In vitro activity of nadifloxacin against several Gram-positive bacteria and analysis of the possible evolution of resistance after 2 years of use in Germany

Glycosides of Nadifloxacin-Synthesis and Antibacterial Activities against Methicillin-Resistant Staphylococcus aureus

The increase in the number of bacteria that are resistant to multiple antibiotics poses a serious clinical problem that threatens the health of humans worldwide. Nadifloxacin (1) is a highly potent antibacterial agent with broad-spectrum activity. However, its poor aqueous solubility has limited its use to topical applications. To increase its solubility, it was glycosylated herein to form a range of trans-linked (3a-e) and cis-linked (7a,b) glycosides, each of which was prepared and purified to afford single anomers. The seven glycoside derivatives (3a-e, 7a,b) were examined for potency against eight strains of S. aureus, four of which were methicillin-resistant. Although less potent than free nadifloxacin (1), the α-L-arabinofuransoside (3a) was effective against all strains that were tested (minimum inhibitory concentrations of 1-8 μg/mL compared to 0.1-0.25 μg/mL for nadifloxacin), demonstrating the potential of this glycoside as an antibacterial agent. Estimation of Log P as well as observations made during preparation of these compounds reveal that the solubilities of the glycosides were greatly improved compared with nadifloxacin (1), raising the prospect of its use in oral applications.

Impact of Parallel Topical Treatment with Nadifloxacin and Adapalene on Acne Vulgaris Severity and Quality of Life: A Prospective, Uncontrolled, Multicentric, Noninterventional Study

Introduction: Daily parallel application of adapalene and nadifloxacin has been determined to be effective and well tolerated in patients with acne vulgaris in randomized, controlled clinical studies. Here, the authors report the results from a large, prospective, uncontrolled, multicentric, noninterventional study under real-life conditions in Germany. The effect of treatment on acne severity, safety, and, for the first time, health-related quality of life (HRQoL) was investigated. Methods: Of the 292 patients (safety collective: 231 adults, 61 adolescents) who had at least grade 4 acne vulgaris on the face as per the Leeds Revised Acne Grading (LRAG), 273 (efficacy collective: 213 adults, 60 adolescents) were treated with adapalene 0.1% cream or gel and nadifloxacin 1% cream for the defined minimum of 28 days. Patients were evaluated for acne severity, acne-related facial symptoms, HRQoL, overall assessment of therapy, and safety. Results: After the median treatment duration of 37 and 38 days (adults and adolescents, respectively), 93.4% and 85.0% of adults and adolescents, respectively, exhibited a sustained decrease in acne severity. The LRAG decreased by at least 3 scores in 29.1% and 24.6% of female and male adults, respectively. HRQoL improved in 67.9% and 63.5% of adults and adolescents, respectively (median improvement in the Dermatology Life Quality Index scores per patient of 3.0 [female adults], 1.0 [male adults], and 2.0 for all adolescents in the Children’s Dermatology Life Quality Index). Female adults were more impaired in terms of HRQoL compared to male adults. The 2 best overall efficacy ratings were provided by physicians in 79.3% and 69.5% and by patients in 68.5% and 58.3% of adult and adolescent cases, respectively. The treatment was well tolerated, as reflected in the low number of 9 mild adverse events (AEs), all of which resolved without treatment. However, 4 patients terminated the study prematurely due to AEs. Conclusion: In this study, the parallel use of adapalene and nadifloxacin for at least 5 weeks resulted in a rapid improvement in acne severity, an increase in HRQoL, and a good safety profile. Therefore, it represents a promising treatment option that offers the possibility of flexible therapy adjustment.

