylene blue (0.01%) was used in association with the diode laser (InGaAlP) with a wavelength of 660 nm. Chlorhexidine digluconate (0.12% CHX) and saline were used as positive and negative controls, respectively. The study design was carried out in complete and randomized blocks. The sample consisted of 15 S. mutans biofilms cultures, randomly divided into five groups and 15 C. albicans cultures, also divided into five groups. The experiment was performed in triplicate (n = 3) and the response variables were obtained through quantitative analysis of bacterial viability, expressed in colony-forming units (CFU) per square millimeter of the specimen area. The data were analyzed with the aid of the ANOVA one-way test and Tukey’s post-test. All analyses were performed using the Graph Pad Prism 4.0 program, with a significance level of 5%. For the S. mutans group, only the saline solution presented a statistically significant difference when compared to the other treatments (p < 0.05), that is, the treatment with aPDT, irrespective of the irradiation time applied, was similar to the treatment with CHX and both were more effective in reducing cariogenic biofilm compared to saline. For the group of C. albicans, there was no statistical difference between the groups (p > 0.05). Therefore, it can be concluded that the treatment with aPDT reduced the number of CFUs of S. mutans in a similar way to CHX, independently of the pre-irradiation time applied. No effect of this therapy or of the different pre-irradiation times on the C. albicans biofilm could be observed. In this way, the pre-irradiation time of 1 min can be used to reduce the microbial load of S. mutans.     

Photoinactivation effect of eosin methylene blue and chlorophyllin sodium-copper against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis>

The use of eosin methylene blue according to Giemsa as photosensitizer is presented for the first time in this paper. The present study evaluated the potential application of chlorophyllin sodium copper salt (CuChlNa) and eosin methylene blue according to Giemsa (EMB) as antimicrobial photosensitizers (aPS) for photodynamic inactivation (PDI) of Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria. The experiments were performed using S. aureus stain ATCC 25923 and E. coli ATCC 25922 in which five aPS concentrations (0.0, 1.0, 2.5, 5.0, 10.0, and 20.0 μM for S. aureus and 0.0, 5.0, 10.0, 20.0, 40.0, and 50.0 μM for E. coli) were prepared and added in 2 mL of a saline solution containing the bacterial inoculum. After aPS incubation, the samples were divided into two groups, one kept in the dark and another submitted to the illumination. Then, the bacterial inactivation was determined 18 h after the incubation at 37 °C by counting the colony-forming units (CFU). The results revealed that both EMB and CuChlNa can be used as aPS for the photoinactivation of S. aureus, while only EMB was able to photoinactivate E. coli. Nevertheless, a more complex experimental setup was needed for photoinactivation of E. coli. The data showed that EMB and CuChlNa presented similar photoinactivation effects on S. aureus, in which bacterial growth was completely inhibited at photosensitizer (PS) concentrations over 5 μM, when samples were previously incubated for 30 min and irradiated by a light dose of 30 J cm^?2 as a result of an illumination of 1 h at 8.3 mW cm^?2 by using a red light at 625 nm with a 1 cm beam diameter and output power of 6.5 mW. In the case of E. coli, bacterial growth was completely inhibited only when combining a PS incubation period of 120 min with concentrations over 20 μM.     

Action of antimicrobial photodynamic therapy on heterotypic biofilm: <Emphasis Type="Italic">Candida albicans</Emphasis> and <Emphasis Type="Italic">Bacillus atrophaeus</Emphasis>

