Reduction In Bacterial Population Research Articles

An Injectable Antibiotic Hydrogel that Scavenges Proinflammatory Factors for the Treatment of Severe Abdominal Trauma

AbstractBacterial infection and excessive inflammation following abdominal injury can cause life‐threatening complications that lead to multiple organ failure and death. Removing bacteria and proinflammatory factors—which are predominantly negatively charged—from the wound site with a cationic, antibiotic‐containing hydrogel wound dressing is therefore a promising treatment approach for severe abdominal trauma. Here an injectable, self‐healing hydrogel composed of the gel‐forming glycosaminoglycan oxidized chondroitin sulfate (OCS), cationic polyethylenimine (PEI), and the antibiotic tobramycin (Tob) via a Schiff's base reaction is developed. Compared with hydrogels lacking either PEI or Tob, only the Tob/PEI/OCS hydrogels exhibit a large binding capacity for negatively‐charged proinflammatory factors including cell‐free DNA, lipopolysaccharides, TNF‐α, and high mobility group box 1 protein, and a large reduction in bacterial populations in vitro. In a murine model of severe abdominal trauma, the Tob/PEI/OCS hydrogel exhibits good biodegradability and biosafety, reduced local and systemic inflammation and infection, and prevents multiple organ failure, resulting in 100% survival. This hydrogel dressing is thus a promising biomaterial for preventing complications and improving outcomes following severe abdominal trauma.

Efficacy of bacteriocin-based formula for reducing staphylococci, streptococci, and total bacterial counts on teat skin of dairy cows

The use of teat dips is one of the most effective strategies to control mastitis by preventing new intramammary infections. Reducing bacterial load on teat skin helps control the spread of pathogens and spoilage and improves the quality of milk. The objective of this study was to evaluate the reduction of bacterial populations through the application of bacteriocin-based teat formulas. Teats of 12 Holstein cows received 2 different concentrations of bactofencin A, nisin, and reuterin alone or in combination, as well as iodine (positive control) and saline (negative control). Teat swabs were collected before and after application of teat formulas and analyzed for staphylococci, streptococci, and total bacteria counts. There were no differences for staphylococci, streptococci, and total bacterial counts for samples collected before application throughout the entire experiment. Reuterin-low and reuterin-high treatments reduced total bacterial count by 0.47 and 0.36 logs, respectively, whereas bactofencin A had no effect on any tested bacterial groups. Nisin-low treatment reduced staphylococci, streptococci, and total bacterial counts by 0.47, 0.30 and 0.50 logs, respectively. Nisin-high treatment resulted in 0.50, 0.50, and 0.47 log reduction for staphylococci, streptococci, and total bacterial counts. The bacteriocin consortium showed the highest reduction rates with 0.91, 0.54, and 0.90 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively, for the low-concentration consortium. Similarly, the high-concentration consortium showed reduction rates with 0.95, 0.60, and 0.82 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively. Thus, nisin and the bacteriocin consortium showed the most promise as a teat disinfectant by reducing staphylococci, streptococci, and total bacteria counts.

Synthesis of biogenic silver nanoparticles using butter fruit pulp extract and evaluation of their antibacterial activity against Providencia vermicola in Rohu

ObjectiveDevelopment of antimicrobial materials using nano approach and several industries like aquaculture greatly depend on novel biogenic materials. Biogenic techniques to develop nanomaterials with potent antimicrobial activity have been explored recently. The present study demonstrates the green synthesis of AgNPs using butter fruit (Persea americana) pulp extract and its antibacterial efficacy against the fish pathogen Providencia vermicola using Rohu fish. ResultsThe AgNPs were prepared and characterized using various spectroscopic and microscopic techniques. The infrared spectroscopic analysis identified that the fruit biological molecules were involved in the stabilization of AgNPs. Transmission electron microscopic analysis revealed that particles size ranged from 20 to 50 nm. Further, the nanoparticles (5 µg) encapsulated fish feed were given to P. vermicola infected Rohu fish. The survival rate observed was 72 % in experimental group as compared to the control group. Total plate count and histopathological results indicated that the AgNPs treated groups showed significant reduction of bacterial population and restore the tissues in the normal range. ConclusionThe results suggest that the green synthesized (AgNPs) using butter fruit pulp have good efficiency in reducing the infection caused by P. vermicola in Rohu fish.

