Anti-infective Agents Research Articles

Ayanin, a natural flavonoid inhibitor of Caseinolytic protease, is a promising therapeutic agent to combat methicillin-resistant Staphylococcus aureus infections

Antimicrobial resistance (AMR) is a global health threat. The dramatic increase of Methicillin-resistant Staphylococcus aureus (MRSA) infections emphasizes the need to find new anti-infective agents with a novel mode of action. The Caseinolytic protease (ClpP) is a central virulence factor in stress survival, virulence, and antibiotic resistance of MRSA. Here, we found ayanin, a flavonoid isolated from Callicarpa nudiflora, was an inhibitor of MRSA ClpP with an IC50 of 19.63 μM. Using quantitative real-time PCR, ayanin reduced the virulence of Staphylococcus aureus (S. aureus) by down-regulating the level of some important virulence factors, including agrA, RNAⅢ, hla, pvl, psmα and spa. The results of cellular thermal shift assay and thermal shift assay revealed a binding between ayanin and ClpP. Molecular docking showed that ASP-168, ASN-173 and ARG-171 were the potential binding sites for ClpP binding to ayanin. ClpP mutagenesis study further indicated that ARG-171 and ASN-173 were the main active sites of ClpP. The affinity constant (KD) value of ayanin with ClpP was 3.15 × 10−5 M measured by surface plasmon resonance. In addition, ayanin exhibited a significant therapeutic effect on pneumonia infection induced by S. aureus in mice in vivo, especially in combination with vancomycin. This is the first report of ayanin with in vivo and in vitro efficacy against S. aureus infection. In conclusion, ayanin is a promising therapeutic agent to combat MRSA infections by targeting ClpP.

Enhanced fungal specificity and in vivo therapeutic efficacy of a C-22-modified FK520 analog against C. neoformans.

Fungal infections cause significant morbidity and mortality globally. The therapeutic armamentarium against these infections is limited, and the development of antifungal drugs has been hindered by the evolutionary conservation between fungi and the human host. With rising resistance to the current antifungal arsenal and an increasing at-risk population, there is an urgent need for the development of new antifungal compounds. The FK520 analogs described in this study display potent antifungal activity as a novel class of antifungals centered on modifying an existing orally active FDA-approved therapy. This research advances the development of much-needed newer antifungal treatment options with novel mechanisms of action.

Bioactive compounds of Citrullus colocynthis aerial parts: characterization and biological properties

In this study, the bioactive components of Citrullus colocynthis extracts were analyzed in view of their potential use as antioxidant/antibacterial agent. The bioactive compounds were extracted in different organic solvents (hexane, ethanol and ethyl acetate) and analyzed by column chromatography, thin-layer chromatography, high-performance liquid chromatography and gas chromatography-mass spectrophotometry (GC-MS). Three distinct fractions were collected and subsequently examined, one from ethyl acetate extraction (I) and two from ethanolic extraction (II and III). p-Coumaric acid was the major phenolic acid from the ethyl acetate extracts (0.11 ± 0.023 mg/kg) while resorcinol was the major phenolic compound from the ethanol extracts (25.00 ± 3.21 mg/kg). Twenty-four bioactive compounds were identified by GC-MS analysis where 1-docosanol pentafluoropropionate was the major bioactive compound in ethanol extracts. Among the ethanol extracts, the highest antioxidant activity was found in fraction III. The highest anti-bacterial activity values, measured in terms of the size of the inhibition zone (mm) against Bacillus cereus and Staphylococcus aureus, i.e. 24 ± 1.62 and 22 ± 2.19 mm, respectively, were attained at 24 µg/mL for fractions III and I. From the results achieved in this work, ethanol extracts of C. colocynthis aerial parts could be considered promising as antioxidant and anti-infectious agents.