The increase in survival and resistance of microorganisms organized in biofilms demonstrates the need for new studies to develop therapies able to break this barrier, such as photodynamic therapy, which is characterized as an alternative, effective, and non-invasive treatment. The objective was to evaluate in vitro the effect of antimicrobial photodynamic therapy on heterotypic biofilms of Candida albicans and Bacillus atrophaeus using rose bengal (12.5 μM) and light-emitting diode (LED) (532 nm and 16.2 J). We used standard strains of B. atrophaeus (ATCC 9372) and C. albicans (ATCC 18804). The biofilm was formed in the bottom of the plate for 48 h. For the photodynamic therapy (PDT) experimental groups, we added 100 μL of rose bengal with LED (P+L+), 100 μL of rose bengal without LED (P+L?), 100 μL of NaCl 0.9 % solution with LED (P?L+), and a control group without photosensitizer or LED (P?L?). The plates remained in agitation for 5 min (pre-irradiation) and were irradiated with LED for 3 min, and the biofilm was detached using an ultrasonic homogenizer for 30 s. Serial dilutions were plated in BHI agar and HiChrom agar and incubated at 37 °C/48 h. There was a reduction of 33.92 and 29.31 % of colony-forming units per milliliter (CFU/mL) for C. albicans and B. atrophaeus, respectively, from the control group to the group subjected to PDT. However, statistically significant differences were not observed among the P+L+, P+L?, P?L+, and P?L? groups. These results suggest that antimicrobial photodynamic therapy using rose bengal (12.5 μM) with a pre-irradiation period of 5 min and LED for 3 min was not enough to cause a significant reduction in the heterotypic biofilms of C. albicans and B. atrophaeus.     

Photodynamic inactivation of pathogenic species <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> and <Emphasis Type="Italic">Candida albicans</Emphasis> with lutetium (III) acetate phthalocyanines and specific light irradiation

Photodynamic inactivation (PDI) is a light-associated therapeutic approach suitable for treatment of local acute infections. The method is based on specific light-activated compound which by specific irradiation and in the presence of molecular oxygen produced molecular singlet oxygen and other reactive oxygen species, all toxic for pathogenic microbial cells. The study presents photodynamic impact of two recently synthesized water-soluble cationic lutetium (III) acetate phthalocyanines (LuPc-5 and LuPc-6) towards two pathogenic strains, namely, the Gram-negative bacterium Pseudomonas aeruginosa and a fungus Candida albicans. The photodynamic effect was evaluated for the cells in suspensions and organized in 48-h developed biofilms. The relatively high levels of uptakes of LuPc-5 and LuPc-6 were determined for fungal cells compared to bacterial cells. The penetration depths and distribution of both LuPcs into microbial biofilms were investigated by means of confocal fluorescence microscopy. The photoinactivation efficiency was studied for a wide concentration range (0.85–30 μM) of LuPc-5 and LuPc-6 at a light dose of 50 J cm^?2 from red light-emitting diode (LED; 665 nm). The PDI study on microbial biofilms showed incomplete photoinactivation (<3 logs) for the used gentle drug-light protocol.     

Photodynamic inactivation in the expression of the <Emphasis Type="Italic">Candida albicans</Emphasis> genes ALS3, HWP1, BCR1, TEC1, CPH1, and EFG1 in biofilms

The objective of this study was to evaluate the effects of photodynamic inactivation (PDI) on Candida albicans biofilms, evaluating its effects on gene expression of ALS3, HWP1, BCR1, TEC1, CPH1, and EFG1 by yeast. Three samples of C. albicans were used in this study: a clinical sample from a patient with HIV (39S), a clinical sample from a patient with denture stomatitis lesion (Ca30), and a standard strain ATCC 18804. The quantification of gene expression was related to the production of those genes in the samples referred above using quantitative polymerase chain reaction (qPCR) assay in real time. The photosensitizer methylene blue at 300 uM and erythrosine at 400 uM, sensitized with low-power laser (visible red, 660 nm) and green LED (532 nm), respectively, were used for PDI. Four groups of each sample and PDI protocol were evaluated: (a) P+L+: sensitization with the photosensitizer and irradiation with light, (b) P+L?: only treatment with the photosensitizer, (c) P?L+: only irradiation with light, and (d) P?L?: without sensitization with the dye and absence of light. The results were analyzed by t test, with a significance level of 5%. The photodynamic inactivation was able to reduce the expression of all genes for both treatments, laser and LED. The fold-decrease for the genes ALS3, HWP1, BCR1, TEC1, CPH1, and EFG1 were 0.73, 0.39, 0.77, 0.71, 0.67, and 0.60 for laser, respectively, and 0.66, 0.61, .050, 0.43, 0.54, and 0.66 for LED, respectively. It could be concluded that PDI showed a reduction in the expression of C. albicans genes, suggesting its virulence decrease.     

