Significant Reduction In Colony Forming Units Research Articles

Safety and efficacy of McCarey-Kaufman medium supplemented with colistin (polymyxin E) and amphotericin B in inhibiting the multidrug-resistant Pseudomonas aeruginosa using an ex vivo donor corneal infection model.

This study aimed to evaluate the efficacy and safety of McCarey-Kaufman (MK) medium supplemented with colistin and amphotericin B in inhibiting the growth of multidrug-resistant Pseudomonas (P.) aeruginosa , using an ex vivo experimental model with human donor corneas. Cadaveric human corneas deemed unsuitable for corneal transplantation were obtained, and MK media were supplemented with colistin and amphotericin B. Multidrug-resistant P. aeruginosa was cultured and used to infect the human donor corneas ex vivo . Infected corneas were placed in the MK media with additional antibiotics (colistin and amphotericin B) and the standard MK media, which served as the control arm for comparison. Corneal opacity due to infiltration and quantitative analysis of colony-forming units (CFUs) were assessed. The viability of the corneal endothelium was assessed using trypan blue staining. Corneas incubated in MK media supplemented with additional antibiotics showed less corneal opacification compared with those in standard MK media at both 48- and 96-hour (hr) time points. Quantitative analysis revealed a lower bacterial load and a significant reduction in CFU in the corneas incubated in MK media with additional antibiotics compared with the control group. At 48 hrs, there was 84% ( P value = 0.024) reduction in bacterial load, and at 96 hr, a 53% ( P value = 0.016) reduction was observed in comparison with those placed in standard MK media. The trypan blue staining tests revealed that the extent of endothelial cell loss in corneas incubated in supplemented MK media was comparable to the ones in standard MK media. The addition of colistin and amphotericin B to MK media demonstrated efficacy in inhibiting the growth of multidrug-resistant P. aeruginosa in an ex vivo cornea infection model. The supplemented media had no detrimental effect on the corneal endothelium. The findings suggest that supplementing the MK media with these broad-spectrum antimicrobial agents may help mitigate the risk of postoperative donor-related infection in the recipients by reducing and containing the load of microbial contamination in donor corneas.

Fomite Contamination of Alginate Impressions and the Role of Herbal and Chemical Disinfectants

Introduction: Contamination of alginate impressions is reported and various methods to disinfect them have been studied. However, contamination of the impressions from the rubber bowl is not known. The transfer of microorganisms to the oral cavity by the alginate mixed in an unsterilized rubber bowl is a possibility. The objective of this study is to find out the fomite contamination of alginate impressions from rubber bowls and evaluate the role of chemical and herbal disinfectants against them. Methodology: Thirty volunteers were included in the study and they were grouped into six groups (one control and five study groups). Three chemical disinfectants and two herbal disinfectants were used to disinfect the rubber bowl before impressions. The presence of pathogens and the number of colony-forming units were evaluated. Results: Harmful pathogens like Staphylococcus species, E. coli, Pseudomonas species, Bacillus species, and Klebsiella species have been detected under a light microscope on the surface of the rubber bowl. There was a significant decrease in the number of colony-forming units on alginate impressions after the rubber bowl was disinfected. Herbal disinfectants showed a profound decrease in the transmission of organisms compared to chemical disinfectants. Conclusion: The presence of fomite contamination in the routine impression has been confirmed in the study. All the disinfectants showed a significant reduction in colony-forming units when the rubber bowl was disinfected. Both the plant extracts showed an effective decrease in Colony-Forming Units (CFU) per ml and were as effective in eliminating pathogens as the chemical disinfectants. Hence, plant extracts of Neem and Babool can be a viable alternative to chemical disinfectants on rubber bowls.

