Gut microbiota response to ionizing radiation and its modulation by HDAC inhibitor TSA.

AIM: Trichostatin A (TSA) has been shown to mitigate whole body γ-radiation-induced morbidity and mortality. The current study aimed at studying the effects of TSA post-irradiation treatment on gut-microbiota, especially the translocation of the microbes from the intestine to other organs in C57 Bl/6 mice model. MATERIALS AND METHODS: On 1st, 3rd 5th 7th 9th 12th and 14th days after various treatments bacteria were isolated from the intestine and nearby organs (mesenteric lymph node, spleen and liver) for further analysis. The jejunum part of all animals was processed for histological analysis. RESULTS: The group radiation + drug showed reduced susceptibility to radiation injury as well as microbiota related anomalies compared to the irradiated alone group. This was described by increased microflora in different parts of the GI tract in the radiation + drug group compared to the irradiated group and reduced histopathological damages in the jejunum. Also, a reduced percentage of translocated bacteria were found in different organs of radiation + drug group animals. CONCLUSION: TSA treatment post-irradiation could effectively control bacterial translocation as well as GI injury in mice.

The effectiveness of germicidal wipes and ultraviolet irradiation in reducing bacterial loads on electronic tablet devices used to obtain patient information in orthopaedic clinics: evaluation of tablet cleaning methods.

BACKGROUND: Electronic tablet devices are commonly used in outpatient clinics to obtain patient information for both clinical and research purposes. These devices are often colonized with bacteria; there are many cleaning methods to reduce this bacterial load. AIM: The primary purpose of this study was to evaluate whether regular cleaning with either germicidal wipes or ultraviolet (UV) irradiation leads to lower bacterial levels compared with irregular cleaning. METHODS: A randomized blinded trial was conducted of tablet cleaning strategies between each patient encounter in orthopaedic clinics. The cleaning method was randomized to either germicidal wipes, UV irradiation, or cleaning only when the tablet was visibly soiled. Research assistants (blinded to the treatment) obtained bacterial cultures from the tablets at the beginning and end of each clinic day. FINDINGS: Using germicidal wipes between each patient encounter vs no routine cleaning resulted in a marked decrease in the amount of bacterial contamination (risk ratio (RR) = 0.17 (0.04-0.67)). Similarly, using UV irradiation between each patient encounter led to significantly lower bacterial contamination rates (RR = 0.29 (95% confidence interval (CI) = 0.09-0.95)) compared with no routine cleaning. The majority of bacteria identified were normal skin flora. No meticillin-resistant Staphylococcus aureus was identified and only sparse colonies of meticillin-sensitive S. aureus. CONCLUSION: Electronic tablets used in orthopaedic trauma clinics are colonized with bacteria if no routine cleaning is performed. Routine use of either UV irradiation or germicidal wipes significantly decreases this bacterial burden. Providers should implement routine cleaning of tablets between each patient encounter to minimize exposure to potential pathogens.

Antimicrobial Blue Light Inactivation of Microbial Isolates in Biofilms.

BACKGROUND AND OBJECTIVES: Biofilms cause more than 80% of infections in humans, including more than 90% of all chronic wound infections and are extremely resistant to antimicrobials and the immune system. The situation is exacerbated by the fast spreading of antimicrobial resistance, which has become one of the biggest threats to current public health. There is consequently a critical need for the development of alternative therapeutics. Antimicrobial blue light (aBL) is a light-based approach that exhibits intrinsic antimicrobial effect without the involvement of exogenous photosensitizers. In this study, we investigated the antimicrobial effect of this non-antibiotic approach against biofilms formed by microbial isolates of multidrug-resistant bacteria. STUDY DESIGN/MATERIALS AND METHODS: Microbial isolates of Acinetobacter baumannii, Candida albicans, Escherichia coli, Enterococcus faecalis, MRSA, Neisseria gonorrhoeae, Pseudomonas aeruginosa, and Proteus mirabilis were studied. Biofilms were grown in microtiter plates for 24 or 48 hours or in the CDC biofilm reactor for 48 hours and exposed to aBL at 405 nm (60 mW/cm2 , 60 or 30 minutes). The anti-biofilm activity of aBL was measured by viable counts. RESULTS: The biofilms of A. baumannii, N. gonorrhoeae, and P. aeruginosa were the most susceptible to aBL with between 4 and 8 log10 inactivation after 108 J/cm2 (60 mW/cm2 , 30 minutes) or 216 J/cm2 (60 mW/cm2 , 60 minutes) aBL were delivered in the microplates. On the contrary, the biofilms of C. albicans, E. coli, E. faecalis, and P. mirabilis were the least susceptible to aBL inactivation (-0.30, -0.24, -0.84, and -0.68 log10 inactivation, respectively). The same aBL treatment in biofilms developed in the CDC biofilm reactor, caused -1.68 log10 inactivation in A. baumannii and -1.74 and -1.65 log10 inactivation in two different strains of P. aeruginosa. CONCLUSIONS: aBL exhibits potential against pathogenic microorganisms and could help with the significant need for new antimicrobials in clinical practice to manage multidrug-resistant infections. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Lightening in a bottle: comparison of ultraviolet light to traditional sterilization in saline irrigations bottles.