The impact of antimicrobial photodynamic therapy in an artificial biofilm model

The susceptibility of bacterial cultures in biofilm formations is important for a variety of clinical treatment procedures. Therefore, the aim of the study was to assess the impact of laser-induced antimicrobial photodynamic therapy on the viability of Streptococcus mutans cells employing an artificial biofilm model. Using sterile chambered coverglasses, a salivary pellicle layer was formed in 40 chambers. Streptococcus mutans cells were inoculated in a sterile culture medium. Employing a live/dead bacterial viability kit, bacteria with intact cell membranes stained fluorescent green. Each pellicle-coated test chamber was filled with 0.7 ml of the bacterial suspension and analysed using a confocal laser scanning microscope within a layer of 10 μm at intervals of 1 μm from the pellicle layer. Phenothiazine chloride was used as a photosensitizer in all 40 test chambers. A diode laser (wavelength 660 nm, output power 100 mW) was used to irradiated 20 chambers for 2 min. Fluorescence values in the test chambers after laser irradiation (median 2.1 U, range 0.4–3.4 U) were significantly lower than baseline values after adding the photosensitizer (median 3.6 U, range 1.1–9.0; p?p?>?0.05). The present study indicated that laser irradiation is an essential part of antimicrobial photodynamic therapy to reduce bacteria within a layer of 10 μm. Further studies are needed to evaluate the maximum biofilm thickness that still allows a toxic effect on microorganisms.     

Virulence factors of fluconazole-susceptible and fluconazole-resistant <Emphasis Type="Italic">Candida albicans</Emphasis> after antimicrobial photodynamic therapy

This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) mediated by Photodithazine® (PDZ) and LED light on the virulence factors of fluconazole-susceptible (CaS) and fluconazole-resistant (CaR) Candida albicans. Standardized suspensions of strains were prepared (10⁷), and after 48 h of biofilm formation, these strains were incubated with PDZ (100 mg/L) for 20 min and exposed to LED light (660 nm, 37.5 J/cm²). Additional samples were treated with PDZ or light only, and the control consisted of biofilms that received no treatment. After aPDT, the cells were recovered and the virulence factors were evaluated. To analyze the capacity of adhesion, cells were recovered after aPDT and submitted to the adhesion process in the bottom of a 96-well plate. After this, metabolic activity tests (XTT assay) and cell viability (colony forming units per milliliter, CFU/mL) were applied. To evaluate the biofilm-forming ability after aPDT, the cells recovered were submitted to biofilm formation procedures, and the biofilm formed was evaluated by XTT, CFU/mL, and total biomass (crystal violet) tests. Lastly, the capacity for synthesizing protease and phospholipase enzymes after aPDT was evaluated by fluorimetric tests. Data were analyzed by two- or three-way ANOVA tests (p?≤?0.05). It was verified that aPDT reduced the viability of both strains, fluconazole-susceptible and fluconazole-resistant C. albicans. It was also observed that the CaR strain had lower susceptibility to the aPDT when compared with the CaS strain. However, regarding the virulence factors evaluated, it was demonstrated that aPDT did not alter the adherence and biofilm formation ability and enzymatic production.     

Determining the optimal parameters of 420-nm intense pulsed light on <Emphasis Type="Italic">Trichophyton rubrum</Emphasis> growth in vitro

The effect of and the optimal parameters for intense pulsed light (IPL) with a 420-nm filter on an isolate of the fungus Trichophyton rubrum (T. rubrum) were examined in vitro. Colonies of T. rubrum were irradiated by using 420-nm IPL with various pulse numbers and energies. Colony areas were photographed and compared with those of untreated colonies to assess growth inhibition. Statistically significant inhibition of T. rubrum growth was detected in colonies treated with 12 pulses of greater than or equal to 12 J/cm². The optimal parameters of 420-nm IPL were 12 pulses of 12 J/cm². However, more in vitro and in vivo studies are necessary to investigate and explore this mechanism to determine whether IPL would have a potential use in the treatment of fungal infections of the skin.     

