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This study aimed to investigate the bacterial characteristics of pneumococcal isolates obtained from a tertiary care hospital in Japan. We analyzed the antimicrobial susceptibility, possession of macrolide resistance genes, pneumococcal serogroup/serotype, and sequence type (ST) of pneumococcal isolates from patients aged 15 years or older between 2011 and 2020 at Nagasaki University Hospital. Of the 73 isolates analyzed, 86.3% showed resistance to macrolides, and 28.8%, 46.6%, and 11.0% harbored mefA, ermB, and both, respectively. Of the isolates possessing ermB, 97.6% showed high levels of macrolide resistance [minimal inhibitory concentration (MIC) range, > 16 µg/mL]. Solithromycin (MIC range, 0.03-0.25 µg/mL), regardless of the presence of macrolide resistance genes, and lascufloxacin (MIC range, 0.06-0.5 µg/mL) showed potent in vitro activity against pneumococci. Serotype 19A was the most prevalent (six isolates), followed by serotypes 10A, 15A, and 15B/C (five isolates each). Four serotypes (11A, 19A, 22F, and 23B) and five STs (36, 99, 433, 558, and 3111) were significantly correlated with the presence of macrolide resistance genes. All four isolates with serotype 11A/ST99 and three isolates with serotype 19A/ST3111 harbored both mefA and ermB. No macrolide resistance genes were detected in either of the two isolates with serotype 22F/ST433, while all ten isolates with serogroup 15 (serotypes 15A and 15B/C, five isolates each) possessed ermB alone. Our study revealed the bacterial characteristics of the pneumococcal isolates obtained from our hospital. In vitro activity of solithromycin and lascufloxacin against these isolates was confirmed. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae is considered as the most common pathogen of hospital-acquired pneumonia. K. pneumoniae has emerged as the superbug which had shown multidrug resistance (MDR) as well as extensively drug resistance. Carbapenem resistant K. pneumoniae (CRKP) has become a menace for the treatment with monotherapy of the patients mainly admitted in intensive care units. Hence, in the present study we collected total 187 sputum isolates of K. pneumoniae and performed the antimicrobial susceptibility testing by using the automated Vitek-2 system and broth micro-dilution method (67 CRKP). The combination study of solithromycin with meropenem, colistin, cefotaxime, piperacillin and tazobactam, nitrofurantoin, tetracycline, levofloxacin, curcumin and nalidixic acid was performed by using checkerboard assay. We observed the high rate of resistance towards ampicillin, cefotaxime, ceftriaxone, cefuroxime and aztreonam. The colistin and tigecycline were the most sensitive drugs. The CRKP were 36%, maximum were from the patients of ICUs. The best synergistic effect of solithromycin was with meropenem and cefotaxime (100%), colistin and tetracycline (80%). So, these combinations can be a choice of treatment for the infections caused by MDR CRKP and other Gram-negative bacteria where the monotherapy could not work. [ABSTRACT FROM AUTHOR]

To assess the efficacy, safety, and tissue penetration of solithromycin for the treatment of otorhinolaryngological infections, we conducted three studies: a tissue penetration study with patients scheduled to undergo otorhinolaryngological tissue removal, an open-label study comprising patients with otitis media, pharyngitis, laryngitis, and tonsillitis, and a non-inferiority study compared with high-dose cefcapene-pivoxil (CFPN-PI). Tissue penetration study; 17 patients with chronic rhinosinusitis, chronic otitis media, chronic tonsillitis, or palatine tonsillar hypertrophy, who required resection or removal of their tissue, were enrolled. Solithromycin was administered orally, and otorhinolaryngological tissues were collected 3.5–6 h after drug administration; blood was collected within 15 min before and after drug administration. The collected tissues and blood concentrations were measured at a central laboratory. Open-label study; 55 patients who were diagnosed with acute otitis media, laryngopharyngitis, or tonsillitis were enrolled. Solithromycin was administered orally 800 mg on Day 1, while on days 2–7, 400 mg of the drug was administered once daily. The primary endpoint is the clinical response at Test-of-Cure (TOC: 5–10 days after completion) Non-inferiority study; 283 patients with acute rhinosinusitis or acute exacerbation of chronic rhinosinusitis were randomized into either the solithromycin group or CFPN-PI group. Solithromycin was administered 800 mg once daily on Day 1 and 400 mg once daily while on Days 2–7 in solithromycin group, and CFPN-PI was administered 150 mg three times a day while on Days 1–7 in CFPN-PI group. The primary endpoint is the clinical response at TOC. In the tissue penetration study, the tissue concentration ratios (tissue concentration/plasma concentration) of solithromycin were 4.19 in the sinonasal mucosa, 1.33 in the middle ear mucosa, and 6.12 in the palatine tonsil tissue. In the open-label study, the efficacy rates at the TOC were 97.0 % for acute otitis media, 100 % for laryngopharyngitis, and 81.8 % for tonsillitis. In the non-inferiority study comprising patients with rhinosinusitis, the efficacy rate at the TOC was 87.7 % for solithromycin and 89.7 % for CFPN-PI. The difference in the efficacy rate (95 % confidence interval) was -2.0 % (-9.4 % to 5.4 %), verifying the non-inferiority of solithromycin to CFPN-PI. The most common adverse events in patients administered solithromycin were diarrhea (20.7 %), nausea and nasopharyngitis (3.6 %,), pharyngitis and elevated hepatic function test results (3.1 %), and abnormal hepatic function (2.1 %). Based on the findings, it is suggested that solithromycin is useful for the treatment of otorhinolaryngological infections. [ABSTRACT FROM AUTHOR]

