Lower Colony-forming Units Research Articles

Effects of various methods of milking, container types, and chilling durations on bacterial load of milk

This study was carried out to evaluate the quality of raw milk measured by Standard Plate Count (SPC). Individual raw milk for the Colony Forming Units (CFU) study was carried out in the National Cattle Research Program Rampur Chitwan, Nepal. Milk from Jersey and Holstein cows with two types of milking (hand and machine milking) in collecting three types of containers (Plastic, aluminum, and steel). Milk had different chilling durations (0, 4, 8, 12, 24, 48, and 72 hours). Altogether, 252 milk samples for SPC were examined at farm levels. Results showed significant variability in SPC throughout the study period. The lowest CFU was observed in Holstein cows (80.49±4.83 × 104), while the highest was found in the Jersey breed (122.88±4.69 × 104). Similarly, the lowest CFU count was recorded in milk from machine milking (92.42±4.69 × 104), whereas the highest CFU count was observed in milk from hand milking (110.95±4.83 × 104). For three milk collecting and transporting containers, the CFU count was lowest in the steel container (90.09±5.82×104) compared to the aluminum container (102.42±5.82×104) and plastic container (112.55±5.82×104). The results of mean CFU for the chilling duration effects at farm 0, 4, 8,12,24,48 and 72 hours were (114.33±8.11×104, 108.21±10.28×104, 107.71±10.28×104, 106.75±10.28 ×104, 104.07±6.36 ×104, 94.79±8.11×104, and 75.94±8.11×104). CFU count in hand and machine milking milk differed significantly (p<0.01) from each record of the same date at the farm level. The CFU in milk from different containers was significant (p<0.05) for the overall experimental period. Steel containers showed a low CFU count compared to Aluminum and plastic containers. The highest number of CFU (114.33×104) was observed in the 0-hour chilling, which was significantly (p <0.05) different from the rest of the chilling duration. The results obtained from the study indicated that the current situation is critical and needs real improvement from farm to chilling centers. The findings could guide dairy producers in adopting effective strategies to enhance milk quality, minimize bacterial contamination, and ensure safer dairy products for consumers by using these results.

Delayed Tooth Development and the Impaired Differentiation of Stem/Progenitor Cells in Incisors from Type 2 Diabetes Mice.

Patients with diabetes mellitus (DM) have an increased risk of tooth decay caused by alterations in their tooth development and their oral environment, as well as a tendency to present with pulp infection due to compromised immune response. The present study analyzed the characteristic alterations in tooth development under DM conditions using incisors from db/db type 2 diabetic mouse model (T2DM mice). In micro-CT analyses, T2DM mice showed delayed dentin and enamel formation. Through transcriptomic analyses, pre-ameloblast- and pre-odontoblast-specific genes were found to be significantly decreased in the incisors of T2DM mice, whereas major ameloblast- and mature odontoblast-specific genes were not changed. Stem cell markers were decreased in T2DM mice compared to those from the control mice, suggesting that the stemness of dental pulp cells (DPCs) is attenuated in T2DM mice. In vitro analyses demonstrated that DPCs from T2DM mice have lower colony-forming units (CFU), slower propagation, and diminished differentiation characteristics compared to the control. These data suggest that T2DM conditions could impair the differentiation property of multiple progenitor/stem cells in the tooth, resulting in delayed tooth development in T2DM mice.

Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model

BackgroundIn diagnosing chronic orthopedic implant infections culture of sonicate represents a supplement to tissue cultures. However, the extent to which biofilm forms on implant surfaces and the degree of dislodgement of bacteria by sonication remains unclear. In this in vivo study using a low bacterial inoculum, we aimed to determine whether a variable effect of sonication could be observed in a standardized in vivo model.Materials and MethodsSeven Wistar rats underwent surgery with intramuscular implantation of two bone xenograft implants, each containing two steel plates. The grafts were inoculated with approximately 500 colony forming units (CFU) of Staphylococcus epidermidis ATCC 35984. After 20 days the rats were sacrificed, and the steel plates were removed from the bone grafts. Epifluorescence microscopy and scanning electron microscopy (SEM) were used to visualize biofilm formation and dislodgement on the plate surfaces. In addition to cultures of sonicate, a quantitative S. epidermidis specific PCR was developed for enumeration of bacteria.ResultsA chronic, low-grade implant infection was successfully established, with all animals remaining in good health. All infected bone graft implants yielded abundant growth of S. epidermidis, with a median of 3.25 (1.6–4.6) × 10⁷ CFU per/graft. We were unable to distinguish infected plates from negative controls using epifluorescence microscopy. On infected plates small colonies of staphylococci were identified by SEM. The number of bacteria detected in the sonicate was low with 500 (100–2400) CFU/plate and 475 (140–1821) copies/plate by qPCR. The difference in area covered by fluorescent material before and after sonication was 10.1 (5.7–12.3) %, p = 0.018.ConclusionDespite the pronounced infection in the surrounding tissue, only few bacteria were detected on the surface of the steel implants. This is evident from the minimal findings by SEM before sonication, as well as the very low CFU counts and DNA copies in the sonicate. Sonication did not show variable effectiveness, indicating it is a valuable addition to, but not a replacement for biopsy cultures in cases of implant-associated infections with low-virulence microorganisms.

Assessment of the potential of microbial consortium for the reclamation of mine tailings containing potentially toxic elements

Bioremediation using microorganisms is an emerging green technology for the remediation of potentially toxic elements (PTEs) in soils and sediments. However, such technology can differently impact PTEs dynamics (e.g., immobilization and mobilization), ultimately affecting the efficiency of the remediation programs. In this study, we aimed to assess different microbial remediation mechanisms triggered by a microbial consortium to bioremediate Fe-rich mining tailings. The tailings were incubated in a mesocosm system for 35 days with increasing colony-forming units (CFU) of a specific microbial consortium (Azospirillum sp., Pseudomonas sp., Saccharomyces sp., and Rhizobium sp.). At the end of the experiment, we determined the geochemical fractionation of Fe and PTEs in the solid phase to assess the effect of treatments on PTE’s bioavailability. Increasing the CFU resulted in higher Fe (15%) and Mn (37%) reductive dissolution compared to the control. As a result, the Fe and Mn concentrations in water increased by 9-fold. In addition, microbial consortium decreased the contents of Fe and Mn associated with oxides (-59% and −79%, respectively) and increased the more bioavailable solid fractions. The microbial consortium also efficiently decreased PTEs pseudo total contents in the mine tailings (Cr: −85%, Cd: −61%, Pb: −55%, and Cu: −49%). In addition, lower CFUs increased PTEs dissolved in the drainage water, indicating a potential for assisting other remediation strategies. Lower CFU also induced high Cr biomineralization (94%). In conclusion, our work provides novel evidence of a microbial consortium for remediating Fe mine tailings through different strategies (biodissolution and biomineralization). In view of the effects of the microbial consortium over Fe and Mn oxyhydroxide dissolution rates, further research should test it on microbially assisted phytoremediation protocols.

Boron-containing coating yields enhanced antimicrobial and mechanical effects on translucent zirconia

