An open, randomised, multi-centre study comparing the safety and efficacy of sitafloxacin and imipenem/cilastatin in the intravenous treatment of hospitalised patients with pneumonia

Population Pharmacokinetics and Pharmacodynamics of Sitafloxacin in Plasma and Alveolar Epithelial Lining Fluid of Critically Ill Thai Patients With Pneumonia

Sitafloxacin is one of the oral respiratory quinolones for the treatment of community-acquired pneumonia. The pharmacokinetic (PK) changes of sitafloxacin in critical illness have been previously reported. However, sitafloxacin exposure and target attainment have never been confirmed in this population. To develop a population pharmacokinetic (PK) model of sitafloxacin, plasma and epithelial lining fluid (ELF) concentrations were obtained after sitafloxacin administration as a 200-mg single dose under fasting condition in 12 subjects. A population pharmacokinetic analysis was performed using a nonlinear mixed-effects modeling approach. The probability of target attainment (PTA) and cumulative fraction of response (CFR) against the MIC distribution of S. pneumoniae isolated from Thai patients was estimated by Monte Carlo simulations. The pharmacokinetics of sitafloxacin in plasma was best described by a one-compartment model linking to the ELF compartment. The partition coefficient which relates drug exposure in ELF to drug exposure in plasma was estimated to be 0.77. Age was a significant covariate that impacted the relative bioavailability. Results from Monte Carlo simulations showed that the maximum approved dose of sitafloxacin 100 mg q 12 h provided > 90% PTA and CFR in both plasma and ELF. The current maximal dosing of sitafloxacin provided adequate exposure in plasma and ELF for the treatment of critically ill Thai patients with pneumonia.

Antibacterial Mechanisms and Clinical Impact of Sitafloxacin

Sitafloxacin is a 4th generation fluoroquinolone antibiotic with broad activity against a wide range of Gram-negative and Gram-positive bacteria. It is approved in Japan and used to treat pneumonia and urinary tract infections (UTIs) as well as other upper and lower respiratory infections, genitourinary infections, oral infections and otitis media. Compared to other fluoroquinolones, sitafloxacin displays a low minimal inhibitory concentration (MIC) for many bacterial species but also activity against anaerobes, intracellular bacteria, and persisters. Furthermore, it has also shown strong activity against biofilms of P. aeruginosa and S. aureus in vitro, which was recently validated in vivo with murine models of S. aureus implant-associated bone infection. Although limited in scale at present, the published literature supports the further evaluation of sitafloxacin in implant-related infections and other biofilm-related infections. The aim of this review is to summarize the chemical-positioning-based mechanisms, activity, resistance profile, and future clinical potential of sitafloxacin.

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.

Empiric antibiotics for community-acquired pneumonia in adult patients: a systematic review and a network meta-analysis

OBJECTIVE

The main aim of this network meta-analysis is to identify the empiric antibiotic (Em-ATB) with the highest probability of being the best (HPBB) in terms of (1) cure rate and (2) mortality rate in hospitalised patients with community acquired pneumonia (CAP) .

METHOD

Inclusion criteria: (1) adult patients (>16 years old) diagnosed with CAP that required hospitalisation; (2) randomised to at least two different Em-ATBs, (3) that report cure rate and (4) are written in English or Spanish.

EXCLUSION CRITERIA

(1) ambiguous antibiotics protocol and (2) published exclusively in abstract or letter format.

DATA SOURCES

Medline, Embase, Cochrane and citation reviews from 1 January 2000 to 31 December 2018. Risk of bias: Cochrane's tool. Quality of the systematic review (SR): A MeaSurement Tool to Assess systematic Reviews-2. Certainity of the evidence: Grading of Recommendations Assessment, Development and Evaluation.

STATISTICAL ANALYSES

frequentist method performed with the 'netmeta' library, R package.

