Levofloxacin : a review of its use as a high-dose, short-course treatment for bacterial infection

Identification of CH2-linker modified desfluoroquinolone-aminopyrimidine hybrids to combat antibiotic-resistant gram-positive bacteria

The increasing prevalence of antibiotic-resistant bacterial infections has emerged as a major public health crisis, necessitating an urgent need for the development of new antimicrobial agents. In this manuscript, structural modifications were conducted on the CH2 linker of the antibacterial desfluoroquinolone-aminopyrimidine hybrids that we had previously obtained, resulting in compounds A7, B1, and D6. These three compounds exhibited potent activity against a panel of antibiotic-resistant Gram-positive bacteria, including fluoroquinolone-resistant Staphylococcus aureus, linezolid-resistant Staphylococcus aureus, vancomycin-intermediate Staphylococcus aureus (VISA), and vancomycin-resistant Enterococcus faecium. Particularly, despite their structural similarity to classical quinolones, compounds A7, B1, and D6 exhibited no cross-resistance with ciprofloxacin. Additionally, the difluorinated CH2-linker modified compound demonstrated enhanced metabolic stability. These promising results encourage us to move forward to the next phase of structural optimization, with a specific focus on reducing mammalian cytotoxicity.

Access to Chiral Dihydro-1,4-Benzoxazine-2-Carboxylates through NHC-Catalyzed Dynamic Kinetic Resolution

A chiral carbene-catalyzed dynamic kinetic resolution for the facile synthesis of enantioenriched dihydro-1,4-benzoxazine-2-carboxylates is disclosed. The reaction conditions are mild, and a diversity of substituents are well-tolerated in this transformation. In addition, our methodology also provides an efficient strategy for building chiral chromane-2-carboxylate and 2,3-dihydro-1,4-benzodioxane-2-carboxylate. The optically pure products generated from this protocol can be easily derived as the key intermediates of chiral drugs and bioactive molecules.

Carbon dots derived from organic drug molecules with improved therapeutic effects and new functions

Carbon dots (CDs) are new types of fluorescent nanomaterials with particle diameters of 1∼10 nm and have excellent photoluminescence (PL) properties, good biocompatibility, simple preparation methods and numerous raw materials; consequently, they are promising in the biomedical field. In recent years, to overcome drug resistance and toxic side effects of traditional organic drugs, the synthesis of CDs from drug molecules has become an effective strategy, which produces CDs with the same therapeutic effects as the raw drugs and even possessing new properties. At present, many CDs derived from organic drugs have been developed, which can be classified according to their sources such as antibiotics, anti-inflammatory drugs, and guanidine drugs. This article focuses on the progress of the above-mentioned drug-derived CDs compared with their drug precursors in terms of therapeutic efficacy, enhanced performance and new additional functions, with special attention to the structure-activity relationship between the drug precursors and the CD-based therapeutic agents. It demonstrates the feasibility of designing new drug-derived CDs for clinical applications, summarizes the shortcomings and research gaps of the existing work, and provides a reference for related work in the future.

Change in Diagnosis of Helicobacter pylori Infection in the Treatment-Failure Era

Helicobacter pylori (H. pylori) infection is a prevalent global health issue, associated with several gastrointestinal disorders, including gastritis, peptic ulcers, and gastric cancer. The landscape of H. pylori treatment has evolved over the years, with increasing challenges due to antibiotic resistance and treatment failure. Traditional diagnostic methods, such as the urea breath test, stool antigen test, and endoscopy with biopsy, are commonly used in clinical practice. However, the emergence of antibiotic-resistant strains has led to a decline in treatment efficacy, necessitating a re-evaluation of common diagnostic tools. This narrative review aims to explore the possible changes in the diagnostic approach of H. pylori infection in the era of treatment failure. Molecular techniques, including polymerase chain reaction and whole genome sequencing, which have high sensitivity and specificity, allow the detection of genes associated with antibiotic resistance. On the other hand, culture isolation and a phenotypic antibiogram could be used in the diagnostic routine, although H. pylori is a fastidious bacterium. However, new molecular approaches are promising tools for detecting the pathogen and its resistance genes. In this regard, more real-life studies are needed to reveal new diagnostic tools suitable for identifying multidrug-resistant H. pylori strains and for outlining proper treatment.

Clinical Experience of Using a Combination of Dexamethasone and Levofloxacin After Cataract Surgery

Background

Where routine prophylactic antibiotics have been adopted following cataract surgery, rates of endophthalmitis have been decreasing. Intracameral and topical antibiotics are currently used to prevent endophthalmitis after cataract surgery. When applying topical antibiotics, there are different recommendations on the frequency and duration of therapy. The development of bacterial resistance to the excessive and long-term use of antibiotics is a growing problem worldwide. The goal is to achieve a good antibiotic effect with the shortest possible use of antibiotics.

Objective

The aim of this study was to compare the effectiveness of a new combination therapy of dexamethasone and levofloxacin for seven days after cataract surgery with the previous regimen of dexamethasone, neomycin sulfate, and polymyxin B, which was given for 21 days.

Methods

A retrospective analysis of medical records and administered a questionnaire was conducted to assess the effectiveness of postoperative therapy in our cataract surgery patients. The study involved 52 patients who underwent surgery within the last year, performed by a single surgeon at our institution. The findings can help us improve the quality of care we provide and optimize our patients' overall quality of life.

Results

We conducted an in-depth study on 52 individuals who underwent cataract surgery at our institution. The prescribed therapeutic regimen for the participants included administering Ducressa solution four times daily for the first seven days and Maxidex solution three times daily for the subsequent 14 days. The study found that none of the participants experienced complications after surgery, and all found it easy to instill the medication. The prescribed regimen effectively managed the postoperative recovery of the participants, and the medication was well-tolerated.

Conclusion

Our research found that a new combination of levofloxacin and dexamethasone, when used topically, may require a shorter treatment period, reducing the risk of antibiotic resistance and providing a safe alternative for endophthalmitis prevention.

Synthesis of fungicidal morpholines and isochromenopyridinones via acid-catalyzed intramolecular reactions of isoindolinones

Acid-catalyzed intramolecular cyclization or rearrangement of isoindolinone derivatives is described. 3-Hydroxy/ethoxy-3,4-dihydro-6H-[1,4]-oxazino-[3,4-a]-isoindol-6-ones are obtained in moderate to good yields. Further acid-catalyzed intramolecular rearrangement reactions give 6H-isochromeno-[4,3-b]-pyridin-6-ones. The mild reaction conditions with convenient starting materials show broad substrate scope and provide the target compounds as novel pesticide leads with good fungicidal or systemical acquired resistance activities.

