Decrease In Colony Forming Units Research Articles

Enhanced phenanthrene biodegradation in river sediments by harnessing calcium peroxide nanoparticles and minerals in Sphingomonas sp. DSM 7526 cultivation

ABSTRACT Coupling chemical oxidation and biodegradation to remediate polycyclic aromatic hydrocarbon (PAH)-contaminated sediment has recently gained significant attention. In this study, calcium peroxide nanoparticles (nCaO2) were utilized as an innovative oxygen-releasing compound for in-situ chemical oxidation. The study investigates the bioremediation of phenanthrene (PHE)-contaminated sediment inoculated with Sphingomonas sp. DSM 7526 bacteria and treated with either aeration or nCaO2. Using three different culture media, the biodegradation efficiencies of PHE-contaminated anoxic sediment, aerobic sediment, and sediment treated with 0.2% w/w nCaO2 ranged from 57.45% to 63.52%, 69.87% to 71.00%, and 92.80% to 94.67%, respectively. These values were significantly higher compared to those observed in non-inoculated sediments. Additionally, the type of culture medium had a prominent effect on the amount of PHE removal. The presence of minerals in the culture medium increased the percentage of PHE removal compared to distilled water by about 2–10%. On the other hand, although the application of CaO2 nanoparticles negatively impacted the abundance of sediment bacteria, resulting in a 30–42% decrease in colony-forming units after 30 days of treatment, the highest PHE removal was obtained when coupling biodegradation and chemical oxidation. These findings demonstrate the successful application of bioaugmentation and chemical oxidation processes for treating PAH-contaminated sediment.

Design, Synthesis, and Biological Evaluation of Novel Arylomycins against Multidrug-Resistant Gram-Negative Bacteria.

G0775, an arylomycin-type SPase I inhibitor that is being evaluated in a preclinical study, exhibited potent antibacterial activities against some Gram-negative bacteria but meanwhile suffered defects such as a narrow antibacterial spectrum and poor pharmacokinetic properties. Herein, systematic structural modifications were carried out, including optimization of the macrocyclic skeleton, warheads, and lipophilic regions. The optimization culminated in the discovery of 138f, which showed more potent activity and a broader spectrum against clinically isolated carbapenem-resistant Gram-negative bacteria, especially against Acinetobacter baumannii and Pseudomonas aeruginosa. 162, the free amine of 138f, exhibited an excellent pharmacokinetic profile in rats. In a neutropenic mouse thigh model of infection with multidrug-resistant P. aeruginosa, the potent in vivo antibacterial efficacy of 162 was confirmed and superior to that of G0775 (3.5-log decrease vs 1.1-log decrease in colony-forming unit (CFU)). These results support 162 as a potential antimicrobial agent for further research.

Comparative Evaluation of Residual Antibacterial Substantivity of Chlorhexidine, MTAD and Chitosan Against Enterococcus Faecalis in Human Root Dentin – An In vitro Study

ABSTRACT Introduction: Complex anatomy of the root canal system results in incomplete debridement with mechanical instrumentation, leaving some areas or root canal walls untouched. There comes the significance of endodontic irrigants with residual antibacterial substantivity which prolongs the post-antibiotic effect, thereby improving the success and predictability of endodontic treatment. Aim: To comparatively evaluate the residual antibacterial substantivity of 2% chlorhexidine, Biopure MTAD and 2% chitosan against Enterococcus faecalis at intervals of 1, 14 and 28 days. Materials and Methods: Seventy-five therapeutically extracted permanent single rooted mandibular premolars teeth were selected. Dentin blocks of 4 mm thickness were prepared and enlarged to 1.6 mm. The autoclaved blocks were inoculated with 24-hour colonies of pure cultures of E. faecalis for 14 days. After the contamination period, canals of each dentin block were irrigated with 5 ml of sterile saline and dried with sterile paper points. A total of 75 dentin blocks were randomly divided into five groups as follows: Group A (21 specimens): 2% chlorhexidine, Group B (21 specimens): Biopure MTAD, Group C (21 specimens): 2% chitosan, Group D (6 specimens): positive control (infected dentin tubes) and Group E (six specimens): negative control (sterile dentin tubes). Then, the lumens of dentin blocks were irrigated with the respective irrigants for 10 mins and were dried using sterile paper points. The specimens were then incubated at 37°C for 28 days to maintain humidity. At experimental intervals of 1, 14 and 28 days, dentin shavings were removed from the canals of respective groups by circumferential filing with sterile no. 35 Hedstrom files. The powdered dentin samples obtained with each dentin block were observed for colony forming units (CFUs) using a Digital Colony counter and were expressed as CFUs/mL. Result: All the irrigants in the study showed a significant decrease in CFUs from day 1 to day 28 indicating that they have residual antibacterial substantivity against E. faecalis. Group B (Biopure MTAD) showed significantly least mean CFUs compared to Group A (2% CHX) and Group C (2% chitosan) against E. faecalis at B1(day 1), B2(day 14) and B3(day 28). Group A (2% CHX) showed significantly higher mean CFUs than Group C (2% chitosan) at A1(day 1). Group C (2% chitosan) showed significantly higher mean CFUs compared to Group A (2% CHX) at C2(day 14) and C3 (day 28). Conclusion: MTAD showed statistically higher residual antibacterial substantivity against E. faecalis at experimental periods of 1, 14 and 28 days. The residual antibacterial effect of 2% chitosan was better compared to 2% CHX at day 1. The residual antimicrobial substantivity of 2% CHX was higher compared to 2% chitosan at intervals of 14 and 28 days.

