An update on the role of nitrofurans in the management of urinary tract infections

Identification of novel GSPT1 degraders by virtual screening and bioassay

GSPT1 plays crucial physiological functions, such as terminating protein translation, overexpressed in various tumors. It is a promising anti-tumor target, but is also considered as an "undruggable" protein. Recent studies have found that a class of small molecules can degrade GSPT1 through the "molecular glue" mechanism with strong antitumor activity, which is expected to become a new therapy for hematological malignancies. Currently available GSPT1 degraders are mostly derived from the scaffold of immunomodulatory imide drug (IMiD), thus more active compounds with novel structure remain to be found. In this work, using computer-assisted multi-round virtual screening and bioassay, we identified a non-IMiD acylhydrazone compound, AN5782, which can reduce the protein level of GPST1 and obviously inhibit the proliferation of tumor cells. Some analogs were obtained by a substructure search of AN5782. The structure-activity relationship analysis revealed possible interactions between these compounds and CRBN-GSPT1. Further biological mechanistic studies showed that AN5777 decreased GSPT1 remarkably through the ubiquitin-proteasome system, and its effective cytotoxicity was CRBN- and GSPT1-dependent. Furthermore, AN5777 displayed good antiproliferative activities against U937 and OCI-AML-2 cells, and dose-dependently induced G1 phase arrest and apoptosis. The structure found in this work could be good start for antitumor drug development.

''Myth Busting in Infectious Diseases'': A Comprehensive Review

Antibiotics have played a pivotal role in modern medicine, drastically reducing mortality rates associated with bacterial infections. Despite their significant contributions, the emergence of antibiotic resistance has become a formidable challenge, necessitating a re-evaluation of antibiotic use practices. The widespread belief in clinical practice that bactericidal antibiotics are inherently superior to bacteriostatic ones lacks consistent support from evidence in randomized controlled trials (RCTs). With the latest evidence, certain infections have demonstrated equal or even superior efficacy with bacteriostatic agents. Furthermore, within clinical practice, there is a tendency to indiscriminately order urine cultures for febrile patients, even in cases where alternative etiologies might be present. Consequently, upon obtaining a positive urine culture result, patients often receive antimicrobial prescriptions despite the absence of clinical indications warranting such treatment. Furthermore, it is a prevailing notion among physicians that extended durations of antibiotic therapy confer potential benefits and mitigate the emergence of antimicrobial resistance. Contrary to this belief, empirical evidence refutes such assertions. This article aims to address common myths and misconceptions within the field of infectious diseases.

History Is the Key to Diagnosis: A Case of Nitrofurantoin-Induced Interstitial Lung Disease

We present the case of a 74-year-old woman with a past medical history (PMH) significant for anxiety, depression, and hypertension who presented to the pulmonary clinic for consultation regarding progressive shortness of breath, which started five months ago after developing COVID-19. Further history-taking revealed that she had been started on nitrofurantoin two months ago for recurrent urinary tract infections (UTIs). Her pulmonary function tests (PFTs) demonstrated a moderately restrictive disease. A CT chest was obtained, showing pleural thickening with bilateral pleural-based ground glass opacities. Nitrofurantoin was then discontinued, and she was started on a prednisone taper for suspected nitrofurantoin-induced interstitial lung disease (ILD). At a follow-up clinic visit six months later, she showed great improvement in her shortness of breath, marked improvement in forced vital capacity (FVC) on PFTs, and near resolution of pleural-based lesions and basal ground glass opacities on CT chest. This case emphasizes the importance of keeping the diagnosis of nitrofurantoin-induced ILD in mind, as well as the need to implement guidelines for the monitoring of this potential pulmonary adverse effect.

Synthesis and Characterization of New N-acyl Hydrazone Derivatives of Carprofen as Potential Tuberculostatic Agents

N-acyl hydrazone (NAH) is recognized as a promising framework in drug design due to its versatility, straightforward synthesis, and attractive range of biological activities, including antimicrobial, antitumoral, analgesic, and anti-inflammatory properties. In the global context of increasing resistance of pathogenic bacteria to antibiotics, NAHs represent potential solutions for developing improved treatment alternatives. Therefore, this research introduces six novel derivatives of (EZ)-N'-benzylidene-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide, synthesized using a microwave-assisted method. In more detail, we joined two pharmacophore fragments in a single molecule, represented by an NSAID-type carprofen structure and a hydrazone-type structure, obtaining a new series of NSAID-N-acyl hydrazone derivatives that were further characterized spectrally using FT-IR, NMR, and HRMS investigations. Additionally, the substances were assessed for their tuberculostatic activity by examining their impact on four strains of M. tuberculosis, including two susceptible to rifampicin (RIF) and isoniazid (INH), one susceptible to RIF and resistant to INH, and one resistant to both RIF and INH. The results of our research highlight the potential of the prepared compounds in fighting against antibiotic-resistant M. tuberculosis strains.

N-Acylhydrazone Pharmacophore's Analgesic and Anti-inflammatory Profile: Recent Advancements during the Past Ten Years

Due to its important biological and pharmacological properties, in the field of medicinal chemistry and drug discovery, the N-acylhydrazone motif has shown to be extremely adaptable and promising. This scaffold has become a crucial component in the synthesis of numerous bioactive agents. N-Acylhydrazones are also interesting biological and synthetic tools due to their easy and straightforward synthesis. The current review provides a summary of the analgesic and anti-inflammatory activities of N-acylhydrazone derivatives over the past ten years. A brief discussion of structure-activity relationships is also provided which may guide researchers in medicinal chemistry to develop derivatives based on N-acylhydrazone scaffold as potent anti-inflammatory candidates.

In Vitro Activities of Oxazolidinone Antibiotics Alone and in Combination with C-TEMPO against Methicillin-Resistant Staphylococcus aureus Biofilms

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a global health concern. The propensity of MRSA to form biofilms is a significant contributor to its pathogenicity. Strategies to treat biofilms often involve small molecules that disperse the biofilm into planktonic cells. Linezolid and, by extension, theoxazolidinones have been developed to treat infections caused by Gram-positive bacteria such as MRSA. However, the clinical development of these antibiotics has mainly assessed the susceptibility of planktonic cells to the drug. Previous studies evaluating the anti-biofilm activity of theoxazolidinones have mainly focused on the biofilm inhibition of Enterococcus faecalis and methicillin-sensitive Staphylococcus aureus, with only a few studies investigating the activity of oxazolidinones for eradicating established biofilms for these species. Very little is known about the ability of oxazolidinones to eradicate MRSA biofilms. In this work, five oxazolidinones were assessed against MRSA biofilms using a minimum biofilm eradication concentration (MBEC) assay. All oxazolidinones had inherent antibiofilm activity. However, only ranbezolid could completely eradicate MRSA biofilms at clinically relevant concentrations. The susceptibility of the MRSA biofilms to ranbezolid was synergistically enhanced by coadministration with the nitroxide biofilm dispersal agent C-TEMPO. We presume that ranbezolid acts as a dual warhead drug, which combines the mechanism of action of the oxazolidinones with a nitric oxide donor or cytotoxic drug.

