Efficacy and safety of oral solithromycin versus oral moxifloxacin for treatment of community-acquired bacterial pneumonia: a global, double-blind, multicentre, randomised, active-controlled, non-inferiority trial (SOLITAIRE-ORAL)

Identifying the Best Initial Oral Antibiotics for Adults with Community-Acquired Pneumonia: A Network Meta-Analysis

BACKGROUND

The objective of this network meta-analysis was to compare rates of clinical response and mortality for empiric oral antibiotic regimens in adults with mild-moderate community-acquired pneumonia (CAP).

METHODS

We searched PubMed, Cochrane, and the reference lists of systematic reviews and clinical guidelines. We included randomized trials of adults with radiologically confirmed mild to moderate CAP initially treated orally and reporting clinical cure or mortality. Abstracts and studies were reviewed in parallel for inclusion in the analysis and for data abstraction. We performed separate analyses by antibiotic medications and antibiotic classes and present the results through network diagrams and forest plots sorted by p-scores. We assessed the quality of each study using the Cochrane Risk of Bias framework, as well as global and local inconsistency.

RESULTS

We identified 24 studies with 9361 patients: six at low risk of bias, six at unclear risk, and 12 at high risk. Nemonoxacin, levofloxacin, and telithromycin were most likely to achieve clinical response (p-score 0.79, 0.71, and 0.69 respectively), while penicillin and amoxicillin were least likely to achieve clinical response. Levofloxacin, nemonoxacin, azithromycin, and amoxicillin-clavulanate were most likely to be associated with lower mortality (p-score 0.85, 0.75, 0.74, and 0.68 respectively). By antibiotic class, quinolones and macrolides were most effective for clinical response (0.71 and 0.70 respectively), with amoxicillin-clavulanate plus macrolides and beta-lactams being less effective (p-score 0.11 and 0.22). Quinolones were most likely to be associated with lower mortality (0.63). All confidence intervals were broad and partially overlapping.

CONCLUSION

We observed trends toward a better clinical response and lower mortality for quinolones as empiric antibiotics for CAP, but found no conclusive evidence of any antibiotic being clearly more effective than another. More trials are needed to inform guideline recommendations on the most effective antibiotic regimens for outpatients with mild to moderate CAP.

Addressing Sexually Transmitted Infections Due to Neisseria gonorrhoeae in the Present and Future

It was in the 1800s when the first public publications about the infection and treatment of gonorrhoea were released. However, the first prevention programmes were only published a hundred years later. In the 1940s, the concept of vaccination was introduced into clinical prevention programmes to address early sulphonamide resistance. Since then, tons of publications on Neisseria gonorrhoeae are undisputed, around 30,000 publications today. Currently, the situation seems to be just as it was in the last century, nothing has changed or improved. So, what are we doing wrong? And more importantly, what might we do? The review presented here aims to review the current situation regarding the resistance mechanisms, prevention programmes, treatments, and vaccines, with the challenge of better understanding this special pathogen. The authors have reviewed the last five years of advancements, knowledge, and perspectives for addressing the Neisseria gonorrhoeae issue, focusing on new therapeutic alternatives.

Clarithromycin for early anti-inflammatory responses in community-acquired pneumonia in Greece (ACCESS): a randomised, double-blind, placebo-controlled trial

BACKGROUND

Addition of macrolide antibiotics to β-lactam antibiotics for the treatment of patients in hospital with community-acquired pneumonia is based on results from observational studies and meta-analyses rather than randomised clinical trials. We investigated if addition of the macrolide clarithromycin to treatment with a β-lactam antibiotic in this population could improve early clinical response-the new regulatory endpoint for community-acquired pneumonia-and explored the possible contribution of modulation of the inflammatory host response to that outcome.

METHODS

The ACCESS trial was a phase 3 prospective, double-blind, randomised controlled trial, in which adults in hospital with community-acquired pneumonia who had systemic inflammatory response syndrome, Sequential Organ Failure Assessment (SOFA) score of 2 or more, and procalcitonin 0·25 ng/mL or more were enrolled in 18 internal medicine departments of public Greek hospitals. Patients were randomly assigned (1:1) by computer-generated block randomisation to standard of care medication (including intravenous administration of a third-generation cephalosporin or intravenous administration of β-lactam plus β-lactamase inhibitor combination) plus either oral placebo or oral clarithromycin 500 mg twice daily for 7 days. Investigators, staff, and patients were masked to group allocation. The primary composite endpoint required that patients fulfilled both of the following conditions after 72 hours (ie, day 4 of treatment): (1) decrease in respiratory symptom severity score of 50% or more as an indicator of early clinical response and (2) decrease in SOFA score of at least 30% or favourable procalcitonin kinetics (defined as ≥80% decrease from baseline or procalcitonin <0·25 ng/mL), or both, as an indicator of early inflammatory response. Participants who were randomly assigned and received allocated treatment were included in the primary analysis population. This trial is complete and is registered with the EU Clinical Trials Register (2020-004452-15) and ClinicalTrials.gov (NCT04724044).

FINDINGS

Patients were enrolled between Jan 25, 2021, and April 11, 2023, and 278 individuals were randomly allocated to receive standard of care in combination with either clarithromycin (n=139) or placebo (n=139). 134 patients in the clarithromycin group (five withdrew consent) and 133 patients in the placebo group (six withdrew consent) were included in the analysis of the primary endpoint. The primary endpoint was met in 91 (68%) patients in the clarithromycin group and 51 (38%) patients in the placebo group (difference 29·6% [95% CI 17·7-40·3]; odds ratio [OR] 3·40 [95% CI 2·06-5·63]; p<0·0001). Serious treatment-emergent adverse events (TEAEs) occurred in 58 (43%) patients in the clarithromycin group and 70 (53%) patients in the placebo group (difference 9·4% [95% CI -2·6 to 20·9]; OR 0·67 [95% CI 0·42 to 1·11]; p=0·14). None of the serious TEAEs was judged to be related to treatment assignment.

INTERPRETATION

Addition of clarithromycin to standard of care enhances early clinical response and attenuates the inflammatory burden of community-acquired pneumonia. The mechanism of benefit is associated with changes in the immune response. These findings suggest the importance of adding clarithromycin to β-lactams for treatment of patients in hospital with community-acquired pneumonia to achieve early clinical response and early decrease of the inflammatory burden.

FUNDING

Hellenic Institute for the Study of Sepsis and Abbott Products Operations.

Antibiotic Strategies for Severe Community-Acquired Pneumonia

Despite advancements in health systems and intensive care unit (ICU) care, along with the introduction of novel antibiotics and microbiologic techniques, mortality rates in severe community-acquired pneumonia (sCAP) patients have not shown significant improvement. Delayed admission to the ICU is a major risk factor for higher mortality. Apart from choosing the appropriate site of care, prompt and appropriate antibiotic therapy significantly affects the prognosis of sCAP. Treatment regimens involving ceftaroline or ceftobiprole are currently considered the best options for managing patients with sCAP. Additionally, several other molecules, such as delafloxacin, lefamulin, and omadacycline, hold promise as therapeutic strategies for sCAP. This review aims to provide a comprehensive summary of the key challenges in managing adults with severe CAP, focusing on essential aspects related to antibiotic treatment and investigating potential strategies to enhance clinical outcomes in sCAP patients.