Evaluation of the Effectiveness of Disinfectants on Impression Materials.

Background The disinfection of dental impression materials is a cornerstone of infection control in dental practice. This study aimed to evaluate the effectiveness of two disinfectants, sodium hypochlorite and iodophor, on alginate and silicone impression materials, which are prone to microbial contamination. Methods The study was structured into two main groups based on the impression material: Group I (alginate) and Group II (addition silicone), each further subdivided into two subgroups for disinfection with sodium hypochlorite and iodophor. For each subgroup, initial microbial swabs were taken before any treatment, followed by a second swab after rinsing and a final swab after disinfection. The mean colony-forming unit (CFU) counts, standard deviations, and standard errors of the mean were calculated for each stage of treatment. Results Prior to disinfection, Group I had a mean CFU count of 2,529.40, while Group II had a lower mean CFU of 1,417.40. After rinsing, there was a significant decrease in CFUs in both groups, with Group I at 1,337.10 and Group II at 415.10. Post-disinfection, Group I showed a mean CFU count of 73.00 for sodium hypochlorite and 0.00 for iodophor. Similarly, Group II achieved a CFU reduction of 99.00 with sodium hypochlorite and 0.00 with iodophor, demonstrating a marked reduction in microbial presence. Conclusion Iodophor was exceptionally effective in disinfecting both alginate and silicone impression materials, eliminating all detectable CFUs. Sodium hypochlorite also significantly reduced microbial counts but was not as effective as iodophor. Rinsing prior to disinfection was instrumental in reducing the microbial load, underscoring its importance in the disinfection protocol.

In vitro study: methylene blue-based antibacterial photodynamic inactivation of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the most antibiotic-resistant and opportunistic pathogens in immunocompromised and debilitated patients. It is considered the cause of most severe skin infections and is frequently found in hospital burn units. Due to its high antibiotic resistance, eliminating P. aeruginosa from skin infections is quite challenging. Therefore, this study aims to assess the novel in vitro antibacterial activity of methylene blue using a 635-nm diode laser to determine the effective power and energy densities for inhibition of P. aeruginosa. The strain was treated with various concentrations of methylene blue and 635-nm diode laser at powers of 300 mW/cm2 and 250 mW/cm2. The diode laser’s potency in the photo-destruction of methylene blue and its degradation through P. aeruginosa were also evaluated. Colony-forming unit (CFU)/ml, fluorescence spectroscopy, optical density, and confocal microscopy were used to measure the bacterial killing effect. As a result, the significant decrease of P. aeruginosa was 2.15-log10, 2.71-log10, and 3.48-log10 at 60, 75, and 90 J/cm2 after excitation of MB for 240, 300, and 360 s at a power of 250 mW/cm2, respectively. However, a maximum decrease in CFU was observed by 2.54-log10 at 72 J/cm2 and 4.32-log10 at 90 and 108 J/cm2 after 300 mW/cm2 of irradiation. Fluorescence images confirmed the elimination of bacteria and showed a high degree of photo-destruction compared to treatment with methylene blue and light alone. In conclusion, MB-induced aPDT demonstrated high efficacy, which could be a potential approach against drug-resistant pathogenic bacteria.Key points• Combination of methylene blue with 635-nm diode laser for antibacterial activity.• Methylene blue photosensitizer is employed as an alternative to antibiotics.• aPDT showed promising antibacterial activity against Pseudomonas aeruginosa.

