Bactericidal Drugs Research Articles

Tuberculosis Drug-Induced Liver Injury

Effective tuberculosis (TB) treatment requires a combination of bactericidal and/or bacteriostatic TB drugs. The combination of these regimens is the standard therapy recommended by World Health Organization (WHO). The standard therapy consists of 5 first-line anti-TB drugs (isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin). TB drugs have mild to severe side effects. Side effects that arise not only cause mortality and morbidity but also cause the cessation of treatment with the effect of not achieving cure, even arising drug resistance. Drug-induced liver injury (DILI) is a form of side effect that causes the cessation of TB treatment or regimen changes due to treatment failure, relapse, and drug resistance. DILI increases the problem, covering more than 7% of all side effects. DILI is also one of the concerns in the treatment of TB.

Induction of Melanogenesis by Fosfomycin in B16F10 Cells Through the Upregulation of P-JNK and P-p38 Signaling Pathways.

Fosfomycin disodium salt (FDS), which is a water-soluble extract, is a bactericidal drug used to inhibit the synthesis of cells. Moreover, it has been found to be effective in the treatment of urinary tract infections. The present study was conducted to investigate the melanogenesis-stimulating effect of FDS in B16F10 cells. Several experiments were performed on B16F10 cells: the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, the melanin content assay, the cellular tyrosinase activity assay, and Western blotting. FDS upregulated the activity of tyrosinase in a dose-dependent manner at a wide concentration range of 0–1 mg/mL, which showed no cytotoxicity. It also increased the melanin content and the activity of the microphthalmia-associated transcription factor (MITF), tyrosinase related protein 1 (TRP-1), and tyrosinase related protein 2 (TRP-2) enzymes in a dose-dependent manner. Western blotting results showed that FDS clearly upregulated the phosphorylation of c-Jun N-terminal kinases (JNK) and p38 pathways. These data are clear evidence of the melanogenesis-inducing effect of FDS in B16F10 murine melanoma cells.

Association between antimicrobial drug class selection for treatment and retreatment of bovine respiratory disease and health, performance, and carcass quality outcomes in feedlot cattle.

Treatment and control of bovine respiratory disease (BRD) is predicated on the use of two categories of antimicrobials, namely bacteriostatic drugs that inhibit bacterial growth and replication (STATIC), and bactericidal drugs that kill bacteria in in vitro culture systems (CIDAL). Recently, we reported that initial BRD treatment with a STATIC antimicrobial followed by retreatment with a CIDAL antimicrobial was associated with a higher frequency of multidrug-resistant bacteria isolated from field cases of BRD submitted to a veterinary diagnostic laboratory. The present study was conducted to test the hypothesis that calves administered the same class of antimicrobial for first and second BRD treatment (i.e., CIDAL-CIDAL or STATIC-STATIC) would have improved health and performance outcomes at the feedlot compared to calves that received a different antimicrobial class for retreatment (i.e., STATIC-CIDAL or CIDAL-STATIC). The association between antimicrobial treatments and health, performance, and carcass quality outcomes were determined by a retrospective analysis of 4,252 BRD treatment records from a commercial feedlot operation collected from 2001 to 2005. Data were compared using generalized linear mixed statistical models that included gender, season, and arrival weight as covariates. The mean (±SE) probability of BRD cases identified as requiring four or more treatments compared to three treatments was greater in calves that received STATIC-CIDAL (73.58 ± 2.38%) or STATIC-STATIC (71.32 ± 2.52%) first and second antimicrobial treatments compared to calves receiving CIDAL-CIDAL (50.35 ± 3.46%) first and second treatments (P < 0.001). Calves receiving CIDAL-CIDAL first and second treatments also had an increased average daily gain (1.11 ± 0.03 kg/d) compared to calves receiving STATIC-CIDAL (0.95 ± 0.03 kg/d) and STATIC-STATIC (0.84 ± 0.02 kg/d) treatments (P < 0.001). Furthermore, CIDAL-CIDAL-treated calves had a higher probability of a choice quality grade at slaughter (36.44 ± 4.80%) compared to STATIC-CIDAL calves (28.09 ± 3.88%) (P = 0.037). There was no effect of antimicrobial treatment combination on BRD mortality (P = 0.855) or yield grade (P = 0.240) outcomes. These observations suggest that consideration should be given to antimicrobial pharmacodynamics when selecting drugs for retreatment of BRD. These findings have implications for developing BRD treatment protocols that address both post-treatment production and antimicrobial stewardship concerns.

