Microplate Dilution Research Articles

Enhanced antimicrobial, anti-biofilm, and efflux pump inhibitory effects of ursolic acid-conjugated magnetic nanoparticles against clinical isolates of multidrug-resistant Pseudomonas aeruginosa.

In the present study, we investigate the effect of Fe3O4 nanoparticles conjugated with ursolic acid (Fe3O4NPs@UA) on inhibiting the growth, biofilm-forming ability and efflux pump activity in clinical isolates of Pseudomonas aeruginosa with multiple drug resistance. Iron oxide NPs conjugated with ursolic acid (Fe3O4NPs@UA) were synthesized. Physicochemical features of the NPs were studied by FT-IR, XRD, EDAX, and TEM. The antibacterial and antibiofilm effects of Fe3O4NPs@UA against P. aeruginosa isolates were determined by broth microdilution and microtiter plate methods, respectively. The efflux pump inhibitory effect of Fe3O4NPs@UA was determined using Cartwheel method and through determining the expression level of efflux pump genes, including mexA and oprD in selected P. aeruginosa isolates treated with sub-MIC concentration of Fe3O4NPs@UA by real-time PCR. In investigating the antimicrobial effect of Fe3O4NPs@UA, the MIC of these nanoparticles varied between 0.19 and 0.78mg/mL and in the study of the anti-biofilm effect of Fe3O4NPs@UA, it caused a 68-75% decrease in biofilm formation compared to the control. Moreover, in the Cartwheel test, the anti-efflux effect of these nanoparticles was confirmed at 1/4-MIC concentrations, and the expression of mexA and oprD genes was reduced in bacteria treated with Fe3O4NPs@UA compared to the control. According to the results, the use of Fe3O4NPs@UA can provide a basis for the development of new treatments against drug-resistant bacteria in P. aeruginosa. This substance can improve the concentration of antibiotics in bacterial cells and increase their effectiveness by inhibiting the efflux in P. aeruginosa isolates.

Molecular docking and antibacterial and antibiotic-modifying activities of synthetic chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one in a MepA efflux pump-expressing Staphylococcus aureus strain.

Bacterial resistance has become a global concern for public health agencies. Various resistance mechanisms found in Staphylococcus aureus strains grant this bacterium resistance to a wide range of antibiotics, contributing to the rise in human mortality worldwide. Resistance mediated by efflux pumps is one of the most prevalent mechanisms in multi-resistant bacteria, which has aroused the interest of several researchers in the search for possible efflux pump inhibitors. In view of the aforementioned considerations, it is important that new strategies, such as the synthesis of chalcones, be made available as a viable strategy in antimicrobial therapy. In this study, the synthesized chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one was tested for its antibacterial activity, focusing on antibiotic modification and the inhibition of the MepA efflux pump present in S. aureus strain K2068. The broth microdilution method, using microdilution plates, was employed in microbiological tests to determine the minimum inhibitory concentration of the chalcone, antibiotics, and ethidium bromide. The results show that while the chalcone did not exhibit direct antibacterial activity, it synergistically enhanced the effects of ciprofloxacin and ethidium bromide, as evidenced by the reduction in MICs. In addition, computer simulations of molecular docking demonstrate that the tested chalcone acts on the same binding site as the efflux pump inhibitor chlorpromazine, interacting with essentially the same residues. These data suggest that the chalcone may act as a MepA inhibitor.

The Push-Out Bond Strength, Surface Roughness, and Antimicrobial Properties of Endodontic Bioceramic Sealers Supplemented with Silver Nanoparticles.