Hemoperfusion in anesthesia and intensive care medicine: benefits, risks, and evidence for different systems

Hemoperfusion is atechnique for the extracorporeal elimination of endogenous and exogenous toxins and harmful mediators by adsorption. It can be used as astand-alone device, as part of aheart-lung machine or extracorporeal membrane oxygenation (ECMO) or, as is currently the case, integrated into akidney replacement procedure. In the meantime, various suppliers offer devices with different technologies. The aim of this work was to evaluate the benefits, risks and evidence of the different systems, how they work and for which indications they are approved in Germany. To achieve this goal, anarrative assessment of the existing literature and guidelines for different indications was performed. The focus was on in vivo studies. In principle, adistinction must be made in adsorption techniques between pure adsorption and the combination as adsorption and kidney replacement therapy. The adsorbers available in Germany include Cytosorb®, HA-330, Seraph®-100 and Toraymyxin. Combined procedures (adsorption and kidney replacement) are offered with coupled plasma filtration and adsorption (CPFA) and oXiris®. Most adsorbers have been developed for cytokine and endotoxin removal in patients with sepsis; however, to date, no randomized controlled trial (RCT) has demonstrated asurvival benefit when using hemoperfusion. Therefore, the S3 guidelines for treatment of sepsis and the surviving sepsis campaign guidelines advise against its routine use. When the corona pandemic began, hemoperfusion was considered as apromising therapeutic approach. Cytosorb®, Seraph®-100, and oXiris® received emergency approval by the FDA to be used in critically ill patients with COVID-19, so questions arose about the appropriateness and importance of its use; however, the data generated did not show positive results, so its use cannot be recommended routinely either. In addition, they are not mentioned as atreatment option in the current guidelines. The use of adsorption procedures in patients with liver failure and rhabdomyolysis has only been rudimentarily studied, so any evidence is currently lacking. The only adsorber that has CE approval in Germany for both applications is Cytosorb®. In the next few years, studies will have to follow that investigate the efficacy and thus either justify or refute the use in clinical routine. Hemoperfusion procedures are used in the heart-lung machine as part of cardiac surgery for either cytokine or anticoagulant adsorption. No congruent data are available to support the use for the elimination of cytokines. If emergency cardiac surgery is required in apatient with pre-existing anticoagulation, hemoperfusion procedures can be used to prevent bleeding complications. Cytosorb® has CE approval for this indication. All available techniques are nonselective adsorption processes, so that adsorption of known and unknown substances can occur. Unintentional adsorption of drugs, such as various anti-infective agents is arelevant risk, especially when used in patients with sepsis. Various adsorption systems can eliminate different known and unknown substances. Currently, there is alack of evidence for all indications and systems to justify their routine use except in clinical trials. Future clinical trials should evaluate the potential benefits but also dangers, so that in the meantime the routine use can be justified or arecommendation against the use can be given.

Benzimidazole and piperidine containing novel 1,2,3-triazole hybrids as anti-infective agents: Design, synthesis, in silico and in vitro antimicrobial efficacy.

Cu alkyne-azide cycloaddition was used to easily synthesize a library of novel heterocycles containing benzimidazole and piperidine based 1,2,3-triazole(7a-7l) derivatives. The synthesized analogs were characterized by various spectroscopic techniques like FTIR, 1 H nuclear magnetic resonance (NMR), 13 C NMR, and mass spectrometry. All these novel bioactive compounds (7a-7l) were evaluated for in vitro antibacterial and antifungal efficacy. Compound 7k exhibited appreciable potent activity against Escherichia coli strain. Compounds 7a, 7b, 7f, and 7i showed excellent potent activity against all bacterial strains. Compound 7b, 7c, 7d, and 7g derivatives showed excellent effects when tested in vitro for antifungal activity against various fungal strains. Additionally, a molecular docking investigation revealed that compound 7k has the ability to bind to the active site of the E. coli DNA gyrase subunit protein and form hydrogen bonds with significant amino acid residues Asp73 and Asp49 in the active sites. In a 100 ns molecular dynamics simulation, the E. coli DNA gyrase protein's steady capacity to bind compound 7k was shown by the low measured root mean square deviation, which was an indication of the complex's conformational stability.

Identification of an Antimicrobial Peptide from the Venom of the Trinidad Thick-Tailed Scorpion Tityus trinitatis with Potent Activity against ESKAPE Pathogens and Clostridioides difficile.