Clinical Study of Antimicrobial Efficacy of Laser Ablation Therapy with Indocyanine Green in Root Canal Treatment

IntroductionLaser ablation (LA) therapy is used as an adjunct to endodontic treatment to improve microbial reduction. However, studies evaluating the impact of LA with indocyanine green (ICG) are scarce. This study aimed to evaluate the antimicrobial efficacy of LA therapy with ICG in root canal treatment. MethodsSixty patients with periapical lesions in teeth with a single canal and absence of pain, edema, and previous treatment were selected. Patients were randomly allocated into 3 groups according to the apical sizes used (n = 20); 25/04, 30/04, and 35/04 were the final sizes used. In half the patients of each group, 2.5% sodium hypochlorite was used as an irrigating solution, and in the other half, saline solution was used. After instrumentation, all patients received LA therapy with ICG. Root canal sampling was performed before (S1) and after (S2) root canal instrumentation and immediately after LA therapy with ICG (S3). Colony-forming units were counted, and statistical tests were applied (P < .05). ResultsThere was a significant reduction in colony-forming units from S1 to S2 in all treatment protocols (P < .05); 2.5% sodium hypochlorite as an irrigating solution showed a greater microbial reduction compared with saline solution (P < .05). LA therapy with ICG further reduced the microbial counts significantly (S2 to S3 and S1 to S3) whether sodium hypochlorite or saline was used (P < .05). ConclusionsLA therapy with ICG significantly increased microbial reduction in root canals regardless of instrumentation sizes or the irrigation solution used.

Impact of Environmental Stresses on the Antibacterial Activity of Graphene Oxide (GO) Nanoparticles against P. putida Biofilms.

As the production of graphene-based nanomaterials such as GO is increasing, it is expected that a large amount of GO waste will be generated. The environment (i.e., soil and aquatic systems) will be amongst the final repositories of these wastes which means important natural microbial communities in such environments will be at risk of GO exposure. However, little is known about how these communities respond to environmental stresses in synergy with the presence of GO. In this study, the effect of three different stress conditions: temperature (5, 25 and 40 °C); pH (5 to 9) and osmotic stress (51, 219 and 320 mM NaCl) in addition to GO treatment was investigated on the viability and physiology of biofilms and planktonic cells of soil bacterium P. putida. It was found that planktonic cells were more resistant to GO alone compared to biofilms. However, the cells were sensitive to GO when exposed to pH or osmotic stresses. Temperature was not found to influence the survival of biofilm with or without exposure to GO. However, low pH caused a reduction in colony-forming units (CFU) at pHs 5 and 6 for the pre-treated samples, while biofilms at pH 7-9 did not show any decrease. Interestingly, the post-treatment of planktonic cells or biofilms with GO showed a significant reduction in CFU at all pH ranges. The effect of higher osmotic stress in combination with GO resulted in a significant reduction in biofilms. These results show that the effect of stresses naturally occurring in the environment can be affected and changed when in combination with GO and can potentially affect the balance of natural biofilms.

Excretory-secretory products from the brown stomach worm, Teladorsagia circumcincta, exert antimicrobial activity in in vitro growth assays

BackgroundOver the past decade, evidence has emerged of the ability of gastrointestinal (GI) helminth parasites to alter the composition of the host gut microbiome; however, the mechanism(s) underpinning such interactions remain unclear. In the current study, we (i) undertake proteomic analyses of the excretory-secretory products (ESPs), including secreted extracellular vesicles (EVs), of the ‘brown stomach worm’ Teladorsagia circumcincta, one of the major agents causing parasite gastroenteritis in temperate areas worldwide; (ii) conduct bioinformatic analyses to identify and characterise antimicrobial peptides (AMPs) with putative antimicrobial activity; and (iii) assess the bactericidal and/or bacteriostatic properties of T. circumcincta EVs, and whole and EV-depleted ESPs, using bacterial growth inhibition assays.MethodsSize-exclusion chromatography was applied to the isolation of EVs from whole T. circumcincta ESPs, followed by EV characterisation via nanoparticle tracking analysis and transmission electron microscopy. Proteomic analysis of EVs and EV-depleted ESPs was conducted using liquid chromatography-tandem mass spectrometry, and prediction of putative AMPs was performed using available online tools. The antimicrobial activities of T. circumcincta EVs and of whole and EV-depleted ESPs against Escherichia coli were evaluated using bacterial growth inhibition assays.ResultsSeveral molecules with putative antimicrobial activity were identified in both EVs and EV-depleted ESPs from adult T. circumcincta. Whilst exposure of E. coli to whole ESPs resulted in a significant reduction of colony-forming units over 3 h, bacterial growth was not reduced following exposure to worm EVs or EV-depleted ESPs.ConclusionsOur data points towards a bactericidal and/or bacteriostatic function of T. circumcincta ESPs, likely mediated by molecules with antimicrobial activity.Graphical

