Chemical structure and pharmacokinetics of novel quinolone agents represented by avarofloxacin, delafloxacin, finafloxacin, zabofloxacin and nemonoxacin

In Vitro Comparison of Antibacterial and Antibiofilm Activities of Selected Fluoroquinolones against Pseudomonas aeruginosa and Methicillin-Resistant Staphylococcus aureus

An in vitro overview of the inhibitory effects of selected fluoroquinolones against planktonic and biofilm cells of the methicillin-resistant Staphylococcus aureus (MRSA) strain American type culture collection (ATCC) 43300 and the Pseudomonas aeruginosa strain ATCC 27853 was carried out. Biofilm cells of both strains were less susceptible to the selected antibiotics than their planktonic counterparts. In addition, certain antibiotics were more effective against biofilm cells, while others performed better on the planktonic cells. Against P. aeruginosa, ciprofloxacin was the most potent on both planktonic and biofilm cells, whereas ofloxacin was the least potent on both biofilm and planktonic cells. Moxifloxacin and gatifloxacin were the most potent against both planktonic and biofilm MRSA bacteria, however, not in the same order of activity. Norfloxacin was the least active when tested against both planktonic and biofilm cells. The results of this work are expected to provide insight into the efficacy of various fluoroquinolones against MRSA and Pseudomonas aeruginosa biofilms. This study could form the basis for future clinical studies that could recommend special guidelines for the management of infections that are likely to involve bacteria in their biofilm state.

Safety of Delafloxacin: Focus on Adverse Events of Special Interest

Background

Fluoroquinolones have been widely used for a variety of Gram-positive and Gram-negative infections, and by 2002 they had become the most commonly prescribed class of antibiotics for adults in the United States. With widespread use, the class has become associated with a range of adverse events. Delafloxacin is a fluoroquinolone approved in the United States for the treatment of adults with acute bacterial skin and skin structure infections (ABSSSIs). Delafloxacin is differentiated from other fluoroquinolones due to structural differences and in its activity against methicillin-resistant Staphylococcus aureus, including quinolone-resistant strains. This paper reviews the safety profile of delafloxacin across clinical studies with an emphasis on the incidence of adverse events of special interest that are associated with fluoroquinolones.

Methods

Data from 2 completed phase III studies of delafloxacin for the treatment of ABSSSIs were pooled and are the primary focus of this paper. Additional support from the full safety analysis set (30 completed phase I to phase III clinical studies) is included where applicable.

Results

Fewer patients in the pooled delafloxacin group had AESIs than in the comparator group (7.0% vs 9.2%, respectively). Delafloxacin had a low rate of discontinuations due to treatment-related adverse events (<1%). Serious adverse events occurred at similar rates in patients treated with delafloxacin vs comparators.

Conclusions

Serious adverse events occurred at similar rates in patients treated with delafloxacin vs nonquinolone comparators used to treat ABSSSIs.

Clinicaltrials.gov identifier

NCT01984684 and NCT01811732

Wagenlehner F, Zimmer KP, Chakraborty T. Treatment Options for Carbapenem- Resistant Gram-Negative Infections

BACKGROUND

Rates of colonization and infection with carbapenem-resistant Gram-negative pathogens are on the rise, particularly in southeastern European countries, and this is increasingly true in Germany as well. The organisms in question include enterobacteriaceae such as Klebsiella pneumoniae and Escherichia coli and non-fermenting bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii. As the carbapenems have been the gold standard to date for the systemic treatment of serious infections with Gram-negative bacteria, carbapenem resistance presents new and difficult challenges in therapeutic decision-making, particularly because of the high frequency of coresistance.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed and on other applicable literature.

RESULTS

Multiresistant Gram-negative (MRGN) pathogens are classified in Germany according to their resistance to four different classes of antibiotics; fluoroquinolones, piperacillin, third-generation cephalosporins, and carbapenems. Quadruple MRGN pathogens are resistant to all four groups, triple MRGN pathogens to three of them. There are a number of therapeutic alternatives to carbapenems that can be applied with the aid of sensitive microbiological and/or molecular genetic testing. The following antibiotics are often the only ones that can be used to treat quadruple MRGN pathogens: colistin, aminoglycosides, tigecycline, fosfomycin, ceftazidime/avibactam, and ceftolozan/tazobactam. Carbapenems, too, may still be an option in certain situations. There is also evidence that combinations of antibiotics against which the pathogen is resistant individually can some- times be a valid treatment option; these include combinations of colistin with one or two carbapenems.

CONCLUSION

The treatment of severe infection with carbapenem-resistant pathogens should be individualized and carried out in an interdisciplinary framework, in consideration of antibiotic pharmacokinetics and pharmacodynamics in each case. The treat- ment options are based on evidence from in vitro studies, retrospective studies, and case series, which must be interpreted with caution. Randomized clinical trials are needed to test each of the various combined approaches.

