Emergence of Neisseria gonorrhoeae Clone with Reduced Susceptibility to Sitafloxacin in China: An In Vitro and Genomic Study

Drug-resistant Neisseria gonorrhoeae poses an urgent threat to public health. Recently, sitafloxacin, a new-generation fluoroquinolone, has shown high in vitro activity against drug-resistant N. gonorrhoeae. However, data on its effectiveness in clinical isolates remains limited. In this study, we collected 507 N. gonorrhoeae isolates from 21 hospitals in Shanghai, China, during 2020 and 2021. Antimicrobial susceptibility testing revealed that sitafloxacin minimum inhibitory concentrations (MICs) exhibited a bimodal distribution, ranging from <0.004 to 2 mg/L. The MIC50 and MIC90 for sitafloxacin were 0.125 mg/L and 0.5 mg/L, respectively, which are 32 and 16 times lower than those for ciprofloxacin (4 mg/L and 8 mg/L, respectively). Sitafloxacin demonstrated high in vitro activity against isolates resistant to either ceftriaxone, azithromycin, or both. Notably, among the isolates with reduced sitafloxacin susceptibility (MIC ≥ MIC90), 83.7% (36/43) were identified as sequence type (ST) 8123. Further phylogenetic analysis showed that ST8123 has evolved into two subclades, designated as subclade-I and subclade-II. A majority of the isolates (80%, 36/45) within subclade-I exhibited reduced susceptibility to sitafloxacin. In contrast, all isolates from subclade-II were found to be susceptible to sitafloxacin. Subsequent genomic investigations revealed that the GyrA-S91F, D95Y, and ParC-S87N mutations, which were exclusively found in ST8123 subclade-I, might be linked to reduced sitafloxacin susceptibility. Our study reveals that sitafloxacin is a promising antibiotic for combating drug-resistant N. gonorrhoeae. However, caution is advised in the clinical application of sitafloxacin for treating N. gonorrhoeae infections due to the emergence of a clone exhibiting reduced susceptibility.

Clinical Efficacy of Sitafloxacin-Colistin-Meropenem and Colistin-Meropenem in Patients with Carbapenem-Resistant and Multidrug-Resistant Acinetobacter baumannii Hospital-Acquired Pneumonia (HAP)/Ventilator-Associated Pneumonia (VAP) in One Super-Tertiary Hospital in Bangkok, Thailand: A Randomized Controlled Trial

BACKGROUND

Carbapenem-resistant A. baumannii (CRAB) hospital-acquired pneumonia (HAP)/ventilator-associated pneumonia (VAP) is now a therapeutic problem worldwide.

METHOD

An open-label, randomized, superiority, single-blind trial was conducted in Rajavithi Hospital, a super-tertiary care facility in Bangkok, Thailand. CRAB HAP/VAP patients were randomly assigned to receive either sitafloxacin-colistin-meropenem or colistin-meropenem. Outcomes in the two groups were then assessed with respect to mortality, clinical response, and adverse effects.

RESULT

Between April 2021 and April 2022, 77 patients were treated with combinations of either sitafloxacin plus colistin plus meropenem (n = 40) or colistin plus meropenem (n = 37). There were no significant differences between the two groups with respect to all-cause mortality rates at 7 days and 14 days (respectively, 7.5% vs. 2.7%; p = 0.616, and 10% vs. 10%; p = 1). Patients who received sitafloxacin-colistin-meropenem showed improved clinical response compared with patients who received colistin-meropenem in terms of both intention-to-treat (87.5% vs. 62.2%; p = 0.016) and per-protocol analysis (87.2% vs. 67.7%; p = 0.049). There were no significant differences between the two groups with respect to adverse effects.

CONCLUSIONS

Adding sitafloxacin as a third agent to meropenem plus colistin could improve clinical outcomes in CRAB HAP/VAP with little or no impact on adverse effects. In short, sitafloxacin-meropenem-colistin could be another therapeutic option for combatting CRAB HAP/VAP.

Pharmacokinetic/pharmacodynamic (PK/PD) simulation for dosage optimization of colistin and sitafloxacin, alone and in combination, against carbapenem-, multidrug-, and colistin-resistant Acinetobacter baumannii

To the best of our knowledge, to date, no study has investigated the optimal dosage regimens of either colistin or sitafloxacin against drug-resistant Acinetobacter baumannii (A. baumannii) infections by using specific parameters. In the current study, we aimed to explore the optimal dosage regimens of colistin and sitafloxacin, either in monotherapy or in combination therapy, for the treatment of carbapenem-, multidrug-, and colistin-resistant A. baumannii infections. A Monte Carlo simulation was applied to determine the dosage regimen that could achieve the optimal probability of target attainment (PTA) and cumulative fraction of response (CFR) (≥90%) based on the specific parameters of each agent and the minimal inhibitory concentration (MIC) of the clinical isolates. This study explored the dosage regimen of 90, 50, 30, and 10 mL/min for patients with creatinine clearance (CrCL). We also explored the dosage regimen for each patient with CrCL using combination therapy because there is a higher possibility of reaching the desired PTA or CFR. Focusing on the MIC90 of each agent in combination therapy, the dosage regimen for colistin was a loading dose of 300 mg followed by a maintenance dose ranging from 50 mg every 48 h to 225 mg every 12 h and the dosage regimen for sitafloxacin was 325 mg every 48 h to 750 mg every 12 h. We concluded that a lower-than-usual dose of colistin based on specific pharmacokinetic data in combination with a higher-than-usual dose of sitafloxacin could be an option for the treatment of carbapenem-, multidrug-, and colistin-resistant. A. baumannii. The lower dose of colistin might show a low probability of adverse reaction, while the high dose of sitafloxacin should be considered. In the current study, we attempted to find if there is a strong possibility of drug selection against crucial drug-resistant pathogen infections in a situation where there is a lack of new antibiotics. However, further study is needed to confirm the results of this simulation study.

Comparison of the in vitro antibacterial activity of ofloxacin, levofloxacin, moxifloxacin, sitafloxacin, finafloxacin, and delafloxacin against Mycobacterium tuberculosis strains isolated in China

Objective

The resistance of Mycobacterium tuberculosis (Mtb) to currently available fluoroquinolones (FQs), namely ofloxacin (OFX), levofloxacin (LFX), and moxifloxacin (MFX), renders the treatment of TB infections less successful. In this study, we aimed to evaluate the susceptibility and intracellular killing assay of Mtb to next-generation FQs in vitro and determine the correlation of FQs resistance and newly detected mutations in gyrB by molecular docking.

Methods

Antimicrobial susceptibility test was performed to determine the minimum inhibitory concentrations (MICs) of six FQs, including currently available FQs (OFX, LFX, and MFX) and next-generation FQs, i.e., sitafloxacin (SFX), finafloxacin (FIN) and delafloxacin (DFX) against Mtb clinical isolates obtained in 2015 and 2022, respectively. Quinolone-resistance-determining regions of gyrA and gyrB were subjected to DNA sequencing and the correlation of FQs resistance and new mutations in gyrB were determined by molecular docking. Furthermore, the intracellular antibacterial activity of the six FQs against Mtb H37Rv in THP-1 cells was evaluated.