Bacterial Persistence in Urinary Tract Infection Among Postmenopausal Population.

Urinary tract infections (UTIs) are common in older-aged women. Our study examined bacterial persistence with commonly prescribed antibiotics. Bacterial growth was demonstrated despite antibiotic treatment. The aims of this study were to quantify the bacterial persister phenotype in urine collected from postmenopausal women with acute and recurrent UTI and to determine the capabilities of first-line antibiotics to effectively treat persister cells. This was an institutional review board-approved cross-sectional analysis within a large academic referral center. Uropathogens were cultured from postmenopausal women with acute or recurrent UTI and screened for persister cells using persistence assays. Demographic and clinical variables were collected and analyzed. The entire experimental process was repeated in triplicate. Data were analyzed for significance (P < 0.05) between the persister culture and antibiotic treatments using a 1-way analysis of variance with multiple comparisons in Prism 9.3.0. Forty participants were included: 62.5% White, 22.5% Black, 3% Asian, and 2% Hispanic with a mean age of 72.3 ± 11.62 years. The persister phenotype was demonstrated in all of Escherichia coli isolates. Treatment with fosfomycin demonstrated reduced colony-forming units per milliliter compared with control (P < 0.01). Among recurrent isolates, there was a statistically significant decrease in colony-forming units per milliliter after antibiotic treatment with all 4 antibiotics (P < 0.05). This study demonstrated in vitro bacterial persistence in uropathogens from urogynecology patients despite treatment with commonly prescribed antibiotics. Fosfomycin generated the least amount of persister cells. Results suggest that persistence may be one bacterial defense mechanism involved in UTIs. Further research is needed to understand the clinical implications.

Evaluation of the efficacy of hydroxyl radical (OH˙) release for disinfection of the air and surfaces in the dental clinic: an in vitro study.

Concerning about the quality of room air has increased exponentially. Specially in dental clinics where diary practice is characterized by the important generation of aerosols. An in vitro model was used in which samples were collected from the surfaces and room air of a dental clinic before and after the use of an OH˙ radical generator. A total of 1260 samples were collected for bacteriological analysis and 14 samples for the detection of SARS-CoV-2. Following OH˙ treatment, the tested surface samples showed a decrease in the number of colony forming units (CFUs) of 76.9% in TSA culture medium. The circulating room air samples in turn showed a decrease in CFUs of 66.7% in Sabouraud medium and 71.4% in Mannitol agar medium. No presence of SARS-CoV-2 was observed on the surface of the face shield. The disinfectant technology based on the use of hydroxyl radicals (OH˙) is effective in reducing the presence of moulds and yeasts and Staphylococcus in the air, and in reducing total aerobic bacteria on the tested surfaces.

The heme oxygenase-1 metalloporphyrin inhibitor stannsoporfin enhances the bactericidal activity of a novel regimen for multidrug-resistant tuberculosis in a murine model.

Multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) poses significant challenges to global tuberculosis (TB) control efforts. Host-directed therapies (HDTs) offer a novel approach to TB treatment by enhancing immune-mediated clearance of Mtb. Prior preclinical studies found that the inhibition of heme oxygenase-1 (HO-1), an enzyme involved in heme metabolism, with tin-protoporphyrin IX (SnPP) significantly reduced mouse lung bacillary burden when co-administered with the first-line antitubercular regimen. Here, we evaluated the adjunctive HDT activity of a novel HO-1 inhibitor, stannsoporfin (SnMP), in combination with a novel MDR-TB regimen comprising a next-generation diarylquinoline, TBAJ-876 (S), pretomanid (Pa), and a new oxazolidinone, TBI-223 (O) (collectively, SPaO), in Mtb-infected BALB/c mice. After 4 weeks of treatment, SPaO + SnMP 5mg/kg reduced mean lung bacillary burden by an additional 0.69 log10 (P = 0.01) relative to SPaO alone. As early as 2 weeks post-treatment initiation, SnMP adjunctive therapy differentially altered the expression of pro-inflammatory cytokine genes and CD38, a marker of M1 macrophages. Next, we evaluated the sterilizing potential of SnMP adjunctive therapy in a mouse model of microbiological relapse. After 6 weeks of treatment, SPaO + SnMP 10mg/kg reduced lung bacterial burdens to 0.71 ± 0.23 log10 colony-forming units (CFUs), a 0.78 log-fold greater decrease in lung CFU compared to SpaO alone (P = 0.005). However, adjunctive SnMP did not reduce microbiological relapse rates after 5 or 6 weeks of treatment. SnMP was well tolerated and did not significantly alter gross or histological lung pathology. SnMP is a promising HDT candidate requiring further study in combination with regimens for drug-resistant TB.