Macrolides for better resolution of community-acquired pneumonia: A global meta-analysis of clinical outcomes with focus on microbial aetiology

OBJECTIVES

This meta-analysis examined the effect of macrolides on resolution of community-acquired pneumonia (CAP) and interpretation of clinical benefit according to microbiology; emphasis is given to data under-reported countries (URCs).

METHODS

This meta-analysis included 47 publications published between 1994 and 2022. Publications were analysed for 30-d mortality (58 759 patients) and resolution of CAP (6465 patients). A separate meta-analysis was done for the prevalence of respiratory pathogens in URCs.

RESULTS

Mortality after 30 d was reduced by the addition of macrolides (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.51-0.82). The OR for CAP resolution when macrolides were added to the treatment regimen was 1.23 (95% CI 1.00-1.52). In the CAP resolution analysis, the most prevalent pathogen was Streptococcus pneumoniae (12.68%; 95% CI 9.36-16.95%). Analysis of the pathogen epidemiology from the URCs included 12 publications. The most prevalent pathogens were S. pneumoniae (24.91%) and Klebsiella pneumoniae (12.90%).

CONCLUSION

The addition of macrolides to the treatment regimen led to 35% relative decrease of 30-d mortality and to 23% relative increase in resolution of CAP.

Solithromycin inhibits IL-13-induced goblet cell hyperplasia and MUC5AC, CLCA1, and ANO1 in human bronchial epithelial cells

Solithromycin is a novel fluoroketolide antibiotic belonging to the class of macrolide antibiotics. Activation of the interleukin (IL)-13 receptor leads to STAT6 activation and subsequent induction of SAM pointed domain containing ETS transcription factor (SPDEF), chloride channel accessory 1 (CLCA1), and anoctamin-1 (ANO1), all of which are associated with the induction of MUC5AC. We examined the effects of solithromycin on mucin production led by IL-13 signaling. Normal human bronchial epithelial cells were grown at the air-liquid interface with IL-13 with/without solithromycin for 14 days. Histochemical analysis was performed using hematoxylin and eosin staining and MUC5AC immunostaining. MUC5AC, SPDEF, CLCA1, and ANO1 mRNA expressions were examined using real-time polymerase chain reaction. Western blot analysis was performed to assess CLCA1 and ANO1 proteins, and phosphorylation of STAT6 and ERK. Solithromycin attenuated IL-13 induction of goblet cell hyperplasia and MUC5AC, CLCA1 and ANO1 mRNA and protein expression induced by IL-13, but had no effect on the phosphorylation of STAT6 and ERK. Our results indicate that solithromycin could attenuate goblet cell hyperplasia and MUC5AC induced by IL-13 through inhibition of CLCA1 and ANO1 mRNA and protein expression. However, much more information is required to clarify the molecular mechanisms underlying the inhibition of CLCA1 and ANO1 by solithromycin.

Synthesis and antibacterial activity of novel 2‑fluoro ketolide antibiotics with 11,12‑quinoylalkyl side chains

A series of novel 2‑fluoro ketolide antibiotics with 11,12‑quinoylalkyl side chains derived from telithromycin and cethromycin were designed and synthesized. The corresponding targets 2a-o were tested for their in vitro activities against a series of macrolide-sensitive and macrolide-resistant pathogens. Some of them showed a similar antibacterial spectrum and comparable or slightly better activity to telithromycin. Among them, compounds 2g and 2k, displayed excellent activities against macrolide-sensitive and macrolide-resistant pathogens.

Solithromycin in Children and Adolescents With Community-acquired Bacterial Pneumonia

BACKGROUND

Solithromycin is a new macrolide-ketolide antibiotic with potential effectiveness in pediatric community-acquired bacterial pneumonia (CABP). Our objective was to evaluate its safety and effectiveness in children with CABP.

METHODS

This phase 2/3, randomized, open-label, active-control, multicenter study randomly assigned solithromycin (capsules, suspension or intravenous) or an appropriate comparator antibiotic in a 3:1 ratio (planned n = 400) to children 2 months to 17 years of age with CABP. Primary safety endpoints included treatment-emergent adverse events (AEs) and AE-related drug discontinuations. Secondary effectiveness endpoints included clinical improvement following treatment without additional antimicrobial therapy.

RESULTS

Unrelated to safety, the sponsor stopped the trial prior to completion. Before discontinuation, 97 participants were randomly assigned to solithromycin (n = 73) or comparator (n = 24). There were 24 participants (34%, 95% CI, 23%-47%) with a treatment-emergent AE in the solithromycin group and 7 (29%, 95% CI, 13%-51%) in the comparator group. Infusion site pain and elevated liver enzymes were the most common related AEs with solithromycin. Study drug was discontinued due to AEs in 3 subjects (4.3%) in the solithromycin group and 1 (4.2%) in the comparator group. Forty participants (65%, 95% CI, 51%-76%) in the solithromycin group achieved clinical improvement on the last day of treatment versus 17 (81%, 95% CI, 58%-95%) in the comparator group. The proportion achieving clinical cure was 60% (95% CI, 47%-72%) and 68% (95% CI, 43%-87%) for the solithromycin and comparator groups, respectively.

CONCLUSIONS

Intravenous and oral solithromycin were generally well-tolerated and associated with clinical improvement in the majority of participants treated for CABP.

Current Treatment Strategies Against Multidrug-Resistant Bacteria: A Review

There are several bacteria called superbugs that are resistant to multiple antibiotics which can be life threatening specially for critically ill and hospitalized patients. This article provides up-to-date treatment strategies employed against some major superbugs, like methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, vancomycin-resistant Enterococcus, multidrug-resistant Pseudomonas aeruginosa, and multidrug-resistant Escherichia coli. The pathogen-directed therapeutics decrease the toxicity of bacteria by altering their virulence factors by specific processes. On the other hand, the host-directed therapeutics limits these superbugs by modulating immune cells, enhancing host cell functions, and modifying disease pathology. Several new antibiotics against the global priority superbugs are coming to the market or are in the clinical development phase. Medicinal plants possessing potent secondary metabolites can play a key role in the treatment against these superbugs. Nanotechnology has also emerged as a promising option for combatting them. There is urgent need to continuously figure out the best possible treatment strategy against these superbugs as resistance can also be developed against the new and upcoming antibiotics in future. Rational use of antibiotics and maintenance of proper hygiene must be practiced among patients.