Results

SFX exhibited the highest antibacterial activity against Mtb isolates (MIC90 = 0.25 μg/mL), whereas DFX and OFX exhibited comparable activity (MIC90 = 8 μg/mL). A statistically significant difference was observed among the MICs of the new generation FQs (SFX, P = 0.002; DFX, P = 0.008). Additionally, a marked increase in MICs was found in strains isolated in 2022 compared with those isolated in 2015. There might be correlation between FQs resistance and mutations in gyrB G520T and G520A. Cross-resistance rate between SFX and MFX was 40.6 % (26/64). At a concentration of 1 μg/mL, SFX exhibited high intracellular antibacterial activity (96.6 % ± 1.5 %) against the Mtb H37Rv, comparable with that of MFX at a concentration of 2 μg/mL.

Conclusion

SFX exhibits the highest inhibitory activity against Mtb in vitro and THP-1 cell lines, which exhibits partial-cross resistance with MFX. There might be correlation between FQs resistance and mutations in gyrB G520T and G520A.Our findings provide crucial insights into the potential clinical application of SFX and DFX in the treatment of Mtb infections.

The Role of Five-Membered Heterocycles in the Molecular Structure of Antibacterial Drugs Used in Therapy

Five-membered heterocycles are essential structural components in various antibacterial drugs; the physicochemical properties of a five-membered heterocycle can play a crucial role in determining the biological activity of an antibacterial drug. These properties can affect the drug's activity spectrum, potency, and pharmacokinetic and toxicological properties. Using scientific databases, we identified and discussed the antibacterials used in therapy, containing five-membered heterocycles in their molecular structure. The identified five-membered heterocycles used in antibacterial design contain one to four heteroatoms (nitrogen, oxygen, and sulfur). Antibacterials containing five-membered heterocycles were discussed, highlighting the biological properties imprinted by the targeted heterocycle. In some antibacterials, heterocycles with five atoms are pharmacophores responsible for their specific antibacterial activity. As pharmacophores, these heterocycles help design new medicinal molecules, improving their potency and selectivity and comprehending the structure-activity relationship of antibiotics. Unfortunately, particular heterocycles can also affect the drug's potential toxicity. The review extensively presents the most successful five-atom heterocycles used to design antibacterial essential medicines. Understanding and optimizing the intrinsic characteristics of a five-membered heterocycle can help the development of antibacterial drugs with improved activity, pharmacokinetic profile, and safety.

Sitafloxacin pharmacokinetics/pharmacodynamics against multidrug-resistant bacteria in a dynamic urinary tract infection in vitro model

OBJECTIVES

Sitafloxacin is one of the newer generation fluoroquinolones with highly active against multidrug-resistant (MDR) bacteria. Our objectives were to identify the sitafloxacin pharmacokinetic/pharmacodynamic (PK/PD) index and breakpoints against MDR isolate in the urinary tract infection model.

METHODS

Forty-eight MDR isolates underwent sitafloxacin and levofloxacin microdilution susceptibility testing. A 24 h in vitro model was established that simulated the healthy subjects urodynamics of sitafloxacin fumarate injection. Ten MDR isolates (four carbapenem-resistant Escherichia coli, three carbapenem-resistant P. aeruginosa and three vancomycin-resistant E. faecium) were selected. The drug efficacy was quantified by the change in log colony counts within 24 h. A sigmoid Emax model was fitted to the killing effect data. Monte Carlo simulations were performed to assess target attainment for the sitafloxacin fumarate doses of 100 and 200 mg q24h.

RESULTS

Analysis indicated that the MICs of sitafloxacin were all significantly lower than that of levofloxacin (P < 0.01). The UAUC0-24h/MIC targets required to achieve stasis, 1-log10 killing and 2-log10 killing were 63.60, 79.49 and 99.45 (carbapenem-resistant E. coli), 60.85, 90.31 and 128.95 (carbapenem-resistant P. aeruginosa), 65.91, 77.81 and 103.11 (vancomycin-resistant E. faecium). Monte Carlo simulation showed the infusion of sitafloxacin fumarate 100 mg q24h was able to achieve 90% probability of target attainment against bacteria with MIC of 8 mg/L for the common complicated urinary tract infections.

CONCLUSIONS

Sitafloxacin fumarate injection is an alternative therapeutic agent for the treatment of UTIs caused by MDR isolates.

Colistin Monotherapy versus Colistin plus Sitafloxacin for Therapy of Carbapenem-Resistant Acinetobacter baumannii Infections: A Preliminary Study

The in vitro study of sitafloxacin against carbapenem-resistant (CR) Acinetobacter baumannii demonstrated activity against most strains of CR A. baumannii, and the combination of colistin and sitafloxacin showed an in vitro synergistic effect against CR A. baumannii. This study aimed to compare efficacy and safety between colistin plus sitafloxacin with colistin alone for therapy for CR A. baumannii infection. This randomized controlled trial enrolled 56 patients with CR A. baumannii infection (28/group) during 2018-2021, and the treatment duration was 7-14 days. The study outcomes were 28-day mortality, clinical and microbiological responses, and adverse events. There was no significant difference in 28-day mortality between groups (32.1% combination vs. 32.1% monotherapy, p = 1.000). Favorable clinical response at the end of treatment was comparable between groups (81.5% combination vs. 77.8% monotherapy, p = 0.788). Microbiological response at the end of treatment was also comparable between groups (73.1% combination vs. 74.1% monotherapy, p = 0.934). Acute kidney injury was found in 53.8% of the combination group, and in 45.8% of the monotherapy group (p = 0.571). In conclusion, there was no significant difference in 28-day mortality between the colistin monotherapy and the colistin plus sitafloxacin groups. There was also no significant difference in adverse events between groups.

Antimicrobial activities of sitafloxacin and comparators against the clinical isolates of less common nonfermenting Gram-negative bacteria

The in vitro antimicrobial activities of sitafloxacin and comparators against 320 clinical isolates of less common nonfermenting Gram-negative bacteria (NFGNB) were assessed by determining the minimum inhibitory concentrations (MICs) using broth microdilution method. In terms of MIC_50/90 values, sitafloxacin was highly active against Stenotrophomonas maltophilia (0.25/1 mg/L), Burkholderia cepacia complex (0.25/2 mg/L), Achromobacter xylosoxidans (0.25/1 mg/L), and Chryseobacterium gleum (1/2 mg/L), but less active for Elizabethkingia (1/8 mg/L) and Chryseobacterium indologenes (16/32 mg/L). Sitafloxacin was more active than other fluoroquinolones against these NFGNB except Chryseobacterium. The results are helpful for clinicians to be aware of the role of sitafloxacin in managing the infections caused by these NFGNB.