Comparison of the local effects of a 600-μm bare fibre at high laser power on lung parenchyma: Nd:YAG laser 1320 vs. 1064 nm

Lung metastases are often resected non-anatomically with a laser using a diode-pumped Nd:YAG laser at a wavelength of 1320 nm with a laser output of up to 60 W. Usually the removal of lesions is carried out in contact mode by means of a bare fibre. We compared the local effects of an Nd:YAG laser at a wavelength of 1064 nm with those at a wavelength of 1320 nm using a 600-μm bare fibre in contact mode in an experimental model. The investigations were carried out on porcine lungs freshly withdrawn at the abattoir. The 600-μm laser fibre was fixed vertically in contact with the lung surface on a fibre holder. The fibre holder was connected to a feeding device that advances the laser fibre at constant speeds (5, 10 or 20 mm/s). In each case, two laser powers were examined: 20 and 60 W. The lung lesions produced by the laser fibre were excised for histological examination. After haematoxylin–eosin staining, the depth of the vaporisation and coagulation zones (in μm) from the laser cuts was measured. For each setting, an average value was calculated. The individual groups were compared for significance using a non-parametric Mann–Whitney U test (p?<?0.05). At a low speed of the bare fibre of 5 mm/s and a laser output of 20 W, the average depth of the vaporisation zone was 858?±?3.3 μm (λ?=?1064 nm) compared to 766.0?±?7.5 μm (λ?=?1320 nm) (p?<?0.01). Upon faster movement (20 mm/s), the extension of the vaporisation zone decreased to 320.3?±?7.1 μm (λ?=?1064 nm). The depth of the vaporisation zone increased significantly at 60 W, both at λ?=?1064 and 1320 nm with 1517.0?±?1.7 μm and 1414.0?±?4.9 μm, respectively. The extent of the coagulation zone was significantly smaller at 20 W and the low speed of 5 mm/s, namely, 200.4?±?3.7 μm (λ?=?1064 nm) and 224.1?±?2.8 μm (1320-nm laser). Upon faster movement of the laser fibre at the same output, the extent of the coagulation zone decreased in both groups. At a laser power of 60 W, the extent of the coagulation zone was significantly less with the 1064-nm laser (110.3?±?2.4 μm) than with the 1320-nm laser (324.8?±?1.9 μm; p?<?0.001). When the laser fibre moves more rapidly, the extent of the coagulation zone decreases further. The Nd:YAG laser with a wavelength of 1320 nm still has the optimal ratio of cutting and coagulation capacity on the resection surface. With the 1064-nm Nd:YAG laser, a higher cutting capacity is associated with a decrease of the coagulation capacity.     

Dentinal tubule sealing effects of 532-nm diode-pumped solid-state laser,gallic acid/Fe<Superscript>3+</Superscript> complex,and three commercial dentin desensitizers

The purpose of this study was to compare dentinal tubule sealing effects of a 532-nm diode-pumped solid-state (DPSS) laser, gallic acid/Fe³⁺ complex, and three commercially available dentin desensitizers. Human premolars (n?=?44) extracted for orthodontics had standardized cervical cavities prepared, etched (37% phosphoric acid) and randomly assigned to either a control (n?=?4), or one of five treatment groups (n?=?8/group). Desensitizing treatments were either a 532-nm DPSS laser, gallic acid/Fe³⁺ complex, oxalate-based Super Seal? (SS), DIO? Enamel Coating Pen Pro Tooth (Dio), or adhesive-type Hybrid Coat? (HC). Dentinal fluid flow (DFF) was monitored continuously in real time during the application of each desensitizing agent, by using a nanoliter-scaled fluid flow-measuring device. Following treatment, morphological changes on dentinal surfaces and within tubules were observed by scanning electron microscopy (SEM). DFF rates were significantly reduced after treatment in all experimental groups (P?<?0.05), except SS (P?>?0.05). The gallic acid/Fe³⁺ complex reduced DFF rates the most, and significantly (P?<?0.05) more than the three commercial dentin desensitizers. There were no significant differences in DFF reduction rates between the gallic acid/Fe³⁺ complex and the DPSS laser groups (P?>?0.05). There were no significant differences in DFF reduction rates among the three commercial dentin desensitizers (P?>?0.05). SEM examination of treated dentin showed that the degree of occlusion of dentinal tubules correlated closely with the corresponding reduction in DFF rates. The gallic acid/Fe³⁺ complex and 532-nm DPSS laser were superior to other desensitizing methods in occluding dentinal tubules and reducing DFF rates.     