Bismuth phosphinato incorporated antibacterial filter paper for drinking water disinfection

Lack of safe drinking water is a major concern, mainly in developing countries. Consequently, there is a significant need for affordable technologies to provide clean drinking water. In this paper, two approaches for drinking water disinfection using nanocellulose and the antimicrobial compound phenyl bis -diphenylphosphinato bismuth (III) complex are studied. The first approach investigates the deactivation of bacteria when contaminated water percolates through a filter paper with a microfibrillated cellulose (MFC) coating containing Bi-complex. Antibacterial activity was studied by filtering bacterial broth with a Gram-positive pathogen Staphylococcus aureus as a test strain and measuring live bacteria in the filtrate. The filter composites did not show any sign of instantaneous killing of bacteria, irrespective of the Bi-complex loading or base paper substrate. However, the effluent demonstrated drastic reduction in bacterial population after resting at 37 °C. Bacteria were completely eradicated 24 h after passing through 5 wt% and 10 wt% Bi-coated filters. If also active against locally important drinking water contaminants, this approach could be used for purification of storage water. The second approach uses a Bi-complex loaded nanofibrillated cellulose (NFC) membrane. Herein, complete and immediate exclusion of bacteria was achieved in the NFC membrane when bacterial broth was passed through it at 1 bar. The 2.5 wt% Bi-loaded membrane could significantly minimise the risk of biofilm formation, even after 4 days of contact with bacterial broth. The Bi-complex concentration in the filtrate (130.6 ± 1.9 ppb) from the 2.5 wt% Bi-loaded microfilter was shown to be non-toxic to murine fibroblast cells. This study outlines the proof of concept of two sustainable prototypes for stored or immediate drinking water purification, but the approach would need to be extended to a broader range of relevant contaminating pathogens of drinking water to fully understand its utility. • Bi-complex coated filters show no instantaneous reduction in bacterial population. • Bi-complex leaches into the filtrate killing bacteria after storage at 37 °C. • Complete exclusion of bacteria achieved by nanofibrillated cellulose (NFC) membrane. • Bi-complex in the NFC membranes minimises the risks of biofilm formation. • In-vitro studies shows the Bi-complex at or below 200 ppb is not cytotoxic.

Survival of Clostridium perfringens, Staphylococcus aureus and Salmonella enterica in alternatively cured bacon during cooking and process deviations

Pork bellies were injected with four different alternative curing brines. The bellies were inoculated on the surface and at a depth of 1 cm with multiple strains of Clostridium perfringens, Staphylococcus aureus and Salmonella enterica. The bellies were processed using either a standard process cycle or an interrupted process cycle to simulate a process deviation. Additionally, laboratory simulation of the same cycles was conducted where surface inoculated pork belly samples (22 ± 1 g) were processed in a circulating water bath. Microbiological populations were determined at the beginning, mid-point and end of the cycles, and the change in population was calculated for each bacterium at each time point, by comparing the population to the initial inoculated population. Irrespective of the brine or process cycle, the populations of all of the inoculated bacteria on both the surface and interior samples had decreased by the end of the process. There was no difference in the reductions in bacterial populations for all of the inoculated bacteria by brine type or by sample location (P > 0.30). There were differences in the microbial population reductions for C. perfringens attributable to the processing cycle (P < 0.001), with less population reductions associated with the standard cycle when compared to the interrupted cycle. However, no differences (P > 0.10) were observed in the population reductions between the two processing cycles for either S. aureus or S. enterica.