This study evaluated push-out bond test (POBT), surface roughness, and antimicrobial properties against Enterococcus faecalis of bioceramic sealers supplemented with silver nanoparticles (AgNPs). The sealers tested were CeraSeal®, EndoSequence® BC SealerTM, and Bio-C® Sealer. The POBT was measured with a Universal Testing Machine, and the type of failure was evaluated with a stereomicroscope. The roughness average (Sa) and peak-valley height (Sy) values were evaluated by atomic force microscopy. The bacterial growth inhibition was evaluated using a disk diffusion test, and antimicrobial activity was determined with the plate microdilution method. The POBT showed no significant difference between sealers with and those without NPs in cervical and apical thirds (p > 0.05). In the middle third, the adhesion force was significant for Endosequence BC Sealer® (p < 0.05). The results showed that the Sa and Sy parameters, when AgNPs were added, did not show a statistically significant difference compared to the groups without nanoparticles (p > 0.05). All tested sealers showed bacterial growth inhibition, but no significant difference was found. Their efficacy, in descending order of antibacterial activity when AgNPs were added, is as follows: EndoSequence® BC SealerTM > Bio-C® Sealer > CeraSeal®. The incorporation of AgNPs into bioceramics improves antimicrobial activity without affecting mechanical properties.

Exploring the antibacterial efficacy of Satureja hortensis and Bacillus subtilis extracts in combating Xanthomonas citri

Biofilm plays a critical role in protecting the associated bacterial colonies. Citrus canker caused by Xanthomonas citri, resulted in remarkable yield reduction in citrus orchards. This study aims to evaluate the anti-biofilm properties of S. hortensis and B. subtilis extracts against X. citri. The antibacterial effects of both extracts were evaluated using the disk diffusion method and 96-well microdilution plates. Crystal violet and XTT procedures were employed to assess the inhibition of adhesion and antibiofilm effects of both extracts. The checkboard titration method was applied to determine the synergistic effects of the plant-bacterial extracts. The antibiofilm effects were confirmed by the light microscopy method. The results showed that the antibacterial and antibiofilm properties of both extracts varied. The MIC values of S. hortensis and B. subtilis extracts were 6.25 and 50 mg/ml, respectively. In these concentrations the inhibition of adhesion effects of S. hortensis and B. subtilis were 70% and 80%, whereas their antibiofilm effects were 60% and 72%. S. hortensis and B. subtilis extracts showed 63% and 76% antibiofilm activity, respectively, using the XTT test. The extracts showed synergistic effects, resulting in higher inhibition rates in combinatorial applications. Molecular docking results also confirmed that the secondary metabolites of S. hortensis could interact with different X. citri proteins differentially. Further large-scale studies on combinatorial antibiofilm effects of plant and bacterial extracts against citrus pathogens will provide new opportunities to develop safe and applicable reagents to control these destructive diseases.

Novel Penicillin Derivatives Against Selected Multiple-drug Resistant Bacterial Strains: Design, Synthesis, Structural Analysis, In Silico and In Vitro Studies.

The rising numbers of multiple drug-resistant (MDR) pathogens and the consequent antibacterial therapy failure that resulted in severe medical conditions push to illustrate new molecules with extended activity against the resistant strains. In this manner, chemical derivatization of known antibiotics is proposed to save efforts in drug discovery, and penicillins serve as an ideal in this regard. Seven synthesized 6-aminopenicillanic acid-imine derivatives (2a-g) were structure elucidated using FT-IR, 1H NMR, 13C NMR, and MS spectroscopy. In silico molecular docking and ADMET studies were made. The analyzed compounds obeyed Lipinski's rule of five and showed promising in vitro bactericidal potential when assayed against E. coli, E. cloacae, P. aeruginosa, S. aureus, and A. baumannii. MDR strains using disc diffusion and microplate dilution techniques. The MIC values were 8 to 32 μg/mL with more potency than ampicillin, explained by better membrane penetration and more ligand-protein binding capacity. The 2g entity was active against E. coli. This study was designed to find new active penicillin derivatives against MDR pathogens. The products showed antibacterial activity against selected MDR species and good PHK, PHD properties, and low predicted toxicity, offering them as future candidates that require further preclinical assays.