BACKGROUND: Nasal saline irrigations (NSIs) are commonplace in treatment of patients with sinonasal disorders. Contamination of both the water source and delivery bottle remains a challenge with this therapy. The goal of this study was to optimize a disinfection technique with various methods of preparation, disinfection, and delivery of NSIs. METHODS: Distilled and tap water sources in NSI bottles were contaminated by 4 bacterial strains: Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Legionella pneumophila. Contaminated bottles were cleaned with tap water, tap water with detergent, or microwave and swabbed for culture. Water-source disinfection was performed with reverse osmosis, distillation, activated carbon filtration, boiling, or ultraviolet (UV) light treatment. Test samples from each experimental group (n = 3/group) were cultivated on the appropriate media with colony-forming units (CFUs) reported. RESULTS: All methods of bottle cleaning with tap water with/without detergent and microwave significantly reduced bacterial load (CFUs) by >99% (p < 0.05). Distillation and boiling of the contaminated water source eliminated 100% of bacteria, whereas reverse osmosis and activated carbon filtration did not. A single UV treatment of contaminated water within a bottle eliminated 99% of bacteria within the water and 100% in the bottle. CONCLUSION: Cleansing of NSI bottles with tap water with/without detergent or microwave produced robust bacterial disinfection. Distillation and boiling of a contaminated water source completely eliminated all bacteria. UV light treatment was capable of simultaneous disinfection of both the water source and bottle, suggesting this may be a convenient, 1-step method of preparing NSIs for patients.

Microbiological evaluation of UV disinfection effectiveness in a specialist cystic fibrosis clinic.

The aim of the study was to evaluate the impact of manual cleaning and manual cleaning followed by Ultraviolet-C disinfection on the colony forming units of bacteria retrievable from equipment and surfaces within clinic rooms following a CF outpatient encounter. While UV disinfection has proven to be effective within general healthcare settings, it has not been evaluated in a CF centre. Microbiological sampling was performed following outpatient encounters involving 11 adult patients with CF and chronic infection with P.aeruginosa, MRSA or E. coli ESBL. The results of this study suggest that manual cleaning followed by UV-C disinfection is more effective than manual cleaning alone at reducing environmental contamination within a CF clinic and that UV-C isinfection is likely to reduce the risk of fomite transmission in the CF outpatient setting.

In-depth analysis of antibacterial mechanisms of laser generated shockwave treatment.

Background and Objectives Laser generated shockwave (LGS) is a novel modality for minimally invasive disruption of bacterial biofilms. The objectives of this study are to determine the mechanisms behind LGS treatment and non-biofilm effects on bacterial disruption, including (1) comparing bacterial load with and without LGS in its planktonic form and (2) estimating bacterial cell permeability following LGS. Study Design/Materials and Methods For the first study, planktonic S. epidermidis were treated with gentamicin (0, 8, 16, 32, 64 µg/ml) with and without LGS (1064 nm Nd:YAG laser, 110.14 mJ/mm2 , pulse duration 9 ns, spot size 3 mm, n = 8/group), and absorbances at 600 nm compared. For the second study, four samples of planktonic S. epidermidis were treated with LGS (same settings). Propidium iodide (PI) uptake via flow cytometry as a measure of cell permeability was measured at 0, 10, and 20 minutes following LGS. RESULTS: In comparing corresponding gentamicin concentrations within both LGS-treated samples and controls at 0 hours, there were no differences in absorbance (P = 0.923 and P = 0.814, respectively). Flow cytometry found modest PI uptake (10.4 ± 2.5%) immediately following LGS treatment, with time-dependent increase and persistence of the signal at 20 minutes (R2 = 0.449, P = 0.048). CONCLUSION: Taken together, LGS does not appear to have direct bacteriocidal properties, but rather by allowing for biofilm disruption and bacterial cell membrane permeabilization, both of which likely increase topical antibiotic delivery to pathogenic organisms. Insight into the mechanisms of LGS will allow for improved clinical applications and facilitate safe and effective translation of this technology. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Ultraviolet Irradiation of Blood: "The Cure That Time Forgot"?