Phosphatidylinositol-phospholipase C1 negatively regulates the hypersensitive response in Nicotiana benthamiana

Phospholipid signaling plays an important role in plant immune responses. Here, we isolated two phospholipase C1 (PLC1) orthologs in the N. benthamiana genome, designated N. benthamiana PLC1-1 and PLC1-2 (NbPLC1-1 and NbPLC1-2). The NbPLC1-2-silenced plants showed an accelerated hypersensitive response (HR) challenged with an incompatible strain of R. solanacearum. Additionally, accelerated hypersensitive cell death was also observed in The NbPLC1-2-silenced plants by the bacterial effectors AvrA and PopA1 and oomycete INF1. Expression of NbPR-1, a marker gene for salicylic acid signaling, and NbPR-4, a marker gene for jasmonic acid signaling, was drastically increased by incompatible R. solanacearum in the NbPLC1-2-silenced plants. Although HR cell death was accelerated, the bacterial population was not reduced in the NbPLC1-2-silenced NahG plants compared to the NbPLC1-2-silenced wild type N. benthamiana plants. The hypersensitive cell death acceleration and bacterial population reduction from the NbPLC1-2 silencing was compromised by concomitant suppression of the NbPLC1-2 with NbCoi1. These results suggested that the NbPLC1-2 might act as a negative regulator for the HR in N. benthamiana. The NbPLC1-2 protein might negatively regulate both cell death and disease resistance via jasmonic acid-dependent signaling and suppress disease resistance via a salicylic acid -dependent pathway.

Novel Antibacterial Modification of Polycarbonate for Increment Prototyping in Medicine.

In the era of modern medicine, the number of invasive treatments increases. Artificial devices used in medicine are associated with an increased risk of secondary infections. Bacterial biofilm development observed on the implanted surface is challenging to treat, primarily due to low antibiotics penetration. In our study, the preparation of a new polycarbonate composite, filled with nanosilver, nanosilica and rhodamine B derivative, suitable for three-dimensional printing, is described. Polymer materials with antimicrobial properties are known. However, in most cases, protection is limited to the outer layers only. The newly developed materials are protected in their entire volume. Moreover, the antibacterial properties are retained after multiple high-temperature processing were performed, allowing them to be used in 3D printing. Bacterial population reduction was observed, which gives an assumption for those materials to be clinically tested in the production of various medical devices and for the reduction of morbidity and mortality caused by multidrug-resistant bacteria.

Fenton-biostimulation sequential treatment of a petroleum-contaminated soil amended with oil palm bagasse (Elaeis guineensis)

ABSTRACT Oil activity has generated severe problems of soil contamination. Different techniques have been employed for the removal of pollutants, which are mainly used separately as treatments, but if combined, removal could be improved. The aim of this study was to remove total petroleum hydrocarbons (TPH) from soil artificially contaminated with crude oil using Fenton oxidation followed by biostimulation with nutrients and oil palm bagasse (OPB) used as an amendment. Microcosm units of soil with hydrocarbons were treated with H2O2 and Fe citrate at 30% humidity and 25 °C. Samples were taken at 0, 10, and 30 days. Each unit was then adjusted to a C:N:P ratio of 100:10:1, which is considered optimal for remediation of soils contaminated with petroleum hydrocarbons, and mixed with OPB at a ratio of 96:4, 30% humidity, and 25 °C. Samples were taken at 0, 10, 30, and 40 days. Physicochemical parameters, TPH, microbial population, and lipase and dehydrogenase activity were monitored. Slight TPH removal (20.3%), a decrease in enzymatic activities, and a reduction in bacterial population were observed with Fenton oxidation. In the case of the biostimulation-amendment treatment, TPH removal was of 55%, with an increase in enzymatic activities and microbial population.