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 ANO1mRNAand 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 andMUC5AC 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. [ABSTRACT FROM AUTHOR]

Gonorrhea is one of the most often sexually transmitted infection in the world. In 2016, WHO stated the Southeast Asia region as the fourth-highest incidence rate and prevalence of gonorrhea. One of the current problems with gonorrhea is related to its emerging resistance to first-line drugs such as cephalosporins, macrolides, and fluoroquinolones. This resistance has an impact on the difficulty of finding effective antibiotics to eradicate the infection, thus risking financial loss and infertility in sexually active age patients. This literature review will discuss solithromycin, the first fluoroketolide in phase III clinical trial, and show its potential as a new antibiotic against infection with resistant Neisseria gonorrhoeae. Literatures are searched using Pubmed and Google Scholar search engines with keywords: antibiotics, CEM-101, clinical trial, Neisseria gonorrhoeae, new treatment, pharmacology, pharmacokinetics, resistance, safety, and solithromycin. This semisynthetic antibiotic is supported by a different chemical structure from previous macrolides; improving solithromycin becomes more stable and able to bind easier with bacterial ribosomes. Pharmacologically, solithromycin provides an advantage in its high bioavailability, easy oral administration route, wide distribution, metabolism mainly in the liver, but not required dosage adjustments due to hepatic impairment, and a single dosage preparation that can increase patient compliance in healing gonorrhea infections. Also, its lower MIC50 than previous antibiotics makes it well-tolerated, therefore making this antibiotic as a potential recommendation for the management of multi-drug resistant gonorrhea in the future. Solithromycin is not inferior to the standard therapy (ceftriaxone and azithromycin), with 80% vs. 84% gonorrhea eradication rates. Per the anatomic site, the eradication rate is 92% in genital, 94% in the pharynx, and 83% in the rectum. However, special attention needs to be paid to the side effects of the gastrointestinal tract of solithromycin, as observed in phase III clinical trials at a dose of 1000 mg in the form of diarrhea (24%) and nausea (21%).

Abstract Background Solithromycin, the fourth generation of ketolides, has been demonstrated potent antibacterial effect against commonly-isolated gram-positive strains. However, Staphylococcus aureus (S. aureus) strains with a higher solithromycin MIC have already been emerged, the mechanism of which is unknown. Methods Antimicrobial susceptibility test was performed on 266 strains of S. aureus. The antibiotic resistance phenotype of erm-positive strain was determined by D-zone test. Spontaneous mutation frequency analysis was performed to compare the risk levels for solithromycin resistance among different strains. Efflux pumps and mutational analysis of ribosomal fragments as well as erm(B) gene domains were detected. Quantitative reverse transcription polymerase chain reaction was conducted to compare the transcriptional expression of the erm gene between the constitutive macrolide-lincosamide-streptogramin B (cMLSB)- and inducible MLSB (iMLSB)-phenotypes. Results In the erm-positive S. aureus strains, the minimum inhibitory concentration (MIC)50/90 of solithromycin (2/> 16 mg/L) was significantly higher than that in the erm-negative strains (0.125/0.25 mg/L). Of note, the MIC50 value of the strains with iMLSB (0.25 mg/L) was significantly lower than that of the strains with cMLSB (4 mg/L). A comparison among strains demonstrated that the median mutational frequency in isolates with cMLSB (> 1.2 × 10− 4) was approximately > 57-fold and > 3333-fold higher than that in iMLSB strains (2.1 × 10− 6) and in erythromycin-sensitive strains (3.6 × 10− 8), respectively. The differential antibiotic in vitro activity against strains between cMLSB and iMLSB could not be explained by efflux pump carriers or genetic mutations in the test genes. The expression of the erm genes in strains with cMLSB did not differ from that in strains with iMLSB. Conclusions The reduced susceptibility to solithromycin by S. aureus was associated with the cMLSB resistance phenotype mediated by erm.