RESULTS

27 randomised controlled trials (RCTs) from the initial 41 307 screened citations were included. Regarding the risk of bias, more than one quarter of the studies presented low risk and no study presented high risk in all domains. The SR quality is moderate. For cure, two networks were constructed. Thus, two Em-ATBs have the HPBB: cetaroline 600 mg (two times a day) and piperacillin 2000 mg (two times a day). For mortality, three networks were constructed. Thus, three Em-ATBs have the HPBB: ceftriaxone 2000 mg (once a day) plus levofloxacin 500 (two times a day), ertapenem 1000 mg (two times a day) and amikacin 250 mg (two times a day) plus clarithromycin 500 mg (two times a day). The certainity of evidence for each results is moderate.

CONCLUSION

For cure rate, ceftaroline and piperaciline are the options with the HPBB. However, for mortality rate, the options are ceftriaxone plus levofloxacin, ertapenem and amikacin plus clarithromycin. It seems necessary to conduct an RCT that compares treatments with the HPBB for each event (cure or mortality) (CRD42017060692).

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.

Empiric antibiotic coverage of atypical pathogens for community-acquired pneumonia in hospitalized adults

BACKGROUND

Community-acquired pneumonia (CAP) is caused by various pathogens, traditionally divided into 'typical' and 'atypical'. Initial antibiotic treatment of CAP is usually empirical, customarily covering both typical and atypical pathogens. To date, no sufficient evidence exists to support this broad coverage, while limiting coverage is bound to reduce toxicity, resistance and expense.

OBJECTIVES

The main objective was to estimate the mortality and proportion with treatment failure using regimens containing atypical antibiotic coverage compared to those that had typical coverage only. Secondary objectives included the assessment of adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) Issue 3, 2012 which includes the Acute Respiratory Infection Group's Specialized Register, MEDLINE (January 1966 to April week 1, 2012) and EMBASE (January 1980 to April 2012).

SELECTION CRITERIA

Randomized controlled trials (RCTs) of adult patients hospitalized due to CAP, comparing antibiotic regimens with atypical coverage (quinolones, macrolides, tetracyclines, chloramphenicol, streptogramins or ketolides) to a regimen without atypical antibiotic coverage.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from included trials. We estimated risk ratios (RRs) with 95% confidence intervals (CIs). We assessed heterogeneity using a Chi(2) test.

MAIN RESULTS

We included 28 trials, encompassing 5939 randomized patients. The atypical antibiotic was administered as monotherapy in all but three studies. Only one study assessed a beta-lactam combined with a macrolide compared to the same beta-lactam. There was no difference in mortality between the atypical arm and the non-atypical arm (RR 1.14; 95% CI 0.84 to 1.55), RR < 1 favors the atypical arm. The atypical arm showed an insignificant trend toward clinical success and a significant advantage to bacteriological eradication, which disappeared when evaluating methodologically high quality studies alone. Clinical success for the atypical arm was significantly higher for Legionella pneumophilae (L. pneumophilae) and non-significantly lower for pneumococcal pneumonia. There was no significant difference between the groups in the frequency of (total) adverse events, or those requiring discontinuation of treatment. However, gastrointestinal events were less common in the atypical arm (RR 0.70; 95% CI 0.53 to 0.92). Although the trials assessed different antibiotics, no significant heterogeneity was detected in the analyses.

AUTHORS' CONCLUSIONS

No benefit of survival or clinical efficacy was shown with empirical atypical coverage in hospitalized patients with CAP. This conclusion relates mostly to the comparison of quinolone monotherapy to beta-lactams. Further trials, comparing beta-lactam monotherapy to the same combined with a macrolide, should be performed.

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.

Current concepts in antimicrobial therapy against resistant gram-negative organisms: extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa

The development of antimicrobial resistance among gram-negative pathogens has been progressive and relentless. Pathogens of particular concern include extended-spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa. Classic agents used to treat these pathogens have become outdated. Of the few new drugs available, many have already become targets for bacterial mechanisms of resistance. This review describes the current approach to infections due to these resistant organisms and elaborates on the available treatment options.