Structural Characterization of the Millennial Antibacterial (Fluoro)Quinolones-Shaping the Fifth Generation

The evolution of the class of antibacterial quinolones includes the introduction in therapy of highly successful compounds. Although many representatives were withdrawn due to severe adverse reactions, a few representatives have proven their therapeutical value over time. The classification of antibacterial quinolones into generations is a valuable tool for physicians, pharmacists, and researchers. In addition, the transition from one generation to another has brought new representatives with improved properties. In the last two decades, several representatives of antibacterial quinolones received approval for therapy. This review sets out to chronologically outline the group of approved antibacterial quinolones since 2000. Special attention is given to eight representatives: besifloxacin, delafoxacin, finafloxacin, lascufloxacin, nadifloxacin and levonadifloxacin, nemonoxacin, and zabofloxacin. These compounds have been characterized regarding physicochemical properties, formulations, antibacterial activity spectrum and advantageous structural characteristics related to antibacterial efficiency. At present these new compounds (with the exception of nadifloxacin) are reported differently, most often in the fourth generation and less frequently in a new generation (the fifth). Although these new compounds' mechanism does not contain essential new elements, the question of shaping a new generation (the fifth) arises, based on higher potency and broad spectrum of activity, including resistant bacterial strains. The functional groups that ensured the biological activity, good pharmacokinetic properties and a safety profile were highlighted. In addition, these new representatives have a low risk of determining bacterial resistance. Several positive aspects are added to the fourth fluoroquinolones generation, characteristics that can be the basis of the fifth generation. Antibacterial quinolones class continues to acquire new compounds with antibacterial potential, among other effects. Numerous derivatives, hybrids or conjugates are currently in various stages of research.

Determination of the Mutant Prevention Concentration and the Mutant Selection Window of Topical Antimicrobial Agents against Propionibacterium acnes

Determination of the mutant prevention concentration (MPC) and the mutant selection window (MSW) of antimicrobial agents used to treat pathogenic bacteria is important in order to apply effective antimicrobial therapies. Here, we determined the MPCs of the major topical antimicrobial agents against Propionibacterium acnes and Staphylococcus aureus which cause skin infections and compared their MSWs. Among the MPCs of nadifloxacin and clindamycin, the clindamycin MPC was determined to be the lowest against P. acnes. In contrast, the nadifloxacin MPC was the lowest against S. aureus. Calculations based on the minimum inhibitory concentrations and MPCs showed that clindamycin has the lowest MSW against both P. acnes and S. aureus. Nadifloxacin MSWs were 4-fold higher against P. acnes than against S. aureus. It is more likely for P. acnes to acquire resistance to fluoroquinolones than S. aureus. Therefore, topical application of clindamycin contributes very little to the emergence of resistant P. acnes and S. aureus strains.

Bactericidal effects of polyhexamethylene biguanide against intracellular Staphylococcus aureus EMRSA-15 and USA 300

OBJECTIVES

The treatment of skin infections caused by Staphylococcus aureus is limited by acquired antibiotic resistance and poor drug delivery into pathogen and host cells. Here, we investigated the antibacterial activities of six topically used antimicrobials and a cationic polymer, polyhexamethylene biguanide (PHMB), against intracellular MSSA strain RN4420 and MRSA strains EMRSA-15 and USA 300.

METHODS

The MICs of antimicrobials were determined for MSSA and MRSA strains, and the bactericidal activities of nadifloxacin and PHMB against intracellular MRSA were determined using infected keratinocytes. Fluorescein-tagged PHMB (PHMB-FITC) was used to study PHMB uptake, co-localization with intracellular EMRSA-15 and retention in keratinocytes. The mechanism(s) of PHMB uptake into keratinocytes were studied using a dynamin inhibitor, dynasore.

RESULTS

Gentamicin, nadifloxacin and PHMB showed the lowest MICs for MRSA. Nadifloxacin at 10 mg/L killed 80% of intracellular EMRSA-15, but was not effective against USA 300. PHMB at 4 mg/L killed almost 100% of intracellular EMRSA-15 and USA 300. PHMB entered keratinocytes, co-localized with intracellular EMRSA-15 and was retained by the cells for over 5 h. PHMB uptake and its intracellular antibacterial activities were inhibited by the dynamin inhibitor, dynasore.

CONCLUSIONS

PHMB kills intracellular MRSA via direct interaction with pathogens inside keratinocytes and host cell entry is dynamin dependent.