High Mobility Group A1 Chromatin Regulators Drive Regenerative Capacity during Stress Hematopoiesis through Modulation of TNF-α and Aging Transcriptional Networks

Introduction: Chromatin structure and epigenetic modifications are key determinants of regenerative function and cell fate decisions, although mechanisms governing these properties in hematopoiesis are only beginning to emerge. The High Mobility Group A1 ( HMGA1) chromatin regulator gene is induced by growth factors and highly expressed during embryogenesis and in hematopoietic stem cells (HSCs), but silenced in differentiated tissues ( Cancer Res 2018,78:1890). In leukemia and solid tumors, HMGA1 is re-expressed where it activates enhancers that induce stem cell transcriptional networks, leading to aberrant proliferation and differentiation ( Blood 2022,139:2797; JCI 2023 133:e151601). HMGA1 also drives self-renewal by amplifying Wnt networks in intestinal stem cells ( Nature Comm 2017,8:15008). However, its role in normal hematopoiesis is unknown. We therefore sought to: 1) Define HMGA1 function in HSC, and, 2) Test the hypothesis that modulating HMGA1 epigenetic networks enhances regenerative function. Methods: First, we compared HMGA1 expression across hematopoietic stem and progenitor cells (HSPC) and differentiated progeny in humans and mice. Next, we generated mice with global Hmga1 knock-out ( Hmga1-KO) or Hmga1 deficiency confined to HSC (vav- Hmga1-KO) to assess HSPC function in clonogenic assays, competitive bone marrow transplantation (cBMT), and following irradiation. To elucidate underlying mechanisms, we performed single cell RNA sequencing (scRNAseq) of bone marrow (BM)-derived Lin -, Sca +, c-kit + (LSK) cells followed by pathway analysis. To assess HMGA1 function in human CD34 + cells, we used CRISPR to inactivate HMGA1. Results: HMGA1 is expressed in HSC, multipotent progenitors (MPP), and megakaryocyte-erythroid progenitors (MEP), with decreasing levels after differentiation, suggesting that HMGA1 functions in stem and progenitors. However, steady state hematopoiesis is unperturbed in both Hmga1-KO and vav- Hmga1-KO mice up to 18 months. By contrast, HSPC lacking Hmga1 show decreases in total colony forming units (CFU), but only after serial replating, suggesting that Hmga1 deficiency impairs long-term HSC (LT-HSC) regenerative function. Accordingly, in cBMT assays, Hmga1-KO HSC are outcompeted by HSC with both Hmga1 alleles, with most pronounced effects after serial transplantation. Serial cBMT from young donors (6 weeks) show decreases in LT-HSC, short-term HSC (ST-HSC), and progenitors from Hmga1 KO HSPC compared to control HSPC. Results were similar with older donors (4 months, 18 months). Following irradiation, vav- Hmga1-KO mice have impaired platelet recovery, although the frequency of HSPC in bone marrow were similar to controls. HSPC function in clonogenic assays is also impaired after irradiation, as evidenced by decreases in total CFU, GM-CFU and megakaryocyte (Mk)-CFU. To determine how HMGA1 modulates cell state, we compared scRNAseq in BM-derived LSK cells from adult mice (4 months old) with intact Hmga1 to those with Hmga1-KO. The transcriptomes in HSPC lacking Hmga1 were distinct from those with both Hmga1 alleles intact. The Hmga1 KO HSPC show a decrease in quiescent HSC (marked by high Procr expression), with a relative expansion in more proliferative HSC and early progenitors. In human CD34 + cells, CRISPR-mediated HMGA1 inactivation decreases total CFU, GM-CFU, and Mk-CFU. To elucidate underlying mechanisms, we applied gene set enrichment analyses to scRNAseq results which revealed that Hmga1 activates TNF-a signaling via NF-κB, a pathway that maintains HSC survival and regeneration following inflammatory stress. Hmga1 also represses aging-related transcriptional networks. Further, TNFa partially rescues HSC with Hmga1 deficiency in serial clonogenicity assays. Conclusions: HMGA1 deficiency impairs HSC regenerative capacity under conditions of stress hematopoiesis by depleting quiescent HSC. Mechanistically, HMGA1 induces transcriptional networks involved in survival signals, including TNFa -NF-κB networks, while repressing transcriptional networks activated with aging. Further, TNF-apartially rescues regenerative capacity in clonogenicity assays. Our findings highlight HMGA1 as a critical factor in stress hematopoiesis and suggest that modifying its function could enhance regenerative capacity and repress aging pathways following BMT or irradiation.