Ultraviolet blood irradiation (UBI) was extensively used in the 1940s and 1950s to treat many diseases including septicemia, pneumonia, tuberculosis, arthritis, asthma and even poliomyelitis. The early studies were carried out by several physicians in USA and published in the American Journal of Surgery. However with the development of antibiotics, UBI use declined and it has now been called "the cure that time forgot". Later studies were mostly performed by Russian workers and in other Eastern countries and the modern view in Western countries is that UBI remains highly controversial.This chapter discusses the potential of UBI as an alternative approach to current methods used to treat infections, as an immune-modulating therapy and as a method for normalizing blood parameters. No resistance of microorganisms to UV irradiation has been reported, and multi-antibiotic resistant strains are as susceptible as their wild-type counterparts. Low and mild doses of UV kill microorganisms by damaging the DNA, while any DNA damage in host cells can be rapidly repaired by DNA repair enzymes. However the use of UBI to treat septicemia cannot be solely due to UV-mediated killing of bacteria in the blood-stream, as only 5-7% of blood volume needs to be treated with UV to produce the optimum benefit. UBI may enhance the phagocytic capacity of various phagocytic cells (neutrophils and dendritic cells), inhibit lymphocytes, and oxidize blood lipids. The oxidative nature of UBI may have mechanisms in common with ozone therapy and other oxygen therapies. There may be some similarities to extracorporeal photopheresis (ECP) using psoralens and UVA irradiation. However there are differences between UBI and ECP in that UBI tends to stimulate the immune system, while ECP tends to be immunosuppressive. With the recent emergence of bacteria that are resistant to all known antibiotics, UBI should be more investigated as an alternative approach to infections, and as an immune-modulating therapy.

Evaluation of an ultraviolet room disinfection protocol to decrease nursing home microbial burden, infection and hospitalization rates.

BACKGROUND: The focus of nursing home infection control procedures has been on decreasing transmission between healthcare workers and residents. Less evidence is available regarding whether decontamination of high-touch environmental surfaces impacts infection rates or resident outcomes. The purpose of this study was to examine if ultraviolet disinfection is associated with changes in: 1) microbial counts and adenosine triphosphate counts on high-touch surfaces; and 2) facility wide nursing home acquired infection rates, and infection-related hospitalization. METHODS: The study was conducted in one 160-bed long-term care facility. Following discharge of each resident, their room was cleaned and then disinfected using a newly acquired ultraviolet light disinfection device. Shared living spaces received weekly ultraviolet light disinfection. Thirty-six months of pretest infection and hospitalization data were compared with 12 months of posttest data. Pre and posttest cultures were taken from high-touch surfaces, and luminometer readings of adenosine triphosphate were done. Nursing home acquired infection rates were analyzed relative to hospital acquired infection rates using analysis of variance procedures. Wilcoxon signed rank tests, The Cochran's Q, and Chi Square were also used. RESULTS: There were statistically significant decreases in adenosine triphosphate readings on all high-touch surfaces after cleaning and disinfection. Culture results were positive for gram-positive cocci or rods on 33% (n = 30) of the 90 surfaces swabbed at baseline. After disinfectant cleaning, 6 of 90 samples (7.1%) tested positive for a gram-positive bacilli, and after ultraviolet disinfection 4 of the 90 samples (4.4%) were positive. There were significant decreases in nursing home acquired relative to hospital-acquired infection rates for the total infections (p = .004), urinary tract infection rates (p = .014), respiratory system infection rates (p = .017) and for rates of infection of the skin and soft tissues (p = .014). Hospitalizations for infection decreased significantly, with a notable decrease in hospitalization for pneumonia (p = .006). CONCLUSIONS: This study provides evidence that the pulsed-xenon ultraviolet disinfection device is superior to manual cleaning alone for decreasing microbes on environmental surfaces, as well as decreasing infection rates, and the rates of hospitalization for infection. Results suggest that placing a stronger emphasis on environmental surface disinfection in long-term care facilities may decrease nursing home acquired infections.

