Colony Forming Unit Per Milliliter Research Articles

Assessment of Quality and Production Conditions of Local Beverages Produced in Ouagadougou, Burkina Faso

Artisanal food production has been developing in recent years in African cities. However, the promoters of the artisanal food production structures do not always apply good hygiene practices (GHP) during their activities, which can lead to the production of food of unsatisfactory quality. Thus, this study was initiated to assess the quality and production conditions of local beverages produced in Ouagadougou. Twelve samples of four beverages (tamarind and pineapple juice, bissap, and toedo) were collected during different productions and then sent to the laboratory. Microbiological and physico-chemical analyzes were done using standard microbiological methods and Association of Official Analytical Chemists (AOAC) methods respectively. The evaluation of the application of GHP was carried out using a checklist. The results obtained show that for all the beverage samples, the pH varies from 2.44±0.02 to 3.55±0.00, The titratable acidity from 0.29±0.02% to 0.75±0.02% and the brix degree from 11.00±0.00% to 16.50±0.11%. Total mesophilic aerobic flora (TMAF) and yeast and mold loads were respectively from 1.00x103 colony forming unit per milliliter (CFU/mL) to 7.30x104 CFU/mL and from <10 CFU/mL to 9.00x102 CFU/mL. All samples had a coliform load less than 10 CFU/mL. Salmonella and Shigella were absent in all samples. This study shows that most of the beverage samples studied have a compliant pH and Brix level. Referring to all the germs studied, 8.33% of local beverage samples are of satisfactory quality, 41.66% of acceptable quality and 50.00% of unsatisfactory quality. GHP assessment showed compliance rates of 100% (raw material), 66.66% (labour), 66.66% (methods), 55.55% (environment) and 25% (equipment). The results of this study indicate the need for the establishment of a quality assurance system followed within local beverage production structures.

A single-center experience with microbiologic surveillance of LivaNova 3T heater-cooler devices (HCDs)

Background: The global outbreak of Mycobacterium chimaera infections associated with HCDs resulted in new maintenance recommendations. Since 2018, HCDs have been disinfected according to instructions for use (IFU), including twice-monthly bleach disinfection and monitoring hydrogen peroxide (H2O2) to maintain a minimum daily concentration of 100 ppm. In February 2020, the IFU added the recommendation to perform microbiologic surveillance of HCD tank water to ensure effectiveness of disinfection to levels of <1 colony forming unit per milliliter (CFU/mL) of nontuberculous mycobacterium (NTM). We report our experience with this microbiologic surveillance as well as that of culturing the HCD environment to investigate modes of transmission. Methods: In 2022, we began culturing tank water in 10 HCDs for NTM. For a subset of 6 HCDs, quantitative NTM culturing of tank water before and after bleach disinfection was done. After initial results indicated widespread-contamination of HCDs with M. chimaera, we performed fill water cultures from 5 sinks in 4 HCD maintenance rooms. We also conducted 20 two-hour NTM settle-plate cultures of a cardiac operating room (OR) at different sites both inside (n = 7) and outside (n = 3) the OR: 10 with the HCD (located outside the OR) turned off (controls) and 10 with HCD turned on (exposure). A paired t test was used to evaluate differences in mean recovery of NTM in tank water samples. Results: Cultures from 7 (70%) of 10 HCDs were positive, with a mean of 13.6 CFU/mL M. chimaera (Table 1). There was no significant difference between the 10 pairs of pre- and postdisinfection NTM cultures done according to the IFU from 6 HCDs: mean predisinfection cultures (15.5 CFU/mL) versus mean postdisinfection cultures (12 CFU/mL) (P = .90) (Table 2). For fill water, 1 of 7 sink samples in 1 of 4 rooms was positive for M. chimaera ( <1 CFU/mL) from a specimen from a fresh 0.2-µm filter that had been stored in the fill-sink splash zone. OR settle-plate cultures showed 0 (0%) of 10 control sites and 1 (10 %) of 10 exposure sites inside the OR positive for NTM, with a single CFU of M. avium–intracellulare complex. Conclusions: Our data cannot clearly refute either of 2 possible scenarios for HCD contamination: cross contamination during device maintenance versus at the point of manufacture. Despite the IFU guidance or disinfection being implemented, disinfection procedures failed to suppress NTM contamination, and tank water within most HCDs was contaminated with M. chimaera regardless of age or whether it was deep cleaned or upgraded with an aerosol containment device.Disclosures: None