Extracellular vesicles from bone marrow mesenchymal stromal cells of severe aplastic anemia patients attenuate hematopoietic functions of CD34+ hematopoietic stem and progenitor cells.

Mesenchymal stromal cells (MSC) regulate hematopoiesis in the bone marrow (BM) niche and extracellular vesicles (EVs) released by BM-MSC are important mediators of the cross-talk between BM-MSC and hematopoietic stem and progenitor cells (HSPC). We have previously demonstrated that BM-MSC of severe aplastic anemia (SAA) patients have an altered expression of hematopoiesis regulatory molecules. In the present study, we observed that CD34+ HSPC when cocultured with BM-MSC EVs from aplastic anemia patients exhibited a significant reduction in colony-forming units (p = .001), cell proliferation (p = .002), and increased apoptosis (p > .001) when compared to coculture with BM-MSC EVs from controls. Collectively, our results highlight that EVs derived from the BM-MSC of SAA patients impair the hematopoiesis supporting function of HSPC.

Copper Tannate (CuTn) Based Coating on 3D Printed Face Masks

The impact of COVID-19 crisis on global supply chains caused a critical shortage of essential goods like medical devices. Additionally, massive consumption increased mask contamination and waste. 3D printing has become a fast and versatile manufacturing alternative that prevents a single use of masks. However, SARS-CoV-2 virus can persist on plastic surfaces for days. This study proposes the optimization of 3D printed masks, by applying a coating rich in hydrolyzable tannins and copper, in order to diminish the virus presence. Different paints were formulated with copper tannate and applied on thermoplastic polyurethane 3D panels to test bacterial stability. Results showed a significant reduction of colony-forming units on coated polymeric surfaces. Paints pigmented with copper tannates could improve the protection provided by printed masks, even against the COVID-19 virus.

Fabrication of antimicrobial polymeric films by compression molding of peptide assemblies and polyethylene.

This paper presents compression molding of peptide assemblies with low-density polyethylene (LDPE) for the robust production of antimicrobial polymeric films. These films show a significant reduction of colony-forming units and plaque-forming units. Moreover, they significantly inhibited the growth of three different fungi. These innovative active polymeric films can potentially be applied for medical device wrapping, food packaging, and agriculture applications.

The Optimum Duration of Flushing Dental Unit Waterlines for Microbial Removal

This study aims to evaluate the optimum duration of flushing dental unit waterlines (DUWLs) in Universiti Sains Islam Malaysia (USIM) dental polyclinics for removal of heterotrophic bacteria. Water samples were obtained from triple air syringes at each dental chair from oral surgery clinic, outpatient clinic and polyclinic 17 at Faculty of Dentistry, USIM after 16 and 64 hours of not operating the dental units as baseline samples. This is followed by sampling after continuous flushing at 30 seconds, 1 minute, 2 minutes and 3 minutes of flushing duration. The levels of heterotrophic plate count (HPC) for each flushing duration were determined by quantification of colony forming units (CFUs) after cultivation of samples on plate count agar (PCA), R2A agar and 5% sheep blood agar (SBA). Statistically, there was no significant reduction in CFUs of HPC for all flushing duration compared to baseline (P &gt; 0.05) with the most notable HPC reducing level after 1 minute and 3 minutes of flushing DUWLs. However, HPC level at USIM dental clinics is still exceeding the recommendation by Centers for Disease Control and Prevention (CDC) which should be less than 500 CFU/mL. The existing method of controlling DUWLs contamination in USIM dental clinics is only by flushing DUWLs 1 minute every morning prior to dental treatment as recommended by Malaysian Dental Council (MDC) without the use of chemical germicides. Thus, the flushing method alone is not reliable to reduce the number of microorganisms in the DUWLs.