Design and Synthesis of Novel Antimicrobial Agents

The necessity for the discovery of innovative antimicrobials to treat life-threatening diseases has increased as multidrug-resistant bacteria has spread. Due to antibiotics' availability over the counter in many nations, antibiotic resistance is linked to overuse, abuse, and misuse of these drugs. The World Health Organization (WHO) recognized 12 families of bacteria that present the greatest harm to human health, where options of antibiotic therapy are extremely limited. Therefore, this paper reviews possible new ways for the development of novel classes of antibiotics for which there is no pre-existing resistance in human bacterial pathogens. By utilizing research and technology such as nanotechnology and computational methods (such as in silico and Fragment-based drug design (FBDD)), there has been an improvement in antimicrobial actions and selectivity with target sites. Moreover, there are antibiotic alternatives, such as antimicrobial peptides, essential oils, anti-Quorum sensing agents, darobactins, vitamin B6, bacteriophages, odilorhabdins, 18β-glycyrrhetinic acid, and cannabinoids. Additionally, drug repurposing (such as with ticagrelor, mitomycin C, auranofin, pentamidine, and zidovudine) and synthesis of novel antibacterial agents (including lactones, piperidinol, sugar-based bactericides, isoxazole, carbazole, pyrimidine, and pyrazole derivatives) represent novel approaches to treating infectious diseases. Nonetheless, prodrugs (e.g., siderophores) have recently shown to be an excellent platform to design a new generation of antimicrobial agents with better efficacy against multidrug-resistant bacteria. Ultimately, to combat resistant bacteria and to stop the spread of resistant illnesses, regulations and public education regarding the use of antibiotics in hospitals and the agricultural sector should be combined with research and technological advancements.

Ratiometric luminescent sensing of a biomarker for sugar consumption in an aqueous medium using a Cu(II) coordination polymer

An innovative [Cu(Hadp)₂(Bimb)]_n (KA@CP-S3) coordination polymer expands its dimensionality from a 1D chain to a 2D network. The topological analysis reveals that KA@CP-S3 has 2-connected uninodal 2D 2C1 topology. KA@CP-S3 has capable luminescent sensing for volatile organic compounds (VOCs), nitroaromatics, heavy metal ions, anions, disposed antibiotics (nitrofurantoin and tetracycline) and biomarkers. Intriguingly, KA@CP-S3 exhibits outstanding selective quenching of about 90.7% and 90.5% for the 125 mg dl^-1 and 150 mg dl^-1 strengths of sucrose, respectively, in aqueous solution along with other ranges in between. The photocatalytic degradation efficiency of KA@CP-S3 for the potentially harmful organic dye Bromophenol Blue displays 95.4%, which is the highest among the 13 dyes that were evaluated.

Anticancer agents incorporating the N-acylhydrazone scaffold: Progress from 2017 to present

The N-acylhydrazone motif has been shown to be particularly adaptable and promising in the area of medicinal chemistry and drug development, due to its significant biological and pharmacological characteristics. Moreover, N-acylhydrazones are appealing synthetic and biological tools because of their simple and straightforward synthesis. This scaffold has emerged as a fundamental building block for the synthesis of bioactive compounds. Particularly, the N-acylhydrazone scaffold served as a base for the synthesis of a number of potent anticancer agents acting via different mechanisms. An updated summary of the anticancer activity of N-acylhydrazone derivatives described in the literature (from 2017 to 2022) is provided in the current review. It discusses the structure-activity relationship (SAR) of N-acylhydrazone derivatives exhibiting anticancer potential, which could be helpful in designing and developing new derivatives as effective antiproliferative candidates in the future.

Design, Synthesis, and Biological Evaluation of 2-Mercaptobenzoxazole Derivatives as Potential Multi-Kinase Inhibitors

A series of 12 compounds was designed and synthesized, based on 2-mercaptobenzoxazole derivatives containing either the substituted benzenes 4a-d, substituted isatins 5a-f, or heterocycles 6a-b. The in vitro antiproliferative activity of the compounds was evaluated against hepatocellular carcinoma (HepG2), mammary gland cancer (MCF-7), breast cancer (MDA-MB-231), and the epithelioid cervix carcinoma (HeLa) cancer cell lines. Compounds 4b, 4d, 5d, and 6b had the most potent antiproliferative activity, with IC₅₀ values ranging from 2.14 to 19.34 µM, compared to the reference drugs, doxorubicin and sunitinib. Compound 6b revealed a remarkably broad antitumor activity pattern against HepG2 (IC₅₀ 6.83 µM), MCF-7 (IC₅₀ 3.64 µM), MDA-MB-231 (IC₅₀ 2.14 µM), and HeLa (IC₅₀ 5.18 µM). In addition, compound 6b showed potent inhibitory activities against EGFR, HER2, VEGFR2, and the CDK2 protein kinase enzymes, with IC₅₀ values of 0.279, 0.224, 0.565, and 0.886 µM, respectively. Moreover, compound 6b induced caspase-dependent apoptosis and cell cycle arrest at the G2/M phase. Finally, a molecular docking simulation was performed for compound 6b to predict the potential ligand-protein interactions with the active sites of the EGFR, HER2, and VEGFR2 proteins.

Genomic Analysis of Two MDR Isolates of Salmonella enterica Serovar Infantis from a Spanish Hospital Bearing the blaCTX-M-65 Gene with or without fosA3 in pESI-like Plasmids

Salmonella enterica serovar Infantis (S. Infantis) is a broiler-associated pathogen which ranks in the fourth position as a cause of human salmonellosis in the European Union. Here, we report a comparative genomic analysis of two clinical S. Infantis isolates recovered in Spain from children who just returned from Peru. The isolates were selected on the basis of resistance to cefotaxime, one of the antibiotics of choice for treatment of S. enterica infections. Antimicrobial susceptibility testing demonstrated that they were resistant to eight classes of antimicrobial agents: penicillins, cephalosporins, phenicols, aminoglycosides, tetracyclines, inhibitors of folate synthesis, (fluoro)quinolones and nitrofurans, and one of them was also resistant to fosfomycin. As shown by whole-genome sequence analysis, each isolate carried a pESI-like megaplasmid of ca. 300 kb harboring multiple resistance genes [bla_CTX-M-65, aph(4)-Ia, aac(3)-IVa, aph(3′)-Ia, floR, dfrA14, sul1, tet(A), aadA1 ± fosA3], as well as genes for resistance to heavy metals and disinfectants (mer, ars and qacEΔ1). These genes were distributed in two complex regions, separated by DNA belonging to the plasmid backbone, and associated with a wealth of transposable elements. The two isolates had a D87Y amino acid substitution in the GyrA protein, and truncated variants of the nitroreductase genes nfsA and nsfB, accounting for chromosomally encoded resistances to nalidixic acid and nitrofurantoin, respectively. The two S. Infantis isolates were assigned to sequence type ST32 by in silico multilocus sequence typing (MLST). Phylogenetic analysis revealed that they were closely related, differing only by 12 SNPs, although they were recovered from different children two years apart. They were also genetically similar to bla_CTX-M-65-positive ± fosA3 isolates obtained from humans and along the poultry production chain in the USA, South America, as well as from humans in several European countries, usually associated with a travel history to America. However, this is the first time that the S. Infantis bla_CTX-M-65 ± fosA3 MDR clone has been reported in Spain.