Vancomycin-modified nitrogen and chloride doped carbon dots and their application as a Staphylococcus aureus probe

In this research, N, Cl-doped carbon dots (N, Cl-CDs) were prepared in choline chloride-glycerol deep eutectic solvent (DES) by microwave method. N, Cl-CDs surface was modified with vancomycin for detection of Staphylococcus aureus (S. aureus) bacteria in the range of 102-107 colony-forming unit per milliliter (CFU/mL). The detection limit was 101 CFU/mL. Morphology and structure of N, Cl-CDs were characterized by transmission electron microscopy (TEM), X-ray photon spectroscopy (XPS), photoluminescence spectroscopy, FT-IR spectroscopy, energy dispersive X-ray spectroscopy (EDXS) and zeta potential. The prepared N, Cl-CDs had excellent dispersion in water, particle size range of 2–3 nm, and quantum yield of 38.75%. Speed, wide linear range and more convenient were advantages of new probe with respect to other methods.

Occurrence and Antimicrobial Susceptibility Profile of Escherichia Coli Isolates from Vended Milk in University of Abuja Community, Federal Capital Territory, Nigeria.

Purpose: This study was conducted to establish occurrence and antimicrobial susceptibility profile of Escherichia coli (E. coli) isolates from cow milk (Nono) sold within University of Abuja campuses.
 Methodology: Fifty (50) samples of “nono” milk were randomly collected from vendors in mini and main campus of University of Abuja from August to October 2021. All samples were analyzed using pour and surface plating methods. Presumptive E. coli isolates on Eosin methylene blue agar were characterized using preliminary and standard biochemical identification methods such as microbial plate count, Gram staining, oxidase, indole, methyl red, voges-proskauer, citrate and catalase tests. Antimicrobial susceptibility testing was conducted on positive isolates using the disc diffusion method.
 Findings: Out of the 50 samples of nono milk cultured, thirty (30) yielded growth for Escherichia coli which appeared as greenish metallic sheen on EMB agar plate and Gram-negative short rods on microscopic examination, representing an overall prevalence of 60%. The overall viable count of all samples was extremely high, with 8.7x10^7cfu/ml recorded as the highest colony forming unit per milliliter (CFU/ml) and 1.5×10^7cfu/ml recorded the lowest colony forming unit per milliliter (CFU/ml). All isolates were indole positive, methyl red positive, oxidase negative, citrate negative, catalase positive and voges-proskauer negative. E. coli isolates in this study were susceptible to sparfloxacin (66.7%), gentamicin (66.7%), ciprofloxacin (60%), streptomycin (60%), and tarivid (53.3%) and resistant to Septrin (73.3%), Augumentin (60%), Pefloxacin (66.7%), chloramphenicol (60%) and amoxicillin (53.3%). In conclusion, this study showed that the degree of contamination of E. coli in vended milk in the study area is higher than the maximum permissible bacteria count recommended by Codex Alimentarius standard for fermented milk products which is indicative of potential hazard to consumers.
 Recommendation: Public enlightenment on hygienic handling of milk during milking and especially vending by milk vendors is hereby recommended. Use of cool thermos for milk hawking is also advocated.

Enhanced Antibacterial Activity of Eugenol-Loaded mPEG-PCL Nanoparticles in Eliminating Resistant Bacteria from Wastewater

In this study, eugenol-loaded mPEG-PCL nanoparticles were used to improve the anti-bacterial properties of eugenol in an attempt to eliminate the resistant bacteria. The mPEG-PCL copolymer was prepared by ring-opening polymerization of [Formula: see text]-caprolactone monomer in the vicinity of a dry mPEG and a tin (II) octoate catalyst. Polymeric nanoparticles were prepared through the nanoprecipitation procedure. The particle size and zeta potential of mPEG-PCL/eugenol were found to be [Formula: see text] nm and [Formula: see text] mV, respectively. The polymeric nanoparticle structure was identified by AFM, FT-IR, and DSC techniques. To evaluate and compare the antibacterial efficiency of mPEG-PCL/eugenol with that of free eugenol, a turbidity assay was used in association with gram-positive and gram-negative bacteria. SEM images were taken from the bacteria before and after exposure to the mPEG-PCL/eugenol. The colony-forming unit per milliliter (CFU/mL) method was used to evaluate the performance of mPEG-PCL/eugenol on the growth rate of bacteria in hospital wastewater. The results showed that the mPEG-PCL/eugenol nanoparticles demonstrated an enormous antibacterial effect in connection with wild gram-negative bacteria strains at 40 [Formula: see text]M concentration and 37∘C. In the original hospital wastewater, mPEG-PCL/eugenol at the concentration of 0.125 [Formula: see text]M at 25∘C showed the largest decrease in the total microbial count.