Discovery and Development of Antibacterial Agents: Fortuitous and Designed

Today, antibacterial drug resistance has turned into a significant public health issue. Repeated intake, suboptimal and/or unnecessary use of antibiotics, and, additionally, the transfer of resistance genes are the critical elements that make microorganisms resistant to conventional antibiotics. A substantial number of antibacterials that were successfully utilized earlier for prophylaxis and therapeutic purposes have been rendered inadequate due to this phenomenon. Therefore, the exploration of new molecules has become a continuous endeavour. Many such molecules are at various stages of investigation. A surprisingly high number of new molecules are currently in the stage of phase 3 clinical trials. A few new agents have been commercialized in the last decade. These include solithromycin, plazomicin, lefamulin, omadacycline, eravacycline, delafloxacin, zabofloxacin, finafloxacin, nemonoxacin, gepotidacin, zoliflodacin, cefiderocol, BAL30072, avycaz, zerbaxa, vabomere, relebactam, tedizolid, cadazolid, sutezolid, triclosan and afabiacin. This article aims to review the investigational and recently approved antibacterials with a focus on their structure, mechanisms of action/resistance, and spectrum of activity. Delving deep, their success or otherwise in various phases of clinical trials is also discussed while attributing the same to various causal factors.

Therapeutic Potential of Sitafloxacin as a New Drug Candidate for Helicobacter Eradication in Korea: An In Vitro Culture-Based Study

Background: Increased prevalence of antibiotic resistance to Helicobacter pylori (H. pylori) infection worldwide has driven the search for a new therapeutic candidate. Recently, sitafloxacin, a novel 4-quinolone agent, has emerged as a new therapeutic option for H. pylori eradication, in Japan. However, data on its efficacy for H. pylori eradication in Korea are limited. Therefore, we aimed to investigate the therapeutic potential of sitafloxacin as a first-line treatment for patients with Helicobacter infection through gastric tissue culture-based studies. Materials and Methods: We prospectively enrolled treatment-naïve patients with H. pylori infection who visited the Gil Medical Center between March 2015 and March 2018. After obtaining written informed consent from patients, a total of 121 H. pylori strains were collected. We tested the susceptibility of these strains to sitafloxacin, and other antibiotics for Helicobacter eradication, including clarithromycin (CLR), metronidazole (MTZ), amoxicillin (AMX), tetracycline (TET), levofloxacin (LEV), and ciprofloxacin (CIP) using the agar dilution technique. The minimum inhibitory concentration (MIC) of these antibiotics against H. pylori strains were determined. Results: None of the H. pylori strains obtained were resistant to sitafloxacin (MIC > 1, n = 0), while other conventional eradication drugs including CLR, MTZ, AMX, and TET showed 24.8% (n = 30), 30.6% (n = 37), 5.0% (n = 6), and 0.8% (n = 1) resistance, respectively. Compared to the resistance rates of other quinolones (LEV [36.4%, n = 44] and CIP [37.2%, n = 45]), sitafloxacin showed the best antibiotic performance against Helicobacter strains (0%, n = 0). Furthermore, sitafloxacin also inhibited the growth of 14 H. pylori strains (12.4%), which were resistant to both of clarithromycin, and metronidazole, and 27 strains (22.3%) with multidrug resistance. Conclusions: Sitafloxacin might be a new promising candidate for Helicobacter eradication where antibiotic resistance for Helicobacter is an emerging medical burden, such as in Korea.

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.

Comparative activities of sitafloxacin against recent clinical isolates in hospitals across China

Sitafloxacin is one of the newer generation fluoroquinolones. Considering the ever-changing antimicrobial resistance, it is necessary to monitor the activities of sitafloxacin against recent pathogenic isolates. Therefore, we determined the minimum inhibitory concentrations (MICs) of sitafloxacin and comparators by broth microdilution or agar dilution method against 1101 clinical isolates collected from 2017 to 2019 in 31 hospitals across China. Sitafloxacin was highly active against gram-positive isolates evidenced by the MICs required to inhibit the growth of 50%/90% isolates (MIC_50/90): ≤ 0.03/0.25, ≤ 0.03/0.125, ≤ 0.03/2, 0.125/0.25, 0.25/2, and 0.125/0.125 mg/L for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-susceptible coagulase-negative Staphylococcus (MSCNS), methicillin-resistant S. aureus (MRSA), methicillin-resistant CNS, Enterococcus faecalis, and Streptococcus pneumoniae, respectively. Sitafloxacin inhibited 82.8% of the MRSA strains and 97.5% of MRCNS strains. Sitafloxacin was also potent against ciprofloxacin-susceptible Escherichia coli (MIC_50/90: ≤ 0.03/0.06 mg/L) and Klebsiella pneumoniae (MIC_50/90: ≤ 0.03/0.125 mg/L), non-ESBL-producing E. coli (MIC_50/90: ≤ 0.03/1 mg/L) and K. pneumoniae (MIC_50/90: ≤ 0.03/0.5 mg/L), Haemophilus influenzae (MIC_50/90: ≤0.015/0.06 mg/L), Haemophilus parainfluenzae (MIC_50/90: 0.125/0.5 mg/L), Moraxella catarrhalis (MIC_50/90: ≤ 0.015/≤ 0.015 mg/L), Bacteroides fragilis (MIC_50/90: 0.06/2 mg/L), Peptostreptococcus (MIC_50/90: 0.125/4 mg/L), and Mycoplasma pneumoniae (≤ 0.03/≤ 0.03 mg/L). However, sitafloxacin was less active for Enterococcus faecium, ciprofloxacin-resistant and/or ESBL-producing E. coli, and K. pneumoniae strains. Sitafloxacin was superior or comparable to most of the comparators in activities against the abovementioned isolates, so sitafloxacin is still highly active against most of the clinical isolates in hospitals across China, proving its utility in treatment of the abovementioned susceptible strains.

A randomized, controlled, multicenter clinical trial to evaluate the efficacy and safety of oral sitafloxacin versus moxifloxacin in adult patients with community-acquired pneumonia

OBJECTIVES

To evaluate the efficacy and safety of oral sitafloxacin versus oral moxifloxacin in the treatment of Chinese adults with community-acquired pneumonia (CAP).

PATIENTS AND METHODS

This is a multicenter, randomized, open-label, positive-controlled clinical trial (chinadrugtrials.org.cn identifier: CTR20130046). CAP patients received sitafloxacin tablets 100 mg once daily (qd) or 100 mg twice daily (bid) to compare with moxifloxacin tablets 400 mg qd, for 7-10 days. The primary outcome was non-inferiority of sitafloxacin to moxifloxacin in clinical cure rate at test of cure (TOC) visit in per-protocol set (PPS).

RESULTS

A total of 343 patients were randomized (sitafloxacin 100 mg qd, n = 117; sitafloxacin 100 mg bid, n = 116; moxifloxacin, n = 110), 291 patients were included in the PPS (sitafloxacin 100 mg qd, n = 96; sitafloxacin 100 mg bid, n = 94; moxifloxacin, n = 101). The clinical cure rate was 94.8% in the sitafloxacin 100 mg qd group, 96.8% in the sitafloxacin 100 mg bid group and 95.0% in the moxifloxacin group. At the TOC visit, the microbiological success rate was 97.0% (32/33) in the sitafloxacin 100 mg qd group, 97.1% (34/35) in the sitafloxacin 100 mg bid group and 94.9% (37/39) in the moxifloxacin group in the microbiological evaluable set (MES). The incidence of study-drug-related adverse events (AEs) was 23.3% (27/116) in the sitafloxacin 100 mg qd group, 29.8% (34/114) in the sitafloxacin 100 mg bid group and 28.2% (31/110) in the moxifloxacin group (p > .05). The common AEs related to study drug were dizziness, nausea, diarrhea, increased platelet count and alanine transaminase (ALT) elevation. All the AEs resolved completely after discontinuation of study drug.