ObjectivesTo evaluate the mechanical and antimicrobial properties of boron-containing coating on translucent zirconia (5Y-PSZ). Methods5Y-PSZ discs (Control) were coated with a glaze (Glaze), silver- (AgCoat), or boron-containing (BCoat) glasses. The coatings' antimicrobial potential was characterized using S. mutans biofilms after 48 h via viable colony-forming units (CFU), metabolic activity (CV) assays, and quantification of extracellular polysaccharide matrix (EPS). Biofilm architectures were imaged under scanning electron and confocal laser scanning microscopies (SEM and CLSM). The cytocompatibility was determined at 24 h via WST-1 and LIVE&DEAD assays using periodontal ligament stem cells (PDLSCs). The coatings' effects on properties were characterized by Vickers hardness, biaxial bending tests, and fractography analysis. Statistical analyses were performed via one-way ANOVA, Tukey's tests, Weibull analysis, and Pearson's correlation analysis. ResultsBCoat significantly decreased biofilm formation, having the lowest CFU and metabolic activity compared with the other groups. BCoat and AgCoat presented the lowest EPS, followed by Glaze and Control. SEM and CLSM images revealed that the biofilms on BCoat were thin and sparse, with lower biovolume. In contrast, the other groups yielded robust biofilms with higher biovolume. The cytocompatibility was similar in all groups. BCoat, AgCoat, and Glaze also presented similar hardness and were significantly lower than Control. BCoat had the highest flexural strength, characteristic strength and Weibull parameters (σF: 625 MPa; σ0: 620 MPa; m = 11.5), followed by AgCoat (σF: 464 MPa; σ0: 478 MPa; m = 5.3). SignificanceBCoat is a cytocompatible coating with promising antimicrobial properties that can improve the mechanical properties and reliability of 5Y-PSZ.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study

BackgroundSeptic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study.Materials and methodsOsteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation.ResultsThe cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture.ConclusionsOur findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness.Level of Evidence: Level 2Trial registration DRKS00014657 (date of registration: 2018/04/26)

The effect of intraoperative immersion solutions on acellular dermal matrix: Biofilm formation and mechanical property

Acellular dermal matrix (ADM) is generally used on implant-based breast operations; However, it can increase surgical site infection. Many immersion solutions are applied to ADM, however, the most effective solution is unknown. The purpose of this study is to determine the effect of different solutions on the biofilm formation and mechanical properties of ADM. Aseptic porcine-derived ADMs were immersed in 5 different solutions for 30min; sterile normal saline, 10% povidone-iodine, 0.5% chlorhexidine, antibiotics (cefazolin, gentamicin, and vancomycin), and taurolidine. They are transferred to 10ml suspension of methicillin-sensitive/resistant Staphylococcus aureus (MSSA/MRSA) or Staphylococcus epidermidis and an overnight culture was performed. After rinsing and sonication to obtain the biofilm on ADM, colony forming unit (CFU) was measured. In addition, the maximum load before ADM deformation and the elongation length of ADM at the start of the maximum load was determined. Regardless of strains, povidone-iodine, chlorhexidine, and taurolidine group had lower CFUs than the saline group with statistical significance. Meanwhile, the antibiotics group did not show statistical difference from the saline group. Moreover, only taurolidine group showed higher tensile strength (MRSA, p=0.0003; S. epidermidis, p=0.0023) and elongation length (MSSA, p=0.0015) than the saline group. The antibiotics and chlorhexidine group yielded lower tensile strength and elongation length than the povidone-iodine and taurolidine groups. It was suggested that the 10% povidone-iodine or taurolidine solution is effective. In contrast, the antibiotics solution could be considered as an effective intraoperative solution.

Identification of food and nutrient components as predictors of Lactobacillus colonization.

A previous double-blind, randomized clinical trial of 42 healthy individuals conducted with Lactobacillus johnsonii N6.2 found that the probiotic's mechanistic tryptophan pathway was significantly modified when the data was stratified based on the individuals' lactic acid bacteria (LAB) stool content. These results suggest that confounding factors such as dietary intake which impact stool LAB content may affect the response to the probiotic treatment. Using dietary intake, serum metabolite, and stool LAB colony forming unit (CFU) data from a previous clinical trial, the relationships between diet, metabolic response, and fecal LAB were assessed. The diets of subject groups with high vs. low CFUs of LAB/g of wet stool differed in their intakes of monounsaturated fatty acids, vegetables, proteins, and dairy. Individuals with high LAB consumed greater amounts of cheese, fermented meats, soy, nuts and seeds, alcoholic beverages, and oils whereas individuals with low LAB consumed higher amounts of tomatoes, starchy vegetables, and poultry. Several dietary variables correlated with LAB counts; positive correlations were determined for nuts and seeds, fish high in N-3 fatty acids, soy, and processed meats, and negative correlations to consumption of vegetables including tomatoes. Using machine learning, predictors of LAB count included cheese, nuts and seeds, fish high in N-3 fatty acids, and erucic acid. Erucic acid alone accurately predicted LAB categorization, and was shown to be utilized as a sole fatty acid source by several Lactobacillus species regardless of their mode of fermentation. Several metabolites were significantly upregulated in each group based on LAB titers, notably polypropylene glycol, caproic acid, pyrazine, and chondroitin sulfate; however, none were correlated with the dietary intake variables. These findings suggest that dietary variables may drive the presence of LAB in the human gastrointestinal tract and potentially impact response to probiotic interventions.