Analysis of multiple bacterial species and antibiotic classes reveals large variation in the association between seasonal antibiotic use and resistance

Understanding how antibiotic use drives resistance is crucial for guiding effective strategies to limit the spread of resistance, but the use-resistance relationship across pathogens and antibiotics remains unclear. We applied sinusoidal models to evaluate the seasonal use-resistance relationship across 3 species (Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) and 5 antibiotic classes (penicillins, macrolides, quinolones, tetracyclines, and nitrofurans) in Boston, Massachusetts. Outpatient use of all 5 classes and resistance in inpatient and outpatient isolates in 9 of 15 species-antibiotic combinations showed statistically significant amplitudes of seasonality (false discovery rate (FDR) < 0.05). While seasonal peaks in use varied by class, resistance in all 9 species-antibiotic combinations peaked in the winter and spring. The correlations between seasonal use and resistance thus varied widely, with resistance to all antibiotic classes being most positively correlated with use of the winter peaking classes (penicillins and macrolides). These findings challenge the simple model of antibiotic use independently selecting for resistance and suggest that stewardship strategies will not be equally effective across all species and antibiotics. Rather, seasonal selection for resistance across multiple antibiotic classes may be dominated by use of the most highly prescribed antibiotic classes, penicillins and macrolides.

Significance of the presence of antibiotics on the microbial consortium in wastewater - The case of nitrofurantoin and furazolidone

Antibiotics in wastewater leads to migration of pollutants and disrupts natural processes of mineralization of organic matter. In order to understand the mechanism of this, research was undertaken on the influence of nitrofurantoin (NFT) and furazolidone (FZD), on the behaviour of a consortium of microorganisms present in a model wastewater in a bioreactor. Our study confirmed biodegradation of the antibiotics by the microbial consortium, with the degradation efficiency within 10 days of 65% for FZD, but only 20% for NFT. The kinetic study proved that the presence of analysed antibiotics had no adverse effect on the microbes, but the consortium behaviour differ significantly with the NFT reducing the consumption of organic carbon in wastewater and increasing the production of extracellular biopolymeric and volatile organic compounds, and the FZD reducing assimilation of other carbon sources to a less extent, at the expense of cellular focus on biodegradation of this antibiotic.

Prediction of the excited-state reaction channels in photo-induced processes of nitrofurantoin using first-principle calculations and dynamics simulations

The understanding of the photochemistry of antibiotic compounds is important because it gives the direct information on the possible environmental pollution caused by them. Due to their large size, the theoretical studies of their excited-state reactions are rather challenging. In current work, we combined the on-the-fly trajectory surface-hopping dynamics, conical-intersection optimizations and excited-state pathway calculations to study the photochemistry of the trans-isomer of nitrofurantoin, a widely-used drug to treat the urinary tract infections. The dynamics-then-pathway approach was taken. First the trajectory surface hopping dynamics at the state-averaged complete-active-space self-consistent-field (SA-CASSCF) level with small active space and small basis sets were run. Second, the minimum-energy conical-intersection optimizations were performed. Finally the excited pathways from the Frank-Condon region to different reaction channels were built at the multi-state multi-reference second-order perturbation (MS-CASPT2) level with large active space and large basis set. Several possible channels responsible for the photo-induced reaction mechanism of the trans-nitrofurantoin were obtained, including the cleavage of the NO bond of the NO₂ moiety, the photoisomerization at the central CN bond, and other internal conversion channels. Our findings give some preliminary explanations on available experimental observations. It is also demonstrates that the current theoretical approach is a powerful tool to explore the excited-state reactions in the photochemistry of media-sized or large-sized drug compounds.

Flavin oxidation state impacts on nitrofuran antibiotic binding orientation in nitroreductases

Nitroreductases catalyse the NAD(P)H-dependent nitro reduction in nitrofuran antibiotics, which activates them into cytotoxic molecules leading to cell death. The design of new effective nitrofuran antibiotics relies on knowledge of the kinetic mechanism and nitrofuran binding mode of microbial nitroreductases NfsA and NfsB. This has been hampered by multiple co-crystallisation studies revealing ligand binding in non-electron transfer competent states. In a recent study by Day et al. (2021) the authors investigated the likely reaction mechanism and mode of nitrofurantoin binding to NfsA using potentiometry, global kinetics analysis, crystallography and molecular dynamics simulations. Their findings suggest nitrofurantoin reduction proceeds via a direct hydride transfer from reduced FMN, while the crystallographic binding orientation is an inhibitory complex. Molecular dynamics simulations suggest ligand binding orientations is dependent on the oxidation state of the FMN. This study highlights the importance of utilising computational studies alongside traditional crystallographic approaches, when multiple stable ligand binding orientations can occur.

Effects of environmental factors on nitrofurantoin photolysis in water and its acute toxicity assessment

Pharmaceuticals have special attention of researchers over the world due to their possible effect on the environment and humans. This paper focuses on the photolysis of nitrofurantoin in different water matrices. Nitrofurantoin photodegradation has been indicated as a pseudo-first order photoreaction. The indirect photodegradation rate of nitrofurantoin (river water, k₁ = 0.0088 min^-1 and synthetic wastewater, k₁ = 0.0154 min^-1) was slower than its direct photolysis rate (ultrapure water, k₁ = 0.0176 min^-1). The highest value of quantum yield of nitrofurantoin photodegradation (ϕ = 0.2047) was observed at pH = 4, while at higher pH-values it decreased. Furthermore, the mechanism of nitrofurantoin photodegradation is proposed. Heterocyclic ring opening and further hydrolysis, nucleophilic aromatic photosubstitution and homolytic N-N bond cleavage are suggested as three main initial processes of nitrofurantoin photodegradation. Acute toxicity study of nitrofurantoin and its photoproducts with regard to luminescence inhibition of Vibrio fischeri showed that the toxic effect of nitrofurantoin (EC₅₀ = 4.0 mg L^-1) decreases by photolysis.