Objectives: Solithromycin is a fluoroketolide that is considered to be a noninducing antibiotic for macrolide–lincosamide–streptogramin B resistance mediated by erm genes. The exact activity of solithromycin to induce erm gene expression remains to be determined. Materials and Methods: The potential of solithromycin to induce erm(A), erm(C), and erm(B) gene expression was examined using a lacZ reporter assay, double-disk diffusion test, and determination of the minimal inhibitory concentration after incubation with subinhibitory concentration of different antibiotics. Results: Neither solithromycin nor the ketolides telithromycin and cethromycin induced erm(A) or erm(C) gene expression. However, solithromycin could significantly induce erm(B) gene expression at levels greater than that seen for cethromycin and clindamycin, but less than that for erythromycin, rokitamycin, and telithromycin. Conclusion: Solithromycin does not induce erm(A) and erm(C) gene expression, but does induce erm(B) gene expression, although to a weaker extent than that seen for macrolides. [ABSTRACT FROM AUTHOR]

Bryan J Donald,1,2 Salim Surani,3–5 Harmeet S Deol,1,6 Uche J Mbadugha,1 George Udeani1,7 1Department of Pharmacy, Corpus Christi Medical Center, Corpus Christi, TX, 2Department of Clinical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA, 3Department of Pulmonology/Critical Care, Corpus Christi Medical Center, Corpus Christi, TX, 4Department of Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX, 5Department of Medicine, College of Osteopathic Medicine, University of North Texas Health Science Center, Denton, TX, 6Department of Pharmacy Services, Yale New Haven Hospital, New Haven, CT, 7Pharmacy Practice, College of Pharmacy, Texas A&M University Health Science Center, Kingsville, TX, USA Abstract: 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. Keywords: solithromycin, macrolide antibiotics, community-acquired bacterial pneumonia, CABP

Novel antibacterial drugs that treat multidrug resistant pathogens are in high demand. We have synthesized analogs of solithromycin using Cu(I)-mediated click chemistry. Evaluation of the analogs using Minimum Inhibitory Concentration (MIC) assays against resistant Staphylococcus aureus, Escherichia coli , and multidrug resistant pathogens Enterococcus faecium and Acinetobacter baumannii showed they possess potencies similar to those of solithromycin, thus demonstrating their potential as future therapeutics to combat the existential threat of multidrug resistant pathogens. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine whether in vitro induced erythromycin resistance facilitates the cross-resistance to the novel fluoroketolide, solithromycin, in Staphylococcus aureus. Four strains of methicillin-susceptible S. aureus strains S2, S3, S5 and S7 were successfully induced to establish erythromycin-resistant strains by continuous in vitro culture with erythromycin. Mutations at drug binding sites were shown to increase the minimal inhibitory concentrations for ketolides, including telithromycin and the novel compound solithromycin, but did not increase for lincosamides, chloramphenicols or oxazolidinones. In S2-, S5- and S7-derived strains, L22 protein mutations occurred first, resulting in a low level of cross-resistance to ketolides (≤4 μg/mL). The L4 protein mutations were dependent on the L22 protein, resulting in high-level cross-resistance to ketolides (≥8 μg/mL). In S3-derived strains, high levels of cross-resistance occurred concurrently in the 23S rRNA domains II/V and the L22 protein. Hence, long-term exposure of erythromycin results in resistance to ketolides in S. aureus through drug binding site mutations. These results demonstrate that since erythromycin has been used clinically for a long time, it is necessary to carefully evaluate the rewards and risks when prescribing solithromycin for the treatment of infectious diseases. [ABSTRACT FROM AUTHOR]