Environmental contamination with highly resistant microorganisms after relocating to a new hospital building with 100% single-occupancy rooms: A prospective observational before-and-after study with a three-year follow-up.

Inanimate surfaces within hospitals can be a source of transmission for highly resistant microorganisms (HRMO). While many hospitals are transitioning to single-occupancy rooms, the effect of single-occupancy rooms on environmental contamination is still unknown. We aimed to determine differences in environmental contamination with HRMO between an old hospital building with mainly multiple-occupancy rooms and a new hospital building with 100% single-occupancy rooms, and the environmental contamination in the new hospital building during three years after relocating. Environmental samples were taken twice in the old hospital, and fifteen times over a three-year period in the new hospital. Replicate Organism Direct Agar Contact-plates (RODACs) were used to determine colony forming units (CFU). Cotton swabs premoistened with PBS were used to determine presence of methicillin-resistant Staphylococcus aureus, carbapenemase-producing Pseudomonas aeruginosa, highly resistant Enterobacterales, carbapenem-resistant Acinetobacter baumannii, and vancomycin-resistant Enterococcus faecium. All identified isolates were subjected to whole genome sequencing (WGS) using Illumina technology. In total, 4993 hospital sites were sampled, 724 in the old and 4269 in the new hospital. CFU counts fluctuated during the follow-up period in the new hospital building, with lower CFU counts observed two- and three years after relocating, which was during the COVID-19 pandemic. The CFU counts in the new building were equal to or surpassed the CFU counts in the old hospital building. In the old hospital building, 24 (3.3%) sample sites were positive for 49 HRMO isolates, compared to five (0.1%) sample sites for seven HRMO isolates in the new building (P<0.001). In the old hospital, 89.8% of HRMO were identified from the sink plug. In the new hospital, 71.4% of HRMO were identified from the shower drain, and no HRMO were found in sinks. Our results indicate that relocating to a new hospital building with 100% single-occupancy rooms significantly decreases HRMO in the environment. Given that environmental contamination is an important source for healthcare associated infections, this finding should be taken into account when considering hospital designs for renovations or the construction of hospitals.

The search for a healthy sugar substitute in aid to lower the incidence of Early Childhood Caries: a comparison of sucrose, xylitol, erythritol and stevia

A pursuit to find a healthy alternative to sucrose with less cariogenic potential, which can potentially lower the incidence of Early Childhood Caries (ECC), by means of comparison. Primary tooth enamel blocks (n=32) were randomly divided into four groups and exposed to 5% concentrations of the respective test groups (sucrose, xylitol, erythritol and stevia). All samples were inoculated with S. mutans standard strain (ATCC 25175) at room temperature. Analysis of Colony Forming Units (CFUs), acidity measurements (pH) and Scanning Electron Microscopy (SEM) observations were done after 6, 12, 18 and 24 h and compared. After 6 h, the marginal mean CFU count indicated equal S. mutans growth in all groups. Stevia showed lower CFU counts compared to other groups at 12, 18 and 24 h. The pH levels for all non-fermentable sugar substitutes (NSS) initially decreased but never below the critical pH=5.5 and stabilized from 12 to 18 h. The pH levels of sucrose dropped and remained below pH=5.5 at all time intervals. The SEM analysis of S. mutans supported the CFU results indicating growth in the presence of sucrose and reduction in the presence of the NSS.Compared to sucrose, xylitol, erythritol and stevia have less cariogenic potential with reduced growth of S. mutans and subsequent acidity levels. Stevia had the least cariogenic potential of all the NSS tested, followed by erythritol and then xylitol.