Rapid killing of bacteria by a new type of photosensitizer.

Photodynamic antimicrobial chemotherapy (PACT) uses non-traditional mechanisms (free radicals) and is a highly advocated method with promise of inactivating drug-resistance bacteria for local infections. However, there is no related drug used in clinical practice yet. Therefore, new photosensitizers for PACT are under active development. Here, we report the synthesis of a series of photosensitizers with variable positive charges (ZnPc(TAP)4n+, n = 0, 4, 8, 12) and their inactivation against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The binding kinetics of ZnPc(TAP)4n+ to bacteria were measured by flow cytometer. Reactive oxygen species (ROS) generation mechanism of the photosensitizers was studied. The toxicity of these compounds to human blood cells was also evaluated. These compounds showed negligible toxicity against human erythocytes but potent bactericidal effects. The compound with 8 positive charges, ZnPc(TAP)48+, turned out to have the strongest antibacterial effect among this series of compounds, giving IC50 value of 59 nM at a light dosage of 5 J/cm2 toward E. coli. For a multi-resistant E. coli strain, ZnPc(TAP)48+ decreased the bacteria load by 1000-fold at a concentration of 1 µM. Interestingly, ZnPc(TAP)412+, instead of ZnPc(TAP)48+, exhibited the highest amount of binding to bacteria. Flow cytometry studies showed that all PSs have fast binding onto bacteria, reaching saturated binding within 5 min. Mechanistically, ZnPc(TAP)412+ generated ROS primarily via Type I mechanism, while ZnPc(TAP)44+ or ZnPc(TAP)48+ created ROS by both type I and type II mechanisms. ZnPc(TAP)4n+ are highly potent, rapid-acting and non-toxic photosensitizers capable of inactivating bacteria.

Laser-generated shockwaves enhance antibacterial activity against biofilms in vitro.

BACKGROUND AND OBJECTIVES: Bacterial biofilm formation within chronic wound beds, which provides an effective barrier against antibiotics, is a known cause of recalcitrant infections and a significant healthcare burden, often requiring repeated surgical debridements. Laser-generated shockwaves (LGS) is a novel, minimally invasive, and nonthermal modality for biofilm mechanical debridement which utilizes compressive stress waves, generated by photonic absorption in thin titanium films to mechanically disrupt the biofilm. Prior studies have demonstrated LGS monotherapy to be selectively efficacious for biofilm disruption and safe for host tissues. In this study, we sought to determine if LGS can enhance the antimicrobial activity and biofilm disruption capability of topical antibiotic therapy. STUDY DESIGN/MATERIALS AND METHODS: Staphylococcus epidermidis biofilms grown in vitro on glass were treated with topical gentamicin (31, 62, and 124 µg/ml) with and without LGS (n = 3-11/treatment group). Mechanical shockwaves were generated with a 1,064 nm Nd:YAG laser (laser fluence 110.14 mJ/mm2 , pulse duration 5 ns, spot size 3 mm). Following a 24-hour incubation period, bacterial viability was assessed by determining the number of colony-forming units (CFU) via the Miles and Misra method. Residual biofilm bioburden was analyzed using the crystal violet biofilm assay. RESULTS: With gentamicin monotherapy, CFU density (CFU/mm2 ) at 31, 62, and 124 µg/ml were (282 ± 84) × 104 , (185 ± 34) × 104 , and (113 ± 9) × 104 , respectively. With LGS and gentamicin therapy, CFU density decreased to (170 ± 44) × 104 , (89 ± 24) × 104 , and (43 ± 3) × 104 , respectively (P = 0.1704, 0.0302, and 0.0004 when compared with gentamicin alone). Biofilm burden as measured by the assay in the gentamicin 31, 62, and 124 µg/ml groups was reduced by 80%, 95%, and 98% when LGS was added (P = 0.0102, >0.0001, and 0.0001 for all groups when compared with gentamicin alone). Furthermore, samples treated with LGS saw an increase in susceptibility to gentamicin, in terms of reduced biofilm bioburden and CFU densities. CONCLUSION: LGS enhances the efficacy of topical antibiotics in an in vitro model. This has significant implications for clinical applications in the management of chronic soft tissue infections and recalcitrant chronic rhinosinusitis. Lasers Surg. Med. 49:539-547, 2017. © 2017 Wiley Periodicals, Inc.