Antibacterial and antioxidant activities of Chlorella vulgaris and Scenedesmus incrassatulus using natural deep eutectic solvent under microwave assisted by ultrasound

Microalgae are increasingly recognized as promising sources of natural bioactive compounds. However, traditional extraction methods using volatile organic solvents (VOCs) pose environmental risks. This study explores renewable deep eutectic solvents (DES) as sustainable alternatives for extracting bioactive compounds from microalgae biomass, focusing on Chlorella vulgaris and Scenedesmus incrassatulus. Four DES systems, comprising choline chloride (ChCl) and glycerol, citric acid, urea, and glucose, were compared with three conventional solvents (ethanol, methanol, and water). Extraction efficiency was assessed based on total phenolic content (TPC), flavonoid content, and tannin content, followed by antioxidant activity evaluation using DPPH, CAT, and FRAP assays. Additionally, antibacterial activity of the DES extracts was determined against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213), and Bacillus subtilis (ATCC 3366) using disc diffusion and microplate dilution methods to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results reveal that DES, particularly choline chloride: citric acid, outperform conventional solvents in terms of polyphenol extraction efficiency, antioxidant activity, and antibacterial activity against both Gram-negative and Gram-positive bacteria. For instance, the citric acid-based DES (SIDES2) showed a TPC of 4.98 mg/g, while the conventional solvent ethanol exhibited a TPC of 3.27 mg/g. Additionally, SIDES2 exhibiting the highest DPPH scavenging activity of 75 %, compared to 60 % for ethanol. Furthermore, SIDES2 showed an MIC of 0.5 mg/ml against Staphylococcus aureus. This study underscores the potential of DES for sustainable extraction of natural antioxidants from microalgae biomass, contributing to the development of environmentally friendly extraction processes in various industries.

Studies, characterizations and evaluation of the antibacterial activity of Silver Titanate Nanotubes

Titanium nanostructures have been widely studied due to their potential for various applications. One of its most promising applications is in the antibacterial activity, in particular, of Silver Titanate Nanoubes (Ag-TiNT). The determining factors for the high efficiency process against bacteria are related to the surface area of the material and the main metal that composes it. Microbial infections continue to be one of the most serious complications in different areas, particularly in the hospital environment. This work was investigated as bactericidal properties of Silver Titanate nanotubes against Gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa and Gram-positive bacteria of Staphylococcus aureus, in systems containing only the Ag-TiNT for the antibiotic compounds. In addition, the study of the main, vibrational and morphological characteristics of Ag-TiNT was carried out. As a result, as microdilution plates accompanying only the positive anti-bacterial dish, while in the microdilution plates containing Ag-TiNT with antibiotics, divergent results. Abstract: Ag-TiNT morphology structures, electron microscopy (SEM, TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and dispersion spectroscopy were detected of X-ray energy (EDS).

Evaluation of commercial, customized microdilution plates for Ureaplasma parvum, Ureaplasma urealyticum, and Mycoplasma hominis antimicrobial susceptibility testing and determination of antimicrobial resistance prevalence in France.

Antimicrobial susceptibility testing of human urogenital mycoplasmas using the CLSI reference broth microdilution method is time-consuming and requires the laborious preparation of antimicrobial stock solutions. Here, we validated the use of reliable, convenient plates designed for antimicrobial susceptibility testing that allows the simultaneous determination of the MICs of eight antibiotics of interest. We then investigated the prevalence and mechanisms of resistance of each of these bacteria to tetracyclines, fluoroquinolones, and macrolides in France in 2020 and 2021. We showed that the prevalence of levofloxacin and moxifloxacin resistance has increased significantly in Ureaplasma spp. from 2010 to 2015 and requires ongoing monitoring.

Niosome gels encapsulate green mangosteen peel extract (Garcinia mangostana L.) as an anti-acne-inducing bacterial and anti-inflammatory activity