CONCLUSION

Sitafloxacin 100 mg qd or 100 mg bid for 7-10 days is not inferior to moxifloxacin 400 mg qd for 7-10 days in clinical efficacy for adult CAP patients. Sitafloxacin provides a safety profile comparable to moxifloxacin.

Rhodium-catalysed diastereo- and enantio-selective cyclopropanation of α-boryl styrenes

A rhodium-catalyzed diastereo- and enantio-selective cyclopropanation of α-boryl styrenes with α-diazoarylacetates was established. Rh₂(S-PTTL)₄ (0.2 mol%) was found to be effective for the conversion, and 21 diastereopure cyclopropylboronates were prepared in high yields with excellent enantioselectivity (ee up to 99%).

In Vitro Activities of Colistin and Sitafloxacin Combinations against Multidrug-, Carbapenem-, and Colistin-Resistant Acinetobacter baumannii Using the Broth Microdilution Checkerboard and Time-Kill Methods

Drug-resistant Acinetobacter baumannii (A. baumannii) infections are a critical global problem, with limited treatment choices. This study aims to determine the in vitro activities of colistin–sitafloxacin combinations against multidrug-, carbapenem- and colistin-resistant A. baumannii (MDR-AB, CRAB, CoR-AB, respectively) clinical isolates from tertiary care hospitals. We used the broth microdilution checkerboard and time-kill methods in this study. Synergy was found using both methods. The colistin–sitafloxacin combination showed synergy in MDR-AB, CRAB, and CoR-AB isolates (3.4%, 3.1%, and 20.9%, respectively). No antagonism was found in any type of drug-resistant isolate. The majority of CoR-AB isolates became susceptible to colistin (95.4%). The time-kill method also showed that this combination could suppress regrowth back to the initial inocula of all representative isolates. Our results demonstrated that the colistin–sitafloxacin combination might be an interesting option for the treatment of drug-resistant A. baumannii. However, further in vivo and clinical studies are required.

Effects of ABCB1, UGT1A1, and UGT1A9 Genetic Polymorphisms on the Pharmacokinetics of Sitafloxacin Granules in Healthy Subjects

Sitafloxacin, a new fluoroquinolone, has strong antibacterial activity. We evaluated the effects of sitafloxacin granules in single‐dose and multidose cohorts and the effects of ABCB1, UGT1A1, and UGT1A9 genetic polymorphisms on the pharmacokinetics (PK) of sitafloxacin in healthy subjects. The single‐dose study included 3 fasted cohorts receiving 50, 100, and 200 mg of sitafloxacin granules and 1 cohort receiving 50 mg of sitafloxacin granules with a high‐fat meal. The multidose study included 1 cohort receiving 100 mg of sitafloxacin granules once daily for 5 days. PK parameters were calculated using noncompartmental parameters based on concentration‐time data. The genotypes for ABCB1, UGT1A1, and UGT1A9 single‐nucleotide polymorphisms were determined using Sanger sequencing. Subsequently, the association between sitafloxacin PK parameters and target single‐nucleotide polymorphisms was analyzed. Sitafloxacin granules were well tolerated up to 200 and 100 mg in the single‐dose and multidose studies, respectively. Sitafloxacin AUC and C_max increased linearly within the detection range, and a steady state was reached within 3 days after the administration of multiple oral doses. Our findings showed that C_max was lower in the ABCB1 (rs1045642) mutation group, whereas t_1/2 was longer in the UGT1A1 (rs2741049) and UGT1A9 (rs3832043) mutation groups. In conclusion, sitafloxacin granules were safe at single doses and multiple doses up to 200 and 100 mg/day, respectively, with a linear plasma PK profile. However, ABCB1 (rs1045642), UGT1A1 (rs2741049), and UGT1A9 (rs3832043) genetic polymorphisms are likely to influence the C_max or t_1/2 and thereby merit further clinical evaluation.

Efficacy and Safety of Sitafloxacin in the Treatment of Acute Bacterial Infection: A Meta-analysis of Randomized Controlled Trials

This meta-analysis aimed to assess the efficacy and safety of sitafloxacin in treating acute bacterial infection. PubMed, Embase, and Cochrane databases were searched up to August 13, 2019. Only randomized controlled trials (RCTs) evaluating sitafloxacin and comparators in the treatment of acute bacterial infections were included. The outcomes were clinical and microbiological responses and the risk of adverse event (AE). Five RCTs were enrolled, including 375 and 381 patients who received sitafloxacin and the comparator, respectively. Overall, the clinical response rate of sitafloxacin in the treatment of acute bacterial infections was 94.6%, which was noninferior to that of the comparator (92.5%) (odds ratio (OR), 1.01; 95% CI, 0.24-4.32; I² = 66%). For patients with complicated urinary tract infection (cUTI)/acute pyelonephritis (APN), the clinical response rate of sitafloxacin and the comparator was 96.9% and 91.3%, respectively (OR, 2.08; 95% CI, 0.35-12.44; I² = 54%). For patients with pneumonia, the clinical response rate of sitafloxacin was 88.6%, which was comparable to that of the comparator (OR, 0.36; 95% CI, 0.11-1.21; I² = 0%). The microbiological response of sitafloxacin was 82.0%, which was noninferior to that of the comparator (77.8%) (OR, 1.59; 95% CI, 0.77-3.28; I² = 47%). The risk of treatment-emergent adverse event (TEAE), drug-related TEAE, and all-cause mortality were similar between sitafloxacin and the comparators (TEAE, OR, 1.14; 95% CI, 0.64-2.01, drug-related TEAE, OR, 1.14; 95% CI, 0.48-2.69, mortality, OR, 0.93; 95% CI, 0.09-9.44). In conclusion, sitafloxacin is noninferior to other commonly used antibiotics with respect to both clinical and microbiological response rates in patients with an acute bacterial infection, including cUTI/APN and pneumonia. In addition, sitafloxacin is also as safe as the comparators.

Pharmacokinetics and Penetration of Sitafloxacin into Alveolar Epithelial Lining Fluid in Critically Ill Thai Patients with Pneumonia

Sitafloxacin showed potent activity against various respiratory pathogens. Blood and bronchoalveolar lavage (BAL) fluid samples were obtained from 12 subjects after a single oral dose of sitafloxacin 200 mg. The mean ± SD (median) maximum ratio of epithelial lining fluid (ELF) to unbound plasma concentration was 1.02 ± 0.58 (1.33). The penetration ratios based on the mean and median area under the curve from 0 to 8 h (AUC_0-8) were 0.85 and 0.79 μg · h/ml, respectively. Sitafloxacin penetrates well into ELF in critically ill Thai patients with pneumonia. (This study has been registered in the Thai Clinical Trials Registry [TCTR] under registration no. TCTR20170222001.).