The structures of E. coli NfsA bound to the antibiotic nitrofurantoin; to 1,4-benzoquinone and to FMN

NfsA is a dimeric flavoprotein that catalyses the reduction in nitroaromatics and quinones by NADPH. This reduction is required for the activity of nitrofuran antibiotics. The crystal structure of free Escherichia coli NfsA and several homologues have been determined previously, but there is no structure of the enzyme with ligands. We present here crystal structures of oxidised E. coli NfsA in the presence of several ligands, including the antibiotic nitrofurantoin. Nitrofurantoin binds with the furan ring, rather than the nitro group that is reduced, near the N5 of the FMN. Molecular dynamics simulations show that this orientation is only favourable in the oxidised enzyme, while potentiometry suggests that little semiquinone is formed in the free protein. This suggests that the reduction occurs by direct hydride transfer from FMNH⁻ to nitrofurantoin bound in the reverse orientation to that in the crystal structure. We present a model of nitrofurantoin bound to reduced NfsA in a viable hydride transfer orientation. The substrate 1,4-benzoquinone and the product hydroquinone are positioned close to the FMN N5 in the respective crystal structures with NfsA, suitable for reaction, but are mobile within the active site. The structure with a second FMN, bound as a ligand, shows that a mobile loop in the free protein forms a phosphate-binding pocket. NfsA is specific for NADPH and a similar conformational change, forming a phosphate-binding pocket, is likely to also occur with the natural cofactor.

A Combined Experimental and Theoretical Study of Nitrofuran Antibiotics: Crystal Structures, DFT Computations, Sublimation and Solution Thermodynamics

Single crystal of furazolidone (FZL) has been successfully obtained, and its crystal structure has been determined. Common and distinctive features of furazolidone and nitrofurantoin (NFT) crystal packing have been discussed. Combined use of QTAIMC and Hirshfeld surface analysis allowed characterizing the non-covalent interactions in both crystals. Thermophysical characteristics and decomposition of NFT and FZL have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and mass-spectrometry. The saturated vapor pressures of the compounds have been measured using the transpiration method, and the standard thermodynamic functions of sublimation were calculated. It was revealed that the sublimation enthalpy and Gibbs energy of NFT are both higher than those for FZL, but a gain in the crystal lattice energy of NFT is leveled by an entropy increase. The solubility processes of the studied compounds in buffer solutions with pH 2.0, 7.4 and in 1-octanol was investigated at four temperatures from 298.15 to 313.15 K by the saturation shake-flask method. The thermodynamic functions of the dissolution and solvation processes of the studied compounds have been calculated based on the experimental data. Due to the fact that NFT is unstable in buffer solutions and undergoes a solution-mediated transformation from an anhydrate form to monohydrate in the solid state, the thermophysical characteristics and dissolution thermodynamics of the monohydrate were also investigated. It was demonstrated that a combination of experimental and theoretical methods allows performing an in-depth study of the relationships between the molecular and crystal structure and pharmaceutically relevant properties of nitrofuran antibiotics.

Nitrofurazone repurposing towards design and synthesis of novel apoptotic-dependent anticancer and antimicrobial agents: Biological evaluation, kinetic studies and molecular modeling

Drug repurposing has gained much attention as a cost-effective strategy that plays an exquisite role in identifying undescribed biological activities in clinical drugs. In the present work, we report the repurposing of the antibacterial drug nitrofurazone (NFZ) as a potential anticancer agent against CaCo-2, MDA-MB 231 and HepG-2 cancer cell lines. Novel series of nitrofurazone analogs were then designed considering the important pharmacologic features present in NFZ. Synthesis and biological evaluation of the target compounds revealed their promising anticancer activities endowed with antimicrobial potential and possessing better lipophilicity than NFZ. Compound 7, exclusively, inhibited the growth of all tested cancer cells more potently than NFZ with the least cytotoxicity against normal cells, displaying anti Gram-positive bacterial activities and antifungal potential. Analysis of the stereo-electronic properties of compound 7 via investigating the energies of HOMO, LUMO, HOMO-LUMO energy gap and MEP maps demonstrated its high reactivity and the expected molecular mechanism of action through reduction of the 5-nitrofuryl moiety. Data of the bioactivity studies indicated that the potent anticancer activity of 7 is mainly through increasing intracellular ROS levels and induction of apoptosis via significantly down-regulating the expression of Bcl-2 while up-regulating BAX, p53 and caspase 3 expression levels. Compound 7 potently inhibited the cellular expression levels of antioxidant enzymes GPx1 and GR compared to NFZ. Antioxidant enzymes kinetic studies and blind molecular docking simulations disclosed the mechanistic and structural aspects of the interaction between 7 and both GR and GPx1. Thus, the successful discovery of 7 as a potential dual anticancer-antimicrobial nitrofurazone analog might validate the applicability of drug repurposing strategy in unravelling the unrecognized bioactivity of the present conventional drugs, besides furnishing the way towards more optimization and development studies.

Evaluation of trypanocidal properties of ferrocenyl and cyrhetrenyl N-acylhydrazones with pendant 5-nitrofuryl group

Four N-acylhydrazones of general formulae [R¹-C(O)-NH-N=C(R²)(5-nitrofuryl)] with (R¹ = ferrocenyl or cyrhetrenyl and R² = H or Me) are synthesized and characterized in solution and in the solid-state. Comparative studies of their stability in solution under different experimental conditions and their electrochemical properties are reported. NMR studies reveal that the four compounds are stable in DMSO‑d₆ and complementary UV-Vis studies confirm that they also exhibit high stability in mixtures DMSO:H₂O at 37 °C. Electrochemical studies show that the half-wave potential of the nitro group of the N-acylhydrazones is smaller than that of the standard drug nifurtimox and the reduction process follows a self-protonation mechanism. In vitro studies on the antiparasitic activities of the four complexes and the nifurtimox against Trypanosoma cruzi and Trypanosoma brucei reveal that: i) the N-acylhydrazones have a potent inhibitory growth activity against both parasites [EC₅₀ in the low micromolar (in T. cruzi) or even in the nanomolar (in T. brucei) range] and ii) cyrhetrenyl derivatives are more effective than their ferrocenyl analogs. Parallel studies on the L₆ rat skeletal myoblast cell line have also been conducted, and the selectivity indexes determined. Three of the four N-acylhydrazones showed higher selectivity towards T. brucei than the standard drug nifurtimox. Additional studies suggest that the organometallic compounds are bioactivated by type I nitroreductase enzymes.