This research aims to develop a niosome gel from green mangosteen peel extract (Garcinia mangostana L.) by maceration with an ethanol solvent. The result of the yield percentage was 14.35 ± 0.90. The result of analyzing the phytochemicals by high-performance liquid chromatography (HPLC) was that tannin and xanthone were equal to 0.7483 ± 0.0825 mg per 100 mg of extract and 0.02964 ± 0.0088 mg per 100 mg of extract, respectively. The results of the determination of the effect include anti-inflammatory and anti-bacterial (Cutibacterium acnes) as anti-inflammatory with nitric oxide from LPS-induced macrophage cells up to a maximum equal to 29.10 ± 4.78% as a concentration at 1 mg mL–1 as acetonide can inhibit nitric oxide equal to 33.12 ± 3.62% as a concentration at 1 mg mL–1. and anti-bacterial (Cutibacterium acnes) by broth microdilution and drop plate methods, it was found that clindamycin has a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 0.08 μg mL–1 and 0.31 μg mL–1, respectively. The development of niosomes consisting of cholesterol, tween 60, and mangosteen peel extract at 1% w w–1 and 2% w w–1 in every formula showed good stability. The reduction of particle size in the formula by an ultrasonic bath at 30 minutes and measurement of particle size with a transmission electron microscope (TEM) were found to be equal to 1,265 and 123 – 219 nm, respectively. The polydispersity index (PDI) was in the range of 0.1 – 0.2, and the zeta potential value was in the range of –26.15 to –28.61 mV. The result of hydration and trans epidermal water loss (TEWL) was found to be that after 4 weeks of use, the formula containing the niosomes of mangosteen peel extract concentrated at 2% w w–1 maximizes skin moisture. It has a value of 346 ± 39.27 and has the least surface water loss. GRAPHICAL ABSTRACT HIGHLIGHTS The green mangosteen peel extract (Garcinia mangostana L.) can inhibiting nitric oxide production from LPS-induced macrophage cells up to 29.10 ± 4.78% at a concentration of 1 mg ml-1, the lowest inhibitory (MIC) and kill (MBC) concentration of C. acnes bacteria less than 0.24 mg ml-1. The particle size of niosomes encapsulate extracts before reducing particle size equal to 1,265 nm. and after reducing particle size in the range of 123 - 219 nm. The skin hydration value after using product for 4 weeks as niosome gel encapsulate extract 2%w w-1 of extract was maximum moisture and minimal water loss.

Marine Microalgae Schizochytrium sp. S31: Potential Source for New Antimicrobial and Antibiofilm Agent.

The rise of antibiotic-resistant bacteria necessitates the discovery of new, safe, and bioactive antimicrobial compounds. The antibacterial and antibiofilm activity of microalgae makes them a potential candidate for developing natural antibiotics to limit microbial infection in various fields. This study aimed to analyze the antibacterial effect of the methanolic extract of Schizochytrium sp. S31 microalgae by broth microdilution and spot plate assays. The antibacterial effects of Schizochytrium sp. S31 extract was studied on gramnegative pathogens, Pseudomonas aeruginosa, Escherichia coli 35218, Klebsiella pneumonia, which cause many different human infections, and the gram-positive pathogen Streptococcus mutans. At the same time, the antibiofilm activity of the Schizochytrium sp. S31 extract on Pseudomonas aeruginosa and Escherichia coli 35218 bacteria were investigated by crystal violet staining method. Schizochytrium sp. S31 extract at a 60% concentration for 8 hours displayed the highest antibacterial activity against P. aeruginosa, E. coli 35218, and K. pneumonia, with a decrease of 87%, 92%, and 98% in cell viability, respectively. The experiment with Streptococcus mutans revealed a remarkable antibacterial effect at a 60% extract concentration for 24 hours, leading to a notable 93% reduction in cell viability. Furthermore, the extract exhibited a dose-dependent inhibition of biofilm formation in P. aeruginosa and E. coli 35218. The concentration of 60% extract was identified as the most effective dosage in terms of inhibition. This research emphasizes the potential of Schizochytrium sp. S31 as a natural antibacterial and antibiofilm agent with promising applications in the pharmaceutical sectors. This is the first study to examine the antibacterial activity of Schizochytrium sp. S31 microalgae using broth microdilution, spot plate assays, and the antibiofilm activity by a crystal staining method. The findings of this study show that Schizochytrium sp. S31 has antibacterial and antibiofilm activities against critical bacterial pathogens.