Antibiotic therapy in children with community-acquired pneumonia

PubMed was reviewed on antibiotic treatment of community-acquired pneumonia (CAP) in children for the years 2011-2020, and three clinical trials in high-income and eight in low-income countries were found. Prospective studies combining laboratory and clinical findings for steering of antibiotic treatment found that five-day courses were equally effective as longer courses. No new antibiotics were launched for children's CAP during the last 10 years. Five-day courses are equally effective as 7- to 10-day courses for CAP in children. Stewardship of antibiotics needs lessening of exposure to antibiotics by better targeting their use and by shortening the lengths of antibiotic courses.

Antibiotics in the pipeline: a literature review (2017-2020)

Introduction

Antimicrobial resistance (AMR) is an emerging global threat. It increases mortality and morbidity and strains healthcare systems. Health care professionals can counter the rising AMR by promoting antibiotic stewardship and facilitating new drug development. Even with the economic and scientific challenges, it is reassuring that new agents continue to be developed.

Methods

This review addresses new antibiotics in the pipeline. We conducted a review of the literature including Medline, Clinicaltrials.org, and relevant pharmaceutical companies for approved and in pipeline antibiotics in phase 3 or new drug application (NDA).

Results

We found a number of new antibiotics and reviewed their current development status, mode of action, spectra of activity, and indications for which they have been approved. The included studies from phase 3 clinical trials were mainly utilized for the treatment of acute bacterial skin and skin structure infections, community-acquired bacterial pneumonia, and pneumonia acquired in the healthcare settings. The number of these agents is limited against high priority organisms. The identified antibiotics were based mainly on previously known molecules or pre-existing antimicrobial agents.

Conclusion

There are a limited number of antibiotics against high priority organisms such as multi-drug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Enterobacteriaceae. New antimicrobial agents directed against the top priority organisms as classified by the World Health Organization are urgently needed.

Leveraging Physiologically Based Pharmacokinetic Modeling and Experimental Data to Guide Dosing Modification of CYP3A-Mediated Drug-Drug Interactions in the Pediatric Population

Solithromycin is a novel fluoroketolide antibiotic that is both a substrate and time-dependent inhibitor of CYP3A. Solithromycin has demonstrated efficacy in adults with community-acquired bacterial pneumonia and has also been investigated in pediatric patients. The objective of this study was to develop a framework for leveraging physiologically based pharmacokinetic (PBPK) modeling to predict CYP3A-mediated drug-drug interaction (DDI) potential in the pediatric population using solithromycin as a case study. To account for age, we performed in vitro metabolism and time-dependent inhibition studies for solithromycin for CYP3A4, CYP3A5, and CYP3A7. The PBPK model included CYP3A4 and CYP3A5 metabolism and time-dependent inhibition, glomerular filtration, P-glycoprotein transport, and enterohepatic recirculation. The average fold error of simulated and observed plasma concentrations of solithromycin in both adults (1966 plasma samples) and pediatric patients from 4 days to 17.9 years (684 plasma samples) were within 0.5- to 2.0-fold. The geometric mean ratios for the simulated area under the concentration versus time curve (AUC) extrapolated to infinity were within 0.75- to 1.25-fold of observed values in healthy adults receiving solithromycin with midazolam or ketoconazole. DDI potential was simulated in pediatric patients (1 month to 17 years of age) and adults. Solithromycin increased the simulated midazolam AUC 4- to 6-fold, and ketoconazole increased the simulated solithromycin AUC 1- to 2-fold in virtual subjects ranging from 1 month to 65 years of age. This study presents a systematic approach for incorporating CYP3A in vitro data into adult and pediatric PBPK models to predict pediatric CYP3A-mediated DDI potential. SIGNIFICANCE STATEMENT: Using solithromycin, this study presents a framework for investigating and incorporating CYP3A4, CYP3A5, and CYP3A7 in vitro data into adult and pediatric physiologically based pharmacokinetic models to predict CYP3A-mediated DDI potential in adult and pediatric subjects during drug development. In this study, minor age-related differences in inhibitor concentration resulted in differences in the magnitude of the DDI. Therefore, age-related differences in DDI potential for substrates metabolized primarily by CYP3A4 can be minimized by closely matching adult and pediatric inhibitor concentrations.

An open label trial of anakinra to prevent respiratory failure in COVID-19

Background:

It was studied if early suPAR-guided anakinra treatment can prevent severe respiratory failure (SRF) of COVID-19.

Methods:

A total of 130 patients with suPAR ≥6 ng/ml were assigned to subcutaneous anakinra 100 mg once daily for 10 days. Primary outcome was SRF incidence by day 14 defined as any respiratory ratio below 150 mmHg necessitating mechanical or non-invasive ventilation. Main secondary outcomes were 30-day mortality and inflammatory mediators; 28-day WHO-CPS was explored. Propensity-matched standard-of care comparators were studied.

Results:

22.3% with anakinra treatment and 59.2% comparators (hazard ratio, 0.30; 95% CI, 0.20–0.46) progressed into SRF; 30-day mortality was 11.5% and 22.3% respectively (hazard ratio 0.49; 95% CI 0.25–0.97). Anakinra was associated with decrease in circulating interleukin (IL)−6, sCD163 and sIL2-R; IL-10/IL-6 ratio on day 7 was inversely associated with SOFA score; patients were allocated to less severe WHO-CPS strata.

Conclusions:

Early suPAR-guided anakinra decreased SRF and restored the pro-/anti-inflammatory balance.

Funding:

This study was funded by the Hellenic Institute for the Study of Sepsis, Technomar Shipping Inc, Swedish Orphan Biovitrum, and the Horizon 2020 Framework Programme.

Clinical trial number:

NCT04357366.

People infected with the SARS-CoV-2 virus, which causes COVID-19, can develop severe respiratory failure and require a ventilator to keep breathing, but this does not happen to every infected individual. Measuring a blood protein called suPAR (soluble urokinase plasminogen activator receptor) may help identify patients at the greatest risk of developing severe respiratory failure and requiring a ventilator. Previous investigations have suggested that measuring suPAR can identify pneumonia patients at highest risk for developing respiratory failure. The protein can be measured by taking a blood sample, and its levels provide a snapshot of how the body’s immune system is reacting to infection, and of how it may respond to treatment.

Anakinra is a drug that forms part of a class of medications called interleukin antagonists. It is commonly prescribed alone or in combination with other medications to reduce pain and swelling associated with rheumatoid arthritis. Kyriazopoulou et al. investigated whether treating COVID-19 patients who had developed pneumonia with anakinra could prevent the use of a ventilator and lower the risk of death.

The findings show that treating COVID-19 patients with an injection of 100 milligrams of anakinra for ten days may be an effective approach because the drug combats inflammation. Kyriazopoulou et al. examined various markers of the immune response and discovered that anakinra was able to improve immune function, protecting a significant number of patients from going on a ventilator. The drug was also found to be safe and cause no significant adverse side effects.

Administering anakinra decreased of the risk of progression into severe respiratory failure by 70%, and reduced death rates significantly. These results suggest that it may be beneficial to use suPAR as an early biomarker for identifying those individuals at highest risk for severe respiratory failure, and then treat them with anakinra. While the findings are promising, they must be validated in larger studies.