Drug-Resistant Tuberculosis 2020: Where We Stand

The control of tuberculosis (TB) is hampered by the emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) strains, defined as resistant to at least isoniazid and rifampin, the two bactericidal drugs essential for the treatment of the disease. Due to the worldwide estimate of almost half a million incident cases of MDR/rifampin-resistant TB, it is important to continuously update the knowledge on the mechanisms involved in the development of this phenomenon. Clinical, biological and microbiological reasons account for the generation of resistance, including: (i) nonadherence of patients to their therapy, and/or errors of physicians in therapy management, (ii) complexity and poor vascularization of granulomatous lesions, which obstruct drug distribution to some sites, resulting in resistance development, (iii) intrinsic drug resistance of tubercle bacilli, (iv) formation of non-replicating, drug-tolerant bacilli inside the granulomas, (v) development of mutations in Mtb genes, which are the most important molecular mechanisms of resistance. This review provides a comprehensive overview of these issues, and releases up-dated information on the therapeutic strategies recently endorsed and recommended by the World Health Organization to facilitate the clinical and microbiological management of drug-resistant TB at the global level, with attention also to the most recent diagnostic methods.

Calycopterin, a major flavonoid from Marcetia latifolia, modulates virulence-related traits in Pseudomonas aeruginosa

Although bacterial resistance is a worldwide growing concern, the development of bacteriostatic and bactericidal drugs has been decreasing in the last decade. Compounds that modulate the microorganism virulence, without killing it, have been considered promising alternatives to combat bacterial infections. However, most signaling pathways that regulate virulence are complex and not completely understood. The rich chemical diversity of natural products offers a good starting point to identify key compounds that shed some light on this matter. Therefore, we investigated the role of Marcetia latifolia ethanolic extract, as well as its major constituent, calycopterin (5,4'-dihydroxy-3,6,7,8-tetramethoxylflavone), in the regulation of virulence-related phenotypes of Pseudomonas aeruginosa. Our results show that calycopterin inhibits pyocyanin production (EC50 = 32 μM), reduces motility and increases biofilm formation in a dose-dependent manner. Such biological profile suggests that calycopterin modulates targets that may act upstream the quorum sensing regulators and points to its utility as a chemical probe to further investigate P. aeruginosa transition from planktonic to sessile lifestyle.

RED MAN SYNDROME IN VANCOMYCIN CARE PATIENTS-A CRITICAL REVIEW

Gram Positive bacterial species such as Streptococci, Staphylococci, Pneumococci and Methicillin Resistant Staphylococcus Aureus (MRSA) are still used extensively against vancomycin, a novel anti-bacterial agent produced about 7 decades ago. The bactericidal drug is responsible for two major reactions of hypersensitivity, namely Red Man Syndrome (RMS) and Anaphylaxis. RMS that occurs mainly due to a rise in infusion volume. This analysis focuses primarily on the facts to indicate RMS incidence. All available papers were compiled from PubMed and Google Scholar, and a comprehensive table with descriptions of all published articles from the past 8 years is listed. Of the 11 case reports that were released, nearly all adopted the Adverse Drug Reaction (ADR) protocol. This ADR may be caused by different routes of administration such as oral (PO), intea peritoneal (IP), intravenous (IV), topical powder, etc. Vancomycin-induced Red Man syndrome is a severe and fatal ADR that can cause complications if not treated on time, particularly in the paediatric population. However, to validate the proof, more confirmatory tests need to be carried out.

