Bacterial Growth Research Articles

Unveiling the Potential of CuO and Cu2O Nanoparticles against Novel Copper-Resistant Pseudomonas Strains: An In-Depth Comparison.

Four novel Pseudomonas strains with record resistance to copper (Cu2+) previously isolated from ecologically diverse samples (P. lactis UKR1, P. panacis UKR2, P. veronii UKR3, and P. veronii UKR4) were tested against sonochemically synthesised copper-oxide (I) (Cu2O) and copper-oxide (II) (CuO) nanoparticles (NPs). Nanomaterials characterisation by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the synthesis of CuO and Cu2O NPs. CuO NPs exhibited better performance in inhibiting bacterial growth due to their heightened capacity to induce oxidative stress. The greater stability and geometrical shape of CuO NPs were disclosed as important features associated with bacterial cell toxicity. SEM and TEM images confirmed that both NPs caused membrane disruption, altered cell morphology, and pronounced membrane vesiculation, a distinctive feature of bacteria dealing with stressor factors. Finally, Cu2O and CuO NPs effectively decreased the biofilm-forming ability of the Cu2+-resistant UKR strains as well as degraded pre-established biofilm, matching NPs' antimicrobial performance. Despite the similarities in the mechanisms of action revealed by both NPs, distinctive behaviours were also detected for the different species of wild-type Pseudomonas analysed. In summary, these findings underscore the efficacy of nanotechnology-driven strategies for combating metal tolerance in bacteria.

Efficacy of antibiotics and bactericides against Xanthomonas axonopodis pv. citri causing bacterial canker disease of acid lime (Citrus aurantifolia)

Diseases are the major constraints for citrus production which impede the fruit yield and quality. Citrus suffers from a number of diseases caused by fungi, bacteria, viruses and viriods. Among these diseases, canker caused by Xanthomonas axonopodis pv. citri, foot rot or gummosis caused by Phytophthora spp., twig blight caused by Diplodia natalensis and Fusarium spp. Three antibiotics and three bactericides viz., Streptocycline, Kasugamycin 5% + Copper oxychloride 45% WP, Kasugamycin, Bacterimycin, Copper oxychloride 50% WP, Copper hydroxide 53.8% W/W were evaluated for their effectiveness in controlling the growth of Xanthomonas axonopodis pv. citri at the Department of Plant Pathology, College of Agriculture, Ummendganj-Kota, (Agricultural University, Kota) Rajasthan. Inhibition was highest in case of copper oxychloride 50% WP (34.20 mm) followed by bronopol 27% (28.90 mm) and streptocycline 90% W/W (12.48 mm) at 500 ppm concentration and no inhibition zone was found in kasugamycin. All the antibiotics/bactericides inhibited bacterial growth at higher concentrations.

Exploring the antimicrobial efficacy of tea tree essential oil and chitosan against oral pathogens to overcome antimicrobial resistance

BackgroundConsidering that antimicrobial resistance among oral pathogens is a significant concern in dental practice, with broader implications for overall health due to the oral microbiota serving as a reservoir for antibiotic resistance genes (ARGs), research into natural products is crucial for addressing this issue. ObjectiveThis study aimed to evaluate tea tree oil (TTO) and chitosan (CH) performance against oral pathogens, including mixed-species biofilm, and its effects on bacteria growth, in addition to chemical characterization and cytotoxicity of TTO. MethodsTea Tree Oil and low molecular weight chitosan were used in this study. The chemical composition of TTO was analyzed using gas chromatography coupled with mass spectrometry (GC-MS). To evaluate TTO's antimicrobial properties, time-kill and cell viability assays were conducted. Additionally, minimum inhibitory concentration (MIC), minimum microbiocidal concentration (MMC), checkerboard, and biofilm assays were performed using TTO and CH alone and in combination. ResultsTTO chromatography peaks found consistent with the standard ISO4730:2017 and literature. TTO and CH exhibited inhibitory activity against all tested microorganisms. The predominantly microbiostatic activity of TTO is probably related to terpinen-4-ol associated with terpinene. The oil at MIC value was able to delay the log phase of Aggregatibacter actinomycetemcomitans growth. Fibroblasts (L929) viability remained above 70 % during 24 h for TTO concentrations ranging from 0.5 to 0.0625 mg/ml. TTO-CH combination showed a synergistic activity (FIC = 0.5) against A. actinomycetemcomitans and Streptococcus sanguinis, at a concentration of 0,25MIC for both species. The compounds at MIC concentration inhibited both monospecies and mixed-species biofilms studied bacteria to the same extent as the azithromycin control. ConclusionTTO and CH demonstrated efficacy in combating oral pathogens and TTO-CH combination offers a promising approach to confront microbial resistance in the oral environment.