Envenomation by the Trinidad thick-tailed scorpion Tityus trinitatis may result in fatal myocarditis and there is a high incidence of acute pancreatitis among survivors. Peptidomic analysis (reversed-phase HPLC followed by MALDI-TOF mass spectrometry and automated Edman degradation) of T. trinitatis venom led to the isolation and characterization of three peptides with antimicrobial activity. Their primary structures were established asTtAP-1 (FLGSLFSIGSKLLPGVFKLFSRKKQ.NH2), TtAP-2 (IFGMIPGLIGGLISAFK.NH2) and TtAP-3 (FFSLIPSLIGGLVSAIK.NH2). In addition, potassium channel and sodium channel toxins, present in the venom in high abundance, were identified by CID-MS/MS sequence analysis. TtAP-1 was the most potent against a range of clinically relevant Gram-positive and Gram-negative aerobes and against the anaerobe Clostridioides difficile (MIC = 3.1-12.5 µg/mL). At a concentration of 1× MIC, TtAP-1 produced rapid cell death (<15 min against Acinetobacter baumannii and Staphylococcus aureus). The therapeutic potential of TtAP-1 as an anti-infective agent is limited by its high hemolytic activity (LC50 = 18 µg/mL against mouse erythrocytes) but the peptide constitutes a template for the design of analogs that maintain the high bactericidal activity against ESKAPE pathogens but are less toxic to human cells. It is suggested that the antimicrobial peptides in the scorpion venom facilitate the action of the neurotoxins by increasing the membrane permeability of cells from either prey or predator.

Cinnamaldehyde for the Treatment of Microbial Infections: Evidence Obtained from Experimental Models.

Cinnamaldehyde (CNM) is a cyclic terpene alcohol found as the major compound of essential oils from some plants of the genus Cinnamomum (Lauraceae). CNM has several reported pharmacological activities, including antimicrobial, antivirulence, antioxidant, and immunomodulatory effects. These properties make CNM an attractive lead molecule for the development of anti-infective agents. In this descriptive review, we discuss the application of CNM in experimental models of microbial infection using invertebrate and vertebrate organisms. CNM (pure or in formulations) has been successfully applied in the treatment of infections caused by a range of bacterial (such as Cronobacter sakazakii, Escherichia coli, Listeria monocytogenes, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, Streptococcus agalactiae, Vibrio cholerae) and fungal (such as Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans) pathogens. All these experimental evidence-based findings have promoted the use of cinnamaldehyde as the leading molecule for developing new anti- infective drugs.

Pyrrole-thiazolidinone hybrids as a new structural class of broad-spectrum anti-infectives

A series of pyrrole-thiazolidinone hybrids was designed, synthesized and evaluated for activities against ESKAP bacteria panel and mycobacterial pathogens. From the series, compound 9d showed prominent activity against S. aureus (MIC = 0.5 μg/mL) and compound 9k showed the most promising activity against M. tuberculosis H37Rv (MIC = 0.5 μg/mL). Potent derivatives were found to be non-toxic when tested against Vero cells. Compound 9d upon evaluation in vitro against several MRSA and VRSA strains produced activity comparable or better than standard drugs. In the anti-biofilm assay, 9d reduced S. aureus biofilm by >11% at 10x MIC. The dual inhibitory effect exhibited by pyrrole-thiazolidinone hybrids confirms their potential as new class of promising anti-infective agents.

Evaluation of extracts from Sida acuta, Phyllanthus amarus, Parkia biglobosa and their herbal ointment for therapeutic and biological activities

Herbal extracts are a well-known source of therapeutically important bioactive chemicals since they are widely available, relatively inexpensive, and have fewer adverse effects. The three plants' leaves have been used to treat a variety of illnesses in Ghana, including skin conditions and wound infections. Their effectiveness as an ointment in treating the aforementioned illnesses has not yet been shown, though.The extracts were made into an ointment with polyethylene glycol (PEG), and both the ointment and the raw extracts were examined for in vitro antibacterial activity. The three (3) chosen bacterial isolates were subjected to potential activities of the plant extracts from different extractants.The minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) values for the plant extracts were both low. The herbal ointment made with Sida acuta extract from both extractants showed significantly different activity (P < 0.05), against the test pathogens when compared to the reference medication (Madecassol®). However, the activities of formulated herbal ointment from both P. amarus and P. biglobosa extracts were comparable at higher concentrations to the standard drug used. Notably, both plant extracts and extract-PEG manufactured ointments exhibit significant in vitro efficacy against the disease-causing bacterial species.The current study is the first in-depth account of Parkia species with regard to an examination of herbal ointments made from leaves extract obtained utilizing solvents such as water and ethanol. Our research findings have important implications for the pharmaceutical industry in terms of providing a suitable, workable, and alternative supply of bioactive compounds and anti-infective agents.

Yellow Himalayan Raspberry (Rubus ellipticus Sm.): Ethnomedicinal, Nutraceutical, and Pharmacological Aspects.

