In vitro activity of nemonoxacin, a novel nonfluorinated quinolone antibiotic, against Chlamydia trachomatis and Chlamydia pneumoniae

Atypical pneumonia (Review)

Atypical pneumonia encompasses diverse pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella species, which differ from typical bacterial pneumonia in their extrapulmonary manifestations. Clinical differentiation relies on systemic involvement rather than on standalone symptoms. Despite challenges in distinct diagnosis, syndromic approaches and weighted point systems aid in accurate presumptive diagnoses. Antibiotic treatment, often non-β-lactams due to the unique cell structures of atypical pathogens, targets intracellular processes. Macrolides, tetracyclines, quinolones and ketolides are effective due to their intracellular penetration, crucial for combating these intracellular pathogens. The prevalence of atypical pneumonia varies globally, with Europe, Asia/Africa and Latin America reporting detection rates between 20-28%. Streptococcus pneumoniae remains a primary cause of pneumonia; however, atypical pathogens contribute significantly to this disease, being more prevalent in outpatient settings and among young adults. Legionella stands out in severe hospitalized cases and is associated with higher mortality rates. Diagnosis proves challenging due to overlapping symptoms with other respiratory infections. Differentiation among pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella relies on subtle clinical variations and imaging findings. Diagnostic methods include serological studies, cultures and polymerase chain reaction, each with limitations in sensitivity or specificity. Prognosis varies widely. Atypical pneumonia can progress to severe forms with fatal outcomes, causing multi-organ damage. Complications extend beyond the respiratory system, affecting the cardiovascular system, exacerbating conditions such as chronic obstructive pulmonary disease and asthma, and potentially linking to conditions such as lung cancer. Increasing antibiotic resistance poses a significant challenge, influencing treatment outcomes and prolonging illness duration.

A multicentre, randomised, double-blind, double-dummy, parallel-controlled, phase 3 clinical trial assessing the efficacy and safety of intravenous nemonoxacin malate vs. levofloxacin for community-acquired pneumonia in adult patients

BACKGROUND

Nemonoxacin malate is a novel non-fluorinated quinolone for oral and intravenous (IV) administration. This phase 3, multicentre, randomised, double-blind, double-dummy, parallel-controlled clinical trial (NCT02205112) evaluated the efficacy and safety of IV nemonoxacin vs. levofloxacin for the treatment of community-acquired pneumonia (CAP) in adult patients.

METHODS

Eligible patients were randomised to receive 500 mg nemonoxacin or levofloxacin via IV infusion, once daily for 7-14 days. The primary endpoint was the clinical cure rate at the test-of-cure (TOC) visit in the modified intent-to-treat (mITT) population. Secondary efficacy and safety were also compared between nemonoxacin and levofloxacin.

RESULTS

Overall, 525 patients were randomised and treated with nemonoxacin (n = 349) or levofloxacin (n = 176). The clinical cure rate was 91.8% (279/304) for nemonoxacin and 85.7% (138/161) for levofloxacin in the mITT population (P > 0.05). The clinical efficacy of nemonoxacin was non-inferior to levofloxacin for treatment of CAP. Microbiological success rate with nemonoxacin was 88.8% (95/107) and with levofloxacin was 87.8% (43/49) (P > 0.05) at the TOC visit in the bacteriological mITT population. The incidence of drug-related adverse events (AEs) was 37.1% in the nemonoxacin group and 22.2% in the levofloxacin group. These AEs were mostly local reactions at the infusion site, nausea, elevated alanine aminotransferase/aspartate aminotransferase (ALT/AST), and QT interval prolongation. The nemonoxacin-related AEs were mostly mild and resolved after discontinuation of nemonoxacin.

CONCLUSIONS

Nemonoxacin 500 mg IV once daily for 7-14 days is effective and safe and non-inferior to levofloxacin for treating CAP in adult patients.

Antistaphylococcal discovery pipeline; where are we now?

The serious spread of antibiotic-resistant Staphylococcal aureus strains is alarming. This is reflected by the measures governments and health-related bodies are offering to ease antibiotic drug development. Finding new active agents, preferably with novel mechanism of action, or even finding new targets for drug development are essential. In this review, we summarize the current status of novel antistaphylococcal agents undergoing clinical trials. We mainly discuss antistaphylococcal small molecules and peptides in the text with a special focus on their chemistry, while antistaphylococcal immunotherapy (antibodies) are mentioned in a summative table. This review shall serve as a summary that influences future synthetic efforts in the antistaphyloccocals development field.