Ultrahigh-sensitivity label-free optical fiber biosensor based on a tapered singlemode- no core-singlemode coupler for Staphylococcus aureus detection

An ultra-high sensitivity label-free optical fiber biosensor for inactivated Staphylococcus aureus (S. aureus) detection is proposed and investigated in this study, with additional advantages of robust and stability compared to traditional tapered fiber structure. The proposed fiber biosensor is based on a tapered singlemode- no core-singlemode fiber coupler (SNSFC) structure, where the no core fiber was tapered to small diameter (taper-waist diameter of about 10 μm) and functionalized with the pig immunoglobulin G (IgG) antibody for detection of S. aureus. The measured maximum wavelength shift of the sensor for an S. aureus concentration of 7 × 101 CFU/mL (colony forming unit per milliliter) is 2.04 nm, which is equivalent to a limit of detection (LOD) of 3.1 CFU/mL (a highest LOD reported so far for optical fiber biosensors), considering the maximum wavelength variation of the sensor in phosphate buffered saline (PBS) is ±0.03 nm over 40 min, where 3 times of maximum wavelength variation (3 × 0.03 = 0.09 nm) is defined as measurement limit. The response time of the developed fiber sensor is less than 30 min. The ultra-sensitive biosensor has potential to be widely applied to various areas such as disease, medical diagnostics and food safety inspection.

Eco-friendly curcumin-loaded nanostructured lipid carrier as an efficient antibacterial for hospital wastewater treatment

Abstract The contamination of wastewater with a wide variety of chemical, microbiological and toxic substances is an area of increasing environmental concern. The present study aimed to introduce a new strategy to remove a variety of bacterial pathogens from hospital wastewater. Eco-friendly curcumin loaded nanostructured lipid carriers (NLC-curcumin) were prepared by the hot high-speed homogenization method. The average particle size and zeta potential of NLC-curcumin were 137.9 ± 3.21 nm and -23.36 ± 3.5 mV, respectively. The nanoparticles were also characterized in terms of morphology, thermal behavior, antioxidant properties, and infrared spectroscopy. In vitro antibacterial effects of the NLC-curcumin and free-curcumin was studied by Turbidity assay in Luria–Bertani (LB) media on the standard and wild bacteria strains. The antibacterial effect of NLC-curcumin on bacteria was also studied by the SEM images. Analysis of colony forming unit per milliliter (CFU/ml) was used to evaluate the potential of NLC-curcumin on the bacteria growth decrease in the real environment of the hospital wastewater. The findings reveal that NLC-curcumin (0.125 μ M) in Mueller–Hinton agar media clearly reduces the percentage of the wild bacteria strains in autoclaved wastewater at 37 °C. For the original hospital wastewater treatment, NLC-Curcumin (0.125 μ M) significantly decreased the percentage of the microbial total count at 25 °C.

Effect of disaccharide-polyol systems on the thermal stability of freeze-dried Mycobacterium bovis

Live attenuated Mycobacterium bovis (M. bovis), marketed as Bacille Calmette-Guérin is the only FDA-approved vaccine against tuberculosis. The prerequisite of cold chain storage between 2 and 8 °C hinders the global vaccination effort. The study aims to investigate the effect of trehalose, sucrose and glycerol combinations in enhancing the stability of M. bovis. The bacilli were formulated in various ratios of trehalose-glycerol, sucrose-glycerol, trehalose-sucrose-glycerol systems (test samples) and sodium glutamate (control), freeze-dried and stored for 28 days at 4 °C, 25 °C and 37 °C. Bacteria viability at pre-, post-freeze-drying and after storage were quantified by its density in colony-forming unit per milliliter (CFU/mL) as obtained through the pour plate method. Formulations were characterized using differential scanning calorimetry. Structural collapsed cakes were found on all freeze-dried formulations because of the low Tg’. Comparing between binary and ternary formulations, trehalose-sucrose-glycerol was found to be a superior lyoprotectant. Upon storage, the viability of bacteria in disaccharide-polyol formulations was highest when stored at 4 °C followed by 25 °C. The lowest viability was found after storage at 37 °C. While the ternary disaccharide-polyol system may be used as a thermoprotectant up to 25 °C, sodium glutamate has a superior thermoprotective effect at temperature above 25 °C.