Mycobacterium tuberculosis ketol-acid reductoisomerase down-regulation affects its ability to persist, and its survival in macrophages and in mice

Branched-chain amino acids (BCAAs) leucine, isoleucine and valine biosynthetic pathways have been reported from plants, fungi and bacteria including Mycobacterium tuberculosis (Mtb) but are absent in animals. This makes interventions with BCAAs biosynthesis an attractive proposition for antimycobacterial drug discovery. In the present study, Mycobacterium tuberculosis H37Ra (Mtb-Ra) ketol-acid reductoisomerase encoding ORF MRA_3031 was studied to establish its role in Mtb-Ra growth and survival. Recombinant knockdown (KD) and complemented (KDC) strains along with wild-type (WT) Mtb-Ra were studied under in-vitro and ex-vivo conditions. KD was defective for survival inside macrophages and showed time dependent decrease in its colony forming unit (CFU) counts, while, WT and KDC showed time dependent increase in CFUs, after macrophage infection. Also, KD showed reduced ability to form persister cells, had altered membrane permeability against ethidium bromide and nile red dyes, and had reduced biofilm maturation, compared to WT and KDC. The in-vivo studies showed that KD infected mice had lower CFU counts in lungs, compared to WT. In summary Mtb shows survival deficit in macrophages and in mice after ketol-acid reductoisomerase down-regulation.

Recovery of Streptococcus Mutans Biofilm after Photodynamic Therapy with Erythrosine and LED Light Source

The aim of this study was to evaluate the effects of erythrosine-mediated photodynamic therapy (PDT) on Streptococcus mutans biofilm recovery by counting its colony-forming units (CFUs) and via confocal laser scanning microscopy analysis at different time points following PDT. In PDT, photosensitizer was an erythrosine. S. mutans ATCC25175 biofilms were irradiated using an LED curing light. Chlorhexidine (CHX) was used as positive control. After each antimicrobial treatment, samples were cultured to allow biofilm recovery. Viability was measured by calculating the CFU counts after treatment and after every 3 hours for up to 24 hours. Immediately after treatment, the PDT and CHX groups showed equally significant decreases in S. mutans CFU counts compared to the negative control. After 12 hours of reculture, the PDT group showed no significant difference in the decrease in CFU count compared to the negative control, whereas the CHX group showed significantly lower CFU counts throughout the 24-hour period. Erythrosine-mediated PDT can effectively inhibit S. mutans biofilm formation. However, biofilm recovery occurred earlier in the CHX group after PDT. This study provides insights into the clinical effectiveness of PDT in preventing dental caries.

A critical appraisal of humanized alternatives to fetal bovine serum for clinical applications of umbilical cord derived mesenchymal stromal cells.

The study is aimed to verify the possibility of using humanized alternatives to fetal bovine serum (FBS) such as umbilical cord blood plasma (CBP) and AB+ plasma to support the long-term growth of mesenchymal stromal cells (MSCs) derived from the umbilical cord. We hypothesized that umbilical CBP would be a potential substitute to FBS, especially for small scale autologous clinical transplantations. The MSCs were cultured for six consecutive passages to evaluate xeno-free media's ability to support long-term growth. Cell proliferation rates, colony-forming-unit (CFU) efficiency and population doublings of expanded MSCs, were investigated. Ex vivo expanded MSCs were further characterized using flow cytometry and quantitative PCR. The impact of cryopreservation and composition of cryomedium on phenotype, viability of MSC was also assessed. Our results on cell proliferation, colony-forming unit efficiency suggested that the expansion of the cells was successfully carried out in media supplemented with humanized alternatives. MSCs showed lower CFU counts in FBS (~ 25) than humanized alternatives (~ 35). The gene expression analysis revealed that transcripts showed significant differential expression by two to three folds in the FBS group compared with MSCs grown in medium with humanized alternatives (p < 0.05). In addition, MSCs grown in a medium with FBS had more osteogenic activity, a signatureof unwanted differentiation. The majority of ex vivo expanded MSCs at early and late passages expressed CD44+, CD73+, CD105+, CD90+, and CD166+ in all the experimental groups tested (~ 90%). In contrast to the other MSC surface markers, expression levels of STRO-1+ (~ 21-10%) and TNAP+ (~ 29-11%) decreased with the increase in passage number for MSCs cultured in a FBS-supplemented medium (p < 0.05). Our results established that CBP supported culture of umbilical cord tissue-derived MSCs and is a safer Xeno free replacement to FBS. The use of CBP also enables the storage of umbilical cord tissue derived MSCs in patient-specific conditions to minimize adverse events if cells are delivered directly to the patient.