The role of an enzymatically inactive CPAF mutant vaccination in Chlamydia muridarum genital tract infection

Chlamydia trachomatis urogenital tract infection causes pelvic inflammatory disease and infertility, increases the risk of co-infection with HPV and HIV. Chlamydial vaccination is considered the most promising approach to prevent and control its infection. Among various chlamydial vaccine candidates, chlamydial protease-like activity factor (CPAF) have been reported to provide robust protective immunity against genital chlamydial infection in mice with reduced vaginal shedding and oviduct pathology. However, CPAF is a serine protease which has enzymatical activity to degrade a large number of substrates. In order to increase the safety of CPAF vaccine, in this study, we used a mutant CPAF that is deficient in enzymatical activity to determine whether proteolytic activity of CPAF affect its vaccine efficacy. The wild type or mutant CPAF immunization causes a significant lower chlamydial shedding from the vaginal and resolve the infection as early as day 20, compared to day 28 in adjuvant control mice. More important, reduced upper reproductive tract pathology were also observed in these two groups. The mutant or wild type CPAF immunization induced not only robust splenic IFN-γ and serum IgG2a but also sIgA secretion in the vaginal fluids. Furthermore, neutralization of chlamydia with immune sera did not provide protection against oviduct pathology. However, adoptive transfer of CD4⁺ splenocytes isolated from the mutant or wild type CPAF immunized mice resulted in a significant and comparable reduced oviduct pathology. Our results indicate mutant CPAF vaccination is as same efficacy as wild type, and the protection relies on CD4⁺ T cells, which will further promote the development of CPAF as clinical chlamydial vaccine.

Investigational and Experimental Drugs for Community-Acquired Pneumonia: the Current Evidence

Community-acquired pneumonia (CAP) is a common infection with a constantly evolving etiological spectrum. This changing etiology conditions the adequate selection of optimal therapeutic regimens, both in empirical and definitive treatments. In recent years, new antimicrobials have been approved by regulatory authorities for use in CAP, although it is necessary to continue incorporating new antimicrobial agents that improve the activity profile in relation to the appearance of bacterial resistance in certain pathogens, such as pneumococcus, Staphylococcus aureus or Pseudomonas aeruginosa. Delafloxacin, omadacycline and lefamulin are the most recently approved antibiotics for CAP. These three antibiotics have shown non-inferiority to their comparators for the treatment of CAP with an excellent safety profile. However, in the 2019 ATS/IDSA guidelines, it has been considered that more information is needed to incorporate these new drugs into community-based treatment. New antimicrobials, such as solithromycin and nemonoxacin, are currently being studied in Phase III clinical trials. Both drugs have shown non-inferiority against the comparators and an acceptable safety profile; however, they have not yet been approved by the regulatory authorities. Several drugs are being tested in Phase I and II clinical trials. These include zabofloxacin, aravofloxacin, nafithromycin, TP-271, gepotidacin, radezolid, delpazolid, and CAL02. The preliminary results of these clinical trials allow us to assure that most of these drugs may play a role in the future treatment of CAP.

The efficacy and safety of nemonoxacin compared with levofloxacin in the treatment of community-acquired pneumonia: a systemic review and meta-analysis of randomized controlled trials

Objectives

This meta-analysis aims to assess the clinical efficacy and safety of nemonoxacin in comparison with levofloxacin in treating community-acquired pneumonia (CAP).

Materials and methods

The Pubmed, Embase, ClinicalTrials.gov., and the Cochrane databases were searched up to September 2018. Only randomized controlled trials (RCTs) evaluating nemonoxacin and levofloxacin in the treatment of CAP were included. The primary outcome was the clinical cure rate, and the secondary outcomes included the microbiologic response rate and the risk of adverse events.

Results

Three RCTs were included. Overall, nemonoxacin and levofloxacin had similar clinical cure rates in the treatment of CAP (OR =1.05, 95% CI =0.67–1.64, I²=0%). Nemonoxacin also had a microbiologic response rate similar to levofloxacin (OR =0.89, 95% CI =0.44–1.81, I²=0%). No significant differences were found in treatment-emergent adverse events between the two drugs (OR =1.08, 95% CI =0.81–1.43, I²=0%). In subgroup analysis, the similarities in the clinical cure rate, microbiologic response rate, and risk of adverse events of these two drugs remained unchanged with the dose of nemonoxacin (500 or 750 mg) and individual pathogens.

Conclusion

The clinical and microbiologic efficacy of nemonoxacin is comparable to that of levofloxacin in the treatment of CAP, and this agent is as well tolerated as levofloxacin.

Atypical Pneumonia: Updates on Legionella, Chlamydophila, and Mycoplasma Pneumonia

Community-acquired pneumonia (CAP) has multiple causes and is associated with illness that requires admission to the hospital and mortality. The causes of atypical CAP include Legionella species, Chlamydophila, and Mycoplasma. Atypical CAP remains a diagnostic challenge and, therefore, likely is undertreated. This article reviews the advancements in the evaluation and treatment of patients and discusses current conflicts and controversies of atypical CAP.