Mucosal Adhesive Chitosan Nanogel Formulations of Antibiotics and Adjuvants (Terpenoids, Flavonoids, etc.) and Their Potential for the Treatment of Infectious Diseases of the Gastrointestinal Tract

Bacterial infections are usually found in the stomach and the first part of the small intestine in association with various pathologies, including ulcers, inflammatory diseases, and sometimes cancer. Treatment options may include combinations of antibiotics with proton pump inhibitors and anti-inflammatory drugs. However, all of them have high systemic exposure and, hence, unfavorable side effects, whereas their exposure in stomach mucus, the predominant location of the bacteria, is limited. Chitosan and nanogels based on chitosan presumably are not absorbed from the gastrointestinal tract and are known to adhere to the mucus. Therefore, they can serve as a basis for the local delivery of antibacterial drugs, increasing their exposure at the predominant location of therapeutic targets, thus improving the risk/benefit ratio. We have used E. coli ATCC 25922 (as a screening model of pathogenic bacteria) and Lactobacilli (as a model of a normal microbiome) to study the antibacterial activity of antibacterial drugs entrapped in a chitosan nanogel. Classical antibiotics were studied in a monotherapeutic regimen as well as in combination with individual terpenoids and flavonoids as adjuvants. It has been shown that levofloxacin (LF) in combination with zephirol demonstrate synergistic effects against E. coli (cell viability decreased by about 50%) and, surprisingly, a much weaker effect against Lactobacilli. A number of other combinations of antibiotic + adjuvant were also shown to be effective. Using FTIR and UV spectroscopy, it has been confirmed that chitosan nanogels with the drug are well adsorbed on the mucosal model, providing prolonged release at the target location. Using an ABTS assay, the antioxidant properties of flavonoids and other drugs are shown, which are potentially necessary to minimize the harmful effects of toxins and radicals produced by pathogens. In vivo experiments (on sturgeon fish) showed the effective action of antibacterial formulations developed based on LF in chitosan nanogels for up to 11 days. Thus, chitosan nanogels loaded with a combination of drugs and adjuvants can be considered as a new strategy for the treatment of infectious diseases of the gastrointestinal tract.

Individualized antibiotic dosage regimens for patients with augmented renal clearance

Objectives: Augmented renal clearance (ARC) is a state of enhanced renal function commonly observed in 30%-65% of critically ill patients despite normal serum creatinine levels. Using unadjusted standard dosing regimens of renally eliminated drugs in ARC patients often leads to subtherapeutic concentrations, poor clinical outcomes, and the emergence of multidrug-resistant bacteria. We summarized pharmaceutical, pharmacokinetic, and pharmacodynamic research on the definition, underlying mechanisms, and risk factors of ARC to guide individualized dosing of antibiotics and various strategies for optimizing outcomes. Methods: We searched for articles between 2010 and 2022 in the MEDLINE database about ARC patients and antibiotics and further provided individualized antibiotic dosage regimens for patients with ARC. Results: 25 antibiotic dosage regimens for patients with ARC and various strategies for optimization of outcomes, such as extended infusion time, continuous infusion, increased dosage, and combination regimens, were summarized according to previous research. Conclusion: ARC patients, especially critically ill patients, need to make individualized adjustments to antibiotics, including dose, frequency, and method of administration. Further comprehensive research is required to determine ARC staging, expand the range of recommended antibiotics, and establish individualized dosing guidelines for ARC patients.

Helicobacter Pylori: A Review of Current Treatment Options in Clinical Practice

BACKGROUND

When prescribing antibiotics, infection eradication rates, local resistance rates, and cost should be among the most essential considerations. Helicobacter pylori is among the most common infections worldwide, and it can lead to burdensome sequela for the patient and the healthcare system, without appropriate treatment. Due to constantly fluctuating resistance rates, regimens must be constantly assessed to ensure effectiveness.

METHODS

This was a narrative review. The sources for this review are as follows: searching on PubMed, Google Scholar, Medline, and ScienceDirect; using keywords: Helicobacter pylori, Treatment Options, Clinical Practice.

RESULTS

Multiple antibiotics are prescribed as part of the regimen to thwart high resistance rates. This can lead to unwanted adverse reactions and adherence issues, due to the amount and timing of medication administration, which also may contribute to resistance. Single-capsule combination capsules have reached the market to ease this concern, but brand-only may be problematic for patient affordability. Due to the previously mentioned factors, effectiveness and affordability must be equally considered.

CONCLUSIONS

This review will utilize guidelines to discuss current treatment options and give cost considerations to elicit the most effective regimen for the patient.

Synthesis of 1,4-benzoxazines via Y(OTf)3-catalyzed ring opening/annulation cascade reaction of benzoxazoles with propargylic alcohols

A convenient Y(OTf)₃-catalyzed cascade formal [4 + 2] cyclization approach for the formation of 1,4-benzoxazine scaffolds from benzoxazoles and propargyl alcohols through a ring-opening and regioselective ring-closure process has been developed. By using this mild and practical protocol, a broad range of aldehyde-containing 1,4-benzoxazine compounds were prepared in moderate to excellent yields with good functional group tolerance. Mechanistic studies indicated that an S_N1 nucleophilic substitution of benzoxazole with a propargyl cation was involved in this transformation.

Levofloxacin-based therapy as an efficient alternative for eradicating Helicobacter pylori infection in Iran: a systematic review and meta-analysis

OBJECTIVES

Despite excessive resistance of Helicobacter pylori to clarithromycin among the Iranian population, clarithromycin-based therapy is still prescribed in Iran. Recent studies have shown high rates of H. pylori eradication in patients treated with levofloxacin. The main purpose of this study was to compare the effect of levofloxacin with clarithromycin on the eradication of H. pylori infection in the Iranian population.

METHODS

A comprehensive meta-analysis was done for relevant cohort studies and clinical trials to compare the therapeutic effects of levofloxacin and clarithromycin in the Iranian population. We pooled the data using odds ratio (OR) and corresponding 95% confidence interval (CI) to determine the clinical efficacy of levofloxacin versus clarithromycin to treat H. pylori infection. Heterogeneity and publication bias were also measured for the included studies.

RESULTS

Thirteen studies were included in the quantitative synthesis. The eradication rate was significantly higher in patients receiving levofloxacin compared with clarithromycin (75.2% vs. 66.3%; OR = 1.76, 95% CI 1.40-2.20). Additionally, in the subgroup analyses it was confirmed that the cure rate was relatively higher in levofloxacin-treated cases. However, there was significant heterogeneity and publication bias, thus the results should be interpreted with caution.

CONCLUSION

We found that the success of levofloxacin treatment was significantly higher than clarithromycin. Therefore, it is suggested that clarithromycin-based triple therapy be replaced by levofloxacin-based triple therapy in countries with high resistance to clarithromycin such as Iran. Nevertheless, the findings of this study need to be approved with a larger investigation on the Iranian population.

Population pharmacokinetics and dose optimization of intravenous levofloxacin in hospitalized adult patients

Although levofloxacin has been used for the last 25 years, there are limited pharmacokinetic data to guide levofloxacin dosing in adult patients. This study aimed to develop a population pharmacokinetic model of levofloxacin for adult hospitalized patients and define dosing regimens that attain pharmacokinetic/pharmacodynamic target associated with maximum effectiveness. Blood samples were drawn from 26 patients during one dosing interval. Population pharmacokinetic modelling and dosign simulations were performed using Pmetrics®. Pathogen minimum inhibition concentration (MIC) distribution data from the European Committee on Antimicrobial Susceptibility Testing database was used to analyse fractional target attainment (FTA). A two-compartment model adequately described the data. The final model included estimated glomerular filtration rate (eGFR) to describe clearance. The population estimate for clearance was 1.12 L/h, while the volume of distribution in the central compartment and peripheral compartments were 27.6 L and 28.2 L, respectively. Our simulation demonstrated that an area under free concentration–time curve to MIC ≥ 80 was hardly achieved for pathogens with MIC ≥ 1 mg/L. Low FTA against Pseudomonas aeruginosa and Streptococcus pneumoniae were observed for patients with higher eGFR (≥ 80 mL/min/1.73m²). A daily levofloxacin dose of 1000 mg is suggested to maximise the likelihood of efficacy for adult patients.