СИНТЕЗ ТА АНТИМІКРОБНА АКТИВНІСТЬ НАНОЧАСТИНОК СРІБЛА СТАБІЛІЗОВАНИХ ЦИТРАТ-АНІОНАМИ

Widespread use of synthetic antimicrobial drugs leads to the development of antibiotic resistance of pathogenic strains of microorganisms. Therefore, today researchers are very interested in drugs based on nanoparticles of metals, in particular silver and copper, which have antibacterial, antifungal and antiviral activity. One of the reasons for the high interest of researchers in AgNPs as an antimicrobial agent is the significantly lower toxicity of AgNPs compared to Ag+ ions. High antibacterial efficiency of silver nano¬particles is achieved due to their developed surface, which provides maximum contact with the environment. In addition, such nanoparticles are quite small and are able to penetrate cell membranes, to affect intracellular processes from within. Therefore, the aim of this work was to obtain concentrated colloidal silver solutions stabilized by citrate anions, which simultaneously provide satisfactory stabilization of colloidal silver solutions and are non-toxic, as well as to investigate the antimicrobial action of synthesized AgNPs. The solution of citrate stabilized silver nanoparticles (AgNPs) have been obtained via the reaction of reduction of silver nitrate by hydrazine in alkaline medium in the presence of sodium citrate. AgNPs were investigated using transmission electron microscopy (TEM) and UV-vis spectroscopy and the particles size and particles size distribution (PSD) were determined. It was observed that obtained AgNPs are mainly spherical shape. It was found that the mean diameter and PSD of AgNPs determined using TEM and UV-vis spectroscopy are close and equal to 14 and 5 nm and 15 and 4 nm respectively. Obtained solution was concentrated by evaporation at 70 C under reduced pressure up to achievement of AgNPs concentration equal to 200 mg/L. On the base of comparison of optical properties of initial silver sol and concentrated solution the minority of agglomeration of AgNPs was statement. At the same time AgNO3 test showed no change of UV-vis spectrum of concentrate that points on the absence of reducing agent in the solution; this fact indicate that hydrazine was eliminated from during the evaporation of initial AgNPs solution and obtained concentrate did not consist the toxic impurities. Antimicrobial activity of obtained citrate stabilised AgNPs against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacterium was tested using disk diffusion method. It was found that AgNPs shown significant bactericidal effect even at low (25 mg/L) concentration as well as some higher efficiency against Gram-negative bacterium. There was also a slightly higher antimicrobial activity of the drug against gram-negative bacteria Escherichia coli compared with gram-positive bacteria Bacillus subtilis, due to the different structure of cell walls. In particular, the walls of gram-positive bacteria consist mainly of peptidoglycan (murein), and gram-negative bacteria have cell walls with a layer of peptidoglycan and an outer membrane with a lipopolysaccharide component, which is not present in gram-positive bacteria. Based on the studies, it can be concluded that the proposed method of synthesis of AgNPs is suitable for obtaining highly concentrated silver sols. This method of synthesis is simple in hardware design, scalable, and the resulting colloidal solutions are stable and do not contain harmful impurities. Therefore, due to the high antibacterial activity of citrate-anion-stabilized AgNPs against certain types of gram-positive and gram-negative bacteria, it can be recommended for the manufacture of bactericidal drugs for biomedical purposes.

Rifampicin-induced lichenoid drug eruption

Rifampicin is a bactericidal drug extensively used for tuberculosis and leprosy. Common adverse drug reactions of rifampicin are hepatotoxicity, flu-like syndrome, gastrointestinal symptoms and thrombocytopenia; cutaneous adverse reaction encountered in...

Determination of minimum bactericidal concentration, in single or combination drugs, against Mycobacterium tuberculosis.

Aim: To evaluate an assay to detect minimum bactericidal concentration (MBC) in Mycobacterium tuberculosis, using as single model rifampicin, isoniazid, levofloxacin (LVX) and linezolid (LNZ) and in combination. Material &methods: MBCs were carried out directly from resazurin microtiter assay plate and 3D checkerboard in M. tuberculosis H37Rv and five resistant clinical isolates. Results: The proposed MBC assay showed similar values to those determined by MGIT™, used as control. LVX and LNZ's MBC values were close to their MIC values. LNZ or LVX combined with isoniazid and rifampicin showed MBC value reduced in 63.7% of the assays. Conclusion: The proposed assay to determine MBCs of drugs can be applied to the study of new compounds with anti-M. tuberculosis activity to detect their bactericidal effect and also in laboratory routine for clinical dose adjustment of drugs according to the patient's profile.