Metabolites Potentiate Nitrofurans in Nongrowing Escherichia coli

Nitrofurantoin (NIT) is a broad-spectrum bactericidal antibiotic used in the treatment of urinary tract infections. It is a prodrug that once activated by nitroreductases goes on to inhibit bacterial DNA, RNA, cell wall, and protein synthesis. Previous work has suggested that NIT retains considerable activity against nongrowing bacteria. Here, we have found that Escherichia coli grown to stationary phase in minimal or artificial urine medium is not susceptible to NIT. Supplementation with glucose under conditions where cells remained nongrowing (other essential nutrients were absent) sensitized cultures to NIT. We conceptualized NIT sensitivity as a multi-input AND gate and lack of susceptibility as an insufficiency in one or more of those inputs. The inputs considered were an activating enzyme, cytoplasmic abundance of NIT, and reducing equivalents required for NIT activation. We systematically assessed the contribution of each of these inputs and found that NIT import and the level of activating enzyme were not contributing factors to the lack of susceptibility. Rather, evidence suggested that the low abundance of reducing equivalents is why stationary-phase E. coli are not killed by NIT and catabolites can resensitize those cells. We found that this phenomenon also occurred when using nitrofurazone, which established generality to the nitrofuran antibiotic class. In addition, we observed that NIT activity against stationary-phase uropathogenic E. coli (UPEC) could also be potentiated through metabolite supplementation. These findings suggest that the combination of nitrofurans with specific metabolites could improve the outcome of uncomplicated urinary tract infections.

Ultrasonic assisted functionalization of MWCNT and synergistic electrocatalytic effect of nano-hydroxyapatite incorporated MWCNT-chitosan scaffolds for sensing of nitrofurantoin

In the present work, we report the fabrication of stable composite of chitosan hydrogels (CHI) on multiwalled carbon nanotubes (MWCNT) using a simple ultrasonic-assisted method. Also, rod-like hydroxyapatite nanoparticles (HA NPs) were synthesised using a hydrothermal route and were incorporated into the highly conductive MWCNT-CHI scaffolds using an ultrasonication method. The functionalization of MWCNT and preparation of HA NPs on MWCNT-CHI nanocomposite were done using the sonication over the frequency of 37 kHz with the ultrasonic power capable of 150 W (Elmasonic Easy 60H bath sonicator). The resulting hybrid HA NPs/MWCNT-CHI nanocomposites have an excellent surface area and high surface to volume ratio, which leads to the sensitive detection of nitrofurantoin than pristine MWCNT and HA NPs. The complete elemental and morphological analyses of the HA NPs/MWCNT-CHI nanocomposites were characterised by XRD, FTIR, RAMAN, FESEM, TEM, EDX, and elemental mapping techniques. Electrochemical analysis of the HA NPs/MWCNT-CHI nanocomposites was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry methods. The modified glassy carbon electrode (GCE) of HA NPs/MWCNT-CHI nanocomposites exhibit the nitrofurantoin detection activity at the linear range of 0.005-982.1 µM with the detection limit of 1.3 nM. The synergistic electrocatalytic activity of HA NPs/MWCNT-CHI nanocomposites modified GCE is correlated to the sensitivity of 0.16 µAµM^-1 cm^-2 with excellent precision and accuracy towards the sensing of nitrofurantoin.

Antibacterial Prodrugs to Overcome Bacterial Resistance

Bacterial resistance to present antibiotics is emerging at a high pace that makes the development of new treatments a must. At the same time, the development of novel antibiotics for resistant bacteria is a slow-paced process. Amid the massive need for new drug treatments to combat resistance, time and effort preserving approaches, like the prodrug approach, are most needed. Prodrugs are pharmacologically inactive entities of active drugs that undergo biotransformation before eliciting their pharmacological effects. A prodrug strategy can be used to revive drugs discarded due to a lack of appropriate pharmacokinetic and drug-like properties, or high host toxicity. A special advantage of the use of the prodrug approach in the era of bacterial resistance is targeting resistant bacteria by developing prodrugs that require bacterium-specific enzymes to release the active drug. In this article, we review the up-to-date implementation of prodrugs to develop medications that are active against drug-resistant bacteria.

A Series of Furan-based Hydrazones: Design, Synthesis, and Evaluation of Antimicrobial Activity, Cytotoxicity and Genotoxicity

Background:

Hydrazones, frequently occurring motifs in many bioactive molecules, have attracted a great deal of interest as potent antimicrobial agents.

Objective:

The aim of this work was to design and synthesize new hydrazone-based antimicrobial agents.

Methods:

4-[2-((5-Arylfuran-2-yl)methylene)hydrazinyl]benzonitrile derivatives (1-10) were obtained via the reaction of 4-cyanophenylhydrazine hydrochloride with 5-arylfurfurals. Compounds 1-10 were evaluated for their antimicrobial effects using a broth microdilution method. Their cytotoxic effects on NIH/3T3 mouse embryonic fibroblast cell line were determined using XTT assay. The most effective antimicrobial agents were investigated for their genotoxic effects using Ames MPF assay. In silico docking and Absorption, Distribution, Metabolism and Excretion (ADME) studies were also performed using Schrödinger’s Maestro molecular modeling package.

Results:

The antifungal effects of the compounds were more significant than their antibacterial effects. Compound 5 bearing 3-nitrophenyl moiety was the most potent antifungal agent against Candida albicans, Trichoderma harzianum and Fusarium species, whereas compound 10 bearing 4- chloro-2-nitrophenyl moiety was the most effective antifungal agent on Aspergillus ochraceus. According to XTT and Ames MPF assays, these compounds were neither cytotoxic nor genotoxic at the concentrations tested. Docking studies suggested that these compounds showed good affinity to the active site of lanosterol 14α-demethylase (CYP51) (PDB code: 5V5Z) and interacted with the key residues such as Hem601 and Cys470. Based on in silico ADME studies, the compounds are expected to have high oral bioavailability.

Conclusion:

According to the in vitro and in silico studies, compounds 5 and 10 stand out as potential orally bioavailable antifungal agents for further studies.

4-Hydroxy-3-methylbenzofuran-2-carbohydrazones as novel LSD1 inhibitors

Histone lysine specific demethylase 1 (LSD1 or KDM1A) is a potential therapeutic target in oncology due to its overexpression in various human tumors. We report herein a new class of benzofuran acylhydrazones as potent LSD1 inhibitors. Among the 31 compounds prepared, 14 compounds exhibited excellent LSD1 inhibitory activity with IC₅₀ values ranging from 7.2 to 68.8 nM. In cellular assays, several compounds inhibited the proliferations of various cancer cell lines, including PC-3, MCG-803, U87 MG, PANC-1, HT-29 and MCF-7. This opens up the opportunity for further optimization and investigation of this class compounds for potential cancer treatment.