The Effect of Diode Laser on Planktonic Enterococcus faecalis in Infected Root Canals in an Ex Vivo Model.

OBJECTIVE: This study examined the bactericidal effect of diode laser irradiation against intracanal Enterococcus faecalis. METHODS AND MATERIALS: m total of 128 extracted single-rooted and single-canal teeth were treated with ProTaper instruments (Dentsply Maillefer, Ballaigues, Switzerland). A total of 120 root canals were inoculated with E. faecalis for 21 days, and the samples were randomly divided into five groups: Group 1 (n = 24) samples were irrigated with only saline solution (positive controls); Group 2 (n = 24) was treated with only 5.25% sodium hypochlorite; Group 3 (n = 24) was irrigated with saline solutions activated by diode laser; Group 4 (n = 24) was treated with 5.25% sodium hypochlorite activated by diode laser; and Group 5 (n = 24) was irrigated with saline solution with methylene blue dye activated by the diode laser Fox (Sweden & Martina, Padova, Italy); additionally, eight teeth were not contaminated and their canals were irrigated with saline solution and used as a negative control. The Uro-Quick system was used to determine the microbial residual charge. The data were analyzed using Pearson's chi-square test (p < 0.001). RESULTS: A statistically significant reduction in bacterial count was observed in Group 2 and Group 4 (p < 0.001). There were no statistically significant differences among the other groups (p > 0.001). CONCLUSIONS: Evidence indicates that the diode laser was not more effective than sodium hypochlorite in reducing free bacteria.

Deep tissue biopsy vs. superficial swab culture, including microbial loading determination, in the microbiological assessment of Skin and Soft Tissue Infections (SSTIs).

Thirty-two patients affected by SSTIs including DFIs were enrolled between 2013 and 2014. Superficial swab was obtained before and after cleansing with sterile saline, and after ultrasonic debridement; deep tissue biopsy was obtained from ulcer base. Samples were diluted with 1 mL of saline, serial 10-fold dilutions to 10-6 were made and 50 µL of each dilution was plated onto appropriate media. Bacteria were identified by Vitek II system. Microbial load was expressed as CFU/mL. Statistical analysis was performed by χ2. Incidence of Gram positives was higher than Gram negatives (S. aureus and P. aeruginosa being the most frequent); concordance (same bacteria isolated before and after debridement) never exceeded 60%. Ultrasonic debridement significantly reduced bacterial load or even suppressed bacterial growth. While reliability of superficial swab is poor for microbiological diagnosis of SSTIs, swabbing after ultrasonic debridement and biopsy of the ulcer base may be equally reliable.

Laser-Generated Shockwaves as a Treatment to Reduce Bacterial Load and Disrupt Biofilm.

OBJECTIVE: The goal of this paper is to demonstrate and evaluate the potential efficacy of laser-generated shockwave (LGS) therapy on biofilm infected tissue. METHODS: To demonstrate proof of concept, Staphylococcus epidermidis was allowed to proliferate on ex vivo pigskin, until mature biofilm formation was achieved, and then subjected to LGS. Bacterial load between control and treated samples was compared using the swab technique and colony counting. Scanning electron microscopy (SEM) was then used to visualize the biofilm growth and resulting reduction in biofilm coverage from treatment. Images were false colored to improve contrast of biofilm, and percent biofilm coverage was computed, along with biofilm cluster size. RESULTS: LGS reduced bacterial load by 69% (p = 0.008). Imaging showed biofilm coverage reduced by 52% and significantly reduced average cluster size (p 0.001). CONCLUSION: LGS therapy reduced the burden of bacterial biofilm on ex vivo pigskin and can be visualized using SEM imaging. SIGNIFICANCE: LGS therapy is a new treatment for infected wounds, allowing rapid disruption of biofilm to 1) remove bacteria and 2) increase susceptibility of remaining biofilm to topical antibiotics. This can lead to improved wound healing times, reduced patient morbidity, and decreased healthcare costs.