Assessment of safety and quality of fermented milk of camels, cows, and goats sold and consumed in five localities of Burkina Faso.

Background and Aim:Fermented milk is food produced and consumed all over the world and plays an important role in human nutrition. This work aimed to evaluate the microbiological and physicochemical quality and mineral composition of fermented milk consumed in Burkina Faso.Materials and Methods:A total of 114 samples of fermented milk from camels, goats, and cows were purchased in the market in five localities in Burkina Faso; Bobo Dioulasso, Djibo, Dori, Gorom-Gorom, and Sebba. Microbiological and physical parameters were monitored using standards methods.Results:Microbiological analysis of fermented milks showed high average values of 7.60±1.50×109 colony-forming unit per milliliter (CFU/ml), 5.72±3.60×107 CFU/ml, 5.53±2.00×105 CFU/ml, 1.97±0.18×103 CFU/ml, 1.98±0.25×103 CFU/ml, and 0.10±0.09×103 CFU/ml for total microbial flora, lactic acid bacteria, yeasts and molds, Staphylococcus aureus, total coliforms, and thermotolerant coliforms, respectively. None of the samples were contaminated by Salmonella or Shigella. The average values of pH, acidity, dry matter, ash, fats, proteins, and total carbohydrates content of samples were ranged, respectively: 3.830-4.137, 1.888-2.822%, 8.271-13.004%, 0.199-0.476%, 1.210-3.863%, 2.125-3.764%, and 3.080-5.428 % (w/w). Na/K and Ca/Mg ratio ranged from 0.104 to 0.909 and from 3.392 to 16.996, respectively. Total microbial flora, yeasts and molds, total coliforms, fats, calcium, potassium, iron, and zinc were significantly different.Conclusion:This research contributed in the evaluation of the hygienic and nutritional qualities of local fermented milk. Results obtained in this study confirm the need to set up the training program on the sanitary condition to traditional maker’s to ensure the good fermented milk with high organoleptic and nutritional qualities.

Functionalized reduced graphene oxide as a lateral flow immuneassay label for one-step detection of Escherichia coli O157:H7

In this study, graphene oxide (GO) and reduced graphene oxide (rGO) were used as visual labels in a lateral flow assay for detection of E. coli O157:H7. The color intensity was employed for the quantitative measurements of the target bacteria. Quantitative results showed that in comparison to GO, rGO can provide higher color intensity owing to enhanced light absorption following chemical reduction. Our results confirm that the visual limit of detection of the target bacteria by rGO is ∼105 colony forming unit per milliliter (CFU/ml), which closely compares with current alternative techniques using gold nanoparticles. The performance and practicability of the rGO-based test strips for detection of the target bacteria in milk and drinking water were validated with conventional plating and colony counting techniques. Results suggest that the proposed lateral flow assay is sensitive, specific, and affordable. It has also the potential to become a widely used detection technique for E. coli O157:H7 and a wide variety of other analytes.

Biosorption of lead using Bacillus badius AK strain isolated from compost of green waste (water hyacinth)

ABSTRACTThe bacterial strain Bacillus badius AK isolated from water hyacinth compost was investigated for biosorption characteristics in Pb(II) removal. Batch mode experiments depicted the optimum conditions for biosorption as pH at 4, the temperature of 30°C, 150 rpm of the rotational speed at biomass concentration of 20 mL with 1.7 × 1016 colony forming unit per milliliter (CFU/mL) value, at 100–150 mg/L concentration of Pb(II). The bacterial biomass was used in its native and non-pretreated state, unlike the dried, freeze-dried or chemically treated biomass. The biosorption followed pseudo-second-order kinetics and isotherm fitted well to the Langmuir model. Maximum Pb(II) biosorption was observed at 1.7 × 1016 CFU/mL. Influence of Pb(II) on the growth of bacterial biomass was examined by fitting the monod’s model. Specific growth rate and maximum specific growth rate of B. badius AK was observed as 0.05 and 2.54 h−1, respectively; biomass yield coefficient was 11.81. The results indicated that bacterial biomass was efficient, robust and cheaper biosorbent for removal of Pb(II).