Thionization Method of Glycosyl Urea and Carbamide Sugars

This work is describing a thionization method for glycosyl urea and carbamide of sugars by using the Lawesson’s reagent. It is proposed the method based on the interaction of glycosyl urea and carbamide of sugars with the Lawessons reagent at a 1:1 ratio in the presence of a pyridine. As a result, sulfur-containing derivatives of sugar carbamides are obtained with the help of Lawesson’s reagent. Obtained experimental data are indicating the developed new method for thionization of sugar carbamides, which opens up broad possibilities for synthesis of various carbohydrate derivatives of thiourea. Significance of this work is that, thiourea derivatives are promising bactericidal, fungicidal and anti-inflammatory drugs. Therefore, the preparation of thiourea derivatives and the study of their properties remain topical tasks in the field of chemistry.

Изменения морфологии S. aureus в условиях их культивирования в присутствии антибактериальных препаратов

The search for new methods for identifying the pathogen in biological material, including microscopic, remains relevant. The study of ultrastructural changes of microorganisms as a result of exposure to various groups of antibiotics is important, because the morphology of the bacterial cell varies considerably depending on the conditions of cultivation. The purpose of the study: 1. To identify the nature of changes in the ultrastructure of preserved bacterial cells of S. aureus, cultivated in the presence of antibiotics. 2. To determine the viability of that part of the population of S. aureus, which remained exposed to suppressive concentrations of antibacterial drugs. 3. To determine whether the ultrastructural changes of the reference strain S. aureus ATCC 25923 in the proposed conditions completely reflect the nature of these changes for strains isolated from clinical material. Materials and methods. Three strains of S. aureus isolated from biological material and the reference strain S. aureus ATCC 25923 were used to investigate the S. aureus ultrastructure. The analysis was carried out on the basis of data obtained using scanning electron microscopy (SEM). In the process of sample preparation, the technique of imprinting bacteria from agarized nutrient medium was applied. Results and conclusions. The most common feature for the strains of clinical isolates of S. aureus was the formation of a large number of bacterial cells of a specific disc-shaped form in zones of influence of bacteriostatic antibiotics. In terms of the use of bactericidal drugs, part of the population remained spherical, the other part had irregular contours. Changes in the size of bacterial cells in growth suppression zones were multidirectional. Cultivation of bacteria under conditions of exposure to suppressive concentrations of antibacterial drugs stimulated the production of exocellular matrix. The ultrastructural changes of phenotypic variability of the reference strain S. aureus ATCC 25923 did not fully correspond to changes in the morphology of the bacterial cells of the strains of clinical isolates. The viability of bacteria remaining in the zones of growth suppression has been confirmed in all cases of antibiotic exposure, except gentamicin. Thus, the study revealed the nature of changes in the ultrastructure of S. aureus as manifestations of phenotypic variability of microorganisms in response to the presence of antibacterial drugs with different mechanisms of action.

Association between antimicrobial drug class for treatment and retreatment of bovine respiratory disease (BRD) and frequency of resistant BRD pathogen isolation from veterinary diagnostic laboratory samples.

Although 90% of BRD relapses are reported to receive retreatment with a different class of antimicrobial, studies examining the impact of antimicrobial selection (i.e. bactericidal or bacteriostatic) on retreatment outcomes and the emergence of antimicrobial resistance (AMR) are deficient in the published literature. This survey was conducted to determine the association between antimicrobial class selection for treatment and retreatment of BRD relapses on antimicrobial susceptibility of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Pathogens were isolated from samples submitted to the Iowa State University Veterinary Diagnostic Laboratory from January 2013 to December 2015. A total of 781 isolates with corresponding animal case histories, including treatment protocols, were included in the analysis. Original susceptibility testing of these isolates for ceftiofur, danofloxacin, enrofloxacin, florfenicol, oxytetracycline, spectinomycin, tilmicosin, and tulathromycin was performed using Clinical and Laboratory Standards Institute guidelines. Data were analyzed using a Bayesian approach to evaluate whether retreatment with antimicrobials of different mechanistic classes (bactericidal or bacteriostatic) increased the probability of resistant BRD pathogen isolation in calves. The posterior distribution we calculated suggests that an increased number of treatments is associated with a greater probability of isolates resistant to at least one antimicrobial. Furthermore, the frequency of resistant BRD bacterial isolates was greater with retreatment using antimicrobials of different mechanistic classes than retreatment with the same class. Specifically, treatment protocols using a bacteriostatic drug first followed by retreatment with a bactericidal drug were associated with a higher frequency of resistant BRD pathogen isolation. In particular, first treatment with tulathromycin (bacteriostatic) followed by ceftiofur (bactericidal) was associated with the highest probability of resistant M. haemolytica among all antimicrobial combinations. These observations suggest that consideration should be given to antimicrobial pharmacodynamics when selecting drugs for retreatment of BRD. However, prospective studies are needed to determine the clinical relevance to antimicrobial stewardship programs in livestock production systems.