Yellow Himalayan raspberry (Rubus ellipticus Sm., Rosaceae) is a native species of the Indian subcontinent, Southern China, and the Philippines, which has been historically used as a traditional medicine and food. All of the parts of this plant have been used in traditional medicine to treat respiratory ailments, diabetes, and gastrointestinal disorder, and as an anti-infective agent. The scientific evaluation revealed a richness of macronutrients, micronutrients, and minerals in the fruits, indicating its potential use as a nutraceutical. Furthermore, this plant has been found to be rich in various secondary metabolites, including polyphenols, flavonoids, anthocyanins, tannins, and terpenoids. Ascorbic acid, kaempferol, gallic acid, and catechin are some of the compounds found in this plant, which have been widely discussed for their health benefits. Furthermore, various extracts and compounds obtained from R. ellipticus have shown antioxidant, antidiabetic, anticancer, anti-inflammatory, nephroprotective, antipyretic, anticonvulsant, and anti-infective activities investigated through different study models. These findings in the literature have validated some of the widespread uses of the fruits in folk medicinal systems and the consumption of this nutritious wild fruit by local communities. In conclusion, R. ellipticus holds strong potential for its development as a nutraceutical. It can also improve the nutritional status of villagers and uplift the economy if properly utilized and marketed.

Antibiotic stewardship

The spread of antimicrobial resistance (AMR) is one of the greatest threats to global health and causes very many deaths. Also in the context of sepsis-the severest complication of certain infectious diseases-does AMR play arole. Wise use of anti-infectives and application of antibiotic stewardship (AMS) principles can reduce the spread of AMR and improve the quality of management of patients with infectious diseases. Correct use of anti-infective agents includes the correct diagnostic approach and documentation of the (suspected) diagnosis, guideline-conform diagnostic workup and treatment selection, re-evaluation and tailoring during the course of treatment, afocus on treatment de-escalation depending on clinical response and microbiology results, dose optimization, and, if possible, conversion to oral therapy, and early termination of treatment if the suspected diagnosis is not confirmed. Particularly adherence to the guideline-conform treatment duration can reduce unnecessary use of anti-infectives. Prevention of infections via adherence to vaccination recommendations also contributes to areduction in the use of anti-infectives. Interdisciplinary collaboration with infectious diseases and AMS specialists, as recommended for sepsis, also improves treatment quality and patient outcomes. Particularly for complex infections such as endocarditis cases should be discussed in multidisciplinary teams including specialists in infectious diseases. In this manner, decisive steps against the spread of AMR and towards maintenance of the efficacy of available anti-infective drugs can be taken.

Anti-microbial resistance and aging-A design for evolution.

The emergence of resistance to anti-infective agents poses a significant threat to successfully treating infections caused by bacteria. Bacteria acquire random mutations due to exposure to environmental stresses, which may increase their fitness to other selection pressures. Interestingly, for bacteria, the frequency of anti-microbial resistance (AMR) seems to be increasing in tandem with the human lifespan. Based on evidence from previous literature, we speculate that increased levels of free radicals (Reactive Oxygen Species-ROS and Reactive Nitrosative Species-RNS), elevated inflammation, and the altered tissue microenvironment in aged individuals may drive pathogen mutagenesis. If these mutations result in the hyperactivation of efflux pumps or alteration in drug target binding sites, it could confer AMR, thus rendering antibiotic therapy ineffective while leading to the selection of novel drug-resistant variants. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Infectious Diseases > Environmental Factors Metabolic Diseases > Environmental Factors.

Drug-induced delusion: A comprehensive overview of the WHO pharmacovigilance database

IntroductionA number of prescribed medicines have been reported in cases of drug-induced delusion, such as dopaminergic agents or psychostimulants. But to this day, most studies are based on a limited number of cases and focus on a few drug classes, so a clear overview of this topic remains difficult. To address this issue, we provide in this article a comprehensive analysis of drug-induced delusion, based on the World Health Organization (WHO) pharmacovigilance database. MethodsWe performed a disproportionality analysis of this database using the information component (IC). The IC compares observed and expected values to find associations between drugs and delusion, using disproportionate Bayesian reporting. An IC0.25 (lower end of the IC 95% credibility interval) > 0 is considered statistically significant. ResultsHere we present an analysis of 4559 suspected drug-induced delusion reports in the WHO pharmacovigilance database. These results identified 66 molecules statistically associated with delusion and an extensive analysis of confounding factors and coprescriptions was performed, using full database as background with an IC0.25 > 0. The main drug classes involved were antidepressants, antiepileptics, dopaminergic agents, opioids, antiinfective agents, benzodiazepines, anti-dementia drugs and psychostimulants. ConclusionThese results will help clinicians identify potential suspected drugs associated with delusion and decide which drug to discontinue and eventually lead to a re-evaluation of drug labels for some molecules.