Clinical and Microbiological Efficacy of Adjunctive Systemic Quinolones to Mechanical Therapy in Periodontitis: A Systematic Review of the Literature

OBJECTIVES

To assess the clinical and microbiological efficacy of systemic quinolones adjunctive to mechanical therapy in periodontitis patients. Materials and Methods. A systematic review of the scientific literature was carried out. The search scheme comprised the Scopus, PubMed/MEDLINE, SCIELO (Scientific Electronic Library Online), and LILACS (Literatura Latinoamericana y del Caribe en Ciencias de la Salud) databases, together with the gray literature. MeSH terms and keywords were utilized to explore publications in all idioms. Only randomized clinical trials (RCTs) that met the selection criteria were included.

RESULTS

A total of 4 RCTs were selected. These RCTs found superior clinical and microbiological efficacy of adjunctive systemic moxifloxacin (MOX) and levofloxacin (LV) compared to subgingival debridement plus placebo. Improvements in PD and CAL were 2.4 ± 0.8 mm and 2.7 ± 0.9 mm for LV, and 1.5 ± 0.5 mm and 1.8 ± 0.5 mm for MOX, respectively. After six months of follow-up, adjunctive MOX reduced the presence of Aggregatibacter actinomycetemcomitans to imperceptible levels, while LV markedly reduced this microorganism. Some adverse events were reported in the LV group and none in the MOX group.

CONCLUSIONS

Adjunctive MOX and LV improve probing depth and clinical attachment level compared with subgingival debridement alone in patients with periodontitis. The efficacy of these quinolones against A. actinomycetemcomitans was also superior.

Phenols in Pharmaceuticals: Analysis of a Recurring Motif

Phenols and phenolic ethers are significant scaffolds recurring both in nature and among approved small-molecule pharmaceuticals. This compendium presents the first comprehensive compilation and analysis of the structures of U.S. FDA-approved molecules containing phenol or phenolic ether fragments. This dataset comprises 371 structures, which are strongly represented by natural products. A total of 55 of the compounds described here are on the World Health Organization's list of essential medicines. Structural analysis reveals significant differences in the physicochemical properties imparted by phenols versus phenol ethers, each having benefits and drawbacks for drug developability. Despite trends over the past decade to increase the fraction of sp³ centers in drug leads, thereby "escaping flatland", phenols and phenolic ethers are represented in 62% of small-molecule drugs approved in 2020, suggesting that this aromatic moiety holds a special place in drugs and natural products.

Combination of Amphiphilic Cyclic Peptide [R4W4] and Levofloxacin against Multidrug-Resistant Bacteria

Bacterial resistance is a growing global concern necessitating the discovery and development of antibiotics effective against the drug-resistant bacterial strain. Previously, we reported a cyclic antimicrobial peptide [R4W4] containing arginine (R) and tryptophan (W) with a MIC of 2.67 µg/mL (1.95 µM) against methicillin-resistant Staphylococcus aureus (MRSA). Herein, we investigated the cyclic peptides [R4W4] or linear (R4W4) and their conjugates (covalent or noncovalent) with levofloxacin (Levo) with the intent to improve their potency to target drug-resistant bacteria. The physical mixture of the Levo with the cyclic [R4W4] proved to be significantly effective against all strains of bacteria used in the study as compared to covalent conjugation. Furthermore, the checkerboard assay revealed the significant synergistic effect of the peptides against all studied strains except for the wild type S. aureus, in which the partial synergy was observed. The hemolysis assay revealed less cytotoxicity of the physical mixture of the Levo with [R4W4] (22%) as compared to [R4W4] alone (80%). The linear peptide (R4W4) and the cyclic [R4W4] demonstrated ~90% and 85% cell viability at 300 µg/mL in the triple-negative breast cancer cells (MDA-MB-231) and the normal kidney cells (HEK-293), respectively. Similar trends were also observed in the cell viability of Levo-conjugates on these cell lines. Furthermore, the time-kill kinetic study of the combination of [R4W4] and Levo demonstrate rapid killing action at 4 h for MRSA (ATCC BAA-1556) and 12 h for E. coli (ATCC BAA-2452), P. aeruginosa (ATCC BAA-1744), and K. pneumoniae (ATCC BAA-1705). These results provide the effectiveness of a combination of Levo with cyclic [R4W4] peptide, which may provide an opportunity to solve the intriguing puzzle of treating bacterial resistance.

Knowledge, attitude, and practice of clinicians about antimicrobial stewardship and resistance among hospitals of Pakistan: a multicenter cross-sectional study

Considering that antimicrobial resistance (AMR) is a global challenge, there is a dire need to assess the knowledge, attitude, and practice (KAP) of clinicians in AMR endemic countries. The current multicenter, cross-sectional study aimed at highlighting gaps in antimicrobial (AM) stewardship and AMR among practicing doctors working in public tertiary care teaching hospitals of Lahore, Pakistan. A KAP survey, based on a self-administered questionnaire containing 45 questions, was distributed among 336 clinicians in 6 randomly selected hospitals. Overall, 92% of the clinicians considered AMR as a worldwide problem but only 66% disagreed that cold and flu symptoms require antibiotics. Moreover, around 68% of the doctors felt confident about their practice in AM but still, 96% felt the need to get more knowledge about AM drugs. The need for refresher courses on rational antibiotic use was expressed by 84% of the participants. The main contributing factors considered for AMR by the doctors included excessive AM usage in the medical profession (87.1%) and multiple antibiotics per prescription (76.4%). Pharmacologically, AM spectrum was accurately chosen by 1.4% for Ampicillin, 0.003% for Erythromycin and 0% for Levofloxacin. Clinically, more than 50% of the clinicians used miscellaneous AM for empirical therapy of respiratory tract infection and cholecystitis. The data was analyzed using Statistical Package for Social Sciences (SPSS) version 25. It is concluded that the knowledge of clinicians is relatively poor for AM spectrum and drugs of choice for certain infections. However, the clinicians are aware of their shortcomings and desire for improvement.

A drift on liposomes to proliposomes: recent advances and promising approaches

Liposomes are nano-structured vesicles, made up of phospholipids that provide active ingredients at the site of action at a predetermined rate and add the advantage of the sustained-release formulation. Liposomes have stability issues that tend to agglomerate and fuse upon storage, which reflects their drawback. Hence to overcome the aggregation, fusion, hydrolysis, and/or oxidation problems associated with liposomes a new technology named Proliposomes has been introduced. Proliposomes are defined as carbohydrate carriers coated with phospholipids, which upon addition of water generate liposomes. The objective of the review is to cover the concept of proliposomes for pulmonary or alveolar delivery of drugs and compare it with that of liposomes; highlight the methods used for preparations along with the characterization parameters. This is the first systematic review that covers the categorization of liposomes, characteristic methods, and recent examples of drugs from 2015 to 2021, supplied in form of proliposomes to the macrophages as well as others and offers an advantage over the free drug by offering a prolonged drug release and sufficient bioavailability in addition to overcome the stability issues related to liposomes. Since this is a very new technology and many scientists are continuously working in this field to make the drug available for clinical trials and ultimately in the market for the targeted delivery of drugs with better storage life.HIGHLIGHTSProliposomes as an alternative to overwhelm the stability and storage-related issues of liposomes.Anhydrous carbohydrate carriers are utilized for proliposomal preparation.Inhaled delivery of drugs as solid lipid nanoparticles offers a significant impact on pulmonary tract infections, particularly in cystic fibrosis.Size of liposomes attained after proliposome hydrolysis is critical for drug delivery via respiration.