An effective antimicrobial strategy of colistin combined with the Chinese herbal medicine shikonin against colistin-resistant Escherichia coli.

The treatment of bacterial infections has become more challenging due to the increasing prevalence of colistin-resistant (Col-R) pathogens. Shikonin is a Chinese herbal medicine that has been proven to have antibacterial properties. In recent years, many studies have shown that the combination of traditional antibiotics and non-antibacterial drugs can effectively treat infections caused by multidrug-resistant bacteria. This study evaluated the potential of shikonin in combination with colistin to inhibit colistin-resistant Escherichia coli (Col-R E. coli), and explored potential interaction. In checkerboard analysis, shikonin could significantly reduce the minimum inhibitory concentration (MIC) of colistin by two to eight times, enhancing the susceptibility of Col-R E. coli to colistin. Shikonin also increased the bactericidal effect of colistin against Col-R E. coli in 24 h time-kill assays, resulting in a >3 log-fold decrease in colony-forming units. In vivo tests showed that the combination of colistin and shikonin could significantly improve the survival rate of Galleria mellonella. In addition, confocal laser scanning microscopy and quantitative real-time polymerase chain reaction showed that colistin/shikonin could inhibit the formation of biofilms, and shikonin could down-regulate the transcription level of biofilm-regulated genes (csgA, csgD, flhC, flhD, fliC, fliM, lsrK, and lsrR). The synergistic mechanism of colistin and shikonin was further revealed by detecting membrane integrity, reactive oxygen species production, and mcr-1 gene expression. Our findings indicate that the colistin/shikonin combination may be a promising alternative approach to treat Col-R E. coli infections. IMPORTANCE Infections caused by multidrug-resistant Escherichia coli (MDR E. coli) have become a major global healthcare problem due to the lack of effective antibiotics today. The emergence of colistin-resistant E. coli strains makes the situation even worse. Therefore, new antimicrobial strategies are urgently needed to combat colistin-resistant E. coli. Combining traditional antibiotics with non-antibacterial drugs has proved to be an effective approach of combating MDR bacteria. This study investigated the combination of colistin and shikonin, a Chinese herbal medicine, against colistin-resistant E. coli. This combination showed good synergistic antibacterial both in vivo and in vitro experiments. Under the background of daily increasing colistin resistance in E. coli, this research points to an effective antimicrobial strategy of using colistin and shikonin in combination against colistin-resistant E. coli.

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.

Limited effectiveness of selected bioeffectors combined with recycling phosphorus fertilizers for maize cultivation under Swiss farming conditions.

The use of plant biostimulants, also known as bioeffectors (BEs), has attracted increasing attention as an environmentally friendly strategy for more sustainable crop production. BEs are substances or microorganisms that are applied to plants or the surrounding soil to stimulate natural processes to enhance nutrient uptake, stress tolerance, and plant growth. Here, we tested the effectiveness of five BEs to enhance maize growth and phosphorus (P) uptake from various recycled P fertilizers in a series of pot and field experiments. First, the impact of two bacterial BEs and one soil-specific plant-based BE on crop performance was assessed in a 4-week screening experiment conducted in two arable, P-deficient soils of differing soil pH (a silty clay loam of pH 7.1 and a silty loam of pH 7.8) amended with recycled P-fertilizers (rock phosphate, biogas digestate, green waste compost, composted dairy manure, and chicken manure pellets). Then, for each soil type, the plant growth-promoting effect of the most promising BE-fertilizer combinations was re-assessed in an 8-week experiment. In addition, over a period of up to 3 years, three field experiments were conducted with maize in which up to two bacterial BEs were used either alone or in combination with a plant-based BE. Our experiments show that while BEs in combination with specific P-fertilizers can promote maize growth within the first weeks of growth under controlled conditions, the observed effects vanished in the long term, both in pots and under field conditions. In a tracing experiment, in which we tested the persistence of one bacterial BE over a period of 5 weeks, we observed a drastic decrease in colony-forming units already 2 weeks after inoculation. As previously shown in other studies, our data indicate that the plant growth-promoting effects of BEs found under controlled conditions are not directly transferable to field conditions. It is suggested that the drastic decline in inoculated bacterial strains in the tracing experiment is the reason for the decline in plant growth effect.