Imipenem resistance of Pseudomonas in pneumonia: a systematic literature review

Background

Pneumonia, and particularly nosocomial (NP) and ventilator-associated pneumonias (VAP), results in high morbidity and costs. NPs in particular are likely to be caused by Pseudomonas aeruginosa (PA), ~20% of which in observational studies are resistant to imipenem. We sought to identify the burden of PA imipenem resistance in pneumonia.

Methods

We conducted a systematic literature review of randomized controlled trials (RCT) of imipenem treatment for pneumonia published in English between 1993 and 2008. We extracted study, population and treatment characteristics, and proportions caused by PA. Endpoints of interest were: PA resistance to initial antimicrobial treatment, clinical success, microbiologic eradication and on-treatment emergence of resistance of PA.

Results

Of the 46 studies identified, 20 (N = 4,310) included patients with pneumonia (imipenem 1,667, PA 251; comparator 1,661, PA 270). Seven were double blind, and 7 included US data. Comparator arms included a β-lactam (17, [penicillin 6, carbapenem 4, cephalosporin 7, monobactam 1]), aminoglycoside 2, vancomycin 1, and a fluoroquinolone 5; 5 employed double coverage. Thirteen focused exclusively on pneumonia and 7 included pneumonia and other diagnoses. Initial resistance was present in 14.6% (range 4.2-24.0%) of PA isolates in imipenem and 2.5% (range 0.0-7.4%) in comparator groups. Pooled clinical success rates for PA were 45.2% (range 0.0-72.0%) for imipenem and 74.9% (range 0.0-100.0%) for comparator regimens. Microbiologic eradication was achieved in 47.6% (range 0.0%-100.0%) of isolates in the imipenem and 52.8% (range 0.0%-100.0%) in the comparator groups. Resistance emerged in 38.7% (range 5.6-77.8%) PA isolates in imipenem and 21.9% (range 4.8-56.5%) in comparator groups.

Conclusions

In the 15 years of RCTs of imipenem for pneumonia, PA imipenem resistance rates are high, and PA clinical success and microbiologic eradication rates are directionally lower for imipenem than for comparators. Conversely, initial and treatment-emergent resistance is more likely with the imipenem than the comparator regimens.

Empiric antibiotic coverage of atypical pathogens for community acquired pneumonia in hospitalized adults

BACKGROUND

Community acquired pneumonia (CAP) is caused by various pathogens, traditionally divided to 'typical' and 'atypical'. Initial antibiotic treatment of CAP is usually empirical, customarily covering both typical and atypical pathogens. To date, no sufficient evidence exists to support this broad coverage, while limiting coverage is bound to reduce toxicity, resistance and expense.

OBJECTIVES

To assess the efficacy and need of adding antibiotic coverage for atypical pathogens in hospitalized patients with CAP, in terms of mortality and successful treatment.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1) which includes the Acute Respiratory Infection Group's specialized register; MEDLINE (January 1966 to March 2007); and EMBASE (January 1980 to January 2007).

SELECTION CRITERIA

Randomized trials of adult patients hospitalized due to CAP, comparing antibiotic regimens with atypical antibiotic coverage to a regimen without atypical antibiotic coverage.

DATA COLLECTION AND ANALYSIS

Two review authors independently appraised the quality of each trial and extracted the data from included trials. Relative risks (RR) with 95% confidence intervals (CI) were estimated, assuming an intention-to-treat (ITT) basis for the outcome measures.

MAIN RESULTS

Twenty five trials were included, encompassing 5244 randomized patients. There was no difference in mortality between the atypical arm and the non-atypical arm (RR 1.15; 95% CI 0.85 to 1.56). The atypical arm showed an insignificant trend toward clinical success and a significant advantage to bacteriological eradication, which disappeared when evaluating methodologically high-quality studies alone. Clinical success for the atypical arm was significantly higher for Legionella pneumophilae (L. pneumophilae) and non-significantly lower for pneumococcal pneumonia. There was no significant difference between the groups in the frequency of (total) adverse events, or those requiring discontinuation of treatment. However, gastrointestinal events were more common in the non-atypical arm (RR 0.73, 95% CI 0.54 to 0.99). All but two included trials compared a single atypical antibiotic to a beta-lactam, while no trials assessing the addition of an atypical antibiotic to a beta-lactam were identified.