Antibiotics in the clinical pipeline at the end of 2015

There is growing global recognition that the continued emergence of multidrug-resistant bacteria poses a serious threat to human health. Action plans released by the World Health Organization and governments of the UK and USA in particular recognize that discovering new antibiotics, particularly those with new modes of action, is one essential element required to avert future catastrophic pandemics. This review lists the 30 antibiotics and two β-lactamase/β-lactam combinations first launched since 2000, and analyzes in depth seven new antibiotics and two new β-lactam/β-lactamase inhibitor combinations launched since 2013. The development status, mode of action, spectra of activity and genesis (natural product, natural product-derived, synthetic or protein/mammalian peptide) of the 37 compounds and six β-lactamase/β-lactam combinations being evaluated in clinical trials between 2013 and 2015 are discussed. Compounds discontinued from clinical development since 2013 and new antibacterial pharmacophores are also reviewed.

Amphipathic β2,2-Amino Acid Derivatives Suppress Infectivity and Disrupt the Intracellular Replication Cycle of Chlamydia pneumoniae

We demonstrate in the current work that small cationic antimicrobial β2,2-amino acid derivatives (Mw < 500 Da) are highly potent against Chlamydia pneumoniae at clinical relevant concentrations (< 5 μM, i.e. < 3.4 μg/mL). C. pneumoniae is an atypical respiratory pathogen associated with frequent treatment failures and persistent infections. This gram-negative bacterium has a biphasic life cycle as infectious elementary bodies and proliferating reticulate bodies, and efficient treatment is challenging because of its long and obligate intracellular replication cycle within specialized inclusion vacuoles. Chlamydicidal effect of the β2,2-amino acid derivatives in infected human epithelial cells was confirmed by transmission electron microscopy. Images of infected host cells treated with our lead derivative A2 revealed affected chlamydial inclusion vacuoles 24 hours post infection. Only remnants of elementary and reticulate bodies were detected at later time points. Neither the EM studies nor resazurin-based cell viability assays showed toxic effects on uninfected host cells or cell organelles after A2 treatment. Besides the effects on early intracellular inclusion vacuoles, the ability of these β2,2-amino acid derivatives to suppress Chlamydia pneumoniae infectivity upon treatment of elementary bodies suggested also a direct interaction with bacterial membranes. Synthetic β2,2-amino acid derivatives that target C. pneumoniae represent promising lead molecules for development of antimicrobial agents against this hard-to-treat intracellular pathogen.

Current and emerging therapies in the management of diabetic foot ulcers

BACKGROUND

Diabetic foot ulcers are one of the major causes of mortality in diabetic patients. Very few drugs and therapies have regulatory approval for this indication and several agents from diverse pharmacological classes are currently in various phases of clinical trials for the management of diabetic foot ulcers.

SCOPE

The purpose of this review is to provide concise information of the drugs and therapies which are approved and present in clinical trials.

REVIEW METHODS

This review was carried out by systematic searches of relevant guidelines, patents, published articles, reviews and abstracts in PubMed/Medline, Web of Science, clinicaltrials.gov, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Google Scholar of all English language articles up to 1 March 2015. The following search terms were used: diabetes, diabetic foot, diabetic foot ulcer, diabetic wound, diabetic foot infections, wound management, randomized controlled trials, approved treatments, new treatments and clinical trials.

CONCLUSIONS

The various drugs and therapies for the management of diabetic foot ulcers comprise antibiotics, neuropathic drugs, wound dressings, skin substitutes, growth factors and inflammatory modulators. The majority of these therapies target the treatment of diabetic foot ulcers to address the altered biochemical composition of the diabetic wound. However, no single treatment can be definitively recommended for the treatment of diabetic foot ulcers.

Treatment of Chlamydial infections: 2014 update

INTRODUCTION

Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is required for intracellular survival and subsequent growth. The life cycle of Chlamydia spp. and the ability to cause persistent, often subclinical infection, has major ramifications for diagnosis and treatment of Chlamydia trachomatis and C. pneumoniae infections in humans.

AREAS COVERED

This paper reviews the current literature on the antimicrobial susceptibilities and treatment of genital infections due to C. trachomatis and respiratory infections due to C. pneumoniae published since 2011.

EXPERT OPINION

Chlamydiae are susceptible to antibiotics that interfere with DNA and protein synthesis, including tetracyclines, macrolides and quinolones, which are the compounds that have been most extensively studied and used for treatment of human infection. Since our original review was published in 2011, there have been some major advances in diagnostic tests for C. trachomatis and the introduction of the first FDA-approved test for the detection of C. pneumoniae in respiratory samples. However, the options for treating chlamydial infections have largely remained the same. There are a small number of new drugs currently in preclinical development and early clinical trials that may have a role in the treatment of chlamydial infections.