Non-standard treatment for uncomplicated Chlamydia trachomatis urogenital infections: a systematic review

OBJECTIVES

To review the literature for non-standard treatment options for uncomplicated Chlamydia trachomatis (CT) infections in adolescents and adults.

DESIGN

Systematic review.

DATA SOURCES

Ovid MEDLINE/PubMed, Ovid EMBASE, Cochrane Trials & Systematic Review Databases, CINAHL Plus with Full Text, Web of Science Core Collection, Scopus, ProQuest Dissertations & Theses Global, ClinicalTrials.gov and Health Canada Trials Database were searched for studies in English or French from 1 January 2006 to 6 August 2017. Keywords included CT, anti-infective or anti-bacterial agents, therapy/pharmacotherapy/management.

REVIEW METHODS

Included were primary research studies. Outcome measures included clinical or microbiological cure, treatment failure and adverse events. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were assessed for risk of bias using the Revised Cochrane Risk of Bias V.2.0 tool for randomised and the Newcastle-Ottawa Quality Assessment Scale for non-randomised studies.

FUNDING SOURCE

Public Health Agency of Canada.

RESULTS

Of the 6899 records identified through the database search, 11 studies were included. One randomised controlled trial reported that delayed release doxycycline was non-inferior to azithromycin. Two studies examined higher doses of azithromycin but reported no additional benefit. One study looked at a 5-day azithromycin treatment regimen and reported a high cure rate. Two studies reported efficacy of sitafloxacin, and a single study supports the use of levofloxacin. Two phase 2 studies reported efficacy of single-dose rifalazil in both men and women. Only one retrospective study was identified that examined treatment in pregnant women and reported that efficacy with single-dose azithromycin exceeded that of amoxicillin and erythromycin. A single study examining the efficacy of a beta-lactam antibiotic was stopped early due to high treatment failures.

CONCLUSIONS

The paucity of existing data highlights the need for further adequately powered studies to evaluate rifalazil, delayed release doxycycline, levofloxacin and other agents for the treatment of uncomplicated CT infections.

PROSPERO REGISTRATION NUMBER

CRD42017073096.

Sulbactam enhances the in vitro activity of sitafloxacin against extensively-drug resistant Acinetobacter baumannii

The present study aimed to determine the in vitro activities of sulbactam and sitafloxacin against extensively-drug resistant Acinetobacter baumannii (XDR-A. baumannii). A total of 50 strains of XDR-A. baumannii were isolated from clinical specimens. Broth microdilution assay was applied to determine the minimum inhibitory concentration (MIC) for sulbactam and sitafloxacin. Microdilution checkerboard method was used to determine the in vitro activity of this antimicrobial combination. Accordingly, the fractional inhibitory concentration (FIC) and FIC index (FICI) were calculated. Time-kill study was also carried out for four strains with different susceptibilities to determine the bactericidal activities of individual or combined use of sitafloxacin and sulbactam. Isolates with MICs of sitafloxacin ≤2 mg/l were considered to be susceptible to sitafloxacin. The susceptibility rate for sitafloxacin was 92% originally. When combined with sulbactam, this rate increased to 96%. Microdilution checkerboard results indicated that, when tested in combination, sulbactam/sitafloxacin exhibited marked synergistic and partial synergistic effects on 16 and 50% of the 50 strains, respectively. Time-kill assay suggested that sulbactam enhanced the bactericidal activity of sitafloxacin and the combination induced a synergistic effect. For strains that were not susceptible to sitafloxacin, the bactericidal activities of the combination of sitafloxacin and sulbactam at a sub-MIC concentration were impaired. However, this impairment could be overcome with the increase of the concentration to 1X MIC. The present study demonstrated that sulbactam enhanced the in vitro antimicrobial activity of sitafloxacin against XDR-A. baumannii.

In vitro activity and time-kill curve analysis of sitafloxacin against a global panel of antimicrobial-resistant and multidrug-resistant Neisseria gonorrhoeae isolates

Treatment of gonorrhoea is a challenge worldwide because of emergence of resistance in N. gonorrhoeae to all therapeutic antimicrobials available and novel antimicrobials are imperative. The newer-generation fluoroquinolone sitafloxacin, mostly used for respiratory tract infections in Japan, can have a high in vitro activity against gonococci. However, only a limited number of recent antimicrobial-resistant isolates from Japan have been examined. We investigated the sitafloxacin activity against a global gonococcal panel (250 isolates cultured in 1991-2013), including multidrug-resistant geographically, temporally and genetically diverse isolates, and performed time-kill curve analysis for sitafloxacin. The susceptibility to sitafloxacin (agar dilution) and seven additional therapeutic antimicrobials (Etest) was determined. Sitafloxacin was rapidly bactericidal, and the MIC range, MIC₅₀ and MIC₉₀ was ≤0.001-1, 0.125 and 0.25 mg/L, respectively. There was a high correlation between the MICs of sitafloxacin and ciprofloxacin; however, the MIC₅₀ and MIC₉₀ of sitafloxacin were 6-fold and >6-fold lower, respectively. Sitafloxacin might be an option for particularly dual antimicrobial therapy of gonorrhoea and for cases with ceftriaxone resistance or allergy. However, further in vitro and particularly in vivo evaluations of potential resistance, pharmacokinetics/pharmacodynamics and ideal dosing for gonorrhoea, as well as performance of randomized controlled clinical, trials are crucial.

Antimicrobial susceptibility profiles of oral Treponema species

Treponemes occur in the microflora of the dental plaque. Certain Treponema species that are frequently isolated from chronic periodontitis lesions are involved in its initiation and progression. In addition to mechanical instrumentation, antimicrobial agents are used as an adjunctive treatment modality for periodontitis. Despite its importance for successful antimicrobial treatment, information about susceptibility is limited for Treponema species. The aim of this study was to assess the susceptibility of Treponema denticola strains, Treponema socranskii, and Treponema vincentii to eleven antimicrobial agents. The minimum inhibitory and minimum bactericidal concentrations of these antimicrobial agents revealed strain-specific variation. Doxycycline, minocycline, azithromycin, and erythromycin were effective against all Treponema species tested in this study, whereas fluoroquinolones only exhibited an equivalent effectiveness on T. socranskii. The susceptibility of one T. denticola strain, T. socranskii, and T. vincentii to kanamycin was influenced by prior exposure to aerobic conditions. The susceptibility to quinolone drugs varied among strains of T. denticola, although they share an amino acid sequence identity of greater than 99% for DNA gyrase (type II topoisomerase) subunit A. In addition, an ATP-binding cassette (ABC) transporter inhibitor assay for T. denticola indicated that the transport of quinolone drugs is partially related to this transporter, although there may be parallel transport mechanisms. Our results provide important insights into antimicrobial agent-Treponema dynamics and establish a basis for developing an appropriate adjunctive therapy for periodontal disease.