Antibacterial activity of black cumin, clove, and ginger essential oils against specific spoilage organisms of ready-to-eat chilli shrimp paste

Ready-to-eat (RTE) chilli shrimp paste has a short shelf life; thus, chemical additives are usually added to extend it. However, certain additives have potential health implications. In this regard, plant essential oils (EOs) which exhibit antibacterial properties can be used as an alternative for extending the shelf life of RTE chilli shrimp paste. The present work intended to (1) establish the microbial profile of RTE chilli shrimp paste, (2) determine the antibacterial activities of black cumin, clove, and ginger EOs against the isolated specific spoilage organisms (SSO) of RTE chilli shrimp paste, and (3) determine their effect on the shelf life of RTE chilli shrimp paste. Biochemical tests and 16S rRNA gene sequencing were used to identify the SSO in RTE chilli shrimp paste. Disc diffusion assay was performed for antibacterial analysis of EOs. To monitor the shelf life of the paste, total plate count (TPC) and yeast and mould count (YMC) were carried out for five days. The results showed that the SSO of RTE chilli shrimp paste were dominated by Staphylococcus spp. followed by Klebsiella aerogenes and Enterobacter tabaci. EOs of black cumin, clove, and ginger showed inhibitory effects against the SSO with the highest inhibition by ginger EO of 27.50 ± 9.19 to 58.00 ± 7.21 mm. Application of ginger EO in RTE chilli shrimp paste showed a 3-log reduction of bacterial population and 4-log reduction for fungal population. It was concluded that ginger EO can be a highly potential candidate to be added into RTE chilli shrimp paste as a natural additive to extend its shelf life.

Correlation Between Three Freshwater Fish Skin Mucus Antiproliferative Effect and Its Elemental Composition Role in Bacterial Growth

Fish skin mucus acts as an immunological barrier that prevents entry of pathogens. However, there are gaps in the knowledge of microbes inhabiting skin mucus constituents to invade the host and induce pathogenecity. Hence, in the present study, skin and skin mucus of three freshwater fishes Cyprinus carpio, Labeo rohita, Cirrhinus mrigala was analyzed to compare histology and mucus activity against cancer cells. The skin mucus elemental composition and its influence on bacterial growth were also investigated. Histological examination of fish skin showed the presence of mucus secreting cells and differences in the distribution of cells were clearly seen depending on fish species. The cytotoxic potential of lyophilized skin mucus against human lung adenocarcinoma cells revealed a higher percentage of cell death at 1000 µg mL-1 in C. mrigala skin mucus when comparing other two fish species. Elemental analysis of lyophilized skin mucus through Field Emission Scanning Electron Microscope coupled with Energy Dispersive X-ray (FESEM-EDX) confirmed the presence of carbon, nitrogen, oxygen and sulfur in C. carpio and C. mrigala. In the case of L. rohita, the element sulfur was absent. The results of bacterial growth in autoclaved skin mucus demonstrated an initial reduction in bacterial population and gradually increased over time. Initial reduction in bacteria might be due to the presence of inhibitory molecules in fish skin mucus. Subsequently, the bacteria utilize the elemental composition of skin mucus as a nutrient source to increase their growth. Study findings suggest that the presence of bioactive compounds in lyophilized skin mucus hinder the proliferation of cancer cells. Nevertheless, after autoclaving the skin mucus components, it supports the growth of bacteria due to the absence of immune molecules. The present study represents the knowledge of skin mucus composition, which could be explored further to understand how pathogens overcome the skin mucus barrier.

Biomimetic surfaces prepared by soft lithography and vapour deposition for hydrophobic and antibacterial performance

ABSTRACT This study demonstrates the synthesis of a bioinspired surface exhibiting hydrophobic and antibacterial functionalities using a two-stage synthesis approach which involves soft lithography and initiated chemical vapour deposition (iCVD). Sandpapers, which are inexpensive and available with desired grit size, were used as the moulds in soft lithography to transfer the rough surface patterns to the PDMS replica surfaces. The antibacterial surface modification of the PDMS replicas was done through vapour-phase deposition of thin poly(diethylaminoethyl methacrylate-vinylbenzyl chloride) (P(DEAEMA-VBC)) films by iCVD method from the corresponding monomers. FTIR analysis of the as-deposited films showed a high retention of the chemical functionalities. The hydrophobicity and antibacterial performances of the flat and rough surfaces were examined as a function of surface roughness. The antibacterial activities were tested against gram-negative E. coli and gram-positive S. aureus. It was found that obtained replicas achieved up to a 7-log reduction in bacterial population and showed high hydrophobicity.