Potential of curcumin-mediated photodynamic inactivation to reduce oral colonization.

OBJECTIVE: The present study assessed the susceptibility of salivary pathogens to photodynamic inactivation (PDI), mediated by a water-soluble mixture of curcuminoids (CRM) and LED light. METHODS: A 10mL sample of unstimulated saliva was collected from volunteers. The inoculum was prepared using 9mL of saline and 1mL of saliva. Inoculum suspensions were divided into 14 groups and treated according to the description below. Groups that received the PDI treatment (light for 1min or 5min and 1.5g/L or 3.0g/L of CRM concentration) were called C1.5L1.8, C1.5L9.0, C3.0L1.8, C3.0L9.0. To evaluate the CRM decontamination alone, the C1.5/1,C1.5/5,C3.0/1 and C3.0/5 groups were assessed. Likewise, light alone was evaluated through the L1.8 and L9.0 groups. Chlorhexidine at 0.12% (CLX) for 1 or 5min was used for the positive control groups (CLX1 and CLX5, respectively); saline was used for 1 or 5min (CTR1, CTR5, respectively) for the negative control groups. After the tests, serial dilutions were performed, and the resulting samples were plated on blood agar in microaerophilic conditions. The number of colony forming units (CFU/mL) was determined and log10-transformed. Data were analyzed using a One-way Analysis of Variance with Welch correction, followed by the Games Howell's test (α=0.05). Log reduction (LR) measure for antimicrobial efficacy was also calculated using data from the CTR5 as untreated samples. RESULTS: The CHX5 showed the best antimicrobial result, followed by the CLX1. The antimicrobial effect of CRM was more pronounced when associated with light (PDI), but significantly lower than the CLX5 effect. The C3.0L9.0 protocol showed similar results to the CLX1. CONCLUSION: The results show that PDI with CRM at the studied concentrations is as effective for oral decontamination in clinical dental care conditions as the CLX at 0.12% for 1min.

Application of microwaves for microbial load reduction in black pepper (Piper nigrum L.).

BACKGROUND: Black pepper (Piper nigrum L.) is exposed to microbial contamination which could potentially create public health risk and also rejection of consignments in the export market due to non-adherance to microbial safety standards. The present study investigates the use of microwave (MW) radiation for microbial load reduction in black pepper and analyses the effect on quality. RESULTS: Black pepper was exposed to MWs at two different power levels (663 and 800 W) at an intensity of 40 W g(-1) for different time intervals (1-15 min) and moisture content (110 and 260 g kg(-1) on a wet basis). The exposure of black pepper to MWs at 663 W for 12.5 min was found to be sufficient to reduce the microbial load to the permissible level suggested by the International Commission on Microbiological Specifications for Foods and the European Spice Association. The retention of volatile oil, piperine and resin was 91.3 ± 0.03, 87.6 ± 0.02 and 90.7 ± 0.05%, respectively, in MW-treated black pepper. The final moisture content after MW treatment was found to be 100 ± 1 g kg(-1) for black pepper containing initial moisture of 260 ± 3 g kg(-1) . CONCLUSION: These results suggest that MW heating can be effectively used for microbial load reduction of black pepper without a significant loss in product quality. © 2016 Society of Chemical Industry.

Antimicrobial Effects of Nisin, Essential Oil, and γ-Irradiation Treatments against High Load of Salmonella typhimurium on Mini-carrots.

UNLABELLED: This study aimed at using essential oil (EO) alone or combined EO with nisin and γ-irradiation to control Salmonella Typhimurium during the refrigerated storage of mini-carrots. Peeled mini-carrots were inoculated with S. Typhimurium at a final concentration of approximately 7 log CFU/g. Inoculated samples were coated by 5 different coating solutions: (i) nisin solution at final concentration of 10(3) IU/mL; (ii) mountain savory EO solution at 0.35%; (iii) carvacrol solution at 0.35%; (iv) mountain savory EO at 0.35% plus nisin solution of 10(3) IU/mL; or (v) carvacrol at 0.35% plus nisin solution of 10(3) IU/mL. Coated mini-carrots were then irradiated at 0.5 or 1.0 kGy and compared to an unirradiated control sample. Samples were kept at 4 °C and microbial analyses were conducted at days 1, 3, 6, and 9. The results showed that mini-carrots coated by carvacrol plus nisin solution or mountain savory EO plus nisin solution in combination with irradiation at 1.0 kGy completely eliminated S. Typhimurium to under the detection limit during the storage. Thus, the combined treatments using carvacrol plus nisin or mountain savory EO plus nisin coating solution and irradiation at 1.0 kGy could be used as an effective method for controlling S. Typhimurium in mini-carrots. PRACTICAL APPLICATION: This study shows the effect of using γ irradiation at low dose (1 kGy) to reduce significantly the growth of Salmonella typhimurium in mini-carrots. It also shows that combination of nisin, essential oils with γ irradiation have the best antibacterial effects against S. Typhimurium during the storage of mini-carrots. The results can be used for practical application in food industry in terms of food safety.