Topical acne treatments in Europe and the issue of antimicrobial resistance

Acne vulgaris (acne) is a chronic inflammatory disease of the sebaceous gland, characterized by follicular hyperkeratinization, excessive colonization by Propionibacterium acnes (P. acnes) as well as immune reactions and inflammation. Despite an armamentarium of topical treatments available including benzoyl peroxide, retinoids and azelaic acid, topical antibiotics in monotherapies, especially erythromycin and clindamycin, are still used in Europe to treat acne. This intensive use led to antimicrobial-resistant P. acnes and staphylococci strains becoming one of the main health issues worldwide. This is an update on the current topical acne treatments available in Europe, their mechanism of action, their potential to induce antimicrobial resistance and their clinical efficacy and safety.

Efficacy and safety of nadifloxacin for bacterial skin infections: results from clinical and post-marketing studies

Introduction

Skin and soft tissue infections involve microbial invasion of the skin and underlying soft tissues and are estimated to affect 7–10% of hospitalized patients worldwide. Nadifloxacin, a topical fluoroquinolone, has been shown to be effective against aerobic Gram-negative, Gram-positive (including MRSA and coagulase-negative staphylococci), and anaerobic bacteria. However, there is paucity of data comparing efficacy and safety of 1% nadifloxacin with other anti-bacterials for skin infections in Indian patients.

Methods

This article presents the results of one post-marketing surveillance (PMS) and three randomized, open, non-blinded, multi-centric clinical studies that compared nadifloxacin with mupirocin and framycetin, and nadifloxacin with fusidic acid. Patients in India, aged from 1 to 65 years old, suffering from mild to moderate bacterial skin infections including impetigo, secondarily infected wounds, folliculitis, infected atopic dermatitis, and furunculosis were randomly allocated to three treatment groups within the studies. Efficacy was assessed by the evaluation of symptoms of erythema, exudation, swelling, pruritus, crusting, pain and tenderness in all the studies.

Results

A total of 272 subjects were enrolled in the study and subjects were randomly assigned to one of the three treatment groups; 92 in the nadifloxacin group, 90 in the mupirocin group, and 90 in the framycetin group. A significant reduction in the mean scores for bacterial infection symptoms in the nadifloxacin groups was observed when compared to mupirocin, framycetin and fusidic acid groups. Both physician and patients rated nadifloxacin as excellent (complete remission of symptoms) on a 4-point scale in the studies. No adverse events (AEs) were reported in the clinical studies. In the PMS, only two patients (of 329, 0.6%) reported AEs including burning and itching, one in each patient that had resolved at the time of reporting.

Conclusion

Nadifloxacin, a fluoroquinolone, is a new alternative topical agent in the treatment of bacterial skin infection with minimal AEs.

Electronic supplementary material

The online version of this article (doi:10.1007/s13555-014-0062-1) contains supplementary material, which is available to authorized users.

Whole animal automated platform for drug discovery against multi-drug resistant Staphylococcus aureus

Staphylococcus aureus, the leading cause of hospital-acquired infections in the United States, is also pathogenic to the model nematode Caenorhabditis elegans. The C. elegans-S. aureus infection model was previously carried out on solid agar plates where the bacteriovorous C. elegans feeds on a lawn of S. aureus. However, agar-based assays are not amenable to large scale screens for antibacterial compounds. We have developed a high throughput liquid screening assay that uses robotic instrumentation to dispense a precise amount of methicillin resistant S. aureus (MRSA) and worms in 384-well assay plates, followed by automated microscopy and image analysis. In validation of the liquid assay, an MRSA cell wall defective mutant, MW2ΔtarO, which is attenuated for killing in the agar-based assay, was found to be less virulent in the liquid assay. This robust assay with a Z'-factor consistently greater than 0.5 was utilized to screen the Biomol 4 compound library consisting of 640 small molecules with well characterized bioactivities. As proof of principle, 27 of the 30 clinically used antibiotics present in the library conferred increased C. elegans survival and were identified as hits in the screen. Surprisingly, the antihelminthic drug closantel was also identified as a hit in the screen. In further studies, we confirmed the anti-staphylococcal activity of closantel against vancomycin-resistant S. aureus isolates and other Gram-positive bacteria. The liquid C. elegans-S. aureus assay described here allows screening for anti-staphylococcal compounds that are not toxic to the host.