Phytochemistry and antimicrobial activity of Moroccan Origanum compactum and Ruta montana essential oils against nosocomial bacteria

Introduction: Healthcare-associated infections are a global public health issue with farreaching individual and economic repercussions. The microorganism’s multi-resistance frequently increases the risk that can be lowered by using biomolecules of medicinal plant essential oils (EOs). This study investigated the phytochemical components and antimicrobial potential of the EOs of Moroccan Origanum compactum and Ruta montana gathered from Taza Region. Methods: The EOs’ chemical analysis was performed by GC/MS and their antimicrobial effects were assessed by the microplate dilution method against eight nosocomial resistantbacterial strains. Results: The main constituents of O. compactum EO were Thymol (29.56%), carvacrol (26.44%), γ-terpinene (18.86%) and p-cymene (12.01%), while those of R. montana EO were 2-undecanone (85.76%), 2-nonanone (3.95%), 2-decanone (3.67%) and 2-dodecanone (1.94%). The O. compactum EO had important antimicrobial effects on all bacteria experienced. The lower minimum inhibitory concentration (MIC) values were obtained for the tested Staphylococcus species (0.062%, 0.125% (v/v)) while the highest one (2% (v/v)) was obtained for Klebsiella pneumonia and Pantoea spp. The R. montana EO showed MIC values of 4% (v/v) for Pantoea spp. and 8% (v/v) for the other tested strains except K. pneumonia for which no effect was shown. Conclusion: Therefore, these EOs, especially the O. compactum one, have an interesting antibacterial potential against nosocomial infections and might be used to develop new antimicrobial agents.

In Vitro Antimycotic Activity and Structural Damage against Canine Malassezia pachydermatis Strains Caused by Mexican Stingless Bee Propolis.

This work describes the antimycotic activity of propolis from the stingless bees Scaptotrigona mexicana and Tetragonisca angustula, collected from two Mexican regions (Veracruz and Chiapas, respectively), against three clinical isolates and the reference strain ATCC 14522 of Malassezia pachydermatis, the causative agent of canine otitis. The chemical components of the ethanolic extracts of propolis were determined by gas chromatography coupled with mass spectrometry (GC-MS), and sesquiterpenes were the predominant compounds. The antimycotic activity was evaluated by plate microdilution. The induced changes in the yeasts were evaluated by fluorescence microscopy and staining with calcofluor white and propidium iodide. The minimum inhibitory concentration (MIC) was 7.11 mg/mL, and the minimum fungicidal concentration was 21.33 mg/mL for both extracts. The EPPs of Scaptotrigona mexicana and Tetragonisca angustula caused substantial damage to yeast morphology, where the propidium iodide staining of the yeasts treated with both EEPs revealed the penetration of this marker, which indicates the destruction of the cell wall and plasma membrane of the fungi. This result suggests that these types of propolis could be used as alternative treatments for canine external otitis. To the best of our knowledge, this seems to be the first scientific report that has demonstrated structural damage in Malassezia pachydermatis by Mexican stingless bee propolis.

In vitro evaluation of the susceptibility of bacterial biofilms to hecogenin acetate

Biofilms are a bacterial resistance strategy through which microorganisms organize themselves in the form of a colony fixed to a surface that is protected by a polymer matrix. Infectious diseases that result in biofilm formation have been considered a relevant public health problem due to the potential to increase patient morbidity and mortality, in addition to increasing the burden on health services. Such pathologies are treated with the use of antimicrobial drugs, the indiscriminate use of which has contributed to the process of bacterial resistance, demanding the need to invest in new alternatives to combat them. Based on this, the present work aimed to evaluate the anti-biofilm formation and eradication capacity of Hecogenin Acetate, a steroidal sapogenin of natural origin with important antibacterial properties. For this, we used strains of Streptococcus mutans INCQS 00,446 (ATCC 25,175), Enterococcus faecalis INCQS 00,018 (ATCC 14,506), Staphylococcus epidermidis INCQS 00,016 (ATCC 12,228), Staphylococcus aureus ATCC 25,923, Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 259,223. The formation, formation inhibition and treatment assays were carried out in microdilution plates and revealed using the crystal violet method. Readings were carried out using absorbance at wavelengths of 492 nm. All tests were performed in triplicate and statistical analyzes were performed using Graphpad Prism v.5.0 software. It was observed that the bacterial strains used have a relevant capacity for biofilm formation, with the Gram positive ones identified in the present study as the best former. In the results of the analyzes with bacterial biofilm, it was identified that Hecogenin Acetate had a relevant antibiofilm capacity, and could therefore serve as a basis for further research into the development of new antimicrobial drugs.