Refrigeration temperature enhanced synergistic interaction of curcumin and 460 nm light-emitting diode against Staphylococcus saprophyticus at neutral pH

Abstract Objectives As considered highly resistant to antibiotics like mecillinam, the rise of Staphylococcus saprophyticus (S. saprophyticus) contamination of fresh foods and food processing environments necessitates the development of a new antimicrobial approach for food safety control. This study aimed to investigate the synergistic effect of food-grade curcumin (CUR) and blue light-emitting diode (LED) on S. saprophyticus. Materials and Methods S. saprophyticus was subjected to the synergistic treatment at 4 and 25 °C. The influence of parameters, including CUR concentration, light dose, and pH incubation time on the inactivation of S. saprophyticus was characterized through plate counting method. Results: The combined treatment of CUR and blue light irradiation significantly (P &amp;lt; 0.05) reduced bacterial counts and the antimicrobial effect was in a CUR concentration and light dose-dependent manner. Moreover, refrigeration temperature (4 °C) significantly (P &amp;lt; 0.05) enhanced the antibacterial effect at neutral pH condition (6.2–7.2), resulting in approximately 6.0 log reductions. Under acidic condition (pH 2.2–5.2), there was no significant difference in bacterial population reduction between treatments at both temperatures. Conclusions These findings proposed that synergistic interaction of CUR and 460 nm LED under refrigerated temperature could enhance the inactivation of S. saprophyticus at neutral pH condition.

Photodynamic Inactivation of Staphylococcus aureus Biofilms Using a Hexanuclear Molybdenum Complex Embedded in Transparent polyHEMA Hydrogels.

Three new photoactive polymeric materials embedding a hexanuclear molybdenum cluster (Bu4N)2[Mo6I8(CH3COO)6] (1) have been synthesized and characterized by means of Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and emission spectroscopy. The materials are obtained in the format of transparent and thin sheets, and the formulations used to synthesize them are comprised of 2-hydroxyethyl methacrylate (HEMA), as a polymerizable monomer, and ethylene glycol dimethacrylate (EGDMA) or poly(ethylene glycol)dimethacrylate (PEGDMA), as cross-linkers. All the polymeric hydrogels generate singlet oxygen (1O2) upon irradiation with visible light (400-700 nm), as demonstrated by the reactivity toward two chemical traps of this reactive species (9,10-dimethylanthracene and 1,5-dihydroxynaphthalene). Some differences have been detected between the photoactive materials, probably attributable to variations in the permeability to solvent and oxygen. Notably, one of the materials resisted up to 10 cycles of photocatalytic oxygenation reactions of 1,5-dihydroxynaphthalene. All three of the polyHEMA hydrogels doped with 1 are efficient against S. aureus biofilms when irradiated with blue light (460 nm). The material made with the composition of 90% HEMA and 10% PEGDMA (Mo6@polymer-III) is especially easy to handle, because of its flexibility, and it achieves a notable level of bacterial population reduction (3.0 log10 CFU/cm2). The embedding of 1 in cross-linked polyHEMA sheets affords a protective environment to the photosensitizer against aqueous degradation while preserving the photochemical and photobactericidal activity.

The effect of vinegar and drying (Solar and Open Sun) on the microbiological quality of ginger (ZINGIBER OFFICINALE ROSCOE) rhizomes.