Spotlight on New Antibiotics for the Treatment of Pneumonia

In the last years, the presence of multidrug-resistant (MDR) Gram-negative (like Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) and Gram-positive bacteria (mostly methicillin-resistant Staphylococcus aureus) was worldwide reported, limiting the options for an effective antibiotic therapy. For these reasons, inappropriate antimicrobial therapy and delayed prescription can lead to an unfavorable outcome, especially in patients with pneumonia. New antibiotics approved belong to classes of antimicrobials, like beta-lactams with or without beta-lactamase inhibitors, aminoglycosides, oxazolidinones, quinolones, and tetracyclines, or based on new mechanisms of action. These new compounds show many advantages, including a broad spectrum of activity against MDR pathogens, good lung penetration, safety and tolerability, and finally the possibility of intravenous and/or oral formulations. However, the new antibiotics under development represent an important possible armamentarium against difficult-to-treat strains. The safety and clinical efficacy of these future drugs should be tested in clinical practice. In this review, there are reported characteristics of newly approved antibiotics that represent potential future options for the treatment of respiratory tract infections, including those caused by multidrug-resistant bacteria. Finally, the characteristics of the drugs under development are briefly reported.

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

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

Meta-analysis of fluoroquinolones versus macrolides for treatment of legionella pneumonia

BACKGROUND

Only a single meta-analysis has reported the clinical benefit of fluoroquinolones (FQs) for Legionella pneumonia; however, there is no robust data available to confirm this result, based on current guidelines.

METHODS

We performed a systematic review and meta-analysis comparing FQs with macrolides (MCs) on their efficacy and safety in Legionella pneumonia, using studies published until January 2020. The outcomes included mortality (overall; 30-day), clinical cure, time to apyrexia, length of hospital stay, and adverse events.

RESULTS

Five RCTs and twelve retrospective studies were identified. Clinical cure was comparable between the treatment groups (risk rate (RR) 1.07, 95% confidential interval (CI) 0.86-1.31). Mortality was significantly higher for MCs than for FQs (overall, odd rate (OR) 0.59, 95% CI 0.35-0.98; 30-day, OR 0.41, 95% CI 0.20-0.85). FQs significantly reduced the length of hospital stay, compared to MCs (mean difference -3.58, 95% CI -5.48-1.69). Other outcomes were not significantly different between the treatment groups (time to apyrexia; mean difference -1.83, 95% CI -5.15-1.5, adverse events; OR 0.61, 95% CI 0.33-1.15). In subgroup analyses, levofloxacin significantly reduced the length of hospital stay over two specific MCs (azithromycin and clarithromycin) (mean difference -3.03, 95% CI -5.33-0.72), whereas mortality was not significantly different between the treatment groups (overall, OR 0.49, 95% CI 0.19-1.24; 30-day, OR 0.38, 95% CI 0.13-1.13).

CONCLUSIONS

FQs exhibited superior effects in terms of mortality and length of hospital stay in Legionella pneumonia. These results support current guidelines recommending FQs for the treatment of Legionella pneumonia.

Pharmacotherapeutic management of bronchial infections in adults: non-cystic fibrosis bronchiectasis and chronic obstructive pulmonary disease

INTRODUCTION

Effective management of both acute and chronic bronchial infections is mandatory due to their high frequency rate, the relevant morbidity and mortality and the significant burden to health care systems, especially with the aging of population. Bacteria are the main causative pathogens, followed by viruses, and less commonly by fungi. The clinical evaluation of new therapeutic associations is mandatory to cope with the increases in resistance, in association with better infection control and antimicrobial policies.

AREAS COVERED

The authors searched Medline for any article published in English language up until March 1, 2020 that concerns the treatment of acute exacerbations and chronic infections in chronic obstructive respiratory disease and bronchiectasis.

EXPERT OPINION

As acute exacerbations are a main common and detrimental event in patients with COPD and bronchiectasis, effective antimicrobial therapies and regimens should be optimized. The development of new molecules or combination regimens is vital to patients with severe and/or difficult-to-treat infections. Moreover, chronic infection control is mandatory in these patients to their improve quality of life, respiratory function and prognosis as well as for reducing health care costs.

Updates on community acquired pneumonia management in the ICU

While the world is grappling with the consequences of a global pandemic related to SARS-CoV-2 causing severe pneumonia, available evidence points to bacterial infection with Streptococcus pneumoniae as the most common cause of severe community acquired pneumonia (SCAP). Rapid diagnostics and molecular testing have improved the identification of co-existent pathogens. However, mortality in patients admitted to ICU remains staggeringly high.

The American Thoracic Society and Infectious Diseases Society of America have updated CAP guidelines to help streamline disease management. The common theme is use of timely, appropriate and adequate antibiotic coverage to decrease mortality and avoid drug resistance. Novel antibiotics have been studied for CAP and extend the choice of therapy, particularly for those who are intolerant of, or not responding to standard treatment, including those who harbor drug resistant pathogens. In this review, we focus on the risk factors, microbiology, site of care decisions and treatment of patients with SCAP.

Burden of Community-Acquired Pneumonia and Unmet Clinical Needs

Community-acquired pneumonia (CAP) is the leading cause of death among infectious diseases and an important health problem, having considerable implications for healthcare systems worldwide. Despite important advances in prevention through vaccines, new rapid diagnostic tests and antibiotics, CAP management still has significant drawbacks. Mortality remains very high in severely ill patients presenting with respiratory failure or shock but is also high in the elderly. Even after a CAP episode, higher risk of death remains during a long period, a risk mainly driven by inflammation and patient-related co-morbidities. CAP microbiology has been altered by new molecular diagnostic tests that have turned viruses into the most identified pathogens, notwithstanding uncertainties about the specific role of each virus in CAP pathogenesis. Pneumococcal vaccines also impacted CAP etiology and thus had changed Streptococcus pneumoniae circulating serotypes. Pathogens from specific regions should also be kept in mind when treating CAP. New antibiotics for CAP treatment were not tested in severely ill patients and focused on multidrug-resistant pathogens that are unrelated to CAP, limiting their general use and indications for intensive care unit (ICU) patients. Similarly, CAP management could be personalized through the use of adjunctive therapies that showed outcome improvements in particular patient groups. Although pneumococcal vaccination was only convincingly shown to reduce invasive pneumococcal disease, with a less significant effect in pneumococcal CAP, it remains the best therapeutic intervention to prevent bacterial CAP. Further research in CAP is needed to reduce its population impact and improve individual outcomes.

Efficacy of Delafloxacin versus Moxifloxacin against Bacterial Respiratory Pathogens in Adults with Community-Acquired Bacterial Pneumonia (CABP): Microbiology Results from the Delafloxacin Phase 3 CABP Trial

Delafloxacin is a novel fluoroquinolone with activity against Gram-positive, Gram-negative, and atypical pathogens, including fluoroquinolone-nonsusceptible methicillin-resistant Staphylococcus aureus (MRSA). The microbiological results of a phase 3 clinical trial in adults with community-acquired pneumonia (CAP) comparing delafloxacin (300 mg intravenously [i.v.] with the option to switch to 450 mg orally every 12 h) to moxifloxacin (400 mg i.v.