Immunomodulating melatonin-decorated silica nanoparticles suppress bacterial wilt (Ralstonia solanacearum) in tomato (Solanum lycopersicum L.) through fine-tuning of oxidative signaling and rhizosphere bacterial community

BackgroundTomato (Solanum lycopersicum L.) production is severely threatened by bacterial wilt, caused by the phytopathogenic bacterium Ralstonia solanacearum. Recently, nano-enabled strategies have shown tremendous potential in crop disease management.ObjectivesThis study investigates the efficacy of biogenic nanoformulations (BNFs), comprising biogenic silica nanoparticles (SiNPs) and melatonin (MT), in controlling bacterial wilt in tomato.MethodsSiNPs were synthesized using Zizania latifolia leaves extract. Further, MT containing BNFs were synthesized through the one-pot approach. Nanomaterials were characterized using standard characterization techniques. Greenhouse disease assays were conducted to assess the impact of SiNPs and BNFs on tomato plant immunity and resistance to bacterial wilt.ResultsThe SiNPs and BNFs exhibited a spherical morphology, with particle sizes ranging from 13.02 nm to 22.33 nm for the SiNPs and 17.63 nm to 21.79 nm for the BNFs, indicating a relatively uniform size distribution and consistent shape across both materials. Greenhouse experiments revealed that soil application of BNFs outperformed SiNPs, significantly enhancing plant immunity and reducing bacterial wilt incidence by 78.29% in tomato plants by maintaining oxidative stress homeostasis via increasing the activities of antioxidant enzymes such as superoxide dismutase (31.81%), peroxidase (32.9%), catalase (32.65%), and ascorbate peroxidase (47.37%) compared to untreated infected plants. Additionally, BNFs induced disease resistance by enhancing the production of salicylic acid and activating defense-related genes (e.g., SlPAL1, SlICS1, SlNPR1, SlEDS, SlPD4, and SlSARD1) involved in phytohormones signaling in infected tomato plants. High-throughput 16 S rRNA sequencing revealed that BNFs promoted growth of beneficial rhizosphere bacteria (Gemmatimonadaceae, Ramlibacter, Microscillaceae, Anaerolineaceae, Chloroplast and Phormidium) in both healthy and diseased plants, while suppressing R. solanacearum abundance in infected plants.ConclusionOverall, these findings suggest that BNFs offer a more promising and sustainable approach for managing bacterial wilt disease in tomato plants.Graphical

Antibiotic Overuse in Pediatric Patients Hospitalized with RSV, COVID-19, and Influenza