The sodium borate relieves the hypertrophic damage induced during pregnancy, it improves contractibility, reduces oxidative stress and stimulates cell proliferation

IntroductionFetal and postnatal hypertrophy develop in response to such different exposures or illnesses the mother suffers during gestation as anti-infectious and physical agents, obesity, hypertension, diabetes, and even advanced maternal age. This gives rise to high comorbidities in the newborn; therefore, looking for alternatives that contribute to cardiac homeostasis is quite necessary to inhibit the overgrowth of myocytes. Boron-derivative compounds could play a key role in exerting a repairing effect on chronic cardiac damage induced during gestation. MethodologyThe cardiotoxic effect of 6.4, 12 and 100 mg/kg of sodium tetraborate administered by oral delivery route to healthy pregnant mice was assessed. After that, the use of the chemical compound was tested in the treatment of pregnant mice previously subjected to isoproterenol (fetal hypertrophy model) on the fifth day post coitus. Prior to the sacrifice of the pups of mice an electrocardiography (ECG) was done. Morphological and histological changes of heart were assessed in newborn pups. As a damage marker, the concentration of p38 nitrogen-activated protein kinases were evaluated by using Western Blot and the levels of malondialdehyde (MDA) as well as glutathione antioxidants (GSH) and glutathione peroxidase (GPx) were tested by spectrometry. Moreover, the mRNA expression for early response genes (c-jun, c-fos y c-myc), late response (GATA-4, Mef2c, NFAT) and heart damage (ANP and BNP) was measured by qPCR real time. ResultsThe supply of 6,4 and 12 mg/kg-sodium tetraborate favored ventricular remodeling with histological alterations. By comparison, 100 mg/kg of sodium tetraborate administered during the fetal stage did not alter neither the cardiac morphology of six-week old pups nor the p38/P-p38MAPK ratio remained the same and no oxidative stress was observed.When pregnant females treated with isoproterenol were treated with 100 mg/kg sodium tetraborate during the fetal stage, an improvement in contractility was detected in the pups with an actual reduction in myocardial fibrosis and oxidative stress, but cardiac mass increased. In addition, the expression levels of c-jun, c-myc, GATA-4, MEF2c and ANP mRNA declined in comparison with CTR. However, the hypertrophic damage mechanism was sustained by c-fos, NFAT and BNP expressions. ConclusionsThe set of results achieved suggests that high concentrations of sodium tetraborate have no cardiotoxic effects. Furthermore, sodium tetraborate mitigates hypertrophy induced during pregnancy, thereby improving contractibility, reducing oxidative stress and stimulating cell proliferation. Therefore, sodium tetraborate could be an excellent prophylactic treatment administered by delivery oral route during pregnancy when there is a risk of developing fetal left ventricular hypertrophy (LVH).

Chemical composition, antioxidant, and antibacterial activity of Ruta graveolens (Rutaceae)

Abstract. Saeed YS, Ali JF, Mohammed MA. 2023. Chemical composition, antioxidant, and antibacterial activity of Ruta graveolens (Rutaceae). Biodiversitas 24: 3162-3168. The present study was carried out to investigate the antioxidant and antibacterial activities of phenolic components isolated from the leaves of Ruta graveolens L. The phenolic compounds were extracted in different organic solvents (hexane, ethanol, and ethyl acetate) and analyzed by column chromatography, thin-layer chromatography, and high-performance liquid chromatography. Three discrete fractions were collected and subsequently examined: one from ethyl acetate extraction (I) and two from ethanolic extraction (II and III). No fractions from hexane were obtained. In particular, the ethanolic fractions were analyzed by HPLC analysis which contained the most bioactive compounds. The major phenolic compounds from the ethanol extracts were catechol and coumarin (1.104966 and 16.612227 mg/kg), followed by catechol and hydroquinone (0.144731 and 1.90781 mg/Kg), whereas, resorcinol and coumarin from the ethyl acetate extracts (14.78298 and 21.75253 mg/kg). The ethanol extract had the highest level of antioxidant activity, and other fractions had antioxidant effects at different levels; because the three fractions' phenolic chemicals have varied redox characteristics, their impacts vary in strength. The highest inhibition zones (mm) of Bacillus cereus and Staphylococcus aureus at 24 ?g/mL for fractions II and I were 23 and 22 mm, respectively. At 24 ?g/mL, Escherichia coli and Proteus vulgaris had inhibition zones of 21 and 20 mm, respectively. Fraction I and II did not show Escherichia coli and Proteus vulgaris inhibition zones (mm) at 1.5 µg/mL. Finally, the study's results suggest that using R. graveolens ethanol extracts may be a natural source of antioxidants and anti-infectious agents.