Hypochlorous Acid 0.01% vs Povidone-Iodine 5% for Ocular Antisepsis.

An alternative ocular antiseptic is needed for patients who do not tolerate povidone-iodine (PI). The purpose of this study is to compare the antimicrobial effect of hypochlorous acid (HA) 0.01% with PI 5% applied topically to the ocular surface. Swabs of the inferior conjunctiva and posterior lower eyelid margin of 40 patients were taken from both eyes and plated onto blood agar plates. One eye was treated with HA and the other with PI, and swabs were taken after 1-minute exposure. The eye treated with PI was rinsed with sterile saline and another swab was taken. Colony-forming units (CFUs) were recorded after 2 days. Patients rated the level of irritation after treatment in each eye. HA and PI both gave significant reduction in CFUs from baseline (P < .001 for HA and P = .002 for PI). The mean reduction in logCFU ± 95% CI was 0.850 ± 0.387 or greater for HA and 0.749 ± 0.385 or greater for PI; this was equivalent to a mean reduction of 7.1-fold or greater or 86% or greater (95% CI, 66%-94%) for HA and 5.6-fold or greater or 82% or greater (95% CI, 57%-93%) for PI. CFUs increased in 17 eyes after saline rinse. PI caused substantial irritation in 31 of the 40 participants, whereas no individuals had any irritation from topical HA. Both HA and PI were effective in reducing ocular bacterial load. Unlike PI, HA was not irritating to the eye. Saline rinse after topical PI may increase bacterial counts in some individuals.

Effectiveness of topical adjuvants in reducing biofilm formation on orthopedic implants: an invitro analysis.

The treatment of periprosthetic joint infection is complicated by the presence of residual biofilm, which resists eradication owing to bacterial adherence to orthopedic implants. The purpose of this study was to compare Bactisure (Zimmer Biomet, Warsaw, IN, USA), povidone-iodine (Betadine), and chlorhexidine gluconate solution (Irrisept; Irrimax, Gainesville, FL, USA) in reducing biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes inoculated on cobalt-chrome, titanium, and stainless steel disks, representing metals commonly used for shoulder arthroplasty. The hypothesis was that there would be no significant difference in biofilm reduction among the 3 topical adjuvants. Strains of S aureus (ATCC 35556), S epidermidis (ATCC 35984), and C acnes (LMG 16711) were grown on cobalt-chrome, titanium, and stainless steel disks. For each strain, the disks were divided into 4 groups: (1) control, (2) povidone-iodine (Betadine), (3) chlorhexidine gluconate (Irrisept), and (4) Bactisure. Bacteria were grown on 5% sheep blood agar plates. Biofilm eradication was quantified using adenosine triphosphate bioluminescence and compared with controls 48 and 72 hours after implementation of the topical adjuvant. At 72 hours after implementation of the topical adjuvant, a statistically significant reduction in colony-forming units was observed for all topical adjuvants across all tested metals, as compared with their respective control. With respect to the topical adjuvants themselves, Bactisure more consistently demonstrated the most significant reduction in colony-forming units across all bacteria when the tested medium was adjusted for, with the exception of S aureus, which showed similar results to Betadine at 72 hours. By use of commonly encountered topical adjuvants on S aureus-, S epidermidis-, and C acnes-inoculated disks of various implant metals, a significant reduction in biofilm production was observed. Bactisure, a recent Food and Drug Administration-approved topical adjuvant, demonstrated the overall greatest efficacy of the agents studied.