This study evaluated the influence of 10% vinegar and solar drying using two solar dryers and open‐sun drying on the microbiological quality of ginger (Zingiber officinale Roscoe) rhizome. The rhizomes were analyzed for bacterial, mold, and Salmonella populations in the raw state, which were water‐washed and soaked in 10% vinegar, and in dried form. The fungal population was isolated and identified. Fresh and dried ginger rhizome contained both bacterial and fungal population in the range of 3.0 x 102 ± 1.14 x 102 to 2,180 x 109 ± 70.7 x 109 CFU/g. The stainless steel solar dryer had fewer fungal loads among the drying methods. Aspergillus and Penicillium species of mycotoxin‐producing potential were identified. The 10% vinegar as pretreatment showed no significant difference (p ≤ .05) in the bacterial population reduction but in the fungal population reduction. Growth of fungi in fresh and dried ginger extracts was lower compared with growth in Potato Dextrose Broth.

Evaluation of a Potential Bacteriophage Cocktail for the Control of Shiga-Toxin Producing Escherichia coli in Food.

Shiga-toxin producing Escherichia coli (STEC) are important foodborne pathogens involved in gastrointestinal diseases. Furthermore, the recurrent use of antibiotics to treat different bacterial infections in animals has increased the spread of antibiotic-resistant bacteria, including E. coli, in foods of animal origin. The use of bacteriophages for the control of these microorganisms is therefore regarded as a valid alternative, especially considering the numerous advantages (high specificity, self-replicating, self-limiting, harmless to humans, animals, and plants). This study aimed to isolate bacteriophages active on STEC strains and to set up a suspension of viral particles that can be potentially used to control STEC food contamination. Thirty-one STEC of different serogroups (O26; O157; O111; O113; O145; O23, O76, O86, O91, O103, O104, O121, O128, and O139) were investigated for their antibiotic resistance profile and sensitivity to phage attack. Ten percent of strains exhibited a high multi-resistance profile, whereas ampicillin was the most effective antibiotic by inhibiting 65% of tested bacteria. On the other side, a total of 20 phages were isolated from feces, sewage, and bedding material of cattle. The viral particles proved not to carry genes codifying Shiga-toxins and intimin. No STEC was resistant to all phages, although some strains revealed weak sensitivity by forming turbid plaques. Three different bacteriophages (forming the “cocktail”) were selected considering their different RAPD (Random Amplification of Polymorphic DNA) profiles and the absence of virulence-encoding genes and antibiotic-resistance genes. The lytic ability against STEC strains was investigated at different multiplicity of infection (MOI = 0.1, 1, and 10). Significant differences (p < 0.05) among mean values of optical density were observed by comparing results of experiments at different MOI and controls. An effective reduction of bacterial population was obtained in 81% of cases, with top performance when the highest MOI was applied. The efficacy of the phage cocktail was tested on fresh cucumbers. Results showed a reduction in pathogenic E. coli by 1.97–2.01 log CFU/g at 25°C and by 1.16–2.01 log CFU/g at 4°C during 24 h, suggesting that the formulated cocktail could have the potential to be used in bio controlling STEC different serogroups.

Sustainable and Ecofriendly Approach of Managing Soil Born Bacterium Ralstonia solanacearum (Smith) Using Dried Powder of Conyza canadensis.