Computational and experimental investigation of antibacterial and antifungal properties of Nicotiana tabacum extracts

Abstract The identification of novel anti-infective agents of synthetic and natural origin represents one of the main aims of contemporary drug discovery. In the current work, four different varieties of Nicotiana tabacum, namely, K399, SPG28, Swat No. 1, and Swat No. 2, were studied to assess the antibacterial and antifungal properties of their extracts. The extracts contain anthraquinones, alkaloids, saponins, terpenoids, tannins, resins, steroids, proteins, and carbohydrates, and the antibacterial and antifungal activities were evaluated toward four bacterial and four fungal strains. N. tabacum K399 showed the highest zone of inhibition against E. coli. Similarly, K399 showed the highest antifungal potential, as the highest zone of inhibition for the set was detected against C. albicans. Then, the underlying molecular mechanism was further investigated, and the extracts were tested for their inhibitory potential against urease, an enzyme which is conserved in bacteria and fungi. Additionally, computational tools were enrolled to assess the role of rutin and chlorogenic acid, which are among the main constituents of N. tabacum leaves, in interacting with urease through molecular docking. Combined together, the computational and experimental results support the antibacterial and antifungal potential of N. tabacum extracts, particularly, that obtained from K399 variety.

Neutropenic Rat Thigh Infection Model for Evaluation of the Pharmacokinetics/Pharmacodynamics of Anti-Infectives.

The neutropenic mouse infection model is extensively used to characterize the pharmacokinetics/pharmacodynamics (PK/PD) of anti-infective agents. However, it is difficult to evaluate agents following intravenous (i.v.) infusions using this model. Furthermore, in many drug discovery programs, lead identification and optimization is performed in rats, and pharmacology is performed in mice. Alternative models of infection are needed for robust predictions of PK/PD in humans. The rat is an alternative model of infection which can overcome the shortcomings of the mouse model. However, the rat neutropenic thigh infection (NTI) model has not been adequately characterized for evaluation of the PK/PD of anti-infectives. The aim of this study was to characterize the PK/PD of ciprofloxacin against bacterial pathogens in a rat NTI model. We studied the PK/PD relationships of ciprofloxacin against wild-type Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae in neutropenic Wistar rats following administration of 10, 30, and 100 mg/kg as single intravenous boluses and 30- and 60-min infusions. The PK/PD of ciprofloxacin against all four pathogens was AUC/MIC dependent and independent of the duration of administration at 10, 30, and 100 mg/kg. At human-equivalent rat doses, the PK/PD targets of ciprofloxacin achieved in rats for microbiological cure were similar to those reported in human patients. The neutropenic rat thigh infection model can be used to evaluate anti-infective agents intended to be administered as infusions in the clinic, and it complements the mouse model, increasing the robustness of PK/PD predictions in humans. IMPORTANCE Many antibiotics are administered as intravenous infusions in the clinic, especially in intensive care units. Anti-infective drug discovery companies develop clinical candidates that are intended to be administered as i.v. infusions in the clinic. However, there are no well-characterized models with which they can evaluate the PK/PD of the candidates following i.v. infusions. The neutropenic rat thigh infection model reported in this study helps in evaluating anti-infective agents that are intended to be administered as i.v. infusions in the clinic. The rat model is useful for simulating the clinical conditions for i.v. infusions for treatment of infections, such as acute bacterial skin and skin structure, lung, and urinary tract infections. This model is predictive of efficacy in humans and can serve as an additional confirmatory model, along with the mouse model, for determining the proof of concept and for making robust predictions of efficacy in humans.

Galacto-Oligosaccharides as an Anti-Infective and Anti-Microbial Agent for Macrolide-Resistant and -Sensitive Mycoplasma pneumoniae.