Comparison of photoinactivation of T. rubrum by new methylene blue (NMB) and indocyanine green (EmunDo®)

BackgroundSuperficial mycotic skin infections which are predominantly caused by Trichophyton rubrum, poorly responsd to conventional therapies. A great amount of attention has focused on finding more effective treatments. The current work is aimed to compare the effectiveness of phoinactivation of Trichophyton rubrum by two relatively new photosensitizers: a phenothiazinium dye(New methylene blue) and Indocyanine green (EmunDo®). Materials and methodsA Final inoculum of T. rubrum which corresponded to 106 colony forming unit per milliliter (CFUml−1) was prepared. Antimicrobial Photodynamic treatment (aPDT) of T. rubrum was carried out by either EmunDo® (1mg/ml, Infra-red laser (IRL, λ=810nm, Energy Density 55J/cm2)) or NMB (10μM, Red laser (RL), λ=630nm, Energy Density of 5J/cm2). The suspensions thereafter were subcultured on Sabouraud dextrose agar (SDA) and were counted on due time. based on colony-forming unit per milliliter (CFU/ml). ResultsaPDT with either EmunDo® (E) or NMB (N) considerably diminished the viability of inoculated T. rubrum with respective reduction of 0.64 log and 0.4 log compared to the control group (P<0.001). No significant difference was found between two laser only groups (P=0.79) and two aPDT groups (P=0.73), however significant reduction of T. rubrum in red laser only group (P=0.04) and EmunDo® only group (P=0.04) was found as compared to the control group (P<0.05). ConclusionThe study provides evidence regarding satisfactory photodynamic inactivation of T. rubrum with EmunDo® or NMB as photosensitizers. Irradiation by only red laser source was found superior to only infra-red laser source. Dark toxicity of EmunDo® was more successful than new methylene blue dye.

TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE AND FOSFOMYCIN SUSCEPTIBILITY RATES IN UNCOMPLICATED URINARY TRACT INFECTIONS: TIME TO CHANGE THE ANTIMICROBIAL PREFERENCES.

Urinary tract infections (UTIs) are among the most common bacterial infections in adult population. They are prevalent in all age groups both in women and men. Also, UTIs are the most frequent indication for empirical antibiotic treatment in emergency department. The aim of this study was to determine the antibiotic resistance rates in the treatment of uncomplicated UTIs. Adult patients admitted to emergency department with uncomplicated UTIs were included in this cross-sectional study. Mid-stream urine samples were obtained under sterile conditions and cultured quantitatively. After 24 hours, the samples showing 10(5) colony forming unit per milliliter (CFU/mL) were tested for antibiotic susceptibility. Resistance to fosfomycin-trometamol (FT), amoxicillin-clavulanic acid (AC), ciprofloxacin (CIP), trimethoprim-sulfamethoxazole (TMP-SMX) and cefpodoxime (CEF) was tested by Kirby-Bauer disc diffusion system. Escherichia (E.) coli accounted for the vast majority (93.4%) of the organisms isolated in the study. Among the E. coli positive patients, resistance to TMP-SMX was the most common antibiotic resistance. The E. coli species detected in our study group were least resistant to FT (2.4%). The resistance rates, especially to CEF, AC and CIP, were significantly higher in patients over 50 years of age. In conclusion, in the treatment of uncomplicated UTIs, TMP-SMX should be excluded from empirical treatment, while fosfomycin could be a viable option in all age groups.

Efficacy of Microwave Disinfection on Moist and Dry Dental Stone Casts with Different Irradiation Times

Objectives: Dental practice contains the use of instruments and multiuse items that should be sterilized or disinfected properly. The aim of the current study was to investigate the effect of microwave irradiation on dental stone cast disinfection in moist and dry condition. Materials and Methods: In this in vitro study, 76 stone casts were prepared by a sterile method. The casts were contaminated by Pseudomonas aeruginosa (ATCC 9027), Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212) as well as Candida albicans (ATCC 10231). Half the samples were dried for two hours and the other half was studied while still moist. The samples were irradiated by a household microwave at 600 W for 3, 5 and 7 minutes. The microorganisms on the samples were extracted by immersion in tryptic soy broth and .001 ml of that was cultured in nutrient agar media, incubated overnight and counted and recorded as colony forming unit per milliliter (CFU/mL). Results: The findings showed that microorganisms reduced to 4.87 logarithm of CFU/mL value on dental cast within seven minutes in comparison with positive control. Although microbial count reduction was observed as a result of exposure time increase, comparison between moist and dried samples showed no significant difference. Conclusions: Seven-minute microwave irradiation at 600 W can effectively reduce the microbial load of dental stone casts. Wetting the casts does not seem to alter the efficacy of irradiation. Keywords: Microwave Disinfection; Dental Stone Casts; Irradiation Times