Comparison of Antimicrobial Activity of Triple, Double, and Cefixime-Based Antibiotic Pastes Against Enterococcus Faecalis: An In Vitro Study.

This in vitro study aims to compare the antimicrobial efficacy of triple antibiotic paste, double antibiotic paste, and cefixime-based triple antibiotic paste againstEnterococcus faecalis. Materials and methods: Fifty single-rooted, caries-free, permanent teeth without any developmental defects were included in this study. The specimens were divided into five groups, with each group consisting of 10 teeth that received a specific medicament. The groups were as follows: Group I: control; Group II: calcium hydroxide;Group III: triple antibiotic paste; Group IV: double antibiotic paste; and Group V: cefixime-based triple antibiotic paste. The antimicrobial activity of the medicaments was assessed againstE. faecalisat the end of the seventhand 14th days. The colony-forming units (CFU) werecalculated using the Kolmogorov-Smirnov and Wilcoxon tests. After seven days of the experimental process, it was observed that the CFU count was highest in group I and lowest in group V. In a similar vein, after 14 days, the maximum decrease in CFU count was observed inGroup V, while the least reduction in CFU count was observed in Group II. On intergroup comparison, it was found that the maximum decrease in CFU was noted inGroup V, followed by Group IV, Group III, and Group II. The study results indicated that the cefixime-enriched antibiotic paste had the greatestantimicrobial effectiveness, while the double and triple antibiotic pastes offered superior antibacterial efficacy againstE. faecalis at the end of the seventhand 14thdays.

Stevia vs. triple antibiotic paste: An intracanal battle?

Intracanal medicaments are vital in treating the infections of the deciduous dentition due to the large percentage of accessory canals that hasten the microbial spread to the periradicular region. Though countless medicaments have been produced to reduce the microbial load and aid symptomatic relief, they still do not fulfill every function of an ideal medicament. The aim of the present study was to evaluate and compare the antimicrobial efficacy of Stevia rebaudiana (S. rebaudiana) and triple antibiotic paste (TAP) against Enterococcus faecalis (E. faecalis). The present in vitro, parallel, double-blinded study had an equal allocation ratio. The specimens were prepared, randomly divided into 4 groups and inoculated with E. faecalis (ATCC35550). Following incubation, the first 3 groups were treated with S. rebaudiana, triple antibiotic therapy or carbopol gel, respectively, with the 4th negative control group left untreated. The microbial samples were collected before and after treatment, and the counts of colony-forming units (CFUs) were compared. The results were analyzed using the Kruskal-Wallis, Dunn's post-hoc and Wilcoxon's signed rank tests. The first 2 groups displayed a significant decrease in CFUs after drug application, while the carbopol and control groups showed an exponential increase. There was no statistically significant difference between the stevia and TAP groups (p = 0.630). Stevia gel was comparable to TAP in terms of antimicrobial efficacy, and can therefore be considered a new alternative in intracanal treatment.

Antimycobacterial pyridine carboxamides: From design to in vivo activity

Tuberculosis is the number one killer of infectious diseases caused by a single microbe, namely Mycobacterium tuberculosis (Mtb). The success rate of curing this infection is decreasing due to emerging antimicrobial resistance. Therefore, novel treatments are urgently needed. As an attempt to develop new antituberculars effective against both drugs-sensitive and drug-resistant Mtb, we report the synthesis of a novel series inspired by combining fragments from the first-line agents isoniazid and pyrazinamide (series I) and isoniazid with the second-line agent 4-aminosalicylic acid (series II). We identified compound 10c from series II with selective, potent in vitro antimycobacterial activity against both drug-sensitive and drug-resistant Mtb H37Rv strains with no in vitro or in vivo cytotoxicity. In the murine model of tuberculosis, compound 10c caused a statistically significant decrease in colony-forming units (CFU) in spleen. Despite having a 4-aminosalicylic acid fragment in its structure, biochemical studies showed that compound 10c does not directly affect the folate pathway but rather methionine metabolism. In silico simulations indicated the possibility of binding to mycobacterial methionine-tRNA synthetase. Metabolic study in human liver microsomes revealed that compound 10c does not have any known toxic metabolites and has a half-life of 630 min, overcoming the main drawbacks of isoniazid (toxic metabolites) and 4-aminosalicylic acid (short half-life).