Sterilizing elastomeric chains without losing mechanical properties. Is it possible?

OBJECTIVE: To investigate the effects of different sterilization/disinfection methods on the mechanical properties of orthodontic elastomeric chains. METHODS: Segments of elastomeric chains with 5 links each were sent for sterilization by cobalt 60 (Co60) (20 KGy) gamma ray technology. After the procedure, the elastomeric chains were contaminated with clinical samples of Streptococcus mutans. Subsequently, the elastomeric chains were submitted to sterilization/disinfection tests carried out by means of different methods, forming six study groups, as follows: Group 1 (control - without contamination), Group 2 (70°GL alcohol), Group 3 (autoclave), Group 4 (ultraviolet), Group 5 (peracetic acid) and Group 6 (glutaraldehyde). After sterilization/disinfection, the effectiveness of these methods, by Colony forming units per mL (CFU/mL), and the mechanical properties of the material were assessed. Student's t-test was used to assess the number of CFUs while ANOVA and Tukey's test were used to assess elastic strength. RESULTS: Ultraviolet treatment was not completely effective for sterilization. No loss of mechanical properties occurred with the use of the different sterilization methods (p > 0.05). CONCLUSION: Biological control of elastomeric chains does not affect their mechanical properties. .

OBJETIVO: verificar os efeitos de diferentes métodos de esterilização/desinfecção nas propriedades mecânicas de elásticos ortodônticos em cadeia. MÉTODOS: segmentos de elástico em cadeia com 5 elos cada foram enviados para esterilização em radiação gama com cobalto 60 (20 KGy). Após esterilização, esses foram contaminados com amostras clínicas de Streptococcus mutans. Passado esse período, foram submetidos aos testes de esterilização/desinfecção por diferentes métodos, formando seis grupos de estudo, assim denominados: Grupo 1 (controle - sem ter sido contaminado), Grupo 2 (álcool 70°GL), Grupo 3 (autoclave), Grupo 4 (ultravioleta), Grupo 5 (ácido peracético) e Grupo 6 (glutaraldeído). Após esterilização/desinfecção, avaliou-se a efetividade desses métodos, por meio de contagem de unidades formadoras de colônias por mL (UFC/mL), e as propriedades mecânicas desses materiais. Utilizou-se o teste t de Student para avaliar o número de UFC, além do ANOVA e, posteriormente, do teste de Tukey para avaliação da força. RESULTADOS: verificou-se que o ultravioleta não obteve eficácia total quanto à esterilização. E não ocorreu perda das propriedades mecânicas dos elásticos, com os diferentes métodos de esterilização utilizados (p > 0,05). CONCLUSÃO: o controle biológico de elásticos em cadeia não interfere nas suas propriedades mecânicas. .

Photosensitization of in vitro biofilms formed on denture base resin.