Abstract Background Children hospitalized with viral respiratory tract infections (RTIs) are often treated with antibiotics due to concern for bacterial co-infection, although most do not have concurrent bacterial infections. This practice leads to unnecessary antibiotic treatment, which can lead to development of resistant bacteria and adverse events. The extent of antibiotic overuse in hospitalized children with community-onset viral RTI has not been well-quantified in recent years and may have worsened during the COVID-19 pandemic. The objectives of this study were to quantify and compare the extent of antibiotic overtreatment and to determine predictors of antibiotic use post-COVID-19 pandemic in children hospitalized with RSV, COVID-19, and influenza. Methods We performed a single center retrospective study evaluating percentages of antibiotic use and bacterial co-infection among children and adolescents aged <19 years old, hospitalized with respiratory syncytial virus (RSV), influenza, or SARS-CoV-2 between April 2020 and May 2023. Bacterial infection was defined as growth of bacteria from any specimen source, including blood, urine, pleural fluid, cerebrospinal fluid, and respiratory secretions, excluding common contaminants like coagulase-negative Staphylococci. Predictors of antibiotic treatment were determined using multivariable logistic regression. Results During the study period 1,718 patients were included (1022 with RSV, 188 with influenza, 535 with COVID-19). RSV patients were younger and more likely to be in the ICU than influenza or COVID-19 patients. The overall proportion of patients with culture-confirmed bacterial co-infection was low at 8% and did not differ greatly by virus type (8% for influenza, 6.9% for RSV, 10.3% for COVID-19, p=0.03). The proportion of children receiving antibiotics was higher for influenza than for other viruses (60.6% for influenza, 41.2% for RSV, and 48.6% for COVID-19, p < 0.001). Among patients with the lowest severity of illness (with normal inflammatory markers [PCT <0.5 ug/mL or CRP <50 mg/L] and not admitted to the ICU), 7.3% had a culture-confirmed bacterial infection while 48.1% received antibiotics. Independent predictors for receiving antibiotics were elevated inflammatory markers (C-reactive protein or procalcitonin), having >3 comorbidities, mechanical ventilation, and influenza diagnosis. Conclusion In children hospitalized with community-onset viral RTIs, antibiotic treatment is substantially higher than the burden of culture-confirmed bacterial infection, suggesting antibiotic overuse. Antibiotic use was greater for patients with influenza than for those with RSV or COVID-19. Antibiotic overuse was estimated to occur in over 40% of patients with low severity of illness. Stewardship programs can use this data to design interventions to promote more judicious antibiotic use. Figure 1. Rates of bacterial co-infection and antibiotic utilization among patients hospitalized with influenza, RSV, and COVID. Blue, percentage of patients who had a culture-confirmed bacterial infection; orange, percentage of patients who received any antibiotics; green, percentage of patients who received >3 days of antibiotics.

Uji Potensi Antituberkulosis Ekstrak N-Heksan dan Ekstrak Etanol Daun Jeruk Nipis (Citrus Aurantiifolia) secara in Vitro

Tuberculosis is a disease caused by Mycobacterium tuberculosis which is widely suffered and causes death. Currently, antituberculosis treatment using synthetic chemicals has been widely resistant. The purpose of this study was to test the potential of lime extract to inhibit the growth of tuberculosis bacteria. This research method uses a quantitative approach and is experimental. The results of the study showed that the results of the phytochemical screening test showed the same group of chemical compounds in fresh leaves, simplex and ethanol extract of lime leaves, namely alkaloids, flavonoids, tannins, saponins, steroids and glycosides. While the n-hexane extract only contains steroids and glycosides. Then the effectiveness of antituberculosis can be seen from the ethanol extract being stronger than the n-hexane extract, namely in the 1st week there was inhibition while the n-hexane extract from the 1st week to the 4th week had bacterial growth.

Indole-3-Acetic Acid Esterified with Waxy, Normal, and High-Amylose Maize Starches: Comparative Study on Colon-Targeted Delivery and Intestinal Health Impact.

Background: Accumulating research suggests that metabolites produced by gut microbiota are essential for maintaining a balanced gut and immune system. Indole-3-acetic acid (IAA), one of tryptophan metabolites from gut microbiota, is critical for gut health through mechanisms such as activating aryl hydrocarbon receptor. Delivery of IAA to colon is beneficial for treatment of gastrointestinal diseases, and one promising strategy is IAA esterified starch, which is digested by gut microbes in colon and releases loaded IAA. Amylose content is a key structural characteristic that controls the physicochemical properties and digestibility of starch. In the current study, IAA was esterified with three typical starches with distinct amylose content to obtain indolyl acetylated waxy maize starch (WMSIAA), indolyl acetylated normal maize starch (NMSIAA), and indolyl acetylated high-amylose maize starch (HAMSIAA). The study comparatively analyzed their respective physicochemical properties, how they behave under in vitro digestion conditions, their ability to deliver IAA directly to the colon, and their effects on the properties of the gut microbiota. The new characteristic peak of 1H NMR at 10.83 ppm, as well as the new characteristic peak of FTIR spectra at 1729 cm-1, represented the successful esterification of IAA on starch backbone. The following in vitro digestion study further revealed that treatment with indolyl acetylation significantly elevated the resistant starch content in the starch samples. In vivo experimental results demonstrated that WMSIAA exhibited the most significant increase in IAA levels in the stomach, whereas HAMSIAA and NMSIAA demonstrated the most remarkable increases in IAA levels in the small intestine and colon, respectively. The elevated IAA levels in the colon are conducive to promoting the growth of beneficial intestinal bacteria and significantly alleviating DSS-induced colitis. This research presents innovative insights and options for the advancement of colon-specific drug delivery systems aimed at preventing and curing gastrointestinal disorders.