In vitro comparison of the effectiveness of various antimicrobial locks with taurolidine in the treatment and prevention of catheter-related bloodstream infections in patients receiving parenteral nutrition

ObjectivesTo evaluate the effectiveness of various taurolidine solutions in the prevention and treatment of catheter-related bloodstream infections (CRBSIs) caused by the entire spectrum of microbes in patients receiving parenteral nutrition in a shorter period of time. MethodsThe in vitro method was used to test for eradication of biofilm. Different locks were used: TauroSept (2%), TauroLock (1.35%), TauroLock half concentration, and 3.5% taurolidine and tested on Staphylococcus (S.) epidermidis, S. aureus, S. hominis, methicillin-resistant S. aureus (MRSA), Pseudomonas (P.) aeruginosa (PSAE), multidrug‐resistant P. aeruginosa (MR PSAE), vancomycin-resistant enterococci, Klebsiella pneumoniae producing carbapenemase (KPC), Klebsiella pneumoniae producing extended-spectrum beta-lactamase (KLPN ESBL), Candida (C.) albicans, and C. glabrata. Broviac catheters were incubated for growth of each organism and then incubated in lock solutions. Colony forming units (CFUs) were then counted after 30 min, 60 min, and 120 min of incubation. ResultsA statistically significant decrease in CFUs was observed after 30 min of taurolidine exposure for S. hominis, PSAE, KLPN ESBL, KLPN KPC, C. albicans, and C. glabrata; after 60 min of exposure for S. epidermidis, PSAE, MR PSAE, KLPN ESBL, KPC, C. albicans, and C. glabrata; and after 120 min of exposure for S. epidermidis, S. hominis, S. aureus, PSAE, MR PSAE, KLPN ESBL, KPC, C. albicans, C. glabrata. ConclusionsThe application of taurolidine is effective in the treatment of CRBSIs. Taurolidine proved to be more effective against Gram-negative microorganisms during a 30-min exposure. Using 0.675% taurolidine is still effective. To achieve the required antimicrobial effect, the catheter must be sanitized for at least 2 h.

Study on the Mechanism of Levofloxacin Combined with Imipenem Against Pseudomonas aeruginosa.

Pseudomonas aeruginosa can develop resistance. Therefore, it is necessary to design proper treatment for it. Pseudomonas aeruginosa can develop resistance against levofloxacin due to the development of efflux pumps. However, the development of these efflux pumps cannot develop resistance against imipenem. Additionally, the MexCDOprJ efflux system which is responsible for the resistance of Pseudomonas aeruginosa to levofloxacin is highly susceptible to imipenem. The objective of the study was to evaluate the emergence of resistance of Pseudomonas aeruginosa against 750mg levofloxacin, 250mg imipenem, and a combination of 750mg levofloxacin and 250mg imipenem. An in vitro pharmacodynamic model was selected for the evaluation of the emergence of resistance. Pseudomonas aeruginosa strain 236, Pseudomonas aeruginosa strain GB2, and Pseudomonas aeruginosa strain GB65 were selected. Susceptibility testing of both antibiotics was done by agar dilution methodology. A disk diffusion bioassay was performed for antibiotics. RT-PCR measurement was done for the evaluation of expressions of Pseudomonas aeruginosa genes. Samples were tested at 2h, 4h, 6h, 8h, 12h, 16h, 24h, and 30h. Levofloxacin and imipenem both individually reported a decrease in colony-forming unit per milliliter of strength in the initial stage but in the later stage both develop resistance individually. Levofloxacin with imipenem had no resistance to Pseudomonas aeruginosa during 30h. Time after the start of development of resistance or decrease in clinical efficacy was higher for levofloxacin and imipenem combination in all strains. The concentration of Pseudomonas aeruginosa at the time after the start of development of resistance or decrease in clinical efficacy was fewer for levofloxacin and imipenem combination. Levofloxacin with imipenem is recommended for the treatment of infection due to Pseudomonas aeruginosa.