Repurposing salicylamide for combating multidrug-resistant Neisseria gonorrhoeae.

The U.S. Centers for Disease Control and Prevention (CDC) lists Neisseria gonorrhoeae as one of the most urgent antibiotic-resistant threats in the United States. This is due to the emergence of clinical isolates that have developed resistance to nearly every antibiotic used to treat gonorrhea and highlights the critical need to find new therapeutics. The present study discovered salicylamide, an analgesic and antipyretic drug, has antibacterial activity against 40 different antibiotic-resistant strains of N. gonorrhoeae (MIC 8-32 μg/ml) with low frequency of resistance <2.4x10-9 Interestingly, salicylamide did not inhibit growth of bacterial species in the vaginal microflora involved in defense against gonococcal infections, such as Lactobacillus gasseri, L. jensenii, L. johnsonii, and L. crispatus A time-kill assay revealed that salicylamide is a rapidly bactericidal drug as it eradicated a high inoculum of N. gonorrhoeae within 10 hours. Salicylamide was superior to the drug of choice, ceftriaxone, in reducing the burden of intracellular N. gonorrhoeae by 97% in infected endocervical cells. Furthermore, salicylamide outperformed ceftriaxone in reducing expression of the pro-inflammatory cytokine IL-8 from endocervical cells infected with N. gonorrhoeae A checkerboard assay revealed that salicylamide exhibited a synergistic interaction with tetracycline and an additive relationship with azithromycin and ciprofloxacin, and ceftriaxone. A more in-depth investigation of the structure-activity-relationship of derivatives of salicylamide revealed the amide and hydroxyl groups are important for anti-gonorrheal activity. In conclusion, this study identified salicylamide as a promising candidate for further investigation as a novel treatment option for multidrug-resistant gonorrhea.

Quantitative analysis of Mycobacterium avium subsp. hominissuis proteome in response to antibiotics and during exposure to different environmental conditions

Mycobacterium avium subsp. hominissuis (MAH) belongs to the clinically important non-tuberculous mycobacterial group that infects immunocompromised patients and individuals with underling lung conditions. The need for prolonged therapy is a major challenge of MAH treatment, influencing the development of persistent and drug-resistant infections. The reason why bactericidal drugs take several months to eliminate MAH is unknown. To investigate MAH proteome remodeling under aerobic, anaerobic and biofilm conditions (as it is encountered in patient lungs) and identify metabolic changes potentially associated with bacterial persistent state, we performed the relative protein quantitative analysis using Tandem Mass Tag Mass Spectrometry sequencing. MAH was exposed to amikacin (4 μg/ml) and clarithromycin (16 μg/ml) under aerobic, anaerobic or biofilm condition for 24 h and the response was compared with bacterial proteomics of the corresponding conditions. Overall, 4000 proteins were identified out of 5313 MAH proteome of across all experimental groups. Numerous sets of de novo synthesized proteins belonging to metabolic pathways not evidenced in aerobic condition were found commonly enriched in both anaerobic and biofilm conditions, including pantothenate and CoA biosynthesis, glycerolipid metabolism, nitrogen metabolism and chloroalkene degradation, known to be associated with bacterial tolerance in M. tuberculosis. The common pathways observed in anaerobic and biofilm conditions following drug treatments were peptidoglycan biosynthesis, glycerophospholipid metabolism and protein export. The LprB lipoprotein, highly synthesized in MAH biofilms during drug treatments and shown to be essential for M. tuberculosis virulence and survival in vivo, was selected and overexpressed in MAH. Results demonstrate that LprB is secreted in MAH biofilms and the overexpression clone is more tolerant to antimicrobials than the wild-type strain. Our study identified promising metabolic pathways that can be targeted to prevent the bacterial tolerance mechanism and, subsequently, reduce the length of MAH therapy.