Does <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> nasal decontamination affect the rate of early surgical site infection in adolescent idiopathic scoliosis surgery?

Purpose

Surgical site infection (SSI) is a main complication after adolescent idiopathic scoliosis (AIS) surgery. Nasal colonization with S. aureus is a known risk factor for developing nosocomial infections in cardiac surgery. However, the risk in orthopedic surgery remains unclear, especially in spine surgery. This study aims to report the efficacy of a preoperative nasal decontamination program in S. aureus carriers on the incidence of early SSI after AIS posterior surgery.

Methods

Between January 2014 and July 2017, all AIS patients were screened preoperatively with nasal swabs and decontaminated if positive 5 days before surgery. Early SSI was identified, and microorganisms findings were analyzed within nasal carriage and compared to a previous series published before the decontamination program (2007–2011).

Results

Among the 331 AIS posterior fusion performed during the study period, incidence of positive nasal swab was 23% (n?=?75). Those were preoperatively decontaminated. In comparison with the period before the nasal decontamination program, incidence of S. aureus early SSI significantly decreased from 5.1 to 1.3%, p?<?0.05. None of those S. aureus decontaminated patients had an early S. aureus SSI. In all cases of S. aureus infections, S. aureus nasal screening was negative with a mean delay of 315 days (±?115) before surgery, which was significantly different from the global cohort (104 days?±?67, p?<?0.05).

Conclusions

Preoperative S. aureus nasal decontamination was associated with a significant decrease in S. aureus SSI. Optimal delay of nasal screening needs to be optimized in order to diagnose intermittent S. aureus carriers.

Graphical abstract

These slides can be retrieved under Electronic Supplementary Material.

Open image in new window

     

Bacterial adhesion to braided surgical sutures: an in vitro study

Background

Surgical suture materials are accepted to be associated with a substantial proportion of surgical site infections. These infections are related with biofilm formation similar to that of other synthetic and implantable medical devices.

Methods

We conducted an in vitro study to investigate the bacterial adherence to different types of braided surgical sutures. The included sutures were polyglactin (Vicryl®) group (VG), rapidly absorbable polyglactin (Rapide-Vicryl®) group (RVG), nitrofurazone-coated polyglactin (Vicryl®) group (FVG), polyethylene terephthalate (Etibond®) group (EG), and natural silk (Silk®) group (SG). All sutures were cut in 1 cm length, embedded into tryptic soy broth, and then 10⁶-CFU/ml Escherichia coli and Staphylococcus aureus were added. After the 24th and 96th hour of incubation, bacterial colonies were counted, and results were expressed as CFU/cm.

Results

E.coli adhesion was significantly lower in VG and significantly higher in SG compared to FVG, RVG, and EG at the 24th and 96th hour of cultivation (p?<?0.05). The S.aureus adhesion results at 24th hour showed that VG had the least bacterial adhesion, and FVG had the most bacterial adhesion compared to other sutures (p?<?0.05). The S.aureus adhesion results at the 96th hour of cultivation showed that bacterial adhesion on sutures was not significantly different between groups (p?>?0.05).

Conclusion

Of all braided surgical sutures, bacterial adhesion is significantly lower in polyglactin and significantly higher in silk sutures. Nitrofurazone coverage of suture worsens S.aureus contamination of the suture.Level of Evidence: Not ratable