Delafloxacin is a novel fluoroquinolone with activity against Gram-positive, Gram-negative, and atypical pathogens, including fluoroquinolone-nonsusceptible methicillin-resistant Staphylococcus aureus (MRSA). The microbiological results of a phase 3 clinical trial in adults with community-acquired pneumonia (CAP) comparing delafloxacin (300 mg intravenously [i.v.] with the option to switch to 450 mg orally every 12 h) to moxifloxacin (400 mg i.v. with the option to switch to 400 mg orally once a day [QD]) were determined. Patients from 4 continents, predominately Europe but also South America and Asia, were enrolled. The microbiological intent-to-treat (MITT) population included 520 patients, and 60.5% of these patients had a bacterial pathogen identified. Multiple diagnostic methods were employed, including culture, serology, PCR, and urinary antigen tests. Based on baseline MIC₉₀ values, delafloxacin exhibited at least 16-fold greater activity than moxifloxacin for Gram-positive and fastidious Gram-negative pathogens. Delafloxacin retained activity against resistant phenotypes found in Streptococcus pneumoniae (penicillin-, macrolide-, and multiple-drug resistant), Haemophilus species (β-lactamase producing and macrolide nonsusceptible), and S. aureus (MRSA and fluoroquinolone-nonsusceptible methicillin-susceptible S. aureus [MSSA]). The microbiological success rates were 92.7% for S. pneumoniae (87.5% for penicillin-resistant S. pneumoniae [PRSP]), 92.6% for S. aureus (100% for MRSA), 100% for Escherichia coli, 82.4% for Klebsiella pneumoniae, 100% for Klebsiella oxytoca, 100% for Moraxella catarrhalis, 91.7% for Haemophilus influenzae, 88.6% for Haemophilus parainfluenzae, 96.7% for Mycoplasma pneumoniae, 93.1% for Legionella pneumophila, and 100% for Chlamydia pneumoniae. There was little correlation between MICs and outcomes, with a high proportion of favorable outcomes observed across all delafloxacin baseline MIC values. Delafloxacin may be considered a treatment option as monotherapy for CAP in adults, where broad-spectrum coverage including MRSA activity is desirable.

Emerging Treatment Options for Infections by Multidrug-Resistant Gram-Positive Microorganisms

Antimicrobial agents are currently the mainstay of treatment for bacterial infections worldwide. However, due to the increased use of antimicrobials in both human and animal medicine, pathogens have now evolved to possess high levels of multi-drug resistance, leading to the persistence and spread of difficult-to-treat infections. Several current antibacterial agents active against Gram-positive bacteria will be rendered useless in the face of increasing resistance rates. There are several emerging antibiotics under development, some of which have been shown to be more effective with an improved safety profile than current treatment regimens against Gram-positive bacteria. We will extensively discuss these antibiotics under clinical development (phase I-III clinical trials) to combat Gram-positive bacteria, such as Staphylococcus aureus, Enterococcus faecium and Streptococcus pneumoniae. We will delve into the mechanism of actions, microbiological spectrum, and, where available, the pharmacokinetics, safety profile, and efficacy of these drugs, aiming to provide a comprehensive review to the involved stakeholders.

A Dried Blood Spot Analysis for Solithromycin in Adolescents, Children, and Infants: A Short Communication

BACKGROUND

Solithromycin is a fourth-generation macrolide antibiotic with potential efficacy in pediatric community-acquired bacterial pneumonia. Pharmacokinetic (PK) studies of solithromycin in pediatric subjects are limited, therefore application of minimally invasive drug sampling techniques, such as dried blood spots (DBS), may enhance the enrollment of children in PK studies. The objectives of this study were to compare solithromycin concentrations in DBS with those in liquid plasma samples (LPS) and to quantify the effects of modeling DBS concentrations on the results of a population PK model.

METHODS

Comparability analysis was performed on matched DBS and LPS solithromycin concentrations collected from two different phase 1 clinical trials of solithromycin treatment in children (clinicaltrials.gov #NCT01966055 and #NCT02268279). Comparability of solithromycin concentrations was evaluated based on DBS:LPS ratio, median percentage prediction error, and median absolute percentage prediction error. The effect of correcting DBS concentrations for both hematocrit and protein binding was investigated. In addition, a previously published population PK model (NONMEM) was leveraged to compare parameter estimates resulting from either DBS or LPS concentrations.

RESULTS

A total of 672 paired DBS-LPS concentrations were available from 95 subjects (age: 0-17 years of age). The median (range) LPS and DBS solithromycin concentrations were 0.3 (0.01-12) mcg/mL and 0.32 (0.01-14) mcg/mL, respectively. Median percentage prediction error and median absolute percentage prediction error of raw DBS to LPS solithromycin concentrations were 5.26% and 22.95%, respectively. In addition, the majority of population PK parameter estimates resulting from modeling DBS concentrations were within 15% of those obtained from modeling LPS concentrations.

CONCLUSIONS

Solithromycin concentrations in DBS were similar to those measured in LPS and did not require correction for hematocrit or protein binding.

Differentiating the Pharmacodynamics and Toxicology of Macrolide and Ketolide Antibiotics

This is a review of the macrolide and ketolide field focusing on differentiating the pharmacodynamics and especially the toxicology of the macrolides and ketolides. We emphasize the diversity in pharmacodynamics and toxicity of the macrolides and ketolides, resulting from even small structural changes, which makes it important to consider the various different compounds separately, not necessarily as a class. The ketolide, telithromycin, was developed because of rising bacterial macrolide resistance but was withdrawn postapproval after visual disturbances, syncope, myasthenia gravis, and hepatotoxicity were noted. These diverse adverse effects could be attributed to inhibition of nicotinic acetylcholine receptors. Solithromycin, a later generation ketolide, was effective in treating bacterial pneumonia, but it was not approved by the U.S. Food and Drug Administration owing, in part, to its structural similarity to telithromycin. This Miniperspective describes that structurally similar macrolides/ketolides have clearly mechanistically distinct effects. Understanding these effects could help in developing and securing regulatory approval of a new macrolide/ketolide that is active against macrolide-resistant pathogenic bacteria.

Emerging antibiotics for community-acquired pneumonia

Introduction: Community-acquired pneumonia is the most common infection leading to hospitalization and death in all age groups, especially in elderly populations. Increasing antibiotic resistance among the common bacterial pathogens associated with community-acquired pneumonia, especially Streptococcus pneumoniae and staphylococci, has made its empirical treatment increasingly problematic, highlighting the need for effective antibiotic therapy.Areas covered: We searched PubMed and ClinicalTrials.gov for English-language reports of phase III clinical trials conducted between 2000 and 2019 concerning the antibiotic treatment of community-acquired pneumonia. We provide a summary of the latest approved drugs for this indication and highlight emerging drugs with a potential indication.Expert opinion: Ceftaroline (a new cephalosporine) and omadacycline (a cycline alternative), either parenterally or orally, are the only two new antibiotics to have been approved by the FDA for the treatment of community-acquired pneumonia in the last five years. Among the antimicrobials in development, Lefamulin (the first pleuromutilin), is currently in phase III development. Among the known antibiotic classes, solithromycin (a macrolide), nemonoxacin (a quinolone), and delafloxacin and zabofloxacin (both fluoroquinolones), have been studied in phase II and III in clinical trials. The availability of these new antibiotics may offer opportunities to improve the empirical treatment for community-acquired pneumonia.