Antimicrobial Agents and Urinary Tract Infections

Urinary Tract Infections (UTIs); second-ranking infectious diseases are regarded as a significant global health care problem. The UTIs annually cost tens of millions of dollars for governments worldwide. The main reason behind these costs is incorrect or indefinite treatment. There are a wide range of gram-negative and grampositive bacteria which may cause UTIs in males and females, children and adults. Among gram-negative bacteria, some members of Enterobacteriaceae such as Escherichia coli (E.coli) strains have significant contribution in UTIs. Uropathogenic E.coli (UPEC) strains are recognized as typical bacterial agents for UTIs. Thus, sharp and accurate diagnostic tools are needed for detection and identification of the microbial causative agents of UTIs. In parallel with the utilization of suitable diagnostic methods-to reduce the number of UTIs, effective and definite treatment procedures are needed. Therefore, the prescription of accurate, specific and effective antibiotics and drugs may lead to a definite treatment. However, there are many cases related to UTIs which can be relapsed. Due to a diversity of opportunistic and pathogenic causative microbial agents of UTIs, the treatment procedures should be achieved by the related antimicrobial agents. In this review, common and effective antimicrobial agents which are often prescribed for UTIs caused by UPEC will be discussed. Moreover, we will have a sharp look at their (antimicrobials) molecular treatment mechanisms.

Single-step synthesis and in vitro anti-mycobacterial activity of novel nitrofurantoin analogues

The emergence of drug-resistant tuberculosis (DR-TB) as well as the requirement for long, expensive and toxic drug regimens impede efforts to control and eliminate TB. Therefore, there's a need for effective and affordable anti-mycobacterial agents which can shorten the duration of therapy and are active against Mycobacterium tuberculosis (Mtb) in both active and latent phases. Nitrofurantoin (NFT) is a hypoxic agent with activity against a myriad of anaerobic pathogens and, like the first-line TB drug, rifampicin (RIF), kills non-replicating bacilli. However, the poor ability of NFT to cross host cell membranes and penetrate tissue means that it does not reach therapeutic concentrations. To improve TB efficacy of NFT, a series of NFT analogues was synthesized and evaluated in vitro for anti-mycobacterial activity against the laboratory strain, Mtb H37Rv, and for potential cytotoxicity using human embryonic kidney (HEK-293) and Chinese hamster ovarian (CHO) cells. The NFT analogues showed good safety profiles, enhanced anti-mycobacterial potency, improved lipophilicity, as well as reduced protein binding affinity. Analogue 9 which contains an eight carbon aliphatic chain was the most active, equipotent to isoniazid (INH), a major front-line agent, with MIC₉₀ = 0.5 μM, 30-fold more potency than the parent drug, nitrofurantoin (MIC₉₀ = 15 μM), and 100-fold more selective towards mycobacteria. Therefore, 9 was identified as a validated hit for further investigation in the urgent search for new, safe and affordable TB drugs.

Efflux pumps AcrAB and OqxAB contribute to nitrofurantoin resistance in an uropathogenic Klebsiella pneumoniae isolate

Klebsiella pneumoniae is a common cause of urinary tract infections (UTIs). Nitrofurantoin (NIT), with high therapeutic concentrations in urine, is recommended as the first-line drug for both empiric treatment and chemoprophylaxis of UTIs. Although NIT resistance in K. pneumoniae is relatively high, the resistance mechanism is not well understood. This study collected a NIT-resistant K. pneumoniae [NRKP, minimum inhibitory concentration (MIC)=128 mg/L] and investigated the resistance mechanism. Addition of efflux pump inhibitors increased the susceptibility of NRKP to NIT (MIC decreased from 128 to 32 mg/L), implying the important role of efflux pumps in NIT resistance. Quantitative reverse transcriptase polymerase chain reaction analysis showed that NRKP had >100-fold increased expression of ramA, which was demonstrated to be caused by ramR mutation. Deletion of ramA led to a four-fold decrease in the MIC of NIT, and the expression levels of efflux pumps acrB and oqxB were downregulated by four- to seven-fold. Complementation of ramA restored both the MIC value and the expression level of acrB and oqxB in the ramA mutant strain. In order to confirm the role of acrB and oqxB in NIT resistance, gene knockout strains were constructed. Deletion of acrB or oqxB alone led to a four-fold decrease in the MIC of NIT, and deletion of acrB and oqxB simultaneously led to a 16-fold decrease in the MIC of NIT. These results demonstrate that AcrAB and OqxAB contribute to NIT resistance in K. pneumoniae.

From enabling technologies to medicinal mechanochemistry: an eco-friendly access to hydantoin-based active pharmaceutical ingredients

The sustainable preparation of hydantoin-based Active Pharmaceutical Ingredients (APIs) using modern non-conventional activation methods, including mechanochemistry is herein described.

Naphthoylhydrazones: coordination to metal ions and biological screening

V^IVO, Cu^II and Zn^II complexes from three new naphthoylhydrazones were screened towards their ability to bind albumin and their cytotoxicity.

Outpatient Antibiotic Consumption for Urinary Infections in Croatia 2005 - 2014: What can be Learned from Utilization Trends

AIM

The aim of this study was to determine quantities of antibiotics used mainly or exclusively for urinary tract infections in Croatia between 2005 and 2014, to describe utilisation trends, and general consequences of antibiotic consumption on antimicrobial resistance.

METHODS

Antibiotic utilisation data were obtained from annual reports of both the Croatian Drug Agency and Croatian Academy of Medical Sciences. Antibiotic consumption was expressed in DDD/1000 inhabitants/day (DDD TID). Antimicrobial resistance was analysed for E. coli, E. faecalis, E. faecium, P. aeruginosa, Klebsiella spp., P. mirabilis. Descriptive statistics were used to process data and calculate trends.

RESULTS

Overall, utilisation of antibacterials decreased by 4.8% (from 3,35 to 3,19 DDD TID), while trends of individual agents varied substantially - from 87% decline for ceftibuten to 160% rise for levofloxacin. The consumption of quinolones increased by 32.3%. This was mostly due to increased ciprofloxacin consumption (144% raise). Sulfamethoxazole-trimethoprim declined by 57%, while nitrofurantoin increased by 86%. The use of fosfomycin was marginal. Antimicrobial resistance of E. coli increased against quinolones by 54.5%, and against nitrofurantoin by 2-3%. Quinolone resistance of other pathogens (Klebiella spp, Proteus mirabilis), increased variably - between 17.2% (Klebsiella) and 90% (Proteus), while for P. aeruginosa remained the same at 22%.

CONCLUSION

High rates of antimicrobial utilisation require prescribing restrictions and educational interventions. The increased use of fluoroquinolones is a potentially serious public health threat due to the rapid development of resistance among uropathogens. This threat can be avoided by greater use of nitrofurantoin and fosfomycin.