The potential role of nemonoxacin for treatment of common infections

INTRODUCTION

Nemonoxacin , a novel non-fluorinated quinolone, exhibits potent activity against Gram-positive bacteria, including MRSA and fluoroquinolone-resistant MRSA, Gram-negative and atypical pathogens. This agent also has a reduced propensity for resistance development in many kinds of pathogens.

AREAS COVERED

This article reviews currently available clinical and in vitro data that support the potential role of nemonoxacin for the treatment of common infectious diseases, including community-acquired pneumonia (CAP), Clostridium difficile infections (CDIs), acute bacterial skin and skin structure infections (ABSSSIs) and sexually transmitted diseases (STDs). One recent Phase II trial comparing either 500 mg or 750 mg oral nemonoxacin with 500 mg oral levofloxacin for mild to moderate CAP demonstrated that nemonoxacin had comparable clinical success with levofloxacin. Nemonoxacin showed lower MICs against clinical C. difficile isolates than commercially available fluoroquinolones, making it a potential therapeutic agent if novel formulations are developed to maintain a higher concentration in the human gut. For STDs, nemonoxacin also showed good activity against some common pathogens, such as Chlamydia trachomatis and Neisseria gonorrhoeae.

EXPERT OPINION

Although in vitro studies have shown promising results regarding the susceptibility to nemonoxacin of common pathogens causing CDIs, ABSSSIs and STDs, further clinical trials are needed to prove its efficacy.

Renaissance of antibiotics against difficult infections: Focus on oritavancin and new ketolides and quinolones

Lipoglycopeptide, ketolide, and quinolone antibiotics are currently in clinical development, with specific advantages over available molecules within their respective classes. The lipoglycopeptide oritavancin is bactericidal against MRSA, vancomycin-resistant enterococci, and multiresistant Streptococcus pneumoniae, and proved effective and safe for the treatment of acute bacterial skin and skin structure infection (ABSSSI) upon administration of a single 1200 mg dose (two completed phase III trials). The ketolide solithromycin (two phase III studies recruiting for community-acquired pneumonia) shows a profile of activity similar to that of telithromycin, but in vitro data suggest a lower risk of hepatotoxicity, visual disturbance, and aggravation of myasthenia gravis due to reduced affinity for nicotinic receptors. Among quinolones, finafloxacin and delafloxacin share the unique property of an improved activity in acidic environments (found in many infection sites). Finafloxacin (phase II completed; activity profile similar to that of ciprofloxacin) is evaluated for complicated urinary tract and Helicobacter pylori infections. The other quinolones (directed towards Gram-positive pathogens) show improved activity on MRSA and multiresistant S. pneumoniae compared to current molecules. They are in clinical evaluation for ABSSSI (avarofloxacin (phase II completed), nemonoxacin and delafloxacin (ongoing phase III)), respiratory tract infections (zabofloxacin and nemonoxacin (ongoing phase III)), or gonorrhea (delafloxacin).

Review of nemonoxacin with special focus on clinical development

Nemonoxacin is a novel C-8-methoxy nonfluorinated quinolone with remarkably enhanced in vitro activity against a wide variety of clinically relevant pathogens, especially gram-positive bacteria, including multidrug-resistant Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus. It has a low propensity for selecting resistant pathogens than fluoroquinolones, since bacteria become resistant to nemonoxacin only when three different mutations occur in their quinolone resistance-determining regions. Nemonoxacin shows greater efficacy than most of the widely used fluoroquinolones in the murine model of systemic, pulmonary, or ascending urinary tract infection. Nemonoxacin has a sound PK profile in healthy volunteers. It rapidly reaches maximum concentration Cmax 1-2 hours after oral administration in the fasting state and has a relatively long elimination half-life of more than 10 hours, which is similar to fluoroquinolones. Approximately 60%-75% of the administered dose is excreted in unchanged form via kidneys over 24-72 hours. Phase II and III studies of oral nemonoxacin and Phase II studies of intravenous nemonoxacin have been completed in patients with community-acquired pneumonia (CAP), before which the Phase I studies of oral and intravenous nemonoxacin indicated sound tolerance and safety with healthy volunteers. The published results demonstrate that an oral dose of either 500 mg or 750 mg nemonoxacin once daily for 7 days is as effective and safe as levofloxacin 500 mg once daily for 7 days. Nemonoxacin is well-tolerated in patients with CAP. The most common adverse events of oral administration are observed in the gastrointestinal and nervous system, the incidence of which is similar to levofloxacin treatment. The Phase III studies of intravenous nemonoxacin for treating CAP and oral nemonoxacin for diabetic foot infection has been registered with promising outcomes to be expected.