One-pot synthesis of 3-trifluoromethylbenzo[b][1,4]oxazines from CF3-imidoyl sulfoxonium ylides with 2-bromophenols

A one-pot two-step fashion for the synthesis of 3-trifluoromethyl-1,4-benzoxazines from CF3-imidoyl sulfoxonium ylides and 2-bromophenols via lithium-bromide-promoted O–H insertion of sulfoxonium ylides and annulation has been demonstrated.

Kinetic Resolution by Lithiation: Highly Enantioselective Synthesis of Substituted Dihydrobenzoxazines and Tetrahydroquinoxalines

Kinetic resolution provided a highly enantioselective method to access a range of 3-aryl-3,4-dihydro-2H-1,4-benzoxazines using n-butyllithium and the chiral ligand sparteine. The enantioenrichment remained high on removing the tert-butoxycarbonyl (Boc) protecting group. The intermediate organolithium undergoes ring opening to an enamine. The kinetic resolution was extended to give enantiomerically enriched substituted 1,2,3,4-tetrahydroquinoxalines and was applied to the synthesis of an analogue of the antibiotic levofloxacin that was screened for its activity against the human pathogen Streptococcus pneumoniae.

A One-Week Course of Levofloxacin/Dexamethasone Eye Drops: A Review on a New Approach in Managing Patients After Cataract Surgery

A new fixed-dose combination of dexamethasone and levofloxacin eye drops has recently been approved for the prevention and treatment of inflammation, and the prevention of infection associated with cataract surgery in adults. This combination has been developed to respond to a series of unmet needs in the practical management of patients undergoing cataract surgery. Namely, despite updated guidelines, many ophthalmologists employ protocols mainly based on their personal experience. As a result, the choice of drugs, treatment duration, and drug association is not evidence-based medicine (EBM)-oriented. In addition, antibiotic resistance may occur since antibiotics are used for an extended length of time, even with tapering. Corticosteroids are also prescribed for prolonged periods, frequently without follow-up. Therefore, patient adherence to postsurgical self-care is low, and mainly affects older patients who are the majority undergoing cataract surgery. In both rabbit and human trials, it has been demonstrated that both active ingredients penetrate the ocular system without pharmacokinetic interaction between the two. The concentrations of both ingredients in aqueous humor after their ocular instillation are high enough at the site of action to carry out their expected potent anti-inflammatory and antibiotic activity. Tested in a pivotal study aimed at investigating efficacy and safety of the intended indication, the mixture/compound was non-inferior to a 2-week treatment with dexamethasone/tobramycin in preventing or reducing inflammation and in preventing infection when administered for 1 week, followed by the administration of dexamethasone alone for another week. The outcomes obtained by this study suggest that a 1-week course of levofloxacin/dexamethasone eye drops is sufficient to resolve inflammation and prevent infection in patients undergoing cataract surgery. In addition, this study underlines that a follow-up visit after 1 week allows for a decision about whether to stop or continue a treatment in patients still experiencing symptoms or inflammation. In conclusion, this new dose combination could represent a turning point in managing patients after cataract surgery, while mostly avoiding antibiotic resistance and improving treatment adherence.

Enantioselective Desymmetrization of 3-Substituted Oxetanes: An Efficient Access to Chiral 3,4-Dihydro-2H-1,4-benzoxazines

Herein, we describe a versatile transition metal/oxidant free synthesis of the chiral 2H-1,4-benzoxazines through chiral phosphoric acid (CPA) catalyzed enantioselective desymmetrization of prochiral oxetanes (30 examples) in up to 99% yield and 99% enantioselectivity under mild reaction conditions. The reported strategy not only complements the conventional 2H-1,4-benzoxazine synthetic strategies but also provides access to key intermediates of therapeutic candidates, i.e., prostaglandin D2 receptor antagonist and M1 positive allosteric modulator (PAM) compound VU0486846.

Ab initio molecular dynamics simulations and experimental speciation study of levofloxacin under different pH conditions

Levofloxacin is an extensively employed broad-spectrum antibiotic belonging to the fluoroquinolone class. Despite the extremely wide usage of levofloxacin for a plethora of diseases, the molecular characterization of this antibiotic appears quite poor in the literature. Moreover, the acid-base properties of levofloxacin - crucial for the design of efficient removal techniques from wastewaters - have never extensively been investigated so far. Here we report on a study on the behavior of levofloxacin under standard and diverse pH conditions in liquid water by synergistically employing static quantum-mechanical calculations along with experimental speciation studies. Furthermore, with the aim of characterizing the dynamics of the water solvation shells as well as the protonation and deprotonation mechanisms, here we present the unprecedented quantum-based simulation of levofloxacin in aqueous environments by means of state-of-the-art density-functional-theory-based molecular dynamics. This way, we prove the cooperative role played by the aqueous hydration shells in assisting the proton transfer events and, more importantly, the key place held by the nitrogen atom binding the methyl group of levofloxacin in accepting excess protons eventually present in water. Finally, we also quantify the energetic contribution associated with the presence of a H-bond internal to levofloxacin which, on the one hand, stabilizes the ground-state molecular structure of this antibiotic and, on the other, hinders the first deprotonation step of this fluoroquinolone. Among other things, the synergistic employment of quantum-based calculations and speciation experiments reported here paves the way toward the development of targeted removal approaches of drugs from wastewaters.

How Safe are Fluoroquinolones for Diabetic Patients? A Systematic Review of Dysglycemic and Neuropathic Effects of Fluoroquinolones

Introduction

The US Food and Drug Administration issued safety warnings about neuropathy in 2013 and dysglycemia in 2018 caused by fluoroquinolone use, mainly based on case reports and case series. We conducted this systematic review to evaluate the safety of fluoroquinolones in diabetic patients by investigating their dysglycemic and neuropathic effects.

Methods

PubMed, Scopus, and Google Scholar were searched for randomized controlled trials and observational studies published from inception till September 2019 evaluating the safety of fluoroquinolones. Efficacy studies of fluoroquinolones reporting these adverse effects were also included. Primary outcomes were hypoglycemia, hyperglycemia, and neuropathy among patients with or without diabetes and treated with fluoroquinolones compared with placebo or other antibiotics. The Cochrane Collaboration tool for randomized controlled trials and modified Newcastle-Ottawa quality-assessment scale were used for assessment of the included studies.

Results and Discussion

A total of 725 studies were identified in the initial search. After screening of titles and abstracts and full-text review, 16 articles fulfilled the inclusion criteria. The sampled patients were aged 30-78 years. Hyperglycemia was reported in 1,588 patients that received fluoroquinolone among eight studies with 4,663 patients, and hypoglycemia was reported in 2,179 patients that received fluoroquinolones among eleven studies with 6,208 patients. Dysglycemia was not generally associated with diabetes mellitus per se. Nevertheless, patients with more comorbidities, especially those with chronic kidney disease, receiving antidiabetics and/or steroids had more glycemic events when treated with fluoroquinolones.

Conclusion

Moxifloxacin was found to be associated the most and ciprofloxacin the least with dysglycemia. fluoroquinolones must be used with great caution among diabetic patients who have comorbidities and are receiving antidiabetics and/or steroids. Further evidence is required from studies on neuropathy caused by fluoroquinolones.