Comparison of the loads and antibiotic-resistance profiles of Enterococcus species from conventional and organic chicken carcasses in South Korea

Antibiotic-resistant bacteria in poultry meat are a threat to public health. In this study, we compared the Enterococcus spp. loads and antibiotic-resistance profiles between carcasses of conventionally and organically raised chickens. A total of 144 chicken carcasses (72 conventional and 72 organic) was collected from local retail markets in Seoul, South Korea. Overall, 77.7% (112 of 144; 75% conventional and 80% organic) of chicken carcasses were positive for Enterococcus. The mean loads of Enterococcus spp. were greater in conventional chicken carcasses, at 2.9 ± 0.4 log CFU/mL, than those in organic chicken carcasses, at 1.78 ± 0.3 log CFU/mL (p < 0.05). A total of 104 isolates (52 from conventional and 52 from organic chicken carcasses) was randomly selected for further analysis. The predominant species was Enterococcus faecalis in both conventional and organic chicken carcasses (57.7 and 76.9%, respectively; P > 0.05). Rates of resistance to ciprofloxacin and erythromycin, which are used in veterinary medicine in South Korea, were significantly higher in conventional chicken carcasses than in organic chicken carcasses. However, we found no difference between the rates of resistance to antibiotics such as vancomycin and tigecycline, which were not registered for use in veterinary medicine in South Korea, of Enterococcus isolates from conventional and organic chicken carcasses. In addition, although multidrug resistant isolates were obtained from both types of chicken samples, the prevalence of samples positive for Enterococcus was significantly higher in conventional chicken carcasses than in organic chicken carcasses (P < 0.05). The most common multidrug resistance pattern was erythromycin-tetracycline-rifampicin in conventional chicken carcasses and quinupristin-dalfopristin-tetracycline-rifampicin in organic chicken carcasses. A high level of gentamicin resistance was observed in isolates from not only conventional (5.8%) but also organic chicken (1.9%) carcasses, with no significant difference in rates between them (P > 0.05). Despite this, our results suggest that organic food certification is effective in reducing fecal contamination and the burden of antibiotic-resistant Enterococcus spp. in chicken carcasses.

Emerging medical and engineering strategies for the prevention of long-term indwelling catheter blockage

Urinary catheters have been used on an intermittent or indwelling basis for centuries, in order to relieve urinary retention and incontinence. Nevertheless, the use of urinary catheters in the clinical setting is fraught with complication, the most common of which is the development of nosocomial urinary tract infections, known as catheter-associated urinary tract infections. Infections of this nature are not only significant owing to their high incidence rate and subsequent economic burden but also to the severe medical consecutions that result. A range of techniques have been employed in recent years, utilising various technologies in attempts to counteract the perilous medical cascade following catheter blockage. This review will focus on the current advancement (within the last 10 years) in prevention of encrustation and blockage of long-term indwelling catheters both from engineering and medical perspectives, with particular emphasis on the importance of stimuli-responsive systems.

Nitrofurantoin hydrolytic degradation in the environment

Occurrence of pharmaceuticals, especially antibiotics in the environment increased attention to their environmental fate. Hydrolysis is one of two abiotic processes by which compounds are degraded in the environment. According to authors knowledge this is the first study investigating hydrolytic degradation of nitrofurantoin at pH-values normally found in the environment. Nitrofurantoin hydrolytic degradation appeared to be much slower at acidic (pH 4) solution compared to neutral (pH 7) and alkaline (pH 9) solutions at all three investigated temperatures (20 °C, 40 °C and 60 °C). In all cases nitrofurantoin hydrolysis followed the first-order kinetics with half-lives ranged from 0.5 days at pH 9 and 60 °C to 3.9 years at pH 4 and 20 °C. Temperature dependence of the hydrolysis rate constant was quantified by Arrhenius equation; obtained E_a values were as follows: 100.7 kJ mol^-1 at pH 4, 111.2 kJ mol^-1 at pH 7 and 102.3 kJ mol^-1 at pH 9. Increase in hydrolysis rate constants for each 10 °C increase in temperature were 3.4, 3.9 and 3.5 at pH 4, pH 7 and pH 9, respectively. The structures of hydrolytic degradation products were determined and degradation pathways were suggested. Three main processes occurred depending on pH-values: protonation of the nitrofurantoin followed by cleavage of the NN single bond, heterocyclic non-aromatic ring cleavage, and reduction of the non-aromatic heterocyclic ring.

Diagnosis, Treatment, and Prevention of Urinary Tract Infection

UTI may involve the lower or upper urinary tract and may be uncomplicated or complicated. The emphasis of this chapter is uncomplicated UTI. The diagnosis of uncomplicated cystitis (bladder infection) and pyelonephritis (kidney infection) is usually easily made based on the clinical presentation, whereas the diagnosis in patients with complicated UTI is often more complex. Thus uncomplicated cystitis is usually manifested by dysuria, frequency and/or urgency without fever, and pyelonephritis is usually manifested by fever and back pain/costovertebral angle tenderness. However, pyuria is usually present with UTI, regardless of location, and its absence suggests that another condition may be causing the patient's symptoms. Treatment of cystitis is usually straightforward with one of several effective short-course antimicrobial regimens, although antimicrobial resistance continues to increase and can complicate treatment choices in certain areas. Likewise, antimicrobial resistance has complicated our management of uncomplicated pyelonephritis since resistance of uropathogens to the fluoroquinolone class, the mainstay of oral treatment for pyelonephritis, is increasing worldwide, and some of the other agents used for cystitis are not recommended for pyelonephritis due to low tissue levels. The goal of prevention of recurrent cystitis is to minimize the use of antimicrobials and there are several research efforts in progress to develop effective and safe antimicrobial-sparing preventive approaches for this common condition.

Revisiting Nitrofurantoin for Vancomycin Resistant Enterococci

INTRODUCTION

Enterococcal infection has emerged as a major therapeutic challenge. Emergence of High Level Aminoglycoside Resistance (HLAR) and Vancomycin-Resistant Enterococcus (VRE) has further limited the drug therapy in enterococcal infections. However, nitrofuratoin being an old drug reported to have less resistance in comparison to the other classes of antimicrobial agents.

AIM

To detect susceptibility of nitrofurantoin against VRE isolates from Urinary Tract Infection (UTI) of outdoor and indoor patient departments.