In vitro photodynamic inactivation of Candida albicans by phenothiazine dye (new methylene blue) and Indocyanine green (EmunDo®)

The application of a new generation of photosensitizers to increase the efficacy of antifungal photodynamic therapy (aPDT) is an important aspect of PDT. Thus, this in vitro study is aimed to evaluate the antifungal efficacy of the photo-elimination of Candida albicans with photothermal and antifungal photodynamic therapy. aPDT with new methylene blue and photothermal therapy with EmunDo® were applied to a fungal suspension, which was then subcultured in Sabouraud dextrose agar (SDA). The C. albicans colonies were counted and are expressed as colony-forming unit per milliliter (CFU/ml). aPDT with either EmunDo® or new methylene blue (NMB) considerably diminished the viability of inoculated C. albicans (P<0.001) by log reduction of 1.9 and 3.37, respectively, compared with the control group respectively, compared with the control group. The antifungal potency or dark toxicity of the two photosensitizers alone did not significantly differ (P=0.70). The same trend was observed for the light sources (λ: 810nm vs. λ: 630nm), which also did not significantly differ (P=0.78). The photo-elimination of C. albicans with either new methylene blue or EmunDo® as a photosensitizer can reduce the viability of fungal cells. Although the result of this study is encouraging, further investigations are warranted to determine clear protocols for the reliable and safe application of this method in clinical practice.

Inactivation of multidrug resistant (MDR)- and extensively drug resistant (XDR)-Mycobacterium tuberculosis by photodynamic therapy

We investigated the effects of photodynamic therapy (PDT) on anti-tuberculosis (TB) activity by measuring inactivation rates, expressed as D-value, of MDR- and XDR-Mycobacterium tuberculosis (M. tb) clinical strains in vitro. Approximately 10(6) colony forming unit per milliliter (CFU/ml) of the bacilli were irradiated with various doses of laser light after exposure to photosensitizers. Survival of M. tb was measured by enumerating CFU in 7H10 medium to measure D-values. No inactivation of M. tb was observed when exposed to photosensitizers (radachlorin or DH-I-180-3) only or laser light only (P>0.1). Treatment with a combination of photosentizer and laser inactivated M. tb although there was a significant difference between the types of photosensitizers applied (P<0.05). Linear inactivation curves for the clinical M. tb strains were obtained up to laser doses of 30 J/cm(2) but prolonged irradiation did not linearly inactivate M. tb, yielding sigmoid PDT inactivation curves. D-values of M. tb determined from the slope of linear regression lines in PDT were not significantly different and ranged from 10.50 to 12.13 J/cm(2) with 670 nm laser irradiation at 100 mW/cm(2) of the fluency rate, except for a drug-susceptible strain among the clinical strains tested. This suggests that PDT inactivated M. tb clinical strains regardless of drug resistance levels of the bacilli. Intermittent and repeated PDT allowed acceleration of the inactivation of the bacilli as a way to avoid the sigmoid inactivation curves. In conclusion, PDT could be alternative as a new option for treatment for MDR- and XDR-tuberculosis.

Comparison of the effect of rose bengal- and eosin Y-mediated photodynamic inactivation on planktonic cells and biofilms of Candida albicans

Candida albicans is an opportunistic yeast that can cause oral candidosis through the formation of a biofilm, an important virulence factor that compromises the action of antifungal agents. The objective of this study was to compare the effect of rose bengal (RB)- and eosin Y (EY)-mediated photodynamic inactivation (PDI) using a green light-emitting diode (LED; 532 ± 10 nm) on planktonic cells and biofilms of C. albicans (ATCC 18804). Planktonic cultures were treated with photosensitizers at concentrations ranging from 0.78 to 400 μM, and biofilms were treated with 200 μM of photosensitizers. The number of colony-forming unit per milliliter (CFU/mL) was compared by analysis of variance and Tukey's test (P ≤ 0.05). After treatment, one biofilm specimen of the control and PDI groups were examined by scanning electron microscopy. The photosensitizers (6.25, 25, 50, 200, and 400 μM of EY, and 6.25 μM of RB or higher) significantly reduced the number of CFU/mL in the PDI groups when compared to the control group. With respect to biofilm formation, RB- and EY-mediated PDI promoted reductions of 0.22 log10 and 0.45 log10, respectively. Scanning electron microscopy showed that the two photosensitizers reduced fungal structures. In conclusion, EY- and RB-mediated PDI using LED irradiation significantly reduced C. albicans planktonic cells and biofilms.