In Vitro Activity of Sitafloxacin and Additional Newer Generation Fluoroquinolones Against Ciprofloxacin-Resistant Neisseria gonorrhoeae Isolates

Emergence of antimicrobial resistance in Neisseria gonorrhoeae is a major public health concern globally, and new antimicrobials for treatment of gonorrhea are imperative. In this study, the in vitro activity of sitafloxacin, a fluoroquinolone mainly used for respiratory tract or urogenital infections in Japan, and additional newer generation fluoroquinolones were determined against ciprofloxacin-resistant N. gonorrhoeae isolates. Minimum inhibitory concentrations (MICs) of ciprofloxacin, levofloxacin, moxifloxacin, sitafloxacin, pazufloxacin, and tosufloxacin against 47 N. gonorrhoeae isolates cultured in 2009 in Japan were determined by agar dilution method. The quinolone resistance-determining region (QRDR) of gyrA and parC was sequenced. The in vitro potency of sitafloxacin was substantially higher compared with all other tested fluoroquinolones. The MICs of sitafloxacin ranged from 0.03 to 0.5 mg/L for 35 ciprofloxacin-resistant N. gonorrhoeae isolates (ciprofloxacin MICs from 2 to 32 mg/L). No identified mutations in GyrA and ParC QRDR resulted in higher sitafloxacin MIC than 0.5 mg/L. Sitafloxacin had a high activity against N. gonorrhoeae isolates, including strains with mutations in DNA gyrase and topoisomerase IV, resulting in high-level resistance to ciprofloxacin and all other newer generation fluoroquinolones examined. However, it was still to a lower extent affected by GyrA and ParC QRDR mutations resulting in sitafloxacin MICs of up to 0.5 mg/L. This indicates that sitafloxacin should not be considered for empirical first-line monotherapy of gonorrhea. However, sitafloxacin could be valuable in a dual antimicrobial therapy and for cases with ceftriaxone resistance or allergy.

In vitro activity of sitafloxacin against Mycobacterium tuberculosis with gyrA/B mutations isolated in Japan

Purpose. Sitafloxacin (SFX) is a new fluoroquinolone (FQ) that has shown a strong bactericidal effect against Mycobacterium tuberculosis (Mtb) in vitro. However, data on SFX efficacy against Mtb with gyrA/B mutations and its epidemiological cut-off (ECOFF) value remain limited. Therefore, we evaluated and compared the in vitro activity of SFX against gyrA/B-mutant Mtb to that of moxifloxacin (MFX), levofloxacin (LFX) and ciprofloxacin (CFX), and determined the ECOFF for SFX.Methodology. A total of 109 clinical Mtb isolates, including 73 multidrug-resistant (MDR) isolates, were subjected to minimum inhibitory concentration (MIC) analysis in oleic-albumin-dextrose-catalase (OADC)-supplemented Middlebrook 7H9 medium. Our results showed that SFX had lower cumulative MIC than MFX, LFX and CFX. Furthermore, we performed direct DNA sequencing of the quinolone-resistance-determining regions (QRDRs).Results. We identified the following mutations: D94G, D94A, A90V, D94H, D94N and G88A in gyrA; and A543V, A543T, E540D, R485C, D500A, I552S and D577A in gyrB. Based on our results, an ECOFF of 0.125 µg ml^-1 was proposed for SFX. With this ECOFF, 15 % of LFX-resistant isolates with MIC ≥2 µg ml^-1 were susceptible to SFX.Conclusion. SFX had the lowest cumulative MIC and a relatively low ECOFF value against Mtb, indicating that SFX was not only more effective against gyrA-mutant isolates, but also MDR isolates in Japan.

Development of hemiacetal esterified levofloxacin to prevent chelation with metal-containing drugs

OBJECTIVES

To avoid the chelate formation between levofloxacin (LVFX) and aluminium hydroxide in gastrointestinal tract, an ethoxycarbonyl 1-ethyl hemiacetal ester of levofloxacin (LVFX-EHE) was synthesised as a prodrug.

METHODS

The effects of aluminium hydroxide on the bioavailability of LVFX following oral administration of LVFX-EHE were investigated in rats. Furthermore, the effects of aluminium hydroxide on small intestinal absorption of LVFX and LVFX-EHE when subjected to a hydrolysis experiment using in situ everted gut sac were investigated, and the minimal inhibitory concentrations (MICs) of LVFX and LVFX-EHE for various intestinal bacteria were measured.

KEY FINDINGS

When LVFX-EHE was co-administered with and without aluminium hydroxide, the AUC_{0-4 h} values of LVFX hydrolysed from LVFX-EHE were similar to that of LVFX alone. In everted gut sac experiments, LVFX-EHE was efficiently absorbed even in the presence of aluminium ions after 1 h of incubation, whereas the absorption of LVFX decreased significantly in the presence of aluminium ions. MIC values of LVFX-EHE were far higher than LVFX.

CONCLUSIONS

This study suggests the benefit of ethoxycarbonyl 1-ethyl hemiacetal esterification of the carboxyl group of new quinolone as a prodrug which is able to avoid chelate formation.

Treatment outcomes of oral sitafloxacin in acute complicated urinary tract infection and pyelonephritis

Background

Data on the success rate of sitafloxacin treatment in acute complicated urinary tract infection and pyelonephritis are limited.

Objectives

To determine the success rate of a new oral fluoroquinolone, sitafloxacin, in acute complicated urinary tract infection and pyelonephritis.

Methods

A prospective study of 30 patients who were diagnosed with acute complicated urinary tract infection and pyelonephritis was conducted. Oral sitafloxacin 50 mg twice a day was given for 7 days. All patients were followed up at baseline, day 7, and day 14.

Results

The patient sample included 67 % females; the mean ± SD age was 49 ± 13 years. Twenty-one (70 %) patients had acute pyelonephritis and 9 (30 %) had complicated urinary tract infections. Twenty-two patients were positive for uropathogens. The most frequently isolated pathogen was E. coli 11 non-extended spectrum beta-lactamase (ESBL) producing and 5 ESBL-producing strains. Of the 22 isolated uropathogens, 19 (86 %) isolates were sensitive to sitafloxacin. At day 14, 29 of 30 (97 %) were clinically cured and 21 of 22 (95 %) were microbiologically cured. No patients discontinued sitafloxacin due to adverse events.

Conclusions

These results support the use of oral sitafloxacin in complicated urinary tract infections and acute pyelonephritis. However, further larger studies are required to confirm these results.

Male non-gonococcal urethritis: From microbiological etiologies to demographic and clinical features

OBJECTIVES

To detect microorganisms responsible for male acute urethritis and to define the microbiology of non-gonococcal urethritis.

METHODS

The present study comprised 424 men with symptoms and signs compatible with acute urethritis. Their urethral swabs and first-voided urine underwent detection of the microorganisms. Demographic characteristics and clinical features of Mycoplasma genitalium-, Ureaplasma urealyticum-, Haemophilus influenza-, adenovirus- or Herpes simplex virus-positive monomicrobial non-gonococcal urethritis, or all-examined microorganism-negative urethritis in heterosexual men were compared with urethritis positive only for Chlamydia trachomatis.