MATERIALS AND METHODS

An observational study was carried out at a tertiary care hospital in New Delhi over a period of six months (from November 2015 to April 2016). A total of 14,714 urine samples were collected and processed from the patients symptomatic for UTI. The enterococcal isolates were identified and confirmed by standard phenotypic tests. The antimicrobial susceptibility tests of isolated organisms were performed by Kirby-Bauer Disc Diffusion Method as per Clinical and Laboratory Standards Institute (CLSI) 2015 guidelines. The Wilcoxon rank-sum (Mann-Whitney) test was used to compare continuous variables. Chi-square or Fisher's exact tests were used to compare categorical variables. p<0.05 was considered as significant.

RESULTS

A total of 70 enterococci species {Enterococcus faecalis (n=9), Enterococcus faecium, (n=61)} were isolated. Twenty six out of 70 isolates were observed resistant to vancomycin. Among 26 VRE, 21(80.76%) were susceptible to nitrofurantoin. Both the species {E. faecalis (80.32%) and E. faecium (88.8%)} were uniformly susceptible to nitrofurantoin.

CONCLUSION

Nitrofurantoin has retained antimicrobial efficacy against emerging VRE in vitro and can be used for treatment of enterococcal urinary tract infections.

Light induced cytotoxicity of nitrofurantoin toward murine melanoma

The cytotoxicity of nitrofurantoin (NFT) in the dark and after light exposure (UVA irradiation, λ = 385 nm) was evaluated in murine melanoma B16F10 cells. NFT induces both cell proliferation and inhibition of cell viability. The dominance of one or the other effect depends on the drug concentration, incubation time (t_inc) and irradiation dose. The uptake of NFT in these cells, as well as its photocytotoxicity, reaches saturation after 24 hours of incubation. The mechanism of cell death in the dark is associated with the enzymatic release of nitric oxide (NO). The increase of NFT cytotoxicity under light irradiation is associated with the increase of NO concentration due to photorelease. NO photorelease by NFT in solution was confirmed by chemiluminescence, while NO formation in cells was confirmed by fluorescence microscopy using DAF-2DA, a specific indicator of NO in living cells. The NFT does not enter nuclei, distributing preferentially in the cell cytoplasm, as shown by fluorescence microscopy.

Incidence and Genetic Bases of Nitrofurantoin Resistance in Clinical Isolates of Two Successful Multidrug-Resistant Clones of Salmonella enterica Serovar Typhimurium: Pandemic "DT 104" and pUO-StVR2

In this study, the incidence and genetic bases of nitrofurantoin resistance were established for clinical isolates of two successful clones of Salmonella enterica serovar Typhimurium, the pandemic "DT 104" and the pUO-StVR2 clone. A total of 61 "DT 104" and 40 pUO-StVR2 isolates recovered from clinical samples during 2008-2014 and assigned to different phage types, were tested for nitrofurantoin susceptibility. As previously shown for older isolates, all newly tested pUO-StVR2 isolates were highly resistant to nitrofurantoin (minimal inhibitory concentration [MIC] of 128 μg/ml), while 42.6%, 24.6%, and 32.8% of the "DT 104" isolates were susceptible, showed intermediate resistance or were highly resistant, with MICs of 8, 64, and 128 μg/ml, respectively. The genetic bases of nitrofurantoin resistance were established by PCR amplification and sequencing of the nfsA and nfsB genes encoding oxygen-insensitive nitroreductases. pUO-StVR2 isolates shared identical alterations in both nfsA (IS1 inserted into the coding region) and nfsB (in frame duplication of two codons). "DT 104" isolates with intermediate or high resistance had a missense mutation affecting the start codon of nfsA, while a single resistant isolate carried an additional frameshift mutation affecting nfsB. Complementation studies, performed with wild-type nfsA and nfsB, cloned independently and together into low and high copy-number vectors, confirmed NfsA and NfsB as responsible for nitrofurantoin toxicity. The same alterations persisted along time in isolates of each clone belonging to different phage types. Accordingly, changes leading to nitrofurantoin resistance have probably occurred before phage type diversification.

Application of Targeted Molecular and Material Property Optimization to Bacterial Attachment-Resistant (Meth)acrylate Polymers

Developing medical devices that resist bacterial attachment and subsequent biofilm formation is highly desirable. In this paper, we report the optimization of the molecular structure and thus material properties of a range of (meth)acrylate copolymers which contain monomers reported to deliver bacterial resistance to surfaces. This optimization allows such monomers to be employed within novel coatings to reduce bacterial attachment to silicone urinary catheters. We show that the flexibility of copolymers can be tuned to match that of the silicone catheter substrate, by copolymerizing these polymers with a lower Tg monomer such that it passes the flexing fatigue tests as coatings upon catheters, that the homopolymers failed. Furthermore, the Tg values of the copolymers are shown to be readily estimated by the Fox equation. The bacterial resistance performance of these copolymers were typically found to be better than the neat silicone or a commercial silver containing hydrogel surface, when the monomer feed contained only 25 v% of the "hit" monomer. The method of initiation (either photo or thermal) was shown not to affect the bacterial resistance of the copolymers. Optimized synthesis conditions to ensure that the correct copolymer composition and to prevent the onset of gelation are detailed.

Digital Quantification of DNA Replication and Chromosome Segregation Enables Determination of Antimicrobial Susceptibility after only 15 Minutes of Antibiotic Exposure

Rapid antimicrobial susceptibility testing (AST) would decrease misuse and overuse of antibiotics. The "holy grail" of AST is a phenotype-based test that can be performed within a doctor visit. Such a test requires the ability to determine a pathogen's susceptibility after only a short antibiotic exposure. Herein, digital PCR (dPCR) was employed to test whether measuring DNA replication of the target pathogen through digital single-molecule counting would shorten the required time of antibiotic exposure. Partitioning bacterial chromosomal DNA into many small volumes during dPCR enabled AST results after short exposure times by 1) precise quantification and 2) a measurement of how antibiotics affect the states of macromolecular assembly of bacterial chromosomes. This digital AST (dAST) determined susceptibility of clinical isolates from urinary tract infections (UTIs) after 15 min of exposure for all four antibiotic classes relevant to UTIs. This work lays the foundation to develop a rapid, point-of-care AST and strengthen global antibiotic stewardship.

Advantage and limitations of nitrofurantoin in multi-drug resistant Indian scenario

Infections caused by antibiotic resistant pathogens are of significant concern and are associated with higher mortality and morbidity. Nitrofurantoin is a broad-spectrum bactericidal antibiotic and is effectively used to treat urinary tract infections (UTIs) caused by E. coli, Klebsiella sp., Enterobacter sp., Enterococcus sp. and Staphylococcus aureus. It interfere with the synthesis of cell wall, bacterial proteins and DNA of both Gram positive and Gram negative pathogens. Nitrofurantoin has been used successfully for treatment and prophylaxis of acute lower urinary tract infections. With the emergence of antibiotic resistance, nitrofurantoin has become the choice of agent for treating UTIs caused by multi-drug resistant pathogens.