Investigation of the effects of three different generations of fluoroquinolone derivatives on antioxidant and immunotoxic enzyme levels in different rat tissues

Fluoroquinolones (FQs) are synthetic and broad-spectrum antimicrobial drugs derived from nalidixic acid. FQs are used against SARS-CoV-2 in our country, and for the treatment of some urinary tract diseases, gastrointestinal diseases, respiratory tract diseases, sexually transmitted diseases, and dermatological diseases. The present study investigated the effect of 1-,7-,14-day treatments of three different FQ derivatives; ciprofloxacin (CIP) 80 mg/kg/day, levofloxacin (LVX) 40 mg/kg/day, and moxifloxacin (MXF) 40 mg/kg/day, on biochemical parameters, lipid peroxidation, antioxidant enzymes, and immunotoxicity. 72 Wistar albino male rats were distributed to four groups including 18 rats in each group and were sacrificed on three different time points. The 14-day treatment of MXF significantly reduced the levels of aspartate aminotransferase (AST), glucose, reduced glutathione (GSH), malondialdehyde (MDA), catalase (CAT), myeloperoxidase (MPO), adenosine deaminase (ADA), and glutathione peroxidase (GPx). Furthermore, 14-day treatment of LVX increased liver [GSH, MPO, ADA, superoxide dismutase (SOD)], and GSH (erythrocyte) levels; whereas it significantly reduced the levels of AST, TG (triglycerides) and associated parameters levels in all the tissues (MDA), erythrocytes, and liver (MPO, CAT, SOD, GPx). After 14-day treatment of CIP; the erythrocyte levels of GSH, MPO, GPx, and CAT significantly decreased; whereas the levels of glucose, creatinine, MPO (liver), and GST (kidney and erythrocyte) significantly increased. It has been concluded that FQ derivatives used in this experiment did not display any correlation in terms of the efficacies in the different time points and tissues. Thus, it is recommended to use such FQ derivatives considering the duration of use and target tissue.

Development of Chitosan/Cyclodextrin Nanospheres for Levofloxacin Ocular Delivery

Levofloxacin (LVF) is an antibacterial drug approved for the treatment of ocular infections. However, due to the low ocular bioavailability, high doses are needed, causing bacterial resistance. Polymeric nanospheres (NPs) loading antibiotic drugs represent the most promising approach to eradicate ocular infections and to treat pathogen resistance. In this study, we have developed chitosan NPs based on sulfobutyl-ether-β-cyclodextrin (CH/SBE-β-CD NPs) for ocular delivery of LVF. CH/SBE-β-CD NPs loading LVF were characterized in terms of encapsulation parameters, morphology, and sizes, in comparison to NPs produced without the macrocycle. Nuclear magnetic resonance and UV–vis spectroscopy studies demonstrated that SBE-β-CD is able to complex LVF and to influence encapsulation parameters of NPs, producing high encapsulation efficiency and LVF loading. The NPs were homogenous in size, with a hydrodynamic radius between 80 and 170 nm and positive zeta potential (ζ) values. This surface property could promote the interaction of NPs with the negatively charged ocular tissue, increasing their residence time and, consequently, LVF efficacy. In vitro, antibacterial activity against Gram-positive and Gram-negative bacteria showed a double higher activity of CH/SBE-β-CD NPs loading LVF compared to the free drug, suggesting that chitosan NPs based on SBE-β-CD could be a useful system for the treatment of ocular infections.

Novel Hydrogels of Chitosan and Poly(vinyl alcohol) Reinforced with Inorganic Particles of Bioactive Glass

Chitosan (CS) and poly(vinyl alcohol) (PVA) hydrogels, a polymeric system that shows a broad potential in biomedical applications, were developed. Despite the advantages they present, their mechanical properties are insufficient to support the loads that appear on the body. Thus, it was proposed to reinforce these gels with inorganic glass particles (BG) in order to improve mechanical properties and bioactivity and to see how this reinforcement affects levofloxacin drug release kinetics. Scanning electron microscopy (SEM), X-ray diffraction (XRD), swelling tests, rheology and drug release studies characterized the resulting hydrogels. The experimental results verified the bioactivity of these gels, showed an improvement of the mechanical properties and proved that the added bioactive glass does affect the release kinetics.

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

Promising Roles of Alternative Medicine and Plant-Based Nanotechnology as Remedies for Urinary Tract Infections

Urinary tract infections (UTIs) are considered to be the most common infections worldwide, having an incidence rate of 40-60% in women. Moreover, the prevalence of this disorder in adult women is 30 times more than in men. UTIs are usually found in many hospitals and clinical practice; as disorders, they are complicated and uncomplicated; in uncomplicated cases, there is no structural or functional abnormality in the urogenital tract. However, obstruction, retention of urine flow and use of catheters increase the complexity. There are several bacteria (e.g., E. coli, Klebsiella pneumoniae, Proteus vulgaris, etc.) successfully residing in the tract. The diagnosis must not only be accurate but rapid, so early detection is an important step in the control of UTIs caused by uropathogens. The treatment of UTIs includes appropriate antimicrobial therapy to control the infection and kill the causal microbes inside the body. A long-time usage of antibiotics has resulted in multidrug resistance causing an impediment in treatment. Thus, alternative, combinatorial medication approaches have given some hope. Available treatments considered Homeopathic, Ayurvedic, Unani, and other herbal-based drugs. There are new upcoming roles of nanoparticles in combating UTIs which needs further validation. The role of medicinal plant-based nanotechnology approaches has shown promising results. Therefore, there must be active research in phyto-based therapies of UTIs, such as Ayurvedic Biology.

One-Pot, Multicomponent, Diastereoselective, Green Synthesis of 3,4-Dihydro-2H-benzo[b][1,4]oxazine Analogues

A novel green and efficient catalyst-free, mild one-pot, multicomponent synthetic strategy has been developed to construct substituted 3,4-dihydro-2H-benzo[b][1,4]oxazine. This reaction proceeds via in situ formation of Schiff-base followed by base mediated alkylation with phenacyl bromide/substituted phenacyl bromide, finally leading to intramolecular cyclization to give a mixture of diastereomers with excellent diastereoselectivity (up to dr = 99:1), which were isolated as a single diastereomer in moderate to excellent yields (41-92%). Besides, this new versatile methodology provides a wide scope for the synthesis of different functionally substituted benzoxazine scaffolds and can be further exploited as building blocks for the synthesis of multifaceted molecular structures, especially for pharmaceutical applications.

A comparison of different antibiotic regimens for the treatment of infective endocarditis

BACKGROUND

Infective endocarditis is a microbial infection of the endocardial surface of the heart. Antibiotics are the cornerstone of treatment, but due to the differences in presentation, populations affected, and the wide variety of micro-organisms that can be responsible, their use is not standardised. This is an update of a review previously published in 2016.

OBJECTIVES

To assess the existing evidence about the clinical benefits and harms of different antibiotics regimens used to treat people with infective endocarditis.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase Classic and Embase, LILACS, CINAHL, and the Conference Proceedings Citation Index - Science on 6 January 2020. We also searched three trials registers and handsearched the reference lists of included papers. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) assessing the effects of antibiotic regimens for treating definitive infective endocarditis diagnosed according to modified Duke's criteria. We considered all-cause mortality, cure rates, and adverse events as the primary outcomes. We excluded people with possible infective endocarditis and pregnant women.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment, and data extraction in duplicate. We constructed 'Summary of findings' tables and used GRADE methodology to assess the quality of the evidence. We described the included studies narratively.