Emerging treatment options for acute bacterial skin and skin structure infections: focus on intravenous delafloxacin

The increase in hospitalization due to acute bacterial skin and skin structure infections (ABSSSI) caused by resistant pathogens supports the need for new treatment options. Antimicrobial options for ABSSSI that provide broad-spectrum coverage, including gram-negative pathogens and multidrug-resistant gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are limited. Delafloxacin is a novel fluoroquinolone available as intravenous and oral formulations and is characterized by an increased efficacy in acidic environments and activity on bacterial biofilm. Delafloxacin displays enhanced in vitro activity against MRSA, and enterococci, while maintaining efficacy against gram-negative pathogens and anaerobes. Delafloxacin has been studied for the treatment of ABSSSI and respiratory infections. Phase III studies have demonstrated noninferiority of delafloxacin compared to vancomycin, linezolid, tigecycline, and the combination of vancomycin plus aztreonam in the treatment of ABSSSI. Due to its favorable pharmacokinetic characteristics, the wide spectrum of action, and the potential for sequential therapy, delafloxacin represents a promising option in the empirical and targeted treatment of ABSSSI, both in hospital- and in community-based care.

Managing community acquired pneumonia in the elderly - the next generation of pharmacotherapy on the horizon

INTRODUCTION

Community acquired pneumonia (CAP) is associated with high rates of morbidity and mortality, especially among the elderly. Antibiotic treatment for CAP in the elderly is particularly challenging for many reasons, including compliance issues, immunosuppression, polypharmacy and antimicrobial resistance. There are few available antibiotics that are able to address these concerns. Areas covered: After a systematic review of the current literature, we describe seven novel antibiotics that are currently in advanced stages of development (phase 3 and beyond) and show promise for the treatment of CAP in those over the age of 65. These antibiotics are: Solithromycin, Pristinamycin, Nemonaxacin, Lefamulin, Omadacycline, Ceftobiprole and Delafloxacin. Using a novel conceptual framework designed by the present authors, known as the 'San Antonio NIPS model', we evaluate their strengths and weaknesses based on their ability to address the unique challenges that face the elderly. Expert opinion: All seven antibiotics have potential value for effective utilization in the elderly, but to varying degrees based on their NIPS model score. The goal of this model is to reorganize a clinician's focus on antibiotic choices in the elderly and bring attention to a seldom discussed topic that may potentially become a health-care crisis in the next decade.

Future trends in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection: An in-depth review of newer antibiotics active against an enduring pathogen

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major public health problem. Vancomycin and teicoplanin have been in clinical use for several decades but their drawbacks are well described. In the last 10 years, several antibiotics have been made available for clinical use. Daptomycin and linezolid have been extensively used during this period. Other agents such as ceftaroline, ceftobiprole, dalbavancin, oritavancin, tedizolid and telavancin have been approved by regulatory agencies since 2009. Many others, such as the newer tetracyclines, fluoroquinolones, oxazolidinones and pleuromutilins, are in various stages of development. In addition, an ongoing multicentre trial is investigating the role of combination of vancomycin or daptomycin with β-lactam antibiotics. This review discusses the role of the newer antibiotics, reflecting the views of the 6th MRSA Consensus Conference meeting of the International Society of Chemotherapy MRSA Working Group that took place in 2016.

Bacterial resistance and failure of clinical cure could be produced by oxidative stress in patients with diabetes or cardiovascular diseases during fluoroquinolone therapy

Fluoroquinolone agents are used widely for the treatment of infectious diseases which are a common cause of deaths around the world. The level of oxidative stress in patients taking fluoroquinolone antibiotics has not been considered a factor to reduce the clinical efficacy of this kind of drugs. Patients with diabetes and/or cardiovascular diseases present abnormal levels of oxidative stress in the blood stream. In this regards, our hypothesis supposes that patients with diabetes and/or cardiovascular disease suffering a bacterial disease could experience a therapeutic failure and bacterial resistance when treated with fluoroquinolones. The crucial mechanism could be an inefficient blood distribution of the drug via red blood cell dysfunction induced by oxidative stress that might reduce the pharmacokinetic-pharmacodinamic ratios. In this way, we review the scientific information to support our hypothesis alongside possible implications. Additionally, this work exhibits the urgent need of studies considering these conditions for quinolone agents.

Delafloxacin: design, development and potential place in therapy

Delafloxacin (DLX) is a new fluoroquinolone pending approval, which has shown a good in vitro and in vivo activity against major pathogens associated with skin and soft tissue infections and community-acquired respiratory tract infections. DLX also shows good activity against a broad spectrum of microorganisms, including those resistant to other fluoroquinolones, as methicillin-resistant Staphylococcus aureus. Its pharmacokinetic properties and excellent activity in acidic environments make DLX an alternative in the treatment of these and other infections. In this manuscript, a detailed analysis of this new fluoroquinolone is performed, from its chemical structure to its in vivo activity in recently published clinical trials. Its possible place in the current antimicrobial outlook and in other infectious models is also discussed.

Antimicrobial Activity of Zabofloxacin against Clinically Isolated Streptococcus pneumoniae

Zabofloxacin is a novel fluoroquinolone agent that has potent activity against gram-positive pathogens. In this study, we confirmed that zabofloxacin showed the most potent in vitro and in vivo activities against drug-resistant Streptococcus pneumoniae. Among the fluoroquinolone compounds, zabofloxacin showed the most potent in vitro activity against clinical isolates of penicillin-sensitive S. pneumoniae (minimum inhibitory concentration, MIC₉₀: 0.03 mg/L) and penicillin-resistant S. pneumoniae (MIC₉₀: 0.03 mg/L). Against quinolone-resistant S. pneumoniae, zabofloxacin (MIC₉₀: 1 mg/L) was more active than ciprofloxacin, sparfloxacin, and moxifloxacin; however, its activity was the same as that of gemifloxacin. The in vivo activity of zabofloxacin was most potent among the quinolone compounds tested against the systemic infection and respiratory tract infection models in mice.