Anti Propionibacterium acnes activity of rhodomyrtone, an effective compound from Rhodomyrtus tomentosa (Aiton) Hassk. leaves

Propionibacterium acnes have been recognized as one of the main causative agents in pathogenesis of acne. Twenty one isolates of P. acnes isolated from acne lesions were screened for lipase and protease activity which are reported to be associated in acne and inflammation. Interestingly, all P. acnes isolates demonstrated lipase activity. Similarly, 90% of test P. acnes produced protease enzyme. Antibacterial activity of the ethanol extract of Rhodomyrtus tomentosa (Aiton) Hassk. leaves and rhodomyrtone, its principle compound were tested against P. acnes using broth macrodilution method. The MIC(90) values of the ethanol extract and rhodomyrtone were 32 and 0.5 μg/mL, respectively. The numbers of the bacterial cells were reduced at least 99% after treatment with the ethanol extract and rhodomyrtone within 72 and 24 h, respectively. Cytotoxicity test of the extract and rhodomyrtone was performed on human normal fibroblast. The IC(50) values of the ethanol extract and rhodomyrtone were 476 and more than 200 μg/mL, approximately 15 and 400 folds higher than the MIC(90) values indicating that both substances were very low cytotoxic which could be applied as topical therapeutic anti-acne agents.

Efficacy and safety of topical nadifloxacin and benzoyl peroxide versus clindamycin and benzoyl peroxide in acne vulgaris: A randomized controlled trial

Background:

Topical therapy with comedolytics and antibiotics are often advocated for mild and moderate severity acne vulgaris. Nadifloxacin, a new fluoroquinolone with anti-Propionibacterium acnes activity and additional anti-inflammatory activity, is approved for use in acne. This randomized controlled assessor blind trial compared the clinical effectiveness and safety of eight weeks therapy of nadifloxacin 1% versus clindamycin 1% as add-on therapy to benzoyl peroxide (2.5%) in mild to moderate grade acne.

Materials and Methods:

The efficacy parameters were changes in the total, inflammatory and non-inflammatory lesion counts, Investigator Global Assessment (IGA), and Cardiff Acne Disability Index (CADI) scales from baseline to study end (eight weeks). All treatment emergent dermatological adverse events were evaluated for safety assessment.

Results:

Out of 84 randomized subjects (43-nadifloxacin arm) and (41-clindamycin) 42 in nadifloxacin group, 37 in clindamycin group completed the study. Reduction from baseline of total, inflammatory and non-inflammatory lesion counts were highly significant in both the groups (P<0.0001), but between group differences were not significant. Significant improvement in CADI and IGA scales were noted in both groups. Between-group comparison showed no significant differences. The safety and tolerability profile of both regimens were good and statistically comparable.

Conclusions:

Topical nadifloxacin, a new fluoroquinolone is effective, tolerable, and safe for mild o moderate facial acne. Its clinical effectiveness is comparable to clindamycin when used as add-on therapy to benzoyl peroxide.

Efficacy of combined topical treatment of acne vulgaris with adapalene and nadifloxacin: a randomized study

Topical retinoid and antibiotic combination therapy is an integral part of acne treatment and is considered the appropriate first-line therapy according to the Japanese guideline for moderate and severe acne. In this combination, clindamycin or doxycycline are mostly used as antibiotics, but there have been no reports on the effectiveness of nadifloxacin, a widely used antibiotic in Japan and European countries for acne, in combination with topical retinoid. To confirm the efficacy and safety of adapalene gel and nadifloxacin cream in the treatment of Japanese patients with acne vulgaris, a total of 50 patients were randomized to the two groups, the combination therapy and the adapalene monotherapy, and each therapy was tested for 8 weeks. The percentage reduction in the number of inflammatory acne lesions was evaluated and the safety was monitored through adverse events. The combination of adapalene gel and nadifloxacin cream produced a significantly higher reduction in the inflammatory lesions at 2 weeks (P = 0.047) and at 8 weeks (P = 0.011) after the starting than did adapalene gel monotherapy. The combination did not elevate the side effects of erythema and scale scores, but rather significantly depressed erythema at 1 week. This study showed the efficacy and safety of the combination therapy of nadifloxacin cream with adapalene gel for the inflammatory acne.