Pharmacotherapy of Lower Respiratory Tract Infections in Elderly-Focused on Antibiotics

Lower respiratory tract infections (LRTIs) refer to the inflammation of the trachea, bronchi, bronchioles, and lung tissue. Old people have an increased risk of developing LRTIs compared to young adults. The prevalence of LRTIs in the elderly population is not only related to underlying diseases and aging itself, but also to a variety of clinical issues, such as history of hospitalization, previous antibacterial therapy, mechanical ventilation, antibiotic resistance. These factors mentioned above have led to an increase in the prevalence and mortality of LRTIs in the elderly, and new medical strategies targeting LRTIs in this population are urgently needed. After a systematic review of the current randomized controlled trials and related studies, we recommend novel pharmacotherapies that demonstrate advantages for the management of LRTIs in people over the age of 65. We also briefly reviewed current medications for respiratory communicable diseases in the elderly. Various sources of information were used to ensure all relevant studies were included. We searched Pubmed, MEDLINE (OvidSP), EMBASE (OvidSP), and ClinicalTrials.gov. Strengths and limitations of these drugs were evaluated based on whether they have novelty of mechanism, favorable pharmacokinetic/pharmacodynamic profiles, avoidance of interactions and intolerance, simplicity of dosing, and their ability to cope with challenges which was mainly evaluated by the primary and secondary endpoints. The purpose of this review is to recommend the most promising antibiotics for treatment of LRTIs in the elderly (both in hospital and in the outpatient setting) based on the existing results of clinical studies with the novel antibiotics, and to briefly review current medications for respiratory communicable diseases in the elderly, aiming to a better management of LRTIs in clinical practice.

Pharmacokinetic/Pharmacodynamic Evaluation of Solithromycin against Streptococcus pneumoniae Using Data from a Neutropenic Murine Lung Infection Model

Solithromycin (CEM-101) is a novel fluoroketolide antimicrobial agent with activity against typical and atypical pathogens associated with community-acquired bacterial pneumonia. Using a neutropenic murine lung infection model, the objectives of this study were to identify the pharmacokinetic/pharmacodynamic (PK/PD) index most closely associated with efficacy and the magnitude of such indices associated with solithromycin efficacy against Streptococcus pneumoniae Plasma and epithelial lining fluid (ELF) samples for pharmacokinetics (PK) were collected serially over 24 hours from healthy mice administered single doses of solithromycin (0.625 to 40 mg/kg). Neutropenic CD-1 mice infected with 10⁸ CFUs of one of five S. pneumoniae isolates were administered solithromycin (0.156 to 160 mg/kg/day) via oral gavage. Doses were administered in a fractionated manner for mice infected with one isolate, while mice infected with the remaining four isolates received solithromycin as either a regimen every 6 hours or every 12 hours. A three-compartment model best described solithromycin PK in the plasma and ELF (r² = 0.935 and 0.831, respectively). The ratio of total-drug ELF to free-drug plasma area under the concentration-time curve (AUC) from time 0 to 24 hours was 2.7. Free-drug plasma and total-drug ELF AUC to minimum inhibitory concentration ratios (AUC/MIC ratios) were most predictive of efficacy (r² = 0.851 and 0.850, respectively). The magnitude of free-drug plasma/total-drug ELF AUC/MIC ratios associated with net bacterial stasis and a 1- and 2-log₁₀ CFU reduction from baseline was 1.65/1.26, 6.31/15.1, and 12.8/59.8, respectively. These data provided dose selection support for solithromycin for clinical trials in patients with community-acquired bacterial pneumonia.

New Antibiotics for Pneumonia

Delayed antimicrobial prescriptions and inappropriate treatment can lead to poor outcomes in pneumonia. In nosocomial infections, especially in countries reporting high rates of antimicrobial resistance, the presence of multidrug-resistant gram-negative and gam-positive bacteria can limit options for adequate antimicrobial treatment. New antibiotics, belonging to known classes of antimicrobials or characterized by novel mechanisms of actions, have recently been approved or are under development. Advantages of the new compounds include enhanced spectrum of activity against resistant bacteria, high lung penetration, good tolerability, and possibility for intravenous to oral sequential therapy. This article reviews characteristics of newly approved and investigational compounds.

Solithromycin versus ceftriaxone plus azithromycin for the treatment of uncomplicated genital gonorrhoea (SOLITAIRE-U): a randomised phase 3 non-inferiority trial

BACKGROUND

Antibiotic-resistant gonorrhoea represents a global public health threat, and new therapies are needed. We aimed to compare the efficacy and safety of solithromycin, a fourth generation macrolide, with ceftriaxone plus azithromycin for the treatment of gonorrhoea.

METHODS

We did an open-label, multicentre, non-inferiority trial of patients aged 15 years or older with uncomplicated untreated genital gonorrhoea at two sites in Australia and one site in the USA. Patients were randomly assigned (1:1) to receive single dose oral solithromycin 1000 mg or intramuscular ceftriaxone 500 mg plus oral azithromycin 1000 mg. Neisseria gonorrhoeae cultures were obtained at baseline and test of cure (day 7 ± 2). The primary outcome was the proportion of patients with eradication of genital N gonorrhoeae based on culture at test of cure, assessed in the microbiological intention-to-treat (mITT) population, which included all randomly assigned patients who received any dose of study drug and had a positive genital culture for N gonorrhoeae at baseline. Non-inferiority of solithromycin was to be concluded if the lower limit of the 95% CI for the between-group differences was greater than -10%. Safety was analysed in all patients who received any dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT02210325.

FINDINGS

Between Sept 3, 2014, and Aug 27, 2015, 262 patients were randomly assigned and 261 received treatment (130 in the solithromycin group and 131 in the ceftriaxone plus azithromycin group). In the mITT population, 99 (80%) of 123 patients in the solithromycin group and 109 (84%) of 129 patients in the ceftriaxone plus azithromycin group had N gonorrhoeae eradication at test of cure (difference -4·0%, 95% CI -13·6 to 5·5), thus solithromycin did not meet the criterion for non-inferiority at the prespecified -10% margin. The frequency of adverse events was higher in the solithromycin group than the ceftriaxone plus azithromycin group (69 [53%] of 130 patients vs 45 [34%] of 131 patients), the most common of which were diarrhoea (31 [24%] of 130 patients vs 20 [15%] of 131 patients), and nausea (27 [21%] of 130 patients vs 15 [11%] of 131 patients).