MAIN RESULTS

Six small RCTs involving 1143 allocated/632 analysed participants met the inclusion criteria of this first update. The included trials had a high risk of bias. Three trials were sponsored by drug companies. Due to heterogeneity in outcome definitions and different antibiotics used data could not be pooled. The included trials compared miscellaneous antibiotic schedules having uncertain effects for all of the prespecified outcomes in this review. Evidence was either low or very low quality due to high risk of bias and very low number of events and small sample size. The results for all-cause mortality were as follows: one trial compared quinolone (levofloxacin) plus standard treatment (antistaphylococcal penicillin (cloxacillin or dicloxacillin), aminoglycoside (tobramycin or netilmicin), and rifampicin) versus standard treatment alone and reported 8/31 (26%) with levofloxacin plus standard treatment versus 9/39 (23%) with standard treatment alone; risk ratio (RR) 1.12, 95% confidence interval (CI) 0.49 to 2.56. One trial compared fosfomycin plus imipenem 3/4 (75%) versus vancomycin 0/4 (0%) (RR 7.00, 95% CI 0.47 to 103.27), and one trial compared partial oral treatment 7/201 (3.5%) versus conventional intravenous treatment 13/199 (6.53%) (RR 0.53, 95% CI 0.22 to 1.31). The results for rates of cure with or without surgery were as follows: one trial compared daptomycin versus low-dose gentamicin plus an antistaphylococcal penicillin (nafcillin, oxacillin, or flucloxacillin) or vancomycin and reported 9/28 (32.1%) with daptomycin versus 9/25 (36%) with low-dose gentamicin plus antistaphylococcal penicillin or vancomycin; RR 0.89, 95% CI 0.42 to 1.89. One trial compared glycopeptide (vancomycin or teicoplanin) plus gentamicin with cloxacillin plus gentamicin (13/23 (56%) versus 11/11 (100%); RR 0.59, 95% CI 0.40 to 0.85). One trial compared ceftriaxone plus gentamicin versus ceftriaxone alone (15/34 (44%) versus 21/33 (64%); RR 0.69, 95% CI 0.44 to 1.10), and one trial compared fosfomycin plus imipenem versus vancomycin (1/4 (25%) versus 2/4 (50%); RR 0.50, 95% CI 0.07 to 3.55). The included trials reported adverse events, the need for cardiac surgical interventions, and rates of uncontrolled infection, congestive heart failure, relapse of endocarditis, and septic emboli, and found no conclusive differences between groups (very low-quality evidence). No trials assessed quality of life.

AUTHORS' CONCLUSIONS

This first update confirms the findings of the original version of the review. Limited and low to very low-quality evidence suggests that the comparative effects of different antibiotic regimens in terms of cure rates or other relevant clinical outcomes are uncertain. The conclusions of this updated Cochrane Review were based on few RCTs with a high risk of bias. Accordingly, current evidence does not support or reject any regimen of antibiotic therapy for the treatment of infective endocarditis.

Antimicrobial Resistance Gene Prevalence in a Population of Patients with Advanced Dementia Is Related to Specific Pathobionts

Long-term care facilities are significant reservoirs of antimicrobial-resistant organisms, and patients with advanced dementia are particularly vulnerable to multidrug-resistant organism (MDRO) acquisition and antimicrobial overuse. In this study, we longitudinally examined a group of patients with advanced dementia using metagenomic sequencing. We found significant inter- and intra-subject heterogeneity in microbiota composition, suggesting temporal instability. We also observed a link between the antimicrobial resistance gene density in a sample and the relative abundances of several pathobionts, particularly Escherichia coli, Proteus mirabilis, and Enterococcus faecalis, and used this relationship to predict resistance gene density in samples from additional subjects. Furthermore, we used metagenomic assembly to demonstrate that these pathobionts had higher resistance gene content than many gut commensals. Given the frequency and abundances at which these pathobionts were found in this population and the underlying vulnerability to MDRO of patients with advanced dementia, attention to microbial blooms of these species may be warranted.

Levofloxacin-induced Desquamation: A Possible and Rare Case Report

Introduction:

Levofloxacin is a fluoroquinolone active against both gram-negative and gram-positive bacteria with a well-defined margin of safety and efficacy. It has various labeled adverse effects like other fluoroquinolones but its adverse effect like desquamation is rarely reported.

Methods:

We present a case report of levofloxacin-induced desquamation in an Indian patient.

Case Report:

A-38-year old female patient presented to the outpatient department, with chief complaints of peeling off her epidermal skin. Initially, Desquamation started on her greater finger, which slowly spread to her hand, feet, lower limbs as well as upper limb and neck region. She was prescribed Levofloxacin for respiratory tract infection.

Results and Discussion:

Considering temporal relationship, upon causality assessment, (Adverse Drug Reaction) ADR was found to be likely, moderate and probable. The drug was withdrawn along with the initiation of supportive therapy and reaction subsided.

Discussion:

Although adverse drug reactions like desquamation are not fatal, this induces anxiety in the patients and reduces patient’s quality of life. This case report will help keep physicians vigilant about the current adverse drug reaction, helping in the early detection and management of ADR.

One-Pot Synthesis of Enantiopure Spiro[3,4-dihydrobenzo[b][1,4]oxazine-2,3'-oxindole] via Regio- and Stereoselective Tandem Ring Opening/Cyclization of Spiroaziridine Oxindoles with Bromophenols

A highly efficient regio- and stereoselective spiroaziridine ring opening with 2-bromophenols and a subsequent tandem cyclization reaction was developed for the one-pot synthesis of enantiopure 3,4-dihydrospiro[benzo[b][1,4]oxazine-2,3'-oxindole] with excellent enantiopurity (ee up to >99%). It is further extended to asymmetric synthesis of NH-free 3,4-dihydrospiro[benzo[b][1,4]oxazine-2,3'-xindole] retaining the optical activity.

Clinical Benefit of Empiric High-Dose Levofloxacin Therapy for Adults With Community-onset Enterobacteriaceae Bacteremia

PURPOSE

Levofloxacin is commonly prescribed to treat varied community-acquired gram-negative infections; knowledge of the therapeutic efficacies of high-dose (HD) administration is helpful to improve patient care.

METHODS

In this 6-year cohort, adults with community-onset Enterobacteriaceae bacteremia were retrospectively studied in 2 hospitals. To overcome the confounding factors in the dosage choice of empiric administration, patients receiving empiric intravenous HD (750 mg/d) therapy were matched with those receiving the conventional dose (CD; 500 mg/d) by using individual propensity scores, calculated by the independent predictors of 30-day crude mortality.

FINDINGS

Initially, more patients with critical illness (Pitt bacteremia score [PBS] ≥4) at bacteremia onset and comorbid malignancies and the higher 15- and 30-day mortality rate were recorded in 136 patients receiving HD therapy, compared to 103 receiving CD therapy. After appropriate matching, differences in patient demographic and clinical characteristics between the HD (n = 103) and CD (n = 103) groups were nonsignificant. Consequently, crude mortality rates at 3, 15, or 30 days after onset of bacteremia did not differ. However, the period of time to defervescence, total intravenous antimicrobial administration, and hospital stay was shorter in the HD group than in the CD group. Similarly, regardless if patients had more critical illness (PBS ≥2) or stabilized illness (PBS <2), the advantage of empiric HD therapy on defervescence remained significant. Within 60 days after discontinuation of intravenous levofloxacin therapy, the proportion of recurrent bacteremia, posttreatment overall infections, and posttreatment crude mortality was similar between the HD and CD groups.