Antimicrobial Activity and Biocompatibility of Antibiotic-Loaded Chitosan Hydrogels as a Potential Scaffold in Regenerative Endodontic Treatment

IntroductionThe objective of this study was to determine the effectiveness of several antibiotic-loaded hydrogel scaffolds against Enterococcus faecalis, as well as their ability to stimulate proliferation and mineralization of dental pulp stem cells. MethodsFibrin (Fg) or chitosan-fibrin hydrogels (Ch) were prepared using 12.5 mg/mL fibrinogen and 0.4% (w/v) chitosan. Triple antibiotics, clindamycin-modified triple antibiotic paste, or double antibiotics were loaded in gels (1 mg/mL). Antibacterial effect against E. faecalis biofilm was determined by using colony-forming units (CFUs) and confocal laser scanning microscope (CLSM). Cell viability and morphology were determined by loading cells into different gels at 7 and 14 days using the water-soluble tetrazolium salt-1 cell viability assay and Live & Dead cell analysis. Mineralization was detected by using alkaline phosphatase and alizarin red staining activity. ResultsAntibiotic-loaded Fg gel and Ch gel alone without antibiotics resulted in a significant reduction in CFUs compared with the positive control (P < .05). When antibiotics were loaded in Ch gel, there were no CFUs detected in any groups (P < .05). CLSM images showed dense red areas with mostly dead bacteria on the dentin surface in antibiotic-loaded Ch groups, which showed significantly less live bacteria compared with the other groups (P < .05). Triple antibiotic-loaded Fg and Ch gels resulted in a dramatic decrease in the mineralized nodule formation compared with all other gel groups (P < .05). Ch hydrogels resulted in round cell morphology up to 7 days. Ch alone or with double antibiotic paste showed more cell spreading with spindle-shaped morphology at 14 days and higher alkaline phosphatase activity compared with other antibiotic-loaded Ch groups (P > .05). ConclusionsDouble antibiotic-loaded Ch gel appears to enhance the antibacterial properties while maintaining higher cell viability, cell spreading, and mineralization activity, compared with all the other scaffolds investigated.

Biocontrol potential of native yeast strains against Aspergillus flavus and aflatoxin production in pistachio

ABSTRACT Aspergillus flavus is the main aflatoxin producer in food and feed and has wide ecological niches. Contamination of food products such as pistachio nuts and aflatoxin secretion directly affects food safety and international food product trades. Abilities of 13 yeast strains isolated from 200 soil and pistachio nut samples collected in Iranian orchards to reduce the growth of A. flavus as well as aflatoxin production were assessed in dual culture, volatile and non-volatile compounds tests. The growth of A. flavus was reduced by 32–60%, 13–31% and 40–61% in dual culture, volatile and non-volatile compounds, respectively, while aflatoxin B1 production was diminished by 90.6–98.3%. Based on these assays, five yeast strains were selected for co-inoculation experiments using soil, pistachio hulls and leaf. A significant reduction in colony-forming units (CFU) ranging from 23% to 110% (p < .05) was observed. Molecular, physiological and morphological identification revealed these were strains of Pichia kudriavzevii and Lachansea thermotolerans. Aflatoxin biocontrol with yeast strains possesses many advantages including the ease of commercial production and organic application which is an environmental approach. More investigation is required to understand the efficiency of selective strains to inhibit A. flavus and aflatoxin production as well as withstand predominant abiotic stress in pistachio orchards and mass production in field application.