INTERPRETATION

Solithromycin as a single 1000 mg dose is not a suitable alternative to ceftriaxone plus azithromycin as first-line treatment for gonorrhoea. If insufficient duration of solithromycin exposure at the infection site in a subset of individuals was the reason for treatment failures, this might be adequately addressed with dose adjustment. However, any further trials with longer dosing need to consider the potential risk of gastrointestinal effects and liver enzyme elevations.

FUNDING

Cempra Pharmaceuticals.

Solithromycin monotherapy for treatment of community-acquired bacterial pneumonia: A meta-analysis of randomised controlled trials

OBJECTIVES

Solithromycin is a new monotherapy option for community-acquired bacterial pneumonia (CABP) patients. However, the efficacy and safety of solithromycin monotherapy for the treatment of CABP remains controversial. The aim of this meta-analysis was to evaluate the role that solithromycin played in the treatment of CABP.

METHODS

We systematically retrieved randomised controlled trials (RCTs) compared solithromycin with other antibiotics in the treatment of CABP, which were published on PubMed, ScienceDirect, Cochrane libary and the Clinical Trials.gov before July 2018. Ultimately, a meta-analysis of all RCTs eligible for inclusion criteria was performed.

RESULTS

Three RCTs, comprising 1855 patients, were included in the meta-analysis. There were no statistically significant differences between patients given solithromycin and those given other antibiotics with regard to early clinical response (ECR) [1855 patients, odds ratio (OR) = 1.00, 95% confidence interval (CI) 0.80 to 1.24, P = 0.99] and clinical success rates at short-term follow-up (SFU) (1855 patients, OR = 0.78, 95% CI 0.60 to 1.01, P = 0.06) in the intention-to-treat (ITT) population, as were the ECR (787 patients, OR = 0.90, 95% CI 0.64 to 1.27, P = 0.55) and clinical success rates at SFU (358 patients, OR = 0.73, 95% CI 0.41 to 1.31, P = 0.30) in microbiological intention-to-treat population (mITT). Similarly, with regard to the occurrence of treatment-emergent adverse events (TEAEs), drug-related adverse events (AEs), serious AEs, serious drug-related AEs and mortality, no statistically significant difference between patients given solithromycin and those given other antibiotics was observed.

CONCLUSION

In the treatment of CABP, solithromycin monotherapy is an effective and safe antibiotic regimen. Other advantages (ie anti-inflammatory effect, potent activity against expected pathogens of CABP and convenient clinical use) of solithromycin may make it a more fascinating option compared with the currently used regimens.

Analyzing the Mechanisms Behind Macrolide Antibiotic-Induced Liver Injury Using Quantitative Systems Toxicology Modeling

PURPOSE

Macrolide antibiotics are commonly prescribed treatments for drug-resistant bacterial infections; however, many macrolides have been shown to cause liver enzyme elevations and one macrolide, telithromycin, has been pulled from the market by its provider due to liver toxicity. This work seeks to assess the mechanisms responsible for the toxicity of macrolide antibiotics.

METHODS

Five macrolides were assessed in in vitro systems designed to test for bile acid transporter inhibition, mitochondrial dysfunction, and oxidative stress. The macrolides were then represented in DILIsym, a quantitative systems pharmacology (QST) model of drug-induced liver injury, placing the in vitro results in context with each compound's predicted liver exposure and known biochemistry.

RESULTS

DILIsym results suggest that solithromycin and clarithromycin toxicity is primarily due to inhibition of the mitochondrial electron transport chain (ETC) while erythromycin toxicity is primarily due to bile acid transporter inhibition. Telithromycin and azithromycin toxicity was not predicted by DILIsym and may be caused by mechanisms not currently incorporated into DILIsym or by unknown metabolite effects.

CONCLUSIONS

The mechanisms responsible for toxicity can be significantly different within a class of drugs, despite the structural similarity among the drugs. QST modeling can provide valuable insight into the nature of these mechanistic differences.

Advances in pediatric antimicrobial agents development

PURPOSE OF REVIEW

Rising rates of multidrug-resistant organisms has necessitated the development of novel antimicrobials. In this review, we will highlight agents that have recently received licensure and those that are in clinical development.

RECENT FINDINGS

In recent years, development of novel antimicrobial agents has accelerated. Although most studies have targeted the adult population, studies in pediatric patients are underway. Adequately powered clinical trials are needed to establish the safety and role of these new drugs.

SUMMARY

The recent development of novel antimicrobials to combat multidrug-resistant organisms is encouraging; however, more studies in the pediatric population are needed.

Antimicrobial Therapy in Community-Acquired Pneumonia in Children

PURPOSE OF REVIEW

Empirical antibiotic therapy remains the cornerstone of treatment in community-acquired pneumonia (CAP). However, the best option for empirical antibiotics for treatment on an ambulatory basis, as well as in those requiring hospitalization, is still unclear. This review tries to answer the question regarding the most appropriate antibiotics in different settings in children with CAP as well as duration of therapy.

RECENT FINDINGS

Recent studies have provided insights regarding use of oral antibiotics in children with mild to moderate CAP, and severe CAP with lower chest retractions but no hypoxia. In view of rapidly emerging resistance among various causative pathogens, several new drugs have been currently approved, or are under trial for CAP in children. Current knowledge suggests that the choice of antibiotics for ambulatory treatment of CAP is oral amoxicillin with a duration of 3-5 days. Children with CAP with lower chest retractions but no hypoxia can be treated with oral amoxicillin. Severe pneumonia can be treated with intravenous antibiotics consisting of penicillin/ampicillin with or without an aminoglycoside. Several new drugs have been developed and approved for use in CAP caused by multidrug-resistant organisms, but these should be used judiciously to avoid emergence of further resistance. Future research is needed regarding the safety and efficacy of newer drugs in children.

Population Pharmacokinetics and Safety of Solithromycin following Intravenous and Oral Administration in Infants, Children, and Adolescents

Solithromycin is a novel fluoroketolide antibiotic which was under investigation for the treatment of community-acquired bacterial pneumonia (CABP). A phase 1 study was performed to characterize the pharmacokinetics (PK) and safety of solithromycin in children. Eighty-four subjects (median age, 6 years [age range, 4 days to 17 years]) were administered intravenous (i.v.) or oral (capsules or suspension) solithromycin (i.v., 6 to 8 mg/kg of body weight; capsules/suspension, 14 to 16 mg/kg on days 1 and 7 to 15 mg/kg on days 2 to 5). PK samples were collected after the first and multidose administration. Data from 83 subjects (662 samples) were combined with previously collected adolescent PK data (n = 13; median age, 16 years [age range, 12 to 17 years]) following capsule administration to perform a population PK analysis. A 2-compartment PK model characterized the data well, and postmenstrual age was the only significant covariate after accounting for body size differences. Dosing simulations suggested that 8 mg/kg i.v. daily and oral dosing of 20 mg/kg on day 1 (800-mg adult maximum) followed by 10 mg/kg on days 2 to 5 (400-mg adult maximum) would achieve a pediatric solithromycin exposure consistent with the exposures observed in adults. Seventy-six treatment-emergent adverse events (TEAEs) were reported in 40 subjects. Diarrhea (6 subjects) and infusion site pain or phlebitis (3 subjects) were the most frequently reported adverse events related to treatment. Two subjects experienced TEAEs of increased hepatic enzymes that were deemed not to be related to the study treatment. (The phase 1 pediatric studies discussed in this paper have been registered at ClinicalTrials.gov under identifiers NCT01966055 and NCT02268279.).