Extracellular Vesicles From Sporothrix brasiliensis Yeast Cells Increases Fungicidal Activity in Macrophages.

Sporotrichosis is a subcutaneous mycosis and is distributed throughout the world, although most cases belong to endemic regions with a warmer climate such as tropical and subtropical areas. The infection occurs mainly by traumatic inoculation of propagules. Similarly, to other organisms,Sporothrix brasiliensisdisplay many biological features that aid in its ability to infect the host, such as extracellular vesicles, bilayered biological structures that provides communication between host cells and between fungi cells themselves. Recently, research onSporothrixcomplex have been focused on finding new molecules and components with potential for therapeutic approaches. Here, we study the relationship among EVs and the host's macrophages as well as their role during infection to assess whether these vesicles are helping the fungi or inducing a protective effect on mice during the infection. We found that after cocultivation with different concentrations of purified yeasts EVs fromSb, J774 macrophages displayed an increased fungicidal activity (Phagocytic Index) resulting in lower colony-forming units the more EVs were added, without jeopardizing the viability of the macrophages. Interleukins IL-6, IL-10, and IL-12 were measured during the infection period, showing elevated levels of IL-12 and IL-6 in a dose-dependent manner, but no significant change for IL-10. We also assessed the expression of important molecules in the immune response, such as MHC class II and the immunoglobulin CD86. Both these molecules were overexpressed inSbyeasts infected mice. Our results indicate that EVs play a protective role duringSporothrix brasiliensisinfections.

In vitro comparison of root surface roughness and bacterial adhesion following treatment with three different instruments.

A novel device, piezoelectric 11 Gracey curet tip, reportedly combines benefits of a piezoelectric device and manual curet. The primary objective of this study was to compare root surface roughness outcomes between traditional manual curets and piezoelectric devices, as compared with this novel device. The secondary aim was to assess the level of adhesion of Streptococcus mutans on the root surface after instrumentation. The groups consisted of the following: 1) Gracey curet; 2) piezoelectric scaler; 3) piezoelectric 11 Gracey curet tip; and 4) untreated control. Root specimens were obtained from extracted human teeth and randomly assigned to each group. Surface roughness measurements (Ra and Rz) were taken with a profilometer before and after instrumentation. After instrumentation, root specimens were inoculated with S. mutans and biofilm was dislodged. Various dilutions of resuspended biofilm were incubated on blood agar plates and colony forming units (CFU) values were measured. The experimental device resulted in significantly lower Ra and Rz compared with other groups (P<0.01), and the Gracey curet was significantly lower than the piezoelectric tip and untreated control (P<0.05). The Gracey curet and experimental device tip had significantly lower CFU values compared with the control (P<0.05). There were no significant CFU value differences between the Gracey curet and both the piezoelectric and experimental device tips. There were no significant CFU differences between piezoelectric tip and both experimental device and control. There was no correlation between Ra and CFU values for Gracey curet, piezoelectric tip, or the control. However, correlation between Ra values and CFU approached significance for the experimental device (correlation=0.66, P=0.05). Piezoelectric 11 Gracey curet tip is effective at resulting in a significantly smoother surface compared with traditional piezoelectric and hand instruments. CFU values with piezoelectric 11 Gracey curet tip were significantly lower than non-instrumented surfaces, but there were no significant differences compared with conventional methods.