196. Reducing bioburden in the operating room: manual cleaning and pulsed-xenon ultraviolet light disinfection produces significant reduction in colony forming units

BACKGROUND CONTEXT Though techniques for sterilizing surgical tools and supplies have steadily improved, current standards for operating room (OR) disinfection have become antiquated – providing continued convenience for pathogenic organisms and surgical site infections. Pulsed-xenon ultraviolet (PX-UV) disinfection is an opportunity for standardized, touch-free disinfection that may serve as a supplement to manual terminal cleaning. The combination of manual and PX-UV disinfection may provide the greatest reduction in OR bioburden, as measured by colony-forming units (CFUs), and frequency of site contamination. Here, the bioburden and site contamination of ORs following manual cleaning and PX-UV disinfection are explored. PURPOSE Determine impact of manual vs manual and PX-UV disinfection on CFUs in spine operating suites. STUDY DESIGN/SETTING N/A PATIENT SAMPLE N/A OUTCOME MEASURES N/A METHODS Fifteen ORs were sampled at three different time points – before terminal manual cleaning, after terminal manual cleaning, and after PX-UV. For each OR, at each time point, five high-touch surfaces were cultured using a Tryptone Soy Agar touch plate. A total of 225 samples were acquired. Samples were incubated for 24 hours and the number of colony-forming units reported. Distinct colonies were identified. Descriptive statistics and Rank Sum Testing with a Bonferroni correction were used to analyze results. RESULTS There was a 26.8% reduction of CFUs after manual cleaning (p>0.8014) and an 81.0% reduction of CFUs after PX-UV (p = 0.0086). Overall, the combination of manual and PX-UV disinfection resulted in an 86.10% reduction in CFUs (p = 0.004). The frequency of sites with CFUs prior to cleaning was 26.7%. There was no change in frequency of sites with CFUs after manual cleaning. Following PX-UV cleaning, the frequency of sites with CFUs reduced to 8.0%, which is a 70.0% reduction in sites with CFUs. Interestingly, the frequency of sites with an increase in CFUs after manual cleaning was 20.0%. There was no occurrence of an increase in CFUs after PX-UV disinfection. CONCLUSIONS The combination of PX-UV with manual cleaning yields the greatest reduction in OR bioburden as measured by CFUs. Manual cleaning alone resulted in a low reduction of CFUs and no change in the frequency of site contamination. Though some individual sites demonstrated elimination of CFUs following manual cleaning, there were a number of sites that had an increase in CFUs. This may represent cross contamination due to the inconsistent nature of manual terminal cleaning. The use of PX-UV disinfection resulted in a significant reduction in CFUs when compared to both the pre- and postmanual cleaning time points. PX-UV disinfection also yielded a reduction in the frequency of site contamination. This reduction in both bioburden and contaminated sites may contribute to a decreased risk of surgical site infection. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Effect of antibiotic infused calcium sulfate/hydroxyapatite (CAS/HA) insets on implant-associated osteitis in a femur fracture model in mice.

Cerament (Bonesupport Holding, Lund, Sweden) is a bioresorbable synthetic bone substitute consisting of calcium sulfate and hydroxyapatite which is successfully used as a bone graft in bone defects or in delayed and non-unions after fractures. Besides, calcium sulfate/ hydroxyapatite (CAS/HA) could have, attributed to its composition and osteoinductive properties, have great importance in the treatment of bone infections with critical size defects (CSD). Aim of the study was to evaluate the effects of antibiotic infused CAS/HA on inflammation and bone healing in an implant-associated osteitis mice model. In a standardized murine model, the left femur of 72 BALB/c mice were osteotomized, generating a CSD (2,5 mm) with stabilization through a 6-hole titanium locking plate. Osteitis has been induced through inoculation of Staphylococcus aureus (SA) into the fracture gap. To analyze the effect of CAS/HA, following groups were generated with either CAS/HA, CAS/HA with gentamycin (CAS/ HA-G) or CAS/HA with vancomycin (CAS/HA-V) insets placed into the osteotomy. Debridément and lavages were progressed on day 7 and 42 to determine the local bacterial growth and the immune reaction. Fracture healing was quantified on day 7 and 42 by x-ray and bone healing markers from blood samples. Progression of infection was assessed by estimation of colony-forming units (CFU) and immune response was analyzed by determination of Interleukin (IL)– 6 and polymorphonuclear neutrophils (PMN) in lavage samples. Osteitis induced higher IL-6 and PMN-levels in the lavage samples on day 7. Both parameters showed a reduction in all groups on day 42. CAS/HA-V revealed a significant reduction of CFU and PMNs in lavage samples on day 42. A positive effect on bone healing could only be shown in non-infected mice. Whereas, application of mere CAS/HA in infected mice did show tendencies of bone destruction and lysis, independent of impregnation with antibiotics or not. Thus, application of CAS/HA in acute implant-associated infections is not recommended. In non-infectious environments or after infect-convalescence CAS/HA could albeit serve as a suggestive tool in trauma and orthopedic surgery.