AUTHORS' CONCLUSIONS

No benefit of survival or clinical efficacy was shown to empirical atypical coverage in hospitalized patients with CAP. This conclusion relates mostly to the comparison of quinolone monotherapy to beta-lactams (BL) or cephalosporins. Further trials, comparing BL or cephalosporins therapy to BL or cephalosporins combined with a macrolide in this population, using mortality as its primary outcome, should be performed.

Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium

Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.

Empiric antibiotic coverage of atypical pathogens for community acquired pneumonia in hospitalized adults

BACKGROUND

Community acquired pneumonia (CAP) is caused by various pathogens, traditionally divided to 'typical' and 'atypical'. Initial antibiotic treatment of CAP is usually empirical, customarily covering both typical and atypical pathogens. To date, no sufficient evidence exists to support this broad coverage, while limiting coverage is bound to reduce toxicity, resistance and expense.

OBJECTIVES

Assess the efficacy and need of adding antibiotic coverage for atypical pathogens in hospitalized patients with CAP, in terms of mortality and successful treatment.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005) which includes the Acute Respiratory Infection Group's specialized register; MEDLINE (January 1966 to January Week 2 2005); and EMBASE (January 1980 to January Week 2 2005).

SELECTION CRITERIA

Randomized trials of adult patients hospitalized due to CAP, comparing antibiotic regimens with atypical antibiotic coverage to a regimen without atypical antibiotic coverage.

DATA COLLECTION AND ANALYSIS

Two reviewers independently appraised the quality of each trial and extracted the data from included trials. Relative risks (RR) with 95% confidence intervals (CI) were estimated, assuming an intention-to-treat (ITT) basis for the outcome measures.

MAIN RESULTS

Twenty four trials were included, encompassing 5015 randomized patients. There was no difference in mortality between the atypical arm and the non-atypical arm (RR 1.13; 95% CI 0.82 to 1.54). The atypical arm showed an insignificant trend toward clinical success and a significant advantage to bacteriological eradication, which disappeared when evaluating methodologically high-quality studies alone. Clinical success for the atypical arm was significantly higher for Legionella pneumophilae (L. pneumophilae) and non-significantly lower for pneumococcal pneumonia. There was no significant difference between the groups in the frequency of (total) adverse events, or those requiring discontinuation of treatment. However, gastrointestinal events were more common in the non-atypical arm (RR 0.73, 95% CI 0.54 to 0.99).

AUTHORS' CONCLUSIONS

No benefit of survival or clinical efficacy was shown to empirical atypical coverage in hospitalized patients with CAP. This conclusion relates mostly to the comparison of quinolone monotherapy to non-atypical monotherapy. Further trials, comparing beta-lactam (BL) or cephalosporin therapy to BL or cephalosporin combined with a macrolide in this population, using mortality as its primary outcome, should be performed.

Novel antibacterial agents for the treatment of serious Gram-positive infections

With the continuing development of clinical drug resistance among bacteria and the advent of resistance to the recently released agents quinupristin-dalfopristin and linezolid, the need for new, effective agents to treat multi-drug-resistant Gram-positive infections remains important. This review focuses on agents presently in clinical development for the treatment of serious multidrug-resistant staphylococcal, enterococcal and pneumococcal infections, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae. Agents to be discussed that affect the prokaryotic cell wall include the antimethicillin-resistant S. aureus cephalosporins BAL9141 and RWJ-54428, the glycopeptides oritavancin and dalbavancin and the lipopeptide daptomycin. Topoisomerase inhibitors include the fluoroquinolones gemifloxacin, sitafloxacin and garenoxacin. Protein synthesis inhibitors are represented by the ketolides telithromycin and cethromycin, the oxazolidinones and the glycylcycline tigecycline. Although each of these compounds has demonstrated antibacterial activity against antibiotic-resistant pathogens, their final regulatory approval will depend on an acceptable clinical safety profile.