RESULTS

Neisseria gonorrhoeae was detected in 127 men (30.0%). In 297 men with non-gonococcal urethritis, C. trachomatis was detected in 143 (48.1%). In 154 men with non-chlamydial non-gonococcal urethritis, M. genitalium (22.7%), M. hominis (5.8%), Ureaplasma parvum (9.1%), U. urealyticum (19.5%), H. influenzae (14.3%), Neisseria meningitidis (3.9%), Trichomonas vaginalis (1.3%), human adenovirus (16.2%), and Herpes simplex virus types 1 (7.1%) and 2 (2.6%) were detected. Although some features of monomicrobial non-chlamydial non-gonococcal urethritis or all-examined microorganism-negative urethritis were significantly different from those of monomicrobial chlamydial non-gonococcal urethritis, most features were superimposed.

CONCLUSIONS

Predicting causative microorganisms in men with non-gonococcal urethritis based on demographic and clinical features is difficult. However, the present study provides useful information to better understand the microbiological diversity in non-gonococcal urethritis, and to manage patients with non-gonococcal urethritis appropriately.

Changes in antimicrobial susceptibility profile and prevalence of quinolone low-sensitive strains in subgingival plaque from acute periodontal lesions after systemic administration of sitafloxacin

This study aimed to assess changes in antimicrobial susceptibilities of subgingival bacteria in acute periodontal lesions following systemic administration of a new-generation fluoroquinolone, sitafloxacin and to monitor the occurrence and fate of quinolone low-sensitive strains. Patients with acute phase of chronic periodontitis were subjected to microbiological assessment of their subgingival plaque samples at baseline (A1). Sitafloxacin was then administered systemically (100 mg/day for 5 days). The microbiological examinations were repeated one week after administration (A2). Susceptibilities of clinical isolates from acute sites to various antimicrobials were determined using broth and agar dilution methods. At A2, subgingival bacteria with low sensitivity to levofloxacin were identified in four patients, and they were subjected to a follow-up microbiological examination at on the average 12 months after sitafloxacin administration (A3). The patients received initial and supportive periodontal therapy during the period A2 to A3. From the examined subgingival sites, 8 and 19 clinical isolates were obtained at A2 and A3, respectively. Some Streptococcus strains isolated at A2 were found to be resistant to levofloxacin (MIC 16-64 μg/ml), azithromycin (MIC 2->128 μg/ml) or clarithromycin (MIC 1->32 μg/ml). At A3, isolated streptococci were highly susceptible to levofloxacin (MIC 0.5-2 μg/ml), while those resistant to azithromycin or clarithromycin were still isolated. It is suggested that the presence of the quinolone low-sensitive strains in initially acute lesions after sitafloxacin administration was transient, and they do not persist in the subgingival milieu during the periodontal therapy.

Effects of systemic administration of sitafloxacin on subgingival microflora and antimicrobial susceptibility profile in acute periodontal lesions

The aim of this study was to assess the effect(s) of systemic administration of sitafloxacin on subgingival microbial profiles of acute periodontal lesions. Antimicrobial susceptibility of clinical isolates was also investigated. Patients with acute phases of chronic periodontitis were subjected to clinical examination and microbiological assessment of their subgingival plaque samples by culture technique. Sitafloxacin was then administered (100 mg/day for 5 days) systemically. The clinical and microbiological examinations were repeated 6-8 days after administration. Susceptibilities of clinical isolates to various antimicrobials were determined using the broth and agar dilution methods. From the sampled sites in 30 participants, a total of 355 clinical isolates (34 different bacterial species) were isolated and identified. Parvimonas micra, Prevotella intermedia and Streptococcus mitis were the most prevalent cultivable bacteria in acute sites. Systemic administration of sitafloxacin yielded a significant improvement in clinical and microbiological parameters. Among the antimicrobials tested, sitafloxacin was the most potent against the clinical isolates with an MIC90 of 0.12 μg/ml at baseline. After administration, most clinical isolates were still highly susceptible to sitafloxacin although some increase in MICs was observed. The results suggest that systemic administration of sitafloxacin is effective against subgingival bacteria isolated from acute periodontal lesions.

Comparative in vitro activity of sitafloxacin against bacteremic isolates of carbapenem resistant Acinetobacter baumannii complex

BACKGROUND

The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) complex has posed a great challenge to clinicians worldwide. Sitafloxacin has been shown to have in vitro activity against pathogens resistant to other fluoroquinolones. However, data comparing the anti-CRAB activity of sitafloxacin with that of other antimicrobial agents are limited.

METHODS

Genospecies were identified by 16S-23S ribosomal RNA intergenic spacer sequencing. Minimum inhibitory concentrations (MICs) were determined by an agar dilution method. Isolates with sitafloxacin MICs ≤ 2 mg/L were provisionally considered as susceptible to sitafloxacin. The MIC breakpoint for tigecycline susceptibility was 2 mg/L.

RESULTS

A total of 167 CRAB complex blood isolates (146 A. baumannii, 7 Acinetobacter pittii, and 14 Acinetobacter nosocomialis) were collected from January 2009 to December 2011. Around 90% of the A. baumannii isolates were resistant to amikacin, cefepime, ceftazidime, piperacillin/tazobactam, ampicillin/sulbactam, ciprofloxacin, and levofloxacin. By contrast, the rate of resistance to colistin, sitafloxacin, and tigecycline was relatively low (0%, 41.1%, and 65.1%, respectively). The MIC50 and MIC90 of ciprofloxacin, levofloxacin, and sitafloxacin were 128 mg/L and >128 mg/L; 16 mg/L and 64 mg/L; 2 mg/L and 8 mg/L, respectively. Compared with ciprofloxacin and levofloxacin, sitafloxacin had a significantly lower MIC (p < 0.001), and the rate of resistance to sitafloxacin was significantly lower than that to ciprofloxacin (97.9% vs. 41.1%, p < 0.001), levofloxacin (97.3% vs. 41.1%, p < 0.001), and tigecycline (p < 0.001).

CONCLUSION

Sitafloxacin has acceptable in vitro activity against CRAB, even against isolates resistant to other fluoroquinolones. Sitafloxacin may be considered an alternative drug of choice in treating CRAB related infections.

Clinical dose findings of sitafloxacin treatment: pharmacokinetic-pharmacodynamic analysis of two clinical trial results for community-acquired respiratory tract infections

The adequacy of sitafloxacin clinical dose regimens was assessed by comparing the efficacy of the administration of 100 mg sitafloxacin once daily (100 mg qd group) and 50 mg sitafloxacin twice daily (50 mg bid group). Patients with respiratory tract infections caused by pneumococci were orally treated with sitafloxacin (100 mg qd or 50 mg bid) for 7 days. The clinical efficacy, pneumococci eradication rate, safety, and pharmacokinetic and pharmacodynamic indices of the two groups were then assessed. The clinical efficacy was 93.5 % in both groups. The pneumococci eradication rate was 98.2 % in the 100 mg qd group and 92.7 % in the 50 mg bid group. The mean of the free AUC0-24h divided by the minimum inhibitory concentration (MIC) (fAUC0-24h/MIC) did not differ significantly between the 100 mg qd (103.24) and the 50 mg bid groups (105.25). The mean of the free C peak divided by the MIC (fC peak/MIC) was higher in the 100 mg qd group (10.19) than in the 50 mg bid group (6.53). The pathogen eradication rate was 98.9 % (89/90) when the fAUC0-24h/MIC was greater than 30, and the eradication rate was 98.9 % (89/90) when the fC peak/MIC was greater than 2. The incidences of adverse drug reactions were 33.7 % in the 100 mg qd group and 40.4 % in the 50 mg bid group. No obvious differences in the efficacy and safety were observed between the dosage groups. For cases in which a sufficiently high C peak is necessary to ensure the susceptibility of the pathogens to the drug, 100 mg sitafloxacin once daily should be administered.