Inhibitory Effects of Lactulose on Enteric Bacterial Dynamics and Gut Permeability in Bile-Duct Ligated Rats

Background and Aim: The prebiotic potential of lactulose is well known, but its effect to inhibit enteric bacterial dynamics and gut permeability has not yet been investigated in experimental studies. The present study aims to assess the effects of lactulose on the enteric bacterial dynamics gut permeability in a model of bile duct ligation in Wistar rats. Methods: Wistar rats were assigned into 3 groups, the Sham-operated control, bile duct ligated (BDL) and BDL+ Lac group on the 28th day of bile duct ligation. Animals of BDL + Lac groups were treated with lactulose (1.0 g/kg), administrated by gavage, once a day for 7 days. Bacterial translocation into the organs and bacterial overgrowth as the indicators of the enteric bacterial dynamics and the levels of DAO and D-lactate as the biochemical makers of the gut permeability were measured in each group. Results: The bacterial colony forming units (CFU) in spleen and liver of BDL+Lac group was significantly decreased compared with BDL model group (P&lt;0.01) and significant decrease of bacterial CFU was seen in the intestinal lavage in BDL+Lac group compared to BDL group (P&lt;0.01). On the other hand, Lactulose revealed significant inhibitory effect as evidence by decreasing plasma DAO activity and D-lactate levels (P&lt;0.01) in this model. Conclusion: These results indicate that lactulose can inhibit the enteric bacterial overgrowth, bacterial translocation (BT) and increasing gut permeability by opening the mucosa tight junction in ductal obstruction and obviate even systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) induced by obstructive jaundice.

SYNERGISTIC ANTIMICROBIAL ACTIVITY BY COMBINING TERBINAFINE WITH BENZOYL PEROXIDE AGAINST САNDIDA ALBICANS AND STAPHYLOCOCCUS AUREUS

The aim. To investigate the ability of microorganisms’ C. albicans and S. aureus to form biofilms. To evaluate the sensitivity of biofilms to combination of terbinafine and benzoyl peroxide on this association.&#x0D; Material and methods. The ability to form biofilms of microorganisms and the antimicrobial effect of the studied drugs was carried out on polystyrene plates for enzyme-linked immunosorbent assay. The optical density (OD) of biofilms was measured at a wavelength of 545 nm on a biochemical analyzer. The viability of microorganisms was determined by counting the number of colony-forming units (CFU) in 1 ml of the culture medium with experimental strains.&#x0D; Results. The average optical density of biofilms was (1.0892±0.006) units. The OD for clinical isolates was (0.0776±0.004) units. It has been proven that combination of the antimycotic substance − terbinafine and the antiseptic − benzoyl peroxide had a high activity in relation to the association of C. albicans and S. aureus with concentration of 1.3 μg/ml. &#x0D; Conclusion. The study showed the ability to form biofilms in clinical strains of microorganisms is more pronounced than the reference strains. The highest rate of biofilm formation was found in the association of microorganisms’ C. albicans and S. aureus. The combination of medicines also effectively operated with planktonic forms of bacteria, but also on microorganisms mobilized in biofilms. A decrease of optical density and 2-fold decrease of CFU demonstrated this.

Evaluation of Escherichia coli Inactivation at High Altitudes Using Solar Water Disinfection.

Solar disinfection (SODIS) is an effective method for microbiologic inactivation of contaminated water using ultraviolet rays at low elevations. The aim of this study was to determine the effectiveness of SODIS at higher elevations. The ability of SODIS to inactivate Escherichia coli bacteria was evaluated at an altitude of ≥1600 m using Nalgene bottles, disposable plastic water bottles, and Ziploc plastic bags. Bacterial viability was determined through measurement of colony forming units (CFUs). Decreases in CFUs were determined at each time point relative to those at the baseline, and a multivariable regression analysis was used to assess significant changes in CFUs. Bacterial CFUs in exposed containers decreased by >5 log after 6 h of exposure to sunlight. In contrast, the CFUs remained nearly unchanged in unexposed containers, showing a mean decrease of 0.3 log. By 2 h, bacterial inactivation at high altitudes was 1.7-fold greater than that at lower altitudes (P<0.05). By 6 h, nearly all bacteria were inactivated at high or low altitudes. At 6 h, no statistical difference was observed in the efficiency of inactivation between elevations. Compared with Nalgene bottles, plastic bottles had a 1.4-fold greater decrease in CFUs (P<0.05). No statistical difference in bacterial inactivation was found between plastic bottles and plastic bags. At high altitudes, SODIS is an effective method for inactivating E coli. Further research investigating other microorganisms is warranted to determine whether SODIS is suitable for disinfecting contaminated water at high altitudes.