IMPLICATIONS

For adults with community-onset Enterobacteriaceae bacteremia, empiric administration of HD levofloxacin was as effective as CD levofloxacin in reducing mortality and, notably, led to more rapid defervescence compared with CD administration.

Comparison of the in Vivo Activities of Garenoxacin and Levofloxacin in a Murine Model of Pneumonia by Mixed-Infection with Streptococcus pneumoniae and Parvimonas micra

Community-acquired pneumonia (CAP) can involve mixed-species bacterial infection. However, few studies have investigated antimicrobial efficacy in the treatment of mixed species infections. This study aimed to compare the in vivo antimicrobial activity of garenoxacin (GRNX) and levofloxacin (LVFX) against Streptococcus pneumoniae and Parvimonas micra in a murine model of mixed species bacterial pneumonia. S. pneumoniae D-6888 and P. micra No. 242 were used in this study. Antimicrobial activity toward each isolate was calculated as the change in bacterial count in the lungs (Δlog₁₀ CFU/mL) of mice after 24 h of treatment compared with the count in pretreated animals (0 h). The MICs of GRNX and LVFX against S. pneumoniae D-6888 were 0.06 and 0.5 mg/L and the MICs against P. micra No. 242 were 0.03 and 0.12 mg/L, respectively. In a murine pneumonia mixed-infection model, GRNX showed significantly higher in vivo antimicrobial activity against S. pneumoniae than LVFX (GRNX; －2.02 ± 0.99 log₁₀ CFU/mL vs. LVFX; －0.97 ± 0.61 log₁₀ CFU/mL, p = 0.0188). GRNX displayed about 2-fold more potent activity against P. micra than LVFX (GRNX; －1.12 ± 0.56 log₁₀ CFU/mL vs. LVFX; －0.61 ± 0.43 log₁₀ CFU/mL, p = 0.1029). These results suggest that GRNX is preferable for the treatment of mixed species bacterial CAP.

In vitro activity of antimicrobial-impregnated catheters against biofilms formed by KPC-producing Klebsiella pneumoniae

AIM

To evaluate the activity and effectiveness of impregnated central venous catheters (CVC) against Klebsiella pneumoniae biofilms.

METHODS AND RESULTS

The antimicrobial activity and durability of impregnated-CVCs were evaluated over time and the size of zones of inhibition (ZI) was measured. Biofilm formation was observed by quantitative culture and also by scanning electron microscopy. The catheters impregnated with chlorhexidine/silver sulfadiazine (CHX/SS) reduced bacteria counts by 0·3 log and were most effective (P < 0·01) against Klebsiella pneumoniae biofilms N-acetylcysteine/levofloxacin (NAC/LEV) catheters. It was observed that the catheter impregnated with NAC/LEV had initially the largest average ZI size being statistically significant (P < 0·01). The NAC/LEV combination remained active until day 30, whereas the combination of CHX/SS was completely inactivated from day 15 on.

CONCLUSIONS

The NAC/LEV combination showed greater durability on the catheters, but it was the CHX/SS combination that had the greater initial efficacy in bacterial inhibition. It was also observed that NAC/LEV-impregnated catheters do not prevent the emergence of resistant subpopulations inside the inhibition halos during antimicrobial susceptibility tests.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results highlighted that the in vitro efficacy of antimicrobial-impregnated CVCs is limited by time and that their colonization occurred earlier than expected. Our data also demonstrated that NAC/LEV remained active until day 30 of evaluation and CHX/SS combination was completely inactivated from day 15 on. Our findings suggested that implantable devices should be carefully used by medical community.

Comparison of high-dose, short-course levofloxacin treatment vs conventional regimen against acute bacterial infection: meta-analysis of randomized controlled trials

Objects: This meta-analysis aims to assess the efficacy and safety of high-dose, short-dose levofloxacin in comparison with conventional therapy on treating acute bacterial infection.

Methods: PubMed, Embase and Cochrane database were searched up to September 2018. Only randomized controlled trials (RCTs) evaluating high-dose, short-course levofloxacin and conventional regimen in the treatment of acute bacterial infection were included. The primary outcomes were clinical responses, microbiologic eradication and adverse effects.

Results: Seven RCTs of 3,731 patients (1,835 in the high-dose, short-course levofloxacin regimen group and 1,896 in the conventional regimen group) were included. Overall, no significant difference between the high-dose, short-course levofloxacin regimen group and the conventional regimen was found in terms of clinical response (risk ratio, RR: 1.01; 95%CI: 0.98–1.04, I²=10%). In addition, the high-dose, short-course levofloxacin regimen had a similar microbiological eradication rate to conventional regimen (RR: 1.02; 95%CI: 0.98–1.06, I²=0%). Moreover, the high-dose, short-course levofloxacin regimen had a similar incidence of treatment-emergent adverse events to conventional regimen (RR: 1.07; 95%CI: 0.99–1.17, I²=0%). This trend was not affected by the different types of infections—community-acquired pneumonia, complicated urinary tract infection/acute pyelonephritis or acute sinusitis, different conventional regimen—levofloxacin (500 mg daily for 7–14 days) or ciprofloxacin (400 mg IV or 500 mg oral, twice daily for 10 days).

Conclusion: High-dose, short-course levofloxacin exhibits similar clinical success and microbiologic eradication rates with conventional regimen in the treatment of acute bacterial infection. Moreover, the high-dose, short-course levofloxacin regimen was well tolerated and had comparable safety profiles with the conventional regimen.

Drug delivery systems designed to overcome antimicrobial resistance

Antimicrobial resistance has emerged as a huge challenge to the effective treatment of infectious diseases. Aside from a modest number of novel anti-infective agents, very few new classes of antibiotics have been successfully developed for therapeutic use. Despite the research efforts of numerous scientists, the fight against antimicrobial (ATB) resistance has been a longstanding continued effort, as pathogens rapidly adapt and evolve through various strategies, to escape the action of ATBs. Among other mechanisms of resistance to antibiotics, the sophisticated envelopes surrounding microbes especially form a major barrier for almost all anti-infective agents. In addition, the mammalian cell membrane presents another obstacle to the ATBs that target intracellular pathogens. To negotiate these biological membranes, scientists have developed drug delivery systems to help drugs traverse the cell wall; these are called "Trojan horse" strategies. Within these delivery systems, ATB molecules can be conjugated with one of many different types of carriers. These carriers could include any of the following: siderophores, antimicrobial peptides, cell-penetrating peptides, antibodies, or even nanoparticles. In recent years, the Trojan horse-inspired delivery systems have been increasingly reported as efficient strategies to expand the arsenal of therapeutic solutions and/or reinforce the effectiveness of conventional ATBs against drug-resistant microbes, while also minimizing the side effects of these drugs. In this paper, we aim to review and report on the recent progress made in these newly prevalent ATB delivery strategies, within the current context of increasing ATB resistance.