Dialyzability and pharmacokinetics of sitafloxacin following multiple oral dosing in infected hemodialysis patients

The pharmacokinetics and dialyzability of oral sitafloxacin, a newly available quinolone, in infected intermittent hemodialysis patients have not been reported previously. Seven infected maintenance hemodialysis patients lacking residual renal function were enrolled. Sitafloxacin (50 mg after hemodialysis on the first day, on the next day and 4 h before scheduled hemodialysis session on the 3rd day) was orally administered. On the 3rd day, blood was taken from arterial and venous sides before and 2 and 4 h after session initiation. Another sampling was performed 1 h after the session and on the 5(th) day of the study. Pharmacokinetic parameters and dialyzability of sitafloxacin were evaluated. All patients exhibited improved symptoms without major problems. Drug concentrations in all arterial samples were above the MIC of targeted bacteria. Dialyzer clearance and elimination fraction were 49.9 ± 0.9 mL/min per m(2) and 53.3 ± 2.1%, respectively. Apparent half-life during dialysis session was significantly shorter than that after the session (4.0 ± 0.4 and 46.5 ± 3.6 h, during and after the session, respectively). Dialyzer clearance was positively correlated with urea reduction ratio and negatively correlated with serum albumin concentration. About 23% of the drug in the body was removed by dialysis. Rebound of the drug concentration after the dialysis was not seen. Oral dosing of this drug at 50 mg daily in maintenance hemodialysis patients provides a safe drug concentration compatible with that of healthy subjects orally receiving 100 mg daily. Because a significant amount of the drug was removed, administration might be undertaken after the dialysis session.

Clinical and bacteriological efficacies of sitafloxacin against community-acquired pneumonia caused by Streptococcus pneumoniae: nested cohort within a multicenter clinical trial

We evaluated the clinical and bacteriological efficacy of oral sitafloxacin (STFX) in clinically diagnosed community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae. Additionally, we cultured these patient samples to test the minimal inhibitory concentrations (MICs) of levofloxacin (LVFX), moxifloxacin (MFLX), STFX, and penicillin G (PCG), as well as identified mutations in the quinolone resistance determinant regions (QRDRs) in LVFX-resistant strains. This study is a nested cohort from a prospective, multicenter clinical trial consisting of 139 patients with community-acquired pneumonia (CAP), from which 72 were included in this study. After diagnosis of CAP caused by S. pneumoniae, STFX (50 mg twice daily, or 100 mg once daily) was orally administered for 7 days. Sixty-five patient sputum samples were then cultured for MIC analysis. In a LVFX-resistant strain that was identified, mutations in the QRDRs of the gyrA, gyrB, parC, and parE genes were examined. Of 72 patients eligible for this study, S. pneumoniae was successfully cultured from the sputum of 65 patients, and only 7 patients were diagnosed by urinary antigen only. Clinical improvement of CAP was obtained in 65 of the 69 clinically evaluable patients (65/69, 94.2 %). Eradication of S. pneumoniae was observed in 62 patients of the 65 bacteriologically evaluable patients (62/65, 95.4 %). Additionally, STFX showed the lowest MIC distribution compared with LVFX, MFLX, and PCG, and no major adverse reactions were observed. STFX treatment in patients with CAP caused by S. pneumoniae was found to be highly effective both clinically (94.2 %) and bacteriologically (95.4 %).

Bacterial Infections in the Elderly Patient: Focus on Sitafloxacin

Sitafloxacin (DU-6859a) is a new-generation oral fluoroquinolone with in vitro activity against a broad range of Gram-positive and -negative bacteria, including anaerobic bacteria, as well as against atypical bacterial pathogens. Particularly in Japan this antibiotic was approved in 2008 for treatment of a number of bacterial infections caused by Gram-positive cocci and Gram-negative cocci and rods, including anaerobia atypical bacterial pathogens. As compared to oral levofloxacin sitafloxacin was non-inferior in the treatment of community-acquired pneumonia and non-inferior in the treatment of complicated urinary tract infections, according to the results of randomized, double-blind, multicentre, non-inferiority trials. Non-comparative studies demonstrated the efficacy of oral sitafloxacin in otorhinolaryngological infections, urethritis in men, cervicitis in women and odontogenic infections. Most common adverse reactions were gastrointestinal disorders and laboratory abnormalities in patients receiving oral sitafloxacin; diarrhea and liver enzyme elevations were among the common. In the Japanese population sitafloxacin covers broad spectrum of bacteria as compared to carbapenems, whereas in the Caucasians its use is currently limited due to the potential for ultraviolet A phototoxicity. Sitafloxacin is a promising therapeutic agent which merits further investigation in randomized clinical trials of elderly patients.

Activity of sitafloxacin against extracellular and intracellular Staphylococcus aureus in vitro and in vivo: comparison with levofloxacin and moxifloxacin

Antibiotic activity can differ depending on whether the bacterial target is extracellular or intracellular. To determine extracellular and intracellular activities of sitafloxacin (STX) against Staphylococcus aureus in comparison with levofloxacin (LVX) and moxifloxacin (MXF) in vivo and in vitro, three S. aureus strains (ATCC25923, 29213, 43300) were evaluated. MIC, MBC and mutant prevention concentration (MPC) of the test quinolone for S. aureus were determined by microdilution in broth, and intracellular activity was determined in RAW264.7 cells after phagocytosis of bacteria. Cellular quinolone accumulation was determined by HPLC. The time- and concentration-kill relationships were examined in vitro (in broth and in RAW264.7 cells, respectively) and in vivo by use of a mouse peritonitis model. The results showed that the activity of STX in broth cultures, including the MIC, MBC, MPC and the time- and concentration-kill relationships, were greater for STX than those for LVX and MXF. In particular, STX exhibited the strongest activity against intramacrophage S. aureus. The intracellular effects could be ranked in the following order as the mean change in the log10 number of cfu ml(-1) (log10 cfu ml(-1)) between treated and untreated mice: STX>LVX>MXF. It also showed that the dominant factor of intracellular activity in vivo was the frequency of doses. There was a poor correlation between the intracellular accumulation of the three different quinolones and the actual intracellular effect. The results of the intracellular and extracellular time- and concentration-kill relationships indicated that STX has the potential to display useful activity against extracellular and intracellular S. aureus.