Bacterial metabolic state more accurately predicts antibiotic lethality than growth rate.

Growth rate and metabolic state of bacteria have been separately shown to affect antibiotic efficacy1-3. However, the two are interrelated as bacterial growth inherently imposes a metabolic burden4; thus, determining individual contributions from each is challenging5,6. Indeed, faster growth is often correlated with increased antibiotic efficacy7,8; however, the concurrent role of metabolism in that relationship has not been well characterized. As a result, a clear understanding of the interdependence between growth and metabolism, and their implications for antibiotic efficacy, are lacking9. Here, we measured growth and metabolism in parallel across a broad range of coupled and uncoupled conditions to determine their relative contribution to antibiotic lethality. We show that when growth and metabolism are uncoupled, antibiotic lethality uniformly depends on the bacterial metabolic state at the time of treatment, rather than growth rate. We further reveal a critical metabolic threshold below which antibiotic lethality is negligible. These findings were general for a wide range of conditions, including nine representative bactericidal drugs and a diverse range of Gram-positive and Gram-negative species (Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus). This study provides a cohesive metabolic-dependent basis for antibiotic-mediated cell death, with implications for current treatment strategies and future drug development.

Photocatalytically Active Zinc Oxide and Titanium Dioxide Nanoparticles in Clonal Micropropagation of Plants: Prospects

The search for effective and nontoxic sterilization drugs for plants against common phytopathogenic microorganisms is a major challenge to improve the biotechnology of plant clonal micropropagation. An analysis of 92 studies that describe the potential use of ZnO and TiO2 nanoparticles as antimicrobial agents in biotechnology showed that their biological effects depend on several factors: photocatalytic activity, particle size, concentration, morphology, and surface modification. The mechanisms of toxicity, among which the primary one is generation of reactive oxygen species leading to oxidative stress, are also due to these factors. The data describing the direct influence of ZnO and TiO2 nanoparticles on plants, however, are contradictory, which is probably because of the various particle shapes and sizes, their concentrations, and the species characteristics of the plants studied. These studies have confirmed that photocatalytically active ZnO and TiO2 nanoparticles may be used as bactericidal and fungicidal drugs for sterilization of explants during clonal micropropagation of plants, while taking into account the possible phytotoxicity of these particles.

Development of anti-virulence polymers targeting mycobacteria

Modern medicine is under the excruciating pressure of drug resistant bacterial strains which are ever advancing with the introduction of every new class of antibiotics. Traditional bactericidal and bacteriostatic drugs, while effective in eliminating the susceptible bacterial strains, also impose a selective pressure on bacteria which often leads to the emergence of antimicrobial resistance. An alternative approach is the development of anti-virulence therapies, which aims reduce bacterial pathogenesis while avoiding the selective pressure of classical antimicrobial inhibitors, thus rendering bacteria harmless and potentiating natural elimination from the host by innate immunity defence mechanisms. We have synthesised a selection of functional polymers of poly(acryloyl hydrazide) using a panel of aldehyde functionalisation groups and evaluated their anti-virulence properties on both Mycobacterium bovis BCG and Mycobacterium smegmatis mc2 155, two surrogate organisms to study Mycobacterium tuberculosis, the etiological agent responsible for tuberculosis. Using a combination of microscopy and in vitro studies, we have shown the effectiveness of anti-virulence polymers in reducing mycobacterial phagocytosis in J774 macrophages with minimal antimicrobial activity.

Isoniazid Bactericidal Activity Involves Electron Transport Chain Perturbation.