A new carbapenem drug dosage metric for carbapenem usage and correlation with carbapenem resistance of Pseudomonas aeruginosa

The emergence and dissemination of antimicrobial resistance is a worldwide problem. Inappropriate antimicrobial use contributes to this resistance, and several metrics of drug usage have been used to monitor their consumption and rational use. We examined several existing drug metrics, and developed a new one, dose/duration-density (D/d²), for a the best correlation between carbapenem usage and carbapenem resistance of Pseudomonas aeruginosa. The annual changes of antimicrobial use density (AUD), days of therapy (DOT), daily dose (DD) and D/d² for meropenem, imipenem and total carbapenems was analyzed for a correlation with carbapenem susceptibility of P. aeruginosa from 2006 through 2015 at a university hospital. The substitution of meropenem for imipenem usage, and an approximate 10% increase in carbapenem susceptibility of P. aeruginosa occurred over the study period. There were significant correlations of the meropenem susceptibility of P. aeruginosa and meropenem usage as measured by the meropenem DD, of imipenem susceptibility and imipenem AUD and DOT, and overall carbapenem susceptibility and imipenem DOT. The D/d² for meropenem, imipenem and total carbapenems had significant correlations with individual and all carbapenem susceptibility of P. aeruginosa. These D/d² is the best single carbapenem use metric for correlating carbapenem usage with P. aeruginosa resistance. Further studies are warranted to consider the value of D/d² for other antimicrobials and bacteria.

Synthesis of Nonracemic 1,4-Benzoxazines via Ring Opening/Cyclization of Activated Aziridines with 2-Halophenols: Formal Synthesis of Levofloxacin

Novel 3,4-dihydro-1,4-benzoxazine derivatives have been synthesized by an efficient and simple method in excellent enantio- and diastereospecificity (ee > 99%, de > 99%). The reaction proceeds via Lewis acid-catalyzed S_N2-type ring opening of activated aziridines with 2-halophenols followed by Cu(I)-catalyzed intramolecular C-N cyclization in a stepwise fashion under one-pot conditions to furnish the 3,4-dihydro-1,4-benzoxazine derivatives in excellent yields (up to 95%). The strategy offers a short and efficient synthesis to ( S)-3-methyl-1,4-benzoxazine ( S)-3v, a late stage intermediate in the synthesis of levofloxacin.

Explorative Randomized Phase II Clinical Study of the Efficacy and Safety of Finafloxacin versus Ciprofloxacin for Treatment of Complicated Urinary Tract Infections

The broad-spectrum C-8-cyano-fluoroquinolone finafloxacin displays enhanced activity under acidic conditions. This phase II clinical study compared the efficacies and safeties of finafloxacin and ciprofloxacin in patients with complicated urinary tract infection and/or pyelonephritis. A 5-day regimen with 800 mg finafloxacin once a day (q.d.) (FINA05) had results similar to those of a 10-day regimen with 800 mg finafloxacin q.d. (FINA10). Combined microbiological and clinical responses at the test-of-cure (TOC) visit were 70% for FINA05, 68% for FINA10, and 57% for a 10-day ciprofloxacin regimen (CIPRO10) in 193 patients (64 for FINA05, 68 for FINA10, and 61 for CIPRO10) of the microbiological intent-to-treat (mITT) population. Additionally, the clinical effects of ciprofloxacin on patients with an acidic urine pH (80% of patients) were reduced, whereas the effects of finafloxacin were unchanged. Finafloxacin was safe and well tolerated. Overall, 43.4% of the patients in the FINA05 group, 42.7% in the FINA10 group, and 54.2% in the CIPRO10 group experienced mostly mild and treatment-emergent but unrelated adverse events. A short-course regimen of 5 days of finafloxacin resulted in high eradication and improved clinical outcome rates compared to those for treatment with ciprofloxacin for 10 days. In contrast to those of ciprofloxacin, the clinical effects of finafloxacin were not reduced by acidic urine pH. Hospitalized adults were randomized 1:1:1 to finafloxacin treatment (800 mg q.d.) for either 5 or 10 days or to ciprofloxacin treatment (400 mg/500 mg b.i.d.) for 10 days with an optional switch from intravenous (i.v.) to oral administration at day 3. The primary endpoint was the combined microbiological and clinical response at the TOC visit in the microbiological intent-to-treat population. (This study has been registered at ClinicalTrials.gov under identifier NCT01928433.).

Intranasal Delivery of Topically-Acting Levofloxacin to Rats: a Proof-of-Concept Pharmacokinetic Study

PURPOSE

To evaluate the potential of levofloxacin intranasal administration as a promising alternative approach to treat local infections such as chronic rhinosinusitis, by delivering drug concentrations directly to the site of infection.

METHODS

Drug concentrations were measured in plasma, olfactory bulb and nasal mucosa of anterior (ANM) and posterior regions after intranasal (0.24 mg/kg) and intravenous (10 mg/kg) administration to rats, and pharmacokinetic parameters were compared between routes. For intranasal administration a thermoreversible in-situ gel was used.

RESULTS

Plasma and olfactory bulb exposure to levofloxacin was minimal following intranasal dose, preventing systemic and central nervous system adverse effects. Levofloxacin concentration-time profile in ANM revealed higher concentrations during the first 60 min of the study following intranasal administration than the corresponding ones obtained after intravenous administration. A rapid and continuous decay of levofloxacin concentration in this nasal region was observed after intranasal delivery, resulting in much lower values at the last sampling time-points.

CONCLUSION

The higher dose-normalized concentrations and pharmacokinetic exposure parameters of levofloxacin in ANM after intranasal administration, demonstrates that intranasal delivery of the formulated gel is, by itself, advantageous for delivering levofloxacin to biophase and thus an attractive approach in management of chronic rhinosinusitis.

Synthesis and Evaluation of Antimicrobial Activity of [R₄W₄K]-Levofloxacin and [R₄W₄K]-Levofloxacin-Q Conjugates

The development of a new class of antibiotics to fight bacterial resistance is a time-consuming effort associated with high-cost and commercial risks. Thus, modification, conjugation or combination of existing antibiotics to enhance their efficacy is a suitable strategy. We have previously reported that the amphiphilic cyclic peptide [R₄W₄] had antibacterial activity with a minimum inhibitory concentration (MIC) of 2.97 µg/mL against Methicillin-resistant Staphylococcus aureus (MRSA). Herein, we hypothesized that conjugation or combination of the amphiphilic cyclic peptide [R₄W₄] with levofloxacin or levofloxacin-Q could improve the antibacterial activity of levofloxacin and levofloxacin-Q. Fmoc/tBu solid-phase chemistry was employed to synthesize conjugates of [R₄W₄K]-levofloxacin-Q and [R₄W₄K]-levofloxacin. The carboxylic acid group of levofloxacin or levofloxacin-Q was conjugated with the amino group of β-alanine attached to lysine in the presence of 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) and N,N-diisopropylethylamine (DIPEA) for 3 h to afford the products. Antibacterial assays were conducted to determine the potency of conjugates [R₄W₄K]-levofloxacin-Q and [R₄W₄K]-levofloxacin against MRSA and Klebsiella pneumoniae. Although levofloxacin-Q was inactive even at a concentration of 128 µg/mL, [R₄W₄K]-levofloxacin-Q conjugate and the corresponding physical mixture showed MIC values of 8 µg/mL and 32 µg/mL against MRSA and Klebsiella pneumonia, respectively, possibly due to the activity of the peptide. On the other hand, [R₄W₄K]-levofloxacin conjugate (MIC = 32 µg/mL and MIC = 128 µg/mL) and the physical mixture (MIC = 8 µg/mL and 32 µg/mL) was less active than levofloxacin (MIC = 2 µg/mL and 4 = µg/mL) against MRSA and Klebsiella pneumoniae, respectively. The data showed that the conjugation of levofloxacin with [R₄W₄K] significantly reduced the antibacterial activity compared to the parent analogs, while [R₄W₄K]-levofloxacin-Q conjugate was more significantly potent than levofloxacin-Q alone.