STATEMENT OF PROBLEM: Proper sterilization or disinfection of removable prostheses and surgical guides has been problematic in dental practice because of the absence of simple and low-cost techniques that do not cause damage to acrylic resins. PURPOSE: The purpose of this study was to study the effect of photodynamic therapy against Streptococcus mutans, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans biofilms formed on acrylic resin specimens. MATERIAL AND METHODS: The specimens were sterilized in ethylene oxide gas and submitted to in vitro biofilm growth. The photodynamic therapy consisted of the application of 0.05% methylene blue (P+) conjugated to irradiation with a light-emitting-diode of 630 nm and 150 mW (L+). The specimens were randomly divided into groups (n=5): negative control (P-L-); stained and irradiated at 10 J/cm(2) (P+L+ 10); stained and irradiated at 30 J/cm(2) (P+L+ 30); stained and not irradiated (P+L-); not stained and irradiated at 10 J/cm(2) (P-L+ 10); not stained and irradiated at 30 J/cm(2) (P-L+ 30); and gold standard (GS), sterilized. Afterward, the specimens were submitted to contact with culture medium agar for 10 minutes in petri plates, which were incubated for 48 hours at 37°C. The number of colony-forming units was obtained, and the data were expressed according to scores (1=0; 2=1-10; 3=11-100; 4=101-1000) and analyzed by the Friedman and Dunn tests (α=.05). RESULTS: Streptococcus mutans was sensitized by (P+L-); P aeruginosa and C albicans were also sensitized by the dye but showed a slight microbial reduction with (P+L+ 30), as did S aureus (P>.05); E coli presented an initial score of 3 and achieved a bacterial reduction to score 2 with (P+L+ 30) (P=.039). CONCLUSIONS: Photodynamic therapy was effective in reducing E coli counts on biofilms formed on acrylic resin specimens. The inhibition of microorganism growth tended to be directly proportional to the amount of energy provided by the light-emitting diode.

Photodynamic potential of curcumin and blue LED against Streptococcus mutans in a planktonic culture.

BACKGROUND: The photodynamic therapy (PDT) involves the use of light of specific wavelength to activate a nontoxic photosensitizing agent or dye in the presence of oxygen for eradication of target cells. In dentistry, this therapy is used to suppress the growth of microorganisms involved directly with dental decay and periodontitis process. There are evidences that curcumin dye is able to control microbial activity when illuminated with specific wavelength. The purpose of this study was to evaluate the in vitro efficacy of PDT using curcumin dye (Cur-C) in combination with a blue LED (L) device on a planktonic model of Streptococcus mutans (S. mutans). METHODS: Suspensions (0.5 mL) containing S. mutans at 1×10(7)CFU mL(-1) were prepared and divided into 4 groups: Group C-L- (control: no treatment and 1 experimental condition), Group C+L- (curcumin at 3 different concentrations: 2000; 4000 and 8000 µM and 3 experimental conditions), Group C-L+ (LED at 3 different dosages: 24, 48 and 72 Jcm(-2) and 3 experimental conditions), and Group C+L+ (PDT group: curcumin at respective concentrations combined to LED dosages and 9 experimental conditions). Samples of each experimental condition were cultured in Petri dishes of BHI agar. Incubation in micro-aerophilia at 37°C for 48 h was performed for subsequent visual counting of CFU/mL. Data were transformed into log10 and analyzed by two-way ANOVA and Tukey's test at p<0.05. RESULTS: Group C+L+, in specific experimental conditions, demonstrated a log bacterial reduction 70% higher than Group C-L-. Both groups C-L+ and C+L- presented a slight decrease in log bacterial counting. CONCLUSION: This in vitro method was able to reduce the number of S. mutans in a planktonic suspension.

Mechanistic studies on the photodynamic effect induced by a dicationic fullerene C60 derivative on Escherichia coli and Candida albicans cells.

The photodynamic mechanism of action induced by N,N-dimethyl-2-(4'-N,N,N-trimethylaminophenyl)fulleropyrrolidinium iodide (DTC60(2+)) was investigated on Candida albicans and Escherichia coli cells. First, photogeneration of superoxide anion radical by DTC60(2+) in the presence of NADH was detected using nitro blue tetrazolium method in reverse micelles. In C. albicans suspensions, 10 µM DTC60(2+) was an effective photosensitizer, producing a ∼5log decrease of cell survival when the cultures were irradiated for 30 min with visible light. Also, C. albicans cells growth was not detected in the presence of 10 µM DTC60(2+) and irradiation. Photodynamic mechanism investigations were compared in both C. albicans and E. coli cells. Studies under anoxic conditions indicated that oxygen was required for the photodynamic inactivation of these microorganisms. The photocytotoxicity induced by DTC60(2+) was similar in D2O than in water cell suspensions. Furthermore, photoinactivation of microbial cells was negligible in the presence of azide ion, while the addition of mannitol produced a photoprotective effect on the cellular survival. These results indicate that DTC60(2+) has potential as agent to the photodynamic inactivation of microbial cells. Also, the photocytotoxicity activity induced by this cationic fullerene derivative can involve the intermediacy of both superoxide anion radical and singlet molecular oxygen.