Bacterial wilt disease caused by Ralstonia solanacearum is a devastating plant disease that inflicts heavy losses to the large number of economic host plants it infects. The potential of dried powder of the Conyza canadensis to control bacterial wilt (BW) of tomato was explored in vitro and in planta. Three application times (16 days before transplanting (DBT), 8 DBT and 0 DBT), three plastic-mulch durations (10 days plastic mulching (DPM), 5DPM and 0DPM) and four doses viz. 0 g, 8 g, 16 g and 24 g of the plant powder were evaluated. SEM analysis was also conducted to observe the change in bacterial cell morphology. Ethanol extract of dried C. canadensis in different concentrations inhibited the in vitro growth of R. solanacearum by as much as 98% of that produced by ampicillin. As evident from the scanning electron micrograph, the highest concentration produced severe morphologic changes, such as rupture of the bacterial cell walls and cell contents leaked out. Results from application time and dose experiment demonstrated that the highest powder dose viz. 24 g kg−1 mixed with infested soil 16 DBT gave maximum root length (34.0 ± 2.5 cm), plant height (74.3 ± 4.7 cm), fresh biomass (58.3 ± 4.3 g), reduction in bacterial population (1.52 log10) and resulted in lowest AUDPC value (1156.6). In case of mulching duration and dose experiment the maximum root length (39.6 ± 3.2 cm), plant height (78.3 ± 5.8 cm), fresh biomass (65.6 ± 4.9 g) reduction in bacterial population (1.59 log10) and lowest AUDPC value (1251.6) was achieved through the application of highest powder dose viz. 24 g kg−1 and longest plastic mulching duration of 10 DPM. The better results of highest dose and longer application time can be explained on the basis of higher amounts of anti-microbial plant bio-active compounds in highest dose and the longer exposure time of the pathogen to these chemicals. The better results of longer mulching duration are due to faster and more complete decomposition (because of 10-days-long plastic-mulch-provided increased solar heat) of the dried powder which produced more amounts of volatile and non-volatile bactericidal compounds. Our results clearly suggest that the use of 24 g kg−1 dried plant powder of C. canadensis plastic-mulched for two weeks could be used as a reliable component of the integrated disease management program against BW.

Influence of ozone application in the stepwise excavation of primary molars: a randomized clinical trial.

The aim of this randomized, controlled, three-arm parallel-group, double-blinded clinical trial was to investigate the clinical and microbiological effects of the ozone application in stepwise excavation of primary molars. This study was conducted in in vivo conditions with 105 lower primary molars that had deep caries lesions. The teeth were randomly divided into three groups: (I) control group, conventional stepwise excavation with no disinfectants; (II) CHX (positive control) group, 2% chlorhexidine digluconate; and (III) experimental group, ozone application. Dentine samples were collected at 4 different time points (T0, at the first appointment, after partial removal of carious dentin; T1, at the first appointment, after applying disinfection procedure; T2, at the second appointment - at the end of the 4-month period - immediately after the removal of the temporary restoration; T3, at the second appointment, after the final excavation) for the microbiological analysis of mutans streptococci and lactobacilli and the total number of colony-forming units. Clinical changes including dentin color, humidity, and consistency were recorded. Data were analyzed using the Mann-Whitney U test, Friedman test, and chi-squared test (p= 0.05). The dentin became harder and drier after 4months in all the groups. There was a gradual reduction in the total number of microorganisms in all the three groups. Bacterial reduction was greater in the CHX group compared to the ozone group (p= 0.002) and was greater in the ozone group compared to the control group (p= 0.015) after 4months (control, 78%; CHX, 93%; ozone, 82%). Stepwise excavation of primary teeth provided successful outcomes in all the groups. Moreover, CHX, due to its practicality and cost-effectiveness, can be effectively used with one- or two-step indirect pulp therapies. Usage of cavity disinfectants in the stepwise excavation procedure contributes to the reduction of bacterial population in the cavity, which may allow the avoidance of the second step of the indirect pulp therapy for primary teeth.

Effectiveness of calcium hydroxide in reducing bacterial load comparing with chemo-mechanical preparation- A systematic review

Aim: To determine and compare to what extent the intra-canal medicament like calcium hydroxide along with chemo-mechanical preparation reduces the bacterial load in infected root canals. Methodology: PubMed Cental, Medline, Google Scholar and hand search was carried out using the keywords calcium hydroxide (Ca(OH)2) , intra-canal medicament(ICM) and chemo-mechanical preparation. Selection Criteria: Clinical trials in which bacterial samples were evaluated at 3 intervals (Baseline, after chemo-mechanical preparation, after dressing with intra canal medicament ICM and trials which use Ca(OH)2 with any vehicle as ICM, but not compared with any other ICM were selected for this review. The data collection form was customized. The primary outcome measures were reduction of bacterial populations in infected root canals. Results: Seven clinical trials that met all inclusion criteria involving 117 participants were reviewed. Included studies showed significant difference in bacterial reduction after chemo-mechanical preparation and placement of Ca(OH)2 dressing for a week. In all included trials, Ca(OH)2 reduced bacterial load further compared with chemo-mechanical preparation. Conclusion: Ca(OH)2 as an inter-appointment medication promoted further decrease in the bacterial bioburden to levels significantly below those achieved by the chemo-mechanical procedures alone. Intra-canal medicament such as Ca(OH)2 should be considered for bacterial reduction along with chemo-mechanical preparation for long term success. Key Words: Intra-canal medicament, calcium hydroxide, Root canal treatment, bacterial load, Pulpitis