Purpose: We previously discovered that azithromycin (AZM) acts directly on immortalized human meibomian gland epithelial cells (IHMGECs) to stimulate their lipid and lysosome accumulation and overall differentiation. We hypothesize that this phospholipidosis-like effect is due to AZM’s cationic amphiphilic drug (CAD) nature. If our hypothesis is correct, then other CADs (e.g., solithromycin [SOL]) should be able to duplicate AZM’s action on IHMGECs. Our purpose was to test this hypothesis. Materials and Methods: IHMGECs were cultured in the presence of vehicle or SOL (2, 10, or 20 µg/ml) for up to 7 days under proliferating or differentiating conditions. Positive (epidermal growth factor and bovine pituitary extract for proliferation; AZM for differentiation) and negative (vehicle) controls were included with the experiments. IHMGECs were evaluated for cell number, neutral lipid content, and lysosome accumulation. Results: Our results demonstrate that SOL induces a rapid and dose-dependent increase in the accumulation of neutral lipids and lysosomes in HMGECs. The lysosomal effects were most prominent with the 10 and 20 µg/ml doses, and occurred earlier (i.e., 1 day) with SOL than with the AZM (10 µg/ml) control. The effects of SOL and AZM on IHMGEC differentiation were essentially the same after 3 days of culture. SOL did not influence the proliferation of HMGECs during a 7-day time period. Conclusions: Our results support our hypothesis that SOL, a CAD, is able to reproduce AZM’s impact on lysosome and lipid accumulation, as well as the differentiation, of HMGECs. The effect of SOL on lysosome appearance was faster than that of AZM. [ABSTRACT FROM AUTHOR]

Solithromycin is a macrolide antibiotic that has undergone review for the treatment of community-acquired bacterial pneumonia. Solithromycin is also being investigated and has shown promise for the treatment of gonorrhea. With increasing antibiotic resistance, the development of novel antibiotics to combat infections is essential. The unique ribosome-binding stability of solithromycin and mild side effect profile make this a promising new antibiotic. This article will provide an overview on the mechanism of action, clinical efficacy, and safety of this drug for the treatment of gonorrhea. Relevant data were identified through a comprehensive literature search using multiple databases using the keywords solithromycin, CEM-101, and gonorrhea. [ABSTRACT FROM AUTHOR]

Antibiotics can cause dormancy (bacteriostasis) or induce death (cidality) of the targeted bacteria. The bactericidal capacity is one of the most important properties of antibacterial agents. However, the understanding of the fundamental differences in the mode of action of bacteriostatic or bactericidal antibiotics, especially those belonging to the same chemical class, is very rudimentary. Here, by examining the activity and binding properties of chemically distinct macrolide inhibitors of translation, we have identified a key difference in their interaction with the ribosome, which correlates with their ability to cause cell death. While bacteriostatic and bactericidal macrolides bind in the nascent peptide exit tunnel of the large ribosomal subunit with comparable affinities, the bactericidal antibiotics dissociate from the ribosome with significantly slower rates. The sluggish dissociation of bactericidal macrolides correlates with the presence in their structure of an extended alkyl-aryl side chain, which establishes idiosyncratic interactions with the ribosomal RNA. Mutations or chemical alterations of the rRNA nucleotides in the drug binding site can protect cells from macrolide-induced killing, even with inhibitor concentrations that significantly exceed those required for cell growth arrest. We propose that the increased translation downtime due to slow dissociation of the antibiotic may damage cells beyond the point where growth can be reinitiated upon the removal of the drug due to depletion of critical components of the gene-expression pathway. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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The activity of solithromycin, a fourth-generation macrolide and novel fluoroketolide, was evaluated by determining its minimum inhibitory concentration (MIC) (via Clinical and Laboratory Standards Institute broth microdilution) against 2797 contemporary clinical respiratory tract isolates collected from North America, Europe, Asia-Pacific and other regions of the world in 2012–13. Solithromycin was very active against Streptococcus pneumoniae and Streptococcus pyogenes , with MIC 90 of 0.25 and 0.12 µg/mL, respectively. Isolates with combined macrolide resistance genes ermB and mefE had a higher solithromycin MIC distribution, but the highest MIC recorded was 1 µg/mL for one S. pneumoniae isolate from Japan and one S. pyogenes isolate from China. Solithromycin was active against methicillin-susceptible Staphylococcus aureus (MIC 90 0.12 µg/mL) but not against methicillin-resistant S. aureus (MRSA) (MIC 90 >32 µg/mL). However, MRSA strains most commonly observed with community-associated infections (i.e. SCC mec IV) were more susceptible than other MRSA SCC mec types. Gram-negative pathogens that cause community-acquired respiratory tract infections ( Haemophilus influenzae and Moraxella catarrhalis ) were inhibited by solithromycin isolated from worldwide locations (MIC 90 2 and 0.25 µg/mL, respectively). These data support the continued development of solithromycin for the treatment of community-acquired pneumonia globally. [ABSTRACT FROM AUTHOR]