Effect of different energy levels of microwave on disinfection of dental stone casts.

Background and aims Current chemical methods may not efficiently disinfect dental stone casts. The aim of this study was to investigate if microwave irradiation is effective for disinfection of stone casts. Materials and methods In this laboratory study, three groups (n = 162) of prepared spherical stone beads as carriers with a diameter of 10 mm were inoculated by separately soaking in three broth culture media, each containing a study microorganism—Pseudomonas aeruginosa, Staphylococcus aureus or Candida albicans. Six inoculated carriers were used for every test, including irradiation in a household microwave oven at 300, 450, 600 or 900 W energy level, or soaking in 0.03%, 0.06%, 0.12%, 0.25% or 0.50% concentration of sodium hypochlorite solution, at 1, 2, or 3-minute test times. Positive and negative control groups were considered for each test. All treated carriers were then individually transferred to nutrient broth culture medium and one milliliter from each tube was cultured in nutrient agar media over night. Colony forming unit per milliliter (CFU/mL) was counted, and multi-factor ANOVA was used to analyze data (α = 0.05). Results Microwave irradiation at 600 W resulted in high-level disinfection in 3 minutes. Immersion of the stone casts in hypochlorite solution at 0.06% concentration resulted in disinfection after 2 minutes. Conclusion According to the results, high level disinfection of the stone casts can be achieved by microwave irradiation at 600 W in 3 minutes, similar to a validated chemical method.

Counting Bacteria Using Functionalized Gold Nanoparticles as the Light-Scattering Reporter

A simple and rapid bacterial counting method was developed based on dark-field light-scattering imaging of bacteria and gold nanoparticle (AuNP) reporter simultaneously. Commercially available DH5α E. coli strain was used as the model bacterium to demonstrate the feasibility of the proposed method. With antibody-conjugated AuNPs, the simple sample treatment and target E. coli strain recognition can be finished within 15-30 min, with a detection limit of 2-6 × 10(4) colony forming unit per milliliter (CFU/mL). By using 90 nm AuNPs as the light-scattering signal reporter, the bacterial recognition and counting can be easily performed with low-cost instrumentation such as an entry-level dark-field microscope setup and a common tungsten lamp as the light source. An automatic image analysis algorithm was also developed to facilitate robust and fast bacterial counting. The preliminary results of water, milk, and fruit juice sample analysis showed that this simple, fast, and cost-effective method can be easily adopted for routine bacterial detection.

Experimental model of Fusarium solani keratitis in rats.

To establish a repeatable rat model of Fusarium solani keratitis (F. solani keratitis) that mimicked fungal keratitis in humans. Wistar rats' corneas were scratched on the superficial stroma after scraping the unilateral corneal epithelia. Then, the corneal surface was inoculated with different inoculum dose of F. solani spore suspension. Doses ranged from 10(6) to 10(9) colony-forming unit per milliliter (CFU/mL). The treated corneas were covered by contact lenses that were made of Parafilm M membrane. Negative controls were inoculated with sterile phosphate-buffered saline (PBS). For statistical analysis, corneas were evaluated daily on a 12-point scale to check the state of corneal inflammation. Furthermore, the pathological characteristics of this model were investigated. The rat model of F. solani keratitis was established by the combination methods of corneal trauma and parafilm-made contact lens and inoculation of fungus spore suspension. 10(6) and 10(7)CFU/mL of F. solani induced mild corneal infection, while 10(8)CFU/mL of F. solani was sufficient to induce moderate infection that was consistent with human keratomycosis. Dose of 10(9)CFU/mL of F. solani was excessive and led to perforated corneas. The rat model of F. solani keratitis, established by the combinational methods of corneal trauma, parafilm-made contact lens and the appropriate dose of inoculum, that imitates the developing processes of F. solani keratitis in human beings and provides a repeatable method of creating a rat model.