Antimicrobial Activity and Physicochemical Properties of Antibiotic Pastes Used In Regenerative Endodontics.

The purpose of this study was to evaluate the pH, solubility and antimicrobial action of Calcium Hydroxide Paste (CH), Double Antibiotic Paste (metronidazole+ciprofloxacin-DAP), calcium hydroxide added to DAP (CH/DAP) and Triple Antibiotic Paste (metronidazole + ciprofloxacin+minocycline-TAP). pH (n=10) were measured by pHmeter. Root canals of acrylic teeth (n=10) were filled with the above-mentioned intracanal-dressings, immersed in ultrapure water, and solubility was measured by the difference between the initial and final volume (7,15 and 30 days) by using micro-computed tomography. Enterococcus faecalis biofilm was induced on bovine dentin disc surfaces (n=20), and treated with the pastes for 7 days. Percentage bacterial viability was verified by confocal microscope, with LIVE/DEAD dye. CH and CH/DAP presented the highest pH values. Regarding solubility, after 7 days, antibiotic groups presented significant volume loss. CH and CH/DAP showed no statistical difference compared with the Control in antimicrobial action against E. faecalis biofilm. However, TAP and DAP presented a significant percentage reduction in bacterial population. Due to high solubility of the pastes, renewing antibiotic dressings every 7 days, or using the medications for this period in regeneration protocols is recommended. DAP is indicated for killing E. faecalis in biofilm because it has antimicrobial action similar to TAP. Adding Calcium Hydroxide to DAP significantly decreased its antimicrobial action. In spite of its the low solubility and high pH values, the CH paste showed a low level of antimicrobial action against E. faecalis in biofilm.

Antibacterial Interactions of Colloid Nanosilver with Eugenol and Food Ingredients

This study was conducted to investigate antibacterial properties of the colloidal silver nanoparticles (SNPs) and eugenol, alone and in combination, on Staphylococcus aureus and Salmonella Typhimurium and their interactions with food constituents (fat, protein, and carbohydrate). We examined antibacterial activities of SNPs and eugenol in Luria-Bertani (LB) broth and 1.5 and 3% fat ultrahigh-temperature (UHT) milk. MICs of eugenol and SNPs (particle size of 31.3 nm) were also investigated in the presence of sunflower oil, meat extract, and starch at concentrations of 2, 5, and 10% to examine the interactions between food constituents and antimicrobial agents. MICs and MBCs of eugenol and SNPs for both bacteria were at 2,500 and 25 μg/mL, respectively. Combinations of the two substances had additive and synergistic effects on Salmonella Typhimurium and S. aureus, respectively. Both compounds had bactericidal activity. In food matrices, results indicated that eugenol only in sunflower oil at 5 and 10% concentrations had significant antibacterial activity. A similar result was achieved for SNPs with 10% meat extract. In LB broth, eugenol at 2,500 and 5,000 μg/mL achieved 6-log reductions in the microbial population of both bacteria after 3 h, while SNPs achieved the same effect after 9 h. In UHT milk with 1.5% fat, eugenol at 5,000 μg/mL and SNPs at 25 μg/mL achieved 6-log reductions in bacterial populations after 24 h. Thus, the antimicrobial activity of both eugenol and SNPs depended on the medium in which the experiment was conducted, and the combination of both antimicrobial agents increased the antimicrobial effect.