Purpose. The pharmacology, pharmacokinetics, pharmacodynamics, antimicrobial activity, clinical safety, and current regulatory status of solithromycin are reviewed. Summary. Solithromycin is a novel ketolide antibiotic developed for the treatment of community-acquired bacterial pneumonia (CABP). Its pharmacologic, pharmacokinetic, and pharmacodynamic properties provide activity against a broad range of intracellular organisms, including retained activity against pathogens displaying various mechanisms of macrolide resistance. Phase III clinical trials of solithromycin demonstrated noninferiority of both oral and i.v.-to-oral regimens of 5-7 days' duration compared with moxifloxacin for patients with moderately severe CABP. -Nearly one third of patients receiving i.v. solithromycin experienced infusion-site reactions. Although no liver-related adverse events were reported in patients receiving oral solithromycin, more patients receiving i.v.-to-oral solithromycin experienced asymptomatic, transient transaminitis, with alanine transaminase levels of >3 to >5 times the upper limit, compared with those treated with moxifloxacin. These results led the Food and Drug Administration to conclude that the solithromycin new drug application was not approvable as filed, adding that the risk of hepatotoxicity had not yet been adequately characterized. The agency further recommended a comparative study of patients with CABP to include approximately 9,000 patients exposed to solithromycin in order to exclude drug-induced liver injury events occurring at a rate of 1 in 3,000 with 95% probability. Conclusion. Solithromycin is a novel ketolide antibiotic with activity against a broad spectrum of intracellular organisms, including those displaying macrolide resistance. While demonstrating noninferiority to a current first-line agent in the treatment of CABP, concerns for drug-induced liver injury and infusion-site reactions have placed its regulatory future in doubt. [ABSTRACT FROM AUTHOR]

Abstract Introduction Solithromycin is a novel fluoroketolide developed to treat pneumonia. But, few studies evaluating its antimicrobial activity against S. pneumoniae in a mixed-infection model with anaerobes are available, while community-acquired pneumonia can involve mixed-infection of Streptococcus pneumoniae and anaerobic bacteria. This study evaluated the antimicrobial activity of solithromycin against macrolide-resistant S. pneumoniae and anaerobic bacteria with a murine pneumonia mixed-infection model. Material and methods We evaluated antimicrobial activity of solithromycin (10 and 20 mg/kg) and levofloxacin (126 mg/kg) against S. pneumoniae with a three-point mutation in penicillin-binding protein and an ermB gene, and Parvimonas micra. Antimicrobial efficacy was calculated for each isolate as the change in bacterial count (Δlog 10 CFU/mL) obtained in the treated mice after 24 h compared with the count in the starting control animals. Results The solithromycin and levofloxacin minimum inhibitory concentrations (MICs) for S. pneumoniae were 0.03 and 0.5 μg/mL, respectively. The solithromycin and levofloxacin MICs for P. micra were 0.015 and 0.12 μg/mL, respectively. In a mixed-infection model, solithromycin showed significantly higher antimicrobial activity against S. pneumoniae than levofloxacin (solithromycin 20 mg/kg; −2.87 ± 1.33 log 10 CFU/mL vs. levofloxacin; −1.35 ± 0.37 log 10 CFU/mL, p = 0.0397). Similarly, solithromycin showed significantly higher antimicrobial activity against P. micra than levofloxacin (solithromycin 20 mg/kg; −2.78 ± 0.98 log 10 CFU/mL vs. levofloxacin; −1.57 ± 0.47 log 10 CFU/mL, p = 0.0400). Discussion Solithromycin showed higher antimicrobial activities against macrolide-resistant S. pneumoniae and P. micra than levofloxacin , even though they were coexisted in murine lung tissue. Our results suggest that solithromycin could be effective for pneumonia patients due to S. pneumoniae to reduce bacterial density in lung tissue. [ABSTRACT FROM AUTHOR]