Accumulating evidence suggests that the bactericidal activity of some antibiotics may not be directly initiated by target inhibition. The activity of isoniazid (INH), a key first-line bactericidal antituberculosis drug currently known to inhibit mycolic acid synthesis, becomes extremely poor under stress conditions, such as hypoxia and starvation. This suggests that the target inhibition may not fully explain the bactericidal activity of the drug. Here, we report that INH rapidly increased Mycobacterium bovis BCG cellular ATP levels and enhanced oxygen consumption. The INH-triggered ATP increase and bactericidal activity were strongly compromised by Q203 and bedaquiline, which inhibit mycobacterial cytochrome bc1 and FoF1 ATP synthase, respectively. Moreover, the antioxidant N-acetylcysteine (NAC) but not 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) abrogated the INH-triggered ATP increase and killing. These results reveal a link between the energetic (ATP) perturbation and INH's killing. Furthermore, the INH-induced energetic perturbation and killing were also abrogated by chemical inhibition of NADH dehydrogenases (NDHs) and succinate dehydrogenases (SDHs), linking INH's bactericidal activity further to the electron transport chain (ETC) perturbation. This notion was also supported by the observation that INH dissipated mycobacterial membrane potential. Importantly, inhibition of cytochrome bd oxidase significantly reduced cell recovery during INH challenge in a culture settling model, suggesting that the respiratory reprogramming to the cytochrome bd oxidase contributes to the escape of INH killing. This study implicates mycobacterial ETC perturbation through NDHs, SDHs, cytochrome bc1, and FoF1 ATP synthase in INH's bactericidal activity and pinpoints the participation of the cytochrome bd oxidase in protection against this drug under stress conditions.

Cargo shuttling by electrochemical switching of core-shell microgels obtained by a facile one-shot polymerization.

Controlling and understanding the electrochemical properties of electroactive polymeric colloids is a highly topical but still a rather unexplored field of research. This is especially true when considering more complex particle architectures like stimuli-responsive microgels, which would entail different kinetic constraints for charge transport within one particle. We synthesize and electrochemically address dual stimuli responsive core-shell microgels, where the temperature-responsiveness modulates not only the internal structure, but also the microgel electroactivity both on an internal and on a global scale. In detail, a facile one-step precipitation polymerization results in architecturally advanced poly(N-isopropylacrylamide-co-vinylferrocene) P(NIPAM-co-VFc) microgels with a ferrocene (Fc)-enriched (collapsed/hard) core and a NIPAM-rich shell. While the remaining Fc units in the shell are electrochemically accessible, the electrochemical activity of Fc in the core is limited due to the restricted mobility of redox active sites and therefore restricted electron transfer in the compact core domain. Still, prolonged electrochemical action and/or chemical oxidation enable a reversible adjustment of the internal microgel structure from core-shell microgels with a dense core to completely oxidized microgels with a highly swollen core and a denser corona. The combination of thermo-sensitive and redox-responsive units being part of the network allows for efficient amplification of the redox response on the overall microgel dimension, which is mainly governed by the shell. Further, it allows for an electrochemical switching of polarity (hydrophilicity/hydrophobicity) of the microgel, enabling an electrochemically triggered uptake and release of active guest molecules. Hence, bactericidal drugs can be released to effectively kill bacteria. In addition, good biocompatibility of the microgels in cell tests suggests suitability of the new microgel system for future biomedical applications.

Construction of multilayer films with bactericidal and long-term antitumor drug release properties as a non-vascular stent coating for therapy in obstruction.

The construction of antibacterial and antitumor coatings could offer effective routes to improve the therapeutic effects of non-vascular stents for unresectable obstructions caused by malignant tumours. Herein, polyelectrolyte multilayers have been explored as bactericidal coatings with controlled antitumor drug release. To solve the challenges of loading and controlled release of small-molecule chemotherapeutic drugs in polyelectrolyte multilayers, the antitumor drug doxorubicin (DOX) was chemically conjugated onto polyethylenimine via cis aconitic anhydride (pH-sensitive linker), thus obtaining the polycation prodrug PEI-CA-DOX. Alginate sodium was oxidized (O-Alg) and mixed with DOX to prepare the O-Alg-DOX complex as a polyanion. QCM-D and contact angle tests were used to monitor and verify the progressive build-up of the PEI-CA-DOX/O-Alg-DOX multilayer films, which show a linear growth. The in vitro antibacterial tests indicated that the PEI-CA-DOX-terminated PEI-CA-DOX/O-Alg-DOX multilayers could kill the bacteria effectively. As-such multilayers also presented a long-term sustained DOX release behaviour in PBS due to the combination of slow release in PEI-CA-DOX and fast release in the O-Alg-DOX complex. The as-designed PEI-CA-DOX/O-Alg-DOX multilayers with combined antibacterial and antitumor properties may have great potential for applications in non-vascular stent coatings for palliative treatment of obstruction caused by malignant tumours.