The worldwide increase in the incidence of antibiotic resistance of the atypical bacterium Mycoplasma pneumoniae (MP) challenges the treatment of MP infections, especially in children. Therefore, alternative strategies for the treatment of MP infections are warranted. Galacto- and fructo-oligosaccharides (GOS and FOS) are a specific group of complex carbohydrates that were recently shown to possess direct anti-pathogenic properties. In this study, we assessed whether GOS and FOS exert anti-microbial and anti-infective effects against MP and, especially, macrolide-resistant MP (MRMP) in vitro. The MIC values of GOS for MP and MRMP were 4%. In contrast, the MIC values of FOS for both MP and MRMP were 16%. A time-kill kinetic assay showed that FOS possess bacteriostatic properties, while for GOS, a bactericidal effect against MP and MRMP was observed after 24 h at a concentration of 4x MIC. In co-cultures with human alveolar A549 epithelial cells, GOS killed adherent MP and MRMP and also concentration-dependently inhibited their adherence to A549 cells. Further, GOS suppressed (MR)MP-induced IL-6 and IL-8 in A549 cells. None of the aforementioned parameters were affected when FOS were added to these co-cultures. In conclusion, the anti-infective and anti-microbial properties of GOS could provide an alternative treatment against MRMP and MP infections.

Small Molecule Attenuates Bacterial Virulence by Targeting Conserved Response Regulator.

Antibiotic tolerance within a biofilm community presents a serious public health challenge. Here, we report the identification of a 2-aminoimidazole derivative that inhibits biofilm formation by two pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. In S. mutans, the compound binds to VicR, a key response regulator, at the N-terminal receiver domain, and concurrently inhibits expression of vicR and VicR-regulated genes, including the genes that encode the key biofilm matrix producing enzymes, Gtfs. The compound inhibits S. aureus biofilm formation via binding to a Staphylococcal VicR homolog. In addition, the inhibitor effectively attenuates S. mutans virulence in a rat model of dental caries. As the compound targets bacterial biofilms and virulence through a conserved transcriptional factor, it represents a promising new class of anti-infective agents that can be explored to prevent or treat a host of bacterial infections. IMPORTANCE Antibiotic resistance is a major public health issue due to the growing lack of effective anti-infective therapeutics. New alternatives to treat and prevent biofilm-driven microbial infections, which exhibit high tolerance to clinically available antibiotics, are urgently needed. We report the identification of a small molecule that inhibits biofilm formation by two important pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. The small molecule selectively targets a transcriptional regulator leading to attenuation of a biofilm regulatory cascade and concurrent reduction of bacterial virulence in vivo. As the regulator is highly conserved, the finding has broad implication for the development of antivirulence therapeutics that selectively target biofilms.

Deciphering dynamic combinatorial libraries of glycoclusters with miniaturized weak affinity chromatography coupled with mass spectrometry (nano-FAC-MS)

We report an original methodology based on affinity chromatography coupled with mass spectrometry to decipher the complexity of dynamic combinatorial libraries (DCLs) of glycoclusters. Such libraries are intended to boost the design of potential therapeutic anti-infectious agents targeting Pseudomonas aeruginosa, which is responsible for numerous diseases, mostly found in hospitals as major a cause of nosocomial infections. Dynamic combinatorial chemistry provides a rapid access to an equilibrating mixture of glycocluster candidates through the formation of reversible covalent bonds under thermodynamic control. Identifying each molecule in the complex mixture overcomes challenges due to the dynamic process. Selection of glycoclusters candidates was first realized on a model lectin (Concanavalin A, ConA). Home-made affinity nanocolumns, containing covalently immobilized ConA and have volumes in the microliter range, were used to separate DCLs of glycoclusters with respect to their specific lectin binding properties under buffered aqueous conditions. Miniaturization facilitates the inline coupling with MS detection in such purely aqueous and buffered conditions and reduces target protein consumption. Monolithic lectin-affinity columns prepared by immobilization of ConA were first characterized using a known ligand. The amount of active binding immobilized lectin is 61 ± 5 pmol on 8.5-cm length column. We demonstrated the ability of our approach to evaluate individual dissociation constants of species directly in the complex mixture. The concept was then successfully applied to the screening of DCLs of more complex glycoclusters to identify (by mass spectrometry) and rank the ligands (by relative breakthrough curve delay) according to their affinity for the immobilized lectin in a single experiment.