Two strains of Streptococcus pneumoniae, one expressing the methyltransferase Erm(B) and the other negative for erm (B), were selected for solithromycin resistance in vitro either with direct drug selection or with chemical mutagenesis followed by drug selection. We obtained a series of mutants that we characterized by next-generation sequencing. We found mutations in various ribosomal proteins (L3, L4, L22, L32, and S4) and in the 23S rRNA. We also found mutations in subunits of the phosphate transporter, in the DEAD box helicase CshB, and in the erm (B)L leader peptide. All mutations were shown to decrease solithromycin susceptibility when transformed into sensitive isolates. Some of the genes derived from our in vitro screens were found to be mutated also in clinical isolates with decreased susceptibility to solithromycin. While many mutations were in coding sequences, some were found in regulatory regions. These included novel phenotypic mutations in the intergenic regions of the macrolide resistance locus mef (E)/ mel and in the vicinity of the ribosome binding site of erm (B). Our screens highlighted that macrolide-resistant S. pneumoniae can easily acquire resistance to solithromycin, and they revealed many new phenotypic mutations., Competing Interests: The authors declare no conflict of interest.

Bronchopulmonary dysplasia (BPD) is the most common morbidity of prematurity. BPD is a chronic respiratory disease related to lung-injury during the primary course of critical lung disease such as respiratory distress syndrome or when abnormal development of the preterm lung occurs. Abnormal lung development not only results from primary lung injury in the first days after birth, but also secondary injury through abnormal repair resulting in arrested and abnormal alveolarization, fibrosis and pulmonary vascular dysgenesis. Chorioamnionitis is a risk factor that plays an important role in the development of BPD. Ureaplasma subspecies (spp.) are the most common isolated organisms from chorioamniotic tissue after premature births. Therefore Ureaplasma spp. appear to play an important role in the development of BPD, and treatment or prophylactic treatment of these infections or colonization may reduce the incidence, morbidity and mortality of BPD. Ureaplasma spp. infections are challenging not only to treat, but also to diagnosis in a timely manner. This review summarizes the current state of treatment and new developments in the treatment of Ureaplasma exposure in premature infants. [ABSTRACT FROM AUTHOR]

The macrolide class of antibiotics, including the early generation macrolides erythromycin, clarithromycin and azithromycin, have been used broadly for treatment of respiratory tract infections. An increase of treatment failures of early generation macrolides is due to the upturn in bacterial macrolide resistance to 48% in the US and over 80% in Asian countries and has led to the use of alternate therapies, such as fluoroquinolones. The safety of the fluoroquinolones is now in question and alternate antibiotics for the outpatient treatment of community acquired bacterial pneumonia are needed. Telithromycin, approved in 2003, is no longer used owing to serious adverse events, collectively called the ‘Ketek effects’. Telithromycin has a side chain pyridine moiety that blocks nicotinic acetylcholine receptors. Blockade of these receptors is known experimentally to cause the side effects seen with telithromycin in patients use. Solithromycin is a new macrolide, the first fluoroketolide, which has been tested successfully in two Phase 3 trials and is undergoing regulatory review at the FDA. Solithromycin is differentiated from telithromycin chemically and biologically in that its side chain is chemically different and does not significantly block nicotinic acetylcholine receptors. Solithromycin was well tolerated and effective in clinical trials. [ABSTRACT FROM AUTHOR]

Solithromycin is a novel fluoroketolide with high activity against bacteria associated with community-acquired respiratory tract infections as well as gonorrhea. However, data on the activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota are scarce. In this study, 1024 Gram-positive and Gram-negative anaerobic isolates from the normal intestinal microbiota were analyzed for in-vitro susceptibility against solithromycin and compared to azithromycin, amoxicillin/clavulanic acid, ceftriaxone, metronidazole and levofloxacin by determining the minimum inhibitory concentration (MIC). Solithromycin was active against Bifidobacteria (MIC 50 , 0.008 mg/L) and Lactobacilli (MIC 50 , 0.008 mg/L). The MIC 50 for Clostridia, Bacteroides, Prevotella and Veillonella were 0.5, 0.5, 0.125 and 0.016 mg/L, respectively. Gram-positive anaerobes were more susceptible to solithromycin as compared to the other antimicrobials tested. The activity of solithromycin against Gram-negative anaerobes was equal or higher as compared to other tested agents. [ABSTRACT FROM AUTHOR]

Background. Solithromycin, a novel macrolide antibiotic with both intravenous and oral formulations dosed once daily, has completed 2 global phase 3 trials for treatment of community-acquired bacterial pneumonia. Methods. A total of 863 adults with community-acquired bacterial pneumonia (Pneumonia Outcomes