Phytochemistry Profile, Antimicrobial and Antitumor Potential of the Methanolic Extract of Tabernaemontana catharinensis A DC and Eragrostis plana NEES.

Natural compounds that have the potential to act as antimicrobials and antitumors are a constant search in the field of pharmacotherapy. Eragrostis plana NEES (Poaceae) is a grass with high allelopathic potential. Allelopathy is associated with compounds generated in the primary and secondary metabolism of the plant, which act to protect it from phytopathogens. Tabernaemontana catharinensis A DC (Apocynaceae), a tree in which its leaves and bark are used for the preparation of extracts and infusions that have anti-inflammatory and antinociceptive effects, is attributed to its phytochemical constitution. The objective of this study was to elucidate the phytochemical constitution, the antibacterial potential, the toxicity against immune system cells, hemolytic potential, and antitumor effect of methanolic extracts of E. plana and T. catharinensis. The phytochemical investigation was carried out using the UHPLC-QTOF MS equipment. The antibacterial activity was tested using the broth microdilution plate assay, against Gram-negative and Gram-positive strains, and cytotoxicity assays were performed on human peripheral blood mononuclear cells (PBMC) and in vitro hemolysis. Antitumor activity was performed against the colon cancer cell line (CT26). Results were expressed as mean and standard deviation and analyzed by ANOVA. p < 0.05 was considered significant. More than 19 possible phytochemical constituents were identified for each plant, with emphasis on phenolic compounds (acids: vanillic, caffeic, and quinic) and alkaloids (alstovenine, rhyncophylline, amezepine, voacangine, and coronaridine). Both extracts showed antibacterial activity at concentrations below 500 µg/mL and were able to decrease the viability of CT26 at concentrations below 2000 µg/mL, without showing cytotoxic effect on PBMCs and in vitro hemolysis at the highest concentration tested. This is the first report of the activity of E. plana and T. catharinensis extracts against colon cancer cell line (CT26). Studies should be carried out to verify possible molecular targets involved in the antitumor effect in vivo.

Antibacterial activity of Siddha formulation of Vellampattai koppali kizhalam (mouthwash) against Klebsiella pneumoniae and Streptococcus pyogenes for oral hygiene

Abstract Background: Poor oral health characterized by inadequate hygiene may result in the formation of extensive dental biofilms (plaque) promoting oral colonization of pathogens. Siddha medicine plays a major role in the oral health care. Traditional claims have to be validated through scientific research for wider acceptance. The Siddha literature Anuboga Vaithiya Bhrama Ragaseyam mentioned Vellampattai Koppali Kizhalam (VKK) for oral hygiene and prevention of periodontal disease. Objective: The study aims to evaluate the anti-bacterial activity of VKK to prevent oral infection. Materials and Methods: VKK is an efficient Siddha formulation used to prevent oral infection. One of the important ingredients is Veppam pattai (Azidarchia indica) which is found to have an antibacterial effect. In the present study, the antibacterial susceptibility test for VKK was done using the microdilution plate method using resazurin. Results: The current study observed that VKK exhibited significant antibacterial activity against Streptococcus pyogenes (MIC 1000 µg) and Klebsiella pneumoniae. The color change was observed and recorded as the minimum inhibitory concentration (MIC) value using the standard drug chloramphenicol (10 µg). Conclusion: The study revealed that the Siddha formulation have strong anti-bacterial activity and offers profound therapeutic effects against periodontal disease and improve oral hygiene.