Vaccine efficacy of a Mycobacterium tuberculosis Beijing-specific proline-glutamic acid (PE) antigen against highly virulent outbreak isolates.

Bacillus Calmette-Guerin vaccine confers insufficient pulmonary protection against tuberculosis (TB), particularly the Mycobacterium tuberculosis (Mtb) Beijing strain infection. Identification of vaccine antigens (Ags) by considering Mtb genetic diversity is crucial for the development of improved TB vaccine. MTBK_20640, a new Beijing genotype-specific proline-glutamic acid-family Ag, was identified by comparative genomic analysis. Its immunologic features were characterized by evaluating interactions with dendritic cells (DCs), and immunogenicity and vaccine efficacy were determined against highly virulent Mtb Beijing outbreak Korean Beijing (K) strain and HN878 strain in murine infection model. MTBK_20640 induced DCs via TLR2 and downstream MAPK and NF-κB signaling pathways, effectively promoting naive CD4-positive (CD4+) T-cell proliferation and IFN-γ production. Different IFN-γ response was observed in mice infected with Mtb K or reference H37Rv strain. Significant induction of T helper type 1 cell-polarized Ag-specific multifunctional CD4+ T cells and a marked Ag-specific IgG2c response were observed in mice immunized with MTBK_20640/glucopyranosyl lipid adjuvant-stable emulsion. The immunization conferred long-term protection against 2 Mtb Beijing outbreak strains, as evidenced by a significant reduction in colony-forming units in the lung and spleen and reduced lung inflammation. MTBK_20640 vaccination conferred long-term protection against highly virulent Mtb Beijing strains. MTBK_20640 may be developed into a novel Ag component in multisubunit TB vaccines in the future.-Kwon, K. W., Choi, H.-H., Han, S. J., Kim, J.-S., Kim, W. S., Kim, H., Kim, L.-H., Kang, S. M., Park, J., Shin, S. J. Vaccine efficacy of a Mycobacterium tuberculosis Beijing-specific proline-glutamic acid (PE) antigen against highly virulent outbreak isolates.

Fluor‑carbonated hydroxyapatite coatings by pulsed laser deposition to promote cell viability and antibacterial properties

Fluorine, an essential element present in bone and dental tissues, promotes mineralization and is directly involved in the bone formation process. The antibacterial effects of fluorine on oral bacteria are also well known. In this study, metallic implants were coated with a thin layer of calcium phosphate enriched with fluorine to improve osteointegration and protect against infections. These coatings were obtained by pulsed laser deposition (PLD) using, as a target, a bioceramic of marine origin, mainly composed of fluorapatite from the enameloid of shark teeth. The compositional dependence of coatings on H2O vapor pressures applied during PLD was analyzed in order to optimize physicochemical properties. Physicochemical characterization to evaluate morphology (SEM), thickness (interferometric profilometry), structure (XRD) and composition (FTIR, XPS) was performed. To evaluate the biological response, both MC3T3-E1 pre-osteoblasts and bacterial strains Staphylococcus aureus and Staphylococcus epidermidis, most responsible for 77% of infections associated with prosthetic implants, were tested. Proper cell proliferation (MTT assay) and ALP synthesis up to 21 days were confirmed. Antibacterial properties were also demonstrated: compared to synthetic hydroxyapatite coatings, there was a significant reduction in colony-forming units (CFUs) for both strains.