Evolving Understanding of the Causes of Pneumonia in Adults, With Special Attention to the Role of Pneumococcus

Before 1945, Streptococcus pneumoniae caused more than 90% of cases of pneumonia in adults. After 1950, the proportion of pneumonia caused by pneumococcus began to decline. Pneumococcus has continued to decline; at present, this organism is identified in fewer than fewer10%-15% of cases. This proportion is higher in Europe, a finding likely related to differences in vaccination practices and smoking. Gram-negative bacilli, Staphylococcus aureus, Chlamydia, Mycoplasma, and Legionella are each identified in 2%-5% of patients with pneumonia who require hospitalization. Viruses are found in 25% of patients, up to one-third of these have bacterial coinfection. Recent studies fail to identify a causative organism in more than 50% of cases, which remains the most important challenge to understanding lower respiratory infection. Our findings have important implications for antibiotic stewardship and should be considered as new policies for empiric pneumonia management are developed.

Metabolism, Excretion, and Mass Balance of Solithromycin in Humans

Solithromycin, a novel macrolide and the first fluoroketolide, is being developed as a therapy for community-acquired bacterial pneumonia, with a distinct mechanism that provides activity against macrolide-resistant bacteria. The pharmacokinetics, metabolism, and excretion of solithromycin were studied in healthy male subjects after oral administration of a single 800-mg (∼100-μCi) dose of [¹⁴C]solithromycin. Solithromycin was well tolerated, and absorption from the solution occurred with a median time to peak concentration of 4.0 h. Solithromycin and the total radioactivity had similar profiles with no long-lived metabolites. The whole-blood total radioactivity was approximately 75% of the plasma total radioactivity. Recovery was essentially complete (mean, 90.6%), with 76.5% and 14.1% of the dose recovered in feces and urine, respectively. Unchanged solithromycin (CEM-101) was the predominant circulating radioactive component in plasma (77% of the total radioactivity area under the concentration-time curve [AUC]), with two minor plasma metabolites, CEM-214 and CEM-122 (N-acetyl-CEM-101), each accounting for approximately 5% of the total radioactivity. Urinary excretion was predominantly like that of the parent. Solithromycin was primarily eliminated in the feces after extensive metabolism via a complex metabolic pathway with CEM-262 as the major constituent (27.36% of the administered dose). Overall oxidative pathways, presumably carried out mostly by CYP3A4, represented the majority of the metabolism, with N-acetylation present to a lesser extent. No disproportionate human metabolites were observed.

Spotlight on solithromycin in the treatment of community-acquired bacterial pneumonia: design, development, and potential place in therapy

Community-acquired bacterial pneumonia (CABP) is a leading cause of death worldwide. However, antibacterial agents used to treat common pathogens in CABP are marked by adverse drug events and increasing antimicrobial resistance. Solithromycin is a new ketolide antibiotic, based on the macrolide antibiotic structure, being studied for use in CABP. It has efficacy in vitro against the common causative pathogens in CABP including Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens. In Phase II and Phase III clinical trials, it has been demonstrated efficacious as a single agent for treatment of CABP with an apparently milder adverse event profile than alternative agents.

Development of an Adult Physiologically Based Pharmacokinetic Model of Solithromycin in Plasma and Epithelial Lining Fluid

Solithromycin is a fluoroketolide antibiotic under investigation for community-acquired bacterial pneumonia (CABP). We developed a whole-body physiologically based pharmacokinetic (PBPK) model for solithromycin in adults using PK-Sim and MoBi version 6.2, which incorporated time-dependent CYP3A4 auto-inhibition. The model was developed and evaluated using plasma and epithelial lining fluid (ELF) concentration data from 100 healthy subjects and 22 patients with CABP (1,966 plasma, 30 ELF samples). We performed population simulations and calculated the number of observations falling outside the 90% prediction interval. For the oral regimen (800 mg on day 1 and 400 mg daily on days 2-5) that was evaluated in phase III studies, 11% and 23% of observations from healthy adults fell outside the 90% prediction interval for plasma and ELF, respectively. This regimen should be effective because ≥97% of simulated adults achieved area under the concentration vs. time curve (AUC) to minimum inhibitory concentration ratios associated with a log₁₀ colony forming unit reduction in ELF.

Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations

Community-acquired pneumonia is a common and serious disease, with high rates of morbidity and mortality. Management and treatment of community-acquired pneumonia are described in three main documents: the 2007 American Thoracic Society guidelines, the 2011 European Respiratory Society guidelines, and the 2009 British Thoracic Society guidelines, updated by the NICE in 2015. Despite the validity of current guidelines in improving prognosis and management of patients with community-acquired pneumonia, not all recommendations have high levels of evidence and there are still some controversial issues. In particular, there are some areas of low evidence such as the efficacy of an antibiotic molecule or scheme in patients with same risk factors; duration of antibiotic treatment, supportive therapy for acute respiratory failure and immunomodulation molecules.

This review will summarize the main recommendations with high level of evidence and discuss the recommendations with lower evidence, analyzing the studies published after the guidelines’ release.

Regional differences in antibiotic-resistant pathogens in patients with pneumonia: Implications for clinicians

Antibiotic resistance is of great concern for both infection control and the treatment of infectious diseases. Previous studies reported that the occurrence of drug-resistant pathogens (DRPs)-for instance, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae-were associated with inappropriate antibiotic treatment that resulted in adverse outcomes. In addition, unnecessary use of broad-spectrum antibiotics for patients with non-DRPs increased mortality. Therefore, the assessment of risk for DRPs at diagnosis is critical to avoid patients' adverse events. In the present review, we discuss regional differences in the prevalence of DRPs, which ranged from 6% to 45%, in patients with community-onset pneumonia, including both community-acquired and healthcare-associated pneumonia. We then introduce the reported risk factors for DRPs in those patients, and present proposed prediction models for identifying patients with DRPs at diagnosis. Physicians should be aware that some of the risk factors for DRPs (e.g. prior antibiotic use and prior hospitalization) were common between regions; however, others may be different or the weighting of the risks may vary, even for the same risk factors. Therefore, a specific evaluation of risk factors for DRPs is recommended for each region and institution. Furthermore, we present a possible strategy for initial antibiotic selection in patients with community-onset pneumonia, considering DRPs risk. We also discuss future directions for the study of DRPs in community-onset, hospital-acquired and ventilator-associated pneumonia to improve the management of patients with pneumonia.