Proficiency testing for drug susceptibility testing of Mycobacterium tuberculosis complex using commercial broth microdilution plate in China in 2021

The characteristic and performance of Broth microdilution (BMD) plates for drug susceptibility of Mycobacterium tuberculosis have not been systematically evaluated in China. This study was designed to review the key information and assess the performance of BMD plates by analysis of proficiency testing results. We retrospectively analysed the proficiency testing results of phenotypic drug susceptibility testing (PT-DST) of 45 laboratories using BMD plates in China in 2021. Critical information, such as drug layout, concentration range of each drug, plate storage conditions and duration, operating procedures, and interpretation criteria for binary results were compared. The performance was also analysed. Eight types of BMD plates produced by four manufactures were reported. The drug layout, number of drugs on plates, and concentration range varied a lot between different plates. The total sensitivity and specificity of BMD plates for drug susceptibility of Mycobacterium tuberculosis to ten drugs (isoniazid (INH), rifampin (RIF), kanamycin (KAM), amikacin (AM), levofloxacin (LFX), moxifloxacin (MFX), bedaquiline (BDQ), linezolid (LZD), clofazimine (CFZ), and delamanid (DLM)) were 93.9% (95% CI 92.-94.9) and 99.1% (95% CI 98.8-99.3), respectively. The lowest sensitivity was 84.8% (95% CI 80.3-88.4) for LFX and 86.4% (95% CI 82.5-89.6) for MFX, or 87.5% (95% CI 84.2-90.2) for Y1 plate and 87.9% (95% CI 83.5-91.1) for T plate. The lowest specificity was 94.4% (95% CI 91.4-96.4) for DLM, or 97.9% (95% CI 96.8-98.7) for B3 plate. Commercial BMD plates in China showed varied drug layouts and operational procedures, indicating the urgency of standardization. The lower performance for some drugs showed the low quality of the plates utilized or lack of proficiency of lab staffs in operating and interpreting results.

Chemical profiling and inhibitory effects of selected South African plants against phytopathogenic bacteria and fungi of tomato

Soilborne pathogens are economically important, causing great losses in agricultural production globally. The high cost and toxicity of antibiotics, coupled with the development of drug-resistant bacteria, has awakened interest in finding alternative methods of plant-pathogen control. This study aimed to screen extracts of selected plants against phytopathogenic bacteria and fungi that infect tomatoes, and to profile their chemical constituents. The antimicrobial activity of acetone, water and dichloromethane: methanol (DCM/MeOH = 1:1) extracts from leaves of ten plants was examined against five phytopathogenic bacterial strains and one fungal strain using a serial microplate dilution method to determine the minimal inhibitory concentration (MIC) values. Gas chromatography-mass spectrometry (GC–MS) was used for profiling constituents in the acetone and DCM/MeOH extracts. The MIC values indicated weak antibacterial activity of all the water extracts against tested bacterial strains. Acetone and DCM/MeOH extracts of Leucosidea sericea and Searsia lancea had very good to outstanding antibacterial activity against most of the tested bacteria with MIC values ranging between 19.5 and 78 µg/mL. All extracts were not active against Fusarium spp. except for the acetone extract of Cotyledon orbiculata and the water extract of Leonotis leonurus which inhibited the growth of F. oxysporum with MIC = 39 and 97.5 µg/mL after 24 h, with further incubation resulting in MICs of 156 and 469 µg/mL respectively. The GC–MS analysis of the acetone and DCM/MeOH extracts indicated the major peaks of 9-octadecenamide, (Z)-, octadecanoic acid and dodecanamide which were present in almost all the extracts. The 9-octadecenamide was found to be the most highly concentrated compound in most extracts. Leucosidea sericea and S. lancea, therefore, contain bioactive compounds that may be used as broad-spectrum antimicrobials against phytopathogenic bacteria and fungi.

Loading of green-synthesized cu nanoparticles on Ag complex containing 1,3,5-triazine Schiff base with enhanced antimicrobial activities