Histotripsy Treatment of S. Aureus Biofilms on Surgical Mesh Samples Under Varying Scan Parameters.

Cavitation-based ultrasound histotripsy has shown potential for treating infections on surgical mesh. The goal of this paper was to explore a new scan strategy while assessing the impact of scan speed, scan step size, and the number of cycles in the tone burst on the destruction of S. aureus biofilms grown on surgical mesh samples using ultrasound histotripsy pulses (150 MPa/-17 MPa). For each exposure, the number of colony forming units (CFUs) on the mesh and released onto the surrounding gel was quantified. Most of the exposed mesh samples had no CFUs, and there was a statistically significant reduction in CFUs on the mesh for each of the exposures, with an average reduction of 3.8 log10 relative to the sham. Compared with the sham, there was also a statistically significant reduction in CFUs on the gel with the highest exposures.

Effect of Violet-Blue Light on Streptococcus mutans-Induced Enamel Demineralization.

Background: This in vitro study determined the effectiveness of violet-blue light (405 nm) on inhibiting Streptococcus mutans-induced enamel demineralization. Materials and Methods: S. mutans UA159 biofilm was grown on human enamel specimens for 13 h in 5% CO2 at 37 °C with/without 1% sucrose. Wet biofilm was treated twice daily with violet-blue light for five minutes over five days. A six-hour reincubation was included daily between treatments excluding the final day. Biofilms were harvested and colony forming units (CFU) were quantitated. Lesion depth (L) and mineral loss (∆Z) were quantified using transverse microradiography (TMR). Quantitative light-induced fluorescence Biluminator (QLF-D) was used to determine mean fluorescence loss. Data were analyzed using one-way analysis of variance (ANOVA) to compare differences in means. Results: The results demonstrated a significant reduction in CFUs between treated and non-treated groups grown with/without 1% sucrose. ∆Z was significantly reduced for specimens exposed to biofilms grown without sucrose with violet-blue light. There was only a trend on reduction of ∆Z with sucrose and with L on both groups. There were no differences in fluorescence-derived parameters between the groups. Conclusions: Within the limitations of the study, the results indicate that violet-blue light can serve as an adjunct prophylactic treatment for reducing S. mutans biofilm formation and enamel mineral loss.

Comparative evaluation of Enterococcus faecalis counts in different tapers of rotary system and irrigation fluids: An ex vivo study

Bacteria and their by-products are etiological factors for the failure of endodontic treatment. Reduction of root canal bacterial contamination is one of the chief aims of root canal therapy. The aim of this study was to compare the effects of different rotary file tapers and two irrigation fluids on Enterococcus faecalis counts. In this ex vivo study Root canals of 72 human upper lateral incisors were enlarged to ISO #20 K-file. Then, the samples were sterilized and inoculated with E. faecalis for 72 h, divided into six experimental groups and prepared with #30 Flexmaster files with 0.02, 0.04, and 0.06 tapers and two different irrigation solutions such as normal saline and sodium hypochlorite. The control group (n = 10) was subdivided into two groups with or without bacterial inoculation and no mechanical instrumentation. Cleaning efficacy was evaluated in terms of the reduction of colony forming units (CFUs). T-test, ANOVA, Duncan, and Tukey tests were applied to the groups. A significant level of α = 0.05 was set for comparison between the groups. The canals instrumented with 0.06 taper exhibited greater significant reduction in CFUs compared to canals instrumented with 0.04 and 0.02 taper (P < 0.05); 0.04 taper also resulted in greater significant reduction in CFUs than 0.02 taper (P < 0.05). In addition, no significant differences were observed in E. faecalis counts between the two irrigation fluids (P > 0.05). Under the conditions of this study, root canal preparation with greater taper resulted in canal cleanliness and better debridement.