A novel three-dimensionally printed model to assess biofilm removal by ultrasonically activated irrigation.

To apply an innovative three-dimensionally printed tooth model to investigate the efficacy of three ultrasonically activated irrigation (UAI) systems in removing multispecies biofilms from dentine samples. Three-dimensionally printed teeth with a curved root canal were fabricated with a standardized slot in the apical third of the root to achieve precision fit of human root dentine specimens. Multispecies biofilms including Enterococcus faecalis, Streptococcus mitis and Campylobacter rectus were developed in the root canal for 21days. The canals were allocated to be irrigated with 1% sodium hypochlorite (NaOCl) using a syringe and needle or ultrasonically activated NaOCl with a stainless-steel file (Irrisafe), a conventional nickel-titanium (Ni-Ti) file (CK) or a blue heat-treated Ni-Ti file (Endosonic Blue). Infected root canals irrigated with distilled water served as controls. Bacterial reduction was determined by colony-forming unit (CFU) counting (n=20), whilst biofilms were analysed using confocal laser scanning microscopy (n=7) and field emission scanning electron microscopy. For CFU counting, the independent two-sample t-test (Welch's t-test) was examined to compare overall bacterial reduction amongst groups. For CLSM analysis, the data were analysed using one-way analysis of variance (ANOVA), followed by the Scheffé post hoc test. The p-values <.05 were considered to indicate statistical significance. All groups in which NaOCl was ultrasonically activated had significantly lower CFU values than the syringe-and-needle irrigation and control groups (p<.05). Ultrasonic activation with the stainless-steel file and blue heat-treated Ni-Ti file significantly reduced the biofilm volume compared with other groups (p<.05). Overall, UAI with the blue heat-treated file resulted in the highest antibacterial and biofilm removal efficacy. UAI with different inserts had differential antibiofilm effects. The blue heat-treated Ni-Ti ultrasonic insert resulted in the greatest antibacterial and biofilm removal from dentine in this standardized root canal model.

Efficacy of Preprocedural Boric Acid Mouthrinse in Reducing Viable Bacteria in Dental Aerosols Produced during Ultrasonic Scaling.

Introduction:Aerosols and droplets contaminated with bacteria and blood are produced during ultrasonic scaling. Measures to control aerosol contamination in dental clinics are recommended by the Centers for Disease Control and Prevention. This study aimed to evaluate the efficacy of preprocedural boric acid (BA) mouthrinse in reducing bacterial contamination in dental aerosols generated during ultrasonic scaling.Materials and Methods:This was a randomised clinical trial in 90 systemically healthy subjects (25-55 yrs) diagnosed with chronic periodontitis who were allocated into three groups of 30 subjects each to receive, Group A - 0.12% chlorhexidine (CHX), Group B - 0.75% BA and Group C-water, as a preprocedural rinse for 1 min. The aerosol generated while performing ultrasonic scaling for 30 min was collected at three locations on blood agar plates. Incubation of the blood agar plates at 37°C for next 48 h for aerobic culture was performed and subsequently colony-forming units (CFUs) were counted.Results:CFUs in Group A were significantly reduced compared with Group B (P < 0.001). When we compare CFUs in all the three groups, CFUs in Groups A and B were statistically significantly reduced compared with Group C (P < 0.001). Furthermore, it was also observed that the assistant's chest area had lowest CFUs whereas patient's chest area had highest.Conclusion:This study recommends routine use of preprocedural mouthrinse as a measure to reduce bacterial aerosols generated during ultrasonic scaling and that 0.12% CHX gluconate is more effective than 0.75% BA mouthwash in reducing CFUs count.