The physicochemical properties of materials change significantly in nanometer dimensions. Therefore, several methods have been proposed for the synthesis of nanoparticles. Plant extracts and essential oils are applied as natural and economic resources to prepare nanomaterials especially metal nanoparticles. In this project, a green, simple and efficient method has been designed for the synthesis of Cu nanoparticles using Purple cabbage extract as a reducing and stabilizing agent. They were successfully loaded onto a new Ag complex containing 1,3,5-triazine Schiff base as ligand to form Cu@Ag-CPX nanocomposite. Phytochemical contents of extract were identified by standard qualitative analyses. The chemical structure of all synthesized compounds was characterized using spectral data. In FT-IR, coordination of C=N bond of Schiff base ligand to Ag+ ions shifted the absorption band from 1641 to 1632 cm−1. The UV–Vis spectrum of Cu@Ag-CPX nanocomposite shown the peak related to Cu nanoparticles in the region of around 251 nm. 5:7 molar ratio of Cu to Ag in Cu@Ag-CPX was determined using ICP-OES. The FESEM, TEM, and DLS techniques provided valuable insights into the morphology and size distribution of the nanocomposite, revealing the presence of rods and monodispersed particles with specific diameter ranges. These analyses of the nanocomposite displayed rods with diameters from 40 to 62 nm as well as monodispersed and uniform particles with average diameter of 45 nm, respectively. The presence of elements including carbon, nitrogen, oxygen, Cu and Ag was proved by EDX-EDS analysis. The XRD pattern of Cu@Ag-CPX shown the diffraction peaks of Cu and Ag particles at 2θ values of 10°–80°, and confirmed its crystalline nature. The inhibitory properties of the synthesized compounds were evaluated in vitro against four Gram-negative and two Gram-positive bacteria, as well as two fungal strains. The MIC, MBC and MFC values obtained from microdilution and streak plate sensitivity tests were ranged from 128 to 4096 µg ml−1. While Cu nanoparticles and Ag complexes were effective against some pathogens, they were not effective against all them. However, the growth of all tested microbial strains was inhibited by Cu@Ag-CPX nanocomposite, and makes it as a new promising antimicrobial agent. Modification of nanocomposite in terms of nanoparticle and complex can improve its blocking activities.

Performance of the MeltPro TB assay as initial test for diagnosis of pulmonary tuberculosis with drug-resistance detection

BackgroundThe MeltPro TB assay (MeltPro) is a molecular rapid diagnostic test designed for detecting resistance to antituberculosis drugs. However, the performance of MeltPro as an initial diagnostic test for simultaneously detecting the presence of Mycobacterium tuberculosis (MTB) and drug resistance has not been evaluated. This study aims to assess the performance of MeltPro as initial diagnostic test for simultaneous detection of MTB and drug resistance in clinical samples from patients with presumptive pulmonary tuberculosis (PTB).MethodsA retrospective analysis was conducted on 1283 patients with presumptive PTB from two clinical centers, out of which 875 were diagnosed with PTB. The diagnostic accuracy of MeltPro, Xpert MTB/RIF (Xpert), and MGIT 960 for PTB detection was evaluated. Rifampicin (RIF), isoniazid (INH), ethambutol (EMB), streptomycin (STR), and fluoroquinolone (FQ) resistance were detected using MeltPro, with Xpert and/or the broth microdilution plate method (MYCOTB) results as references.ResultsFor the diagnosis of PTB, MeltPro showed a sensitivity of 69.0%, which was similar to Xpert (72.7%; P > 0.05) and higher than MGIT (58.1%; P < 0.001). The specificity of MeltPro was 97.1%, similar to Xpert (98.0%; P > 0.05). In smear-negative patients, MeltPro's sensitivity was 50.9%, similar to Xpert (56.5%; P > 0.05), and higher than MGIT (33.1%; P < 0.001). Based on Xpert and/or MYCOTB results, MeltPro exhibited a sensitivity and specificity of 98.3% and 99.2%, respectively, for detecting RIF resistance. Based on MYCOTB results, MeltPro's sensitivity for detecting resistance to INH, EMB, STR, and FQ was 96.4%, 89.1%, 97.5%, and 90.3%, respectively, with specificities of 96.0%, 96.0%, 95.2%, and 99.4%, respectively.ConclusionThe MeltPro TB assay could potentially be an effective alternative as the initial test for rapid diagnosis of PTB with drug-resistance detection in clinical practice.

Correlation of drug exposure and bacterial susceptibility with treatment response for Mycobacterium avium complex lung disease: protocol for a prospective observational cohort study

IntroductionThe burden of Mycobacterium avium complex (MAC) lung disease is increasing globally and treatment outcome is in general poor. Therapeutic drug monitoring has the potential to improve treatment outcome by...