Harnessing Prebiotics to Improve Type 2 Diabetes Outcomes.

The gut microbiota, a complex ecosystem of microorganisms in the human gastrointestinal tract (GI), plays a crucial role in maintaining metabolic health and influencing disease susceptibility. Dysbiosis, or an imbalance in gut microbiota, has been linked to the development of type 2 diabetes mellitus (T2DM) through mechanisms such as reduced glucose tolerance and increased insulin resistance. A balanced gut microbiota, or eubiosis, is associated with improved glucose metabolism and insulin sensitivity, potentially reducing the risk of diabetes-related complications. Various strategies, including the use of prebiotics like inulin, fructooligosaccharides, galactooligosaccharides, resistant starch, pectic oligosaccharides, polyphenols, β-glucan, and Dendrobium officinale have been shown to improve gut microbial composition and support glycemic control in T2DM patients. These prebiotics can directly impact blood sugar levels while promoting the growth of beneficial bacteria, thus enhancing glycemic control. Studies have shown that T2DM patients often exhibit a decrease in beneficial butyrate-producing bacteria, like Roseburia and Faecalibacterium, and an increase in harmful bacteria, such as Escherichia and Prevotella. This review aims to explore the effects of different prebiotics on T2DM, their impact on gut microbiota composition, and the potential for personalized dietary interventions to optimize diabetes management and improve overall health outcomes.

Studying the Influence of Salt Concentrations on Betalain and Selected Physical and Chemical Properties in the Lactic Acid Fermentation Process of Red Beetroot

This study emphasizes the significance of optimizing salt content during the fermentation of red beetroot to produce healthier and high-quality fermented products. It investigates the impact of different salt levels on fermentation, analyzing various parameters such as pH levels, dry matter content, total acidity, salt content, color changes, pigment content, and lactic acid bacteria count. This study identifies the most favorable salt concentration for bacterial growth during fermentation and storage as 2–3%. It was evaluated that salt levels fluctuated significantly during fermentation, with nearly 50% of the added salt absorbed by the beetroot tissues, mainly when lower salt concentrations were used. The fermentation process had a negative effect on the content of betalain pigments, as well as yellow pigments, including vulgaxanthin-I. It was also found that fermentation and storage affected the proportions of red pigments, with betacyanins proving to be more stable than betaxanthins, and that salt addition affected negatively pH and total acidity while causing an increase in yellow color. The pH was negatively correlated with the duration of the process, the amount of red pigment, and bacterial count. The results indicate that lower salt levels can lead to favorable physicochemical and microbiological parameters, allowing for the production of fermented red beetroot with reduced salt content without compromising quality.

Photosensitizer conjugated carbon dots@dopamine-copper sulfide nanocomposites: Advanced photoactive agents for antibacterial applications through experimental and theoretical insights

The massive use and abuse of antibiotics has given birth to drug-resistant bacteria and emergence of severe bacterial infections in people. Intriguingly, light activated antimicrobial activity i.e. antimicrobial photodynamic therapy has gained enhanced therapeutic potential and efficacy in killing the bacterial cells. Therefore, the present study investigates the efficacy of employing advanced nanocomposites for biocidal inhibition of bacterial growth through enhanced sterilization capabilities. Specifically, dopamine functionalized CuS NPs combined with carbon dots (CDs@Dop-CuS) were selected for their remarkable photodynamic potential when used in conjunction with methylene blue (MB). Comparative and synergistic application of Dop-CuS, CDs, and MB revealed the superior singlet oxygen generation potency of MB/CDs@Dop-CuS. Furthermore, the structural changes in the E. coli bacterial cells membrane were elucidated through scanning electron microscopy imaging, demonstrating superior inhibition rates of MB/CDs@Dop-CuS compared to MB alone under 660 nm irradiation. The commendable docking score and binding potential of CDs@Dop-CuS nanocomposites obtained via molecular docking simulations further validate their efficacy as photosensitizers against E. coli bacterial cells. Thus, this novel MB/CDs@Dop-CuS photosensitizer provides enhanced efficacy as an alternative to traditional antibiotic treatments, offering a superior disinfection for public utility services and addressing the growing issue of drug-resistant bacterial infections.

Understanding Bacterial Roles in Cancer Chemo-resistance: A Signaling Pathway Mapping Study

Introduction: Chemoresistance is one of the leading causes of chemotherapy failure among cancer patients. Out of several hypotheses proposed for chemoresistance, bacteria-mediated chemoresistance to cancer drugs has not been well established. Thus, the aim of this review is to map the pathways by which bacteria exhibit chemoresistance in specific cancers. Material and Methods: Relevant articles on bacteria-mediated chemoresistance in cancer were retrieved by conducting a systematic search across PubMed, Scopus and Web of Science databases. The search was limited to English original articles published until 15th December 2023. Results: A total of nine articles were included to map the pathways involved in chemoresistance. Numerous pathways have been connected to various forms of cancer, such as autophagy pathway in colorectal and esophageal cancers by Fusobacterium nucleatum causing oxaliplatin and 5-FU resistance; DNA damage response pathway also by Fusobacterium nucleatum promoting CDDP resistance in esophageal cancer; Porphyromonas gingivalis led to oral and esophageal cancer resistance to paclitaxel via JAK/STAT pathway. NF-κB pathway involved in gastric cancer in the presence of Helicobacter pylori towards cisplatin, and also 5-FU resistance via the apoptotic pathway. Cellular metabolism modulation by Lactobacillus iners was also implicated in cervical cancer chemoresistance. Conclusion: We conclude that bacteria can mediate chemoresistance not merely to antibiotics but also to anticancer drugs. Thus, a detailed understanding of the pathways associated with chemoresistance mediated via bacteria might help in targeting these pathways or antibiotics to prevent bacterial growth could help overcome resistance.

A study on bacterial inactivation using green synthesized photocatalytically active TiO2, MgO, TiO2/MgO nanoparticles

Madhuca longifolia (Mahua) flower extracts were utilised to perform the green synthesis of titanium dioxide (TiO2), magnesium oxide (MgO) nanoparticles, and a nanocomposite consisting of TiO2/MgO. Mahua flower extracts were used as both reducing and capping agents in a sol-gel synthesis method. The effectiveness of the green reducing agent in improving the surface structure of the green nanoparticles was demonstrated. FTIR, XRD, FESEM, and UV vis spectroscopy were employed to analyse the successful synthesis of TiO2, MgO, and TiO2/MgO nanocomposites. A study was done to examine the process of employing these nanoparticles to deactivate Escherichia coli (E. coli) by photocatalysis. The effectiveness of these nanoparticles in inhibiting the growth of the bacterial species was demonstrated. The optimisation of the bacterial inactivation experiment was performed using Design Expert's RSM CCD model on all three nanoparticle samples. The optimisation study investigated the impact of nanoparticle concentration and exposure duration on the inhibition of bacterial growth. The highest levels of percent inhibition (%I) were recorded as 85.4 % for TiO2/MgO, 82.8 % for TiO2, and 65.14 % for MgO at a concentration of 50 mg/2 ml and an exposure time of 2 h. The effectiveness of these nanoparticles in exhibiting inhibition has been limited, indicating their prospective use in the advancement of antimicrobial coatings and other applications, such as disinfectants, in the future.

Case Report: Delayed Diagnosis of Leprosy-Related Neuropathic Ulcer, Insights from a Case of Delay to Diagnose across Four Clinical Settings

Background Neuropathy is common in both Diabetes Mellitus (DM) and Leprosy, often resulting in neuropathic ulcers. Leprosy-related neuropathic ulcers are frequently misdiagnosed as DM-related, causing delays in appropriate care. This case report underscores the importance of timely recognition and a better understanding of Leprosy-related neuropathic ulcers to prevent misdiagnosis and improve patient outcomes. Methods The case report adopt the CARE Guidelines and was conducted at the Wound Care Specialist Clinic, Griya Afiat, Makassar, East Indonesia. Data were collected using a Minimum Data Sheet (MDS) to capture demographics, health history, and history of treatments. A head-to-toe assessment focused on the eyes, hands, and feet, with neuropathy, confirmed using the Semmes Weinstein Monofilament test, and angiopathy was assessed by palpating the dorsal pedis and posterior tibialis pulse. Wound care interventions consisted of cleansing, debridement, and dressing. Given the similarities between Leprosy-related neuropathic ulcers and DM-related neuropathic ulcers, the DMIST (depth, maceration, inflammation/infection, size, tissue type of the wound bed, type of wound edge, and tunnelling/undermining) tool was used to evaluate wound healing progress. Results Anamnesis indicated patient has no DM, with normal blood glucose; however, the patient had neuropathic wounds on her feet, asymmetrical eyebrow distribution, and rashes on her hands and calves, with neuropathy confirmed by a monofilament test—initial treatment involved Cadexomer Iodine powder to control bacterial growth and Honey-based gel to promote granulation. Over 62 days, 11 treatments were administered, with an average dressing change every 5.6 days, which improved the DMIST score from 12 to 4 by the end of observation day. Conclusions This case report highlights the significance of distinguishing leprosy-related neuropathic ulcers from those associated with DM to ensure accurate diagnosis and timely treatment. By employing comprehensive assessment tools and targeted wound care interventions, significant improvements in wound healing were achieved, emphasizing the need for greater awareness and clinical vigilance in managing Leprosy-related neuropathic ulcers.

Gut bacteria of lepidopteran herbivores facilitate digestion of plant toxins

Lepidopterans commonly feed on plant material, being the most significant insect herbivores in nature. Despite plant resistance to herbivory, such as producing toxic secondary metabolites, herbivores have developed mechanisms encoded in their genomes to tolerate or detoxify plant defensive compounds. Recent studies also highlight the role of gut microbiota in mediating detoxification in herbivores; however, convincing evidence supporting the significant contribution of gut symbionts is rare in Lepidoptera. Here, we show that the growth of various lepidopteran species was inhibited by a mulberry-derived secondary metabolite, 1-deoxynojirimycin (DNJ); as expected, the specialist silkworm Bombyx mori grew well, but interestingly, gut microbiota of early-instar silkworms was affected by the DNJ level, and several bacterial species responded positively to enriched DNJ. Among these, a bacterial strain isolated from the silkworm gut (Pseudomonas fulva ZJU1) can degrade and utilize DNJ as the sole energy source, and after inoculation into nonspecialists (e.g., beet armyworm Spodoptera exigua), P. fulva ZJU1 increased host resistance to DNJ and significantly promoted growth. We used genomic and transcriptomic analyses to identify genes potentially involved in DNJ degradation, and CRISPR-Cas9-mediated mutagenesis verified the function of ilvB, a key binding protein, in metabolizing DNJ. Furthermore, the ilvB deletion mutant, exhibiting normal bacterial growth, could no longer enhance nonspecialist performance, supporting a role in DNJ degradation in vivo. Therefore, our study demonstrated causality between the gut microbiome and detoxification of plant chemical defense in Lepidoptera, facilitating a mechanistic understanding of host-microbe relationships across this complex, abundant insect group.

Tripartite synergy: Photodegradation of congo red and bromothymol blue with concurrent bacterial photoinhibition using ZnCe/Bi2Mn2O6/rGO nanocomposites

The present research studies show the multidimensional characteristics of ZnCe/Bi2Mn2O6/rGO nanostructures for photocatalytic degradation of bromothymol blue (BTB), Congo red (CR) and photoinhibition of E. coli and S. aureus. A new solvothermal protocol was applied for the synthesis of ZnCe/Bi2Mn2O6/rGO nanomaterial. Important analytical techniques were applied for the characterization of the said nanomaterials. When allowed to visible light, the said nanostructure demonstrated excellent photocatalytic degradation of both the said dyes. The findings revealed that almost 99 % of both dyes were eliminated in just 30 min. In the absence of light, there was less than 60 % decline in both dyes even after 100 min. The ZnCe/Bi2Mn2O6/rGO was tested multiple times against the said dyes, and after seven cycles, its efficiency was reduced by only 15 %. Moreover, the nanostructures exhibited promising antibacterial properties by inducing photoinhibition of both E. coli and S. aureus bacteria. The inhibition zones of ZnCe/Bi2Mn2O6/rGO under visible light irradiation were measured to be approximately 17 ± 0.2 mm against E. coli and 19 ± 0.3 mm against S. aureus. These nanostructures effectively impeded bacterial growth and viability, underscoring their potential for applications in water disinfection and as antibacterial coatings. They are promising options for a variety of applications, especially as catalysts in many industries, due to their non-toxic nature and thermal stability. This work presents fascinating avenues for further investigation into the application of nanocomposites in healthcare and environmental preservation.

Inhibition of Citronella Essential Oil (Cymbopogon Nardus) Bengkulu on Bacterial Growth after Endodontic Treatment

Background: Root canal treatment aims to address pulpal infection and prevent reinfection, which is often caused by bacteria such as Enterococcus faecalis and Staphylococcus aureus. Citronella essential oil (Cymbopogon nardus) from Bengkulu, containing antibacterial compounds, has potential to inhibit the growth of these bacteria. Objective: This study evaluated the effectiveness of citronella essential oil against E. faecalis and S. aureus. Materials and Methods: The method used was the disc diffusion technique with 20 samples each of E. faecalis and S. aureus in BHI media. Citronella essential oil was tested at concentrations of 50%, 75%, and 100%, with 2% CHX as the positive control. The inhibition zones were measured after 24 hours. Results: The highest inhibition for E. faecalis was found at 100% concentration (2.56 mm), while for S. aureus, it was at 50% concentration (1.67 mm). Significant differences (p<0.05) were observed at all concentrations of citronella essential oil for both bacteria. Conclusion: Citronella essential oil from Bengkulu exhibited weak antibacterial activity against E. faecalis and S. aureus. Its potential as an alternative for root canal treatment requires further development.

Rapid growth rate of Enterobacter sp. SM3 determined using several methods

BackgroundBacterial growth rate, commonly reported in terms of doubling time, is frequently determined by one of two techniques: either by measuring optical absorption of a growing culture or by taking samples at different times during their growth phase, diluting them, spreading them on agar plates, incubating them, and counting the colonies that form. Both techniques require measurements of multiple repeats, as well careful assessment of reproducibility and consistency. Existing literature using either technique gives a wide range of growth rate values for even the most extensively studied species of bacteria, such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This work aims to apply several methods to reliably determine the growth rate of a recently identified species of Enterobacteriaceae, called Enterobacter sp. SM3, and to compare that rate with that of a well-known wildtype E. coli strain KP437.ResultsWe extend conventional optical density (OD) measurements to determine the growth rate of Enterobacter sp. SM3. To assess the reliability of this technique, we compare growth rates obtained by fitting the OD data to exponential growth, applying a relative density method, and measuring shifts in OD curves following set factors of dilution. The main source of error in applying the OD technique is due to the reliance on an exponential growth phase with a short span. With proper choice of parameter range, however, we show that these three methods yield consistent results. We also measured the SM3 division rate by counting colony-forming units (CFU) versus time, yielding results consistent with the OD measurements. In lysogeny broth at 37oC, SM3 divides every 21 ± 3 min, notably faster than the RP437 strain of E. coli, which divides every 29 ± 2 min.ConclusionThe main conclusion of this report is that conventional optical density (OD) measurements and the colony-forming units (CFU) method can yield consistent values of bacterial growth rate. However, to ensure the reproducibility and reliability of the measured growth rate of each bacterial strain, different methods ought to be applied in close comparison. The effort of checking for consistency among multiple techniques, as we have done in this study, is necessary to avoid reporting variable values of doubling time for particular species or strains of bacteria, as seen in the literature.

Applications of bioactive glass: A review

The scope of research on dental materials has significantly increased throughout the last century. Bioactive glass has become an attractive option in biomaterials because of its unique qualities that promote advantageous biological responses. Compared to traditional dental glasses, bioactive glasses are innovative dental materials. As bioactive glass can form bonds with live tissues, mainly composed of calcium, phosphorus, and silicon, it is an excellent choice for many biomedical uses. At the vanguard of biomaterials, bioactive glass provides a unique blend of bioactivity, flexibility, and versatility. The bioactivity of bioactive glass is one of its primary characteristics. Bioactive glass generates a hydroxyapatite coating on its surface when it comes into contact with physiological fluids. The potential for introducing growth factors and bioactive substances to enhance the material's capacity to communicate with biological tissues has been studied. Various uses of bioactive glass have been discovered, including wound healing, bone grafts, dentin hypersensitivity, regeneration, implant devices, etc. Cement was used for dental applications, and the attachment of joint prostheses to bone was also made using bioactive glass. Bioactive glasses are present in the composition of several dental and oral hygiene products. Because of their many benefits—such as their capacity to maintain biological tissues' structural integrity, their usefulness as scaffolds, and their capacity to inhibit bacterial growth—bioactive glasses are becoming increasingly valuable in several dental specialties.

Differential requirement of formyl peptide receptor 1 in macrophages and neutrophils in the host defense against Mycobacterium tuberculosis Infection

Formyl peptide receptors (FPR), part of the G-protein coupled receptor superfamily, are pivotal in directing phagocyte migration towards chemotactic signals from bacteria and host tissues. Although their roles in acute bacterial infections are well-documented, their involvement in immunity against tuberculosis (TB) remains unexplored. Here, we investigate the functions of Fpr1 and Fpr2 in defense against Mycobacterium tuberculosis (Mtb), the causative agent of TB. Elevated levels of Fpr1 and Fpr2 were found in the lungs of mice, rabbits and peripheral blood of humans infected with Mtb, suggesting a crucial role in the immune response. The effects of Fpr1 and Fpr2 deletion on bacterial load, lung damage, and cellular inflammation were assessed in a murine TB model utilizing hypervirulent strain of Mtb from the W-Beijing lineage. While Fpr2 deletion had no impact on disease outcome, Fpr1-deficient mice demonstrated improved bacterial control, especially by macrophages. Bone marrow-derived macrophages from these Fpr1−/− mice exhibited an enhanced ability to contain bacterial growth over time. Contrarily, treating genetically susceptible mice with Fpr1-specific inhibitors caused impaired early bacterial control, corresponding with increased Mtb persistence in necrotic neutrophils. Furthermore, ex vivo assays revealed that Fpr1−/− neutrophils were unable to restrain Mtb growth, indicating a differential function of Fpr1 among myeloid cells. These findings highlight the distinct and complex roles of Fpr1 in myeloid cell-mediated immunity against Mtb infection, underscoring the need for further research into these mechanisms for a better understanding of TB immunity.

Use of Cyrene™, as an alternative to dimethyl sulfoxide, as a diluent for Melatonin to determine its in vitro antimicrobial capacity

Melatonin (MLT) is a methoxyindole that has potent antioxidant actions, anti-inflammatory, and antiapoptotic capacity. However, its in vitro antibacterial capacity has been the least studied of its properties. Dimethylsulfoxide (DMSO) has been the most used solvent for these tests, but it shows an antimicrobial effect if it is not dissolved. Cyrene™ is a new solvent that has emerged as an alternative to DMSO. Therefore, this study aimed to determine the antimicrobial capacity of MLT by MIC assays, using Cyrene™ as a solvent. Likewise, the solubility of MLT in this solvent and whether it exerted any effect on bacterial growth at different percentages was also determined. Different dilutions of MLT in Cyrene™ with different concentrations, were prepared. No growth inhibition caused by MLT was observed. The growth inhibition observed was because of Cyrene™. The maximum amount of MLT that can be diluted in 100% Cyrene is 10 mg/mL, but this percentage of solvent shows a bactericidal effect. Therefore, it must be dissolved at 5% to avoid this effect, so only 4 mg/mL of MLT can be diluted in it. Therefore, if no other solvents are available, the in vitro antibacterial role of MLT cannot be adequately assessed.