Chitosan and Byrsonima crassifolia-based nanostructured coatings: Characterization and effect on tomato preservation during refrigerated storage

Current concerns about the use of synthetic pesticides for preserving horticultural commodities have triggered the search for environmentally friendly packaging. In this regard, this study evaluated the effect of chitosan nanoparticle and chitosan-Byrsonima crassifolia nanoparticle coatings on the postharvest quality of tomato and on the incidence of Pectobacterium carotovorum after 19 days of storage. Thickness and swelling properties as well as the quality and physiological variables, and antimicrobial activity were determined. From the results, confocal laser scanning micrographs showed the interaction between the tomato and the coating containing the rhodamine-labeled chitosan nanoparticles. Changes in chroma and hue angle values as well as for firmness, with an increase in ascorbic acid content and lower CFU (colony-forming units) for the tomatoes coated with chitosan nanoparticles at a concentration of 30% were observed. The weight loss values were less than 13%. There was a decrease in CO2 and ethylene production at the end of the storage period. Chitosan-based nanostructured coating represents an alternative for preserving tomatoes against P. carotovorum.

Operating Room and Hospital Air Environment.

One method of preventing surgical-site infection is lowering intraoperative environmental contamination. The authors sought to evaluate their hospital's operating room (OR) contamination rate and compare it with the remainder of the hospital. They tested environmental contamination in preoperative, intraoperative, and postoperative settings for a total joint arthroplasty patient. A total of 190 air settle plates composed of trypsin soy agar were placed in 19 settings within the hospital. Locations included the OR with light and heavy traffic, with and without masks, jackets, and shoe covers; the substerile room; OR hallways; the sterile equipment processing center; preoperative areas; post-anesthesia care units; orthopedic floors; the emergency department; OR locker rooms and restrooms; a resident's home; and controls. The trypsin soy agar plates were incubated at 36 °C for 48 hours. Colony counts were performed for each plate. Average colony-forming units (CFUs) were calculated in each setting. The highest CFUs were in the OR locker room, at 28 CFUs per plate per hour. Preoperative and post-anesthesia care unit holding areas were 7.4 CFUs and 9.6 CFUs, respectively. The main orthopedic surgical ward had 10.0 CFUs per plate per hour, whereas the VIP hospital ward had 17.0 CFUs per plate per hour. All OR environments had low CFUs. A live OR had slightly higher CFUs than settings without OR personnel. In comparison with the local community household, the OR locker room, restrooms, hospital orthopedic wards, emergency department, preoperative holding, post-anesthesia care unit, and OR hallway all had higher airborne contamination. On the basis of these results, the authors recommend environmental sampling as a simple, fast, inexpensive tool for monitoring airborne contamination. [Orthopedics. 2021;44(3):e414-e416.].

Comparison of Live Bacteria Aerosolization during Removal of Dental Enamel Using a 9.3μm CO2 Laser, a 2.78μm Erbium Laser and a High-Speed Dental Drill

Purpose: To measure the amount of viable pathogens in the aerosol/splatter generated during dental procedures using lasers and high-speed drill. Methods: Three systems were used in this in vitro study: 9.3μm CO2 laser, 2.78μm erbium laser and a high-speed drill. 45 uncleaned human molars were randomly selected to be used for the test groups for the three systems. Bacteria ejected while cutting the buccal or lingual surfaces were collected on tryptic soy agar (TSA) plates in identical conditions for each measurement. On the opposite surface of each tooth, a non-cutting mist spray was applied. Results: The CO2 laser resulted in colony-forming units (CFU) with a mean of 1570 ± 3850 CFU/m3/s, which is statistically different (p &lt; 0.001) relative to both the erbium laser and the drill with a mean of 185,000 ± 182,000 CFU/m3/s and 440,000 ± 496,000 CFU/m3/s, respectively. CFU measured from the non-cutting mist spray on the teeth was higher for the drill than for the lasers. Conclusion: The 9.3μm CO2 laser resulted in the lowest CFU in the aerosol/splatter during enamel removal as compared to that of the 2.78μm erbium laser and the traditional high-speed drill. Furthermore, the CO2 laser was the only system that did not increase aerosolization of bacteria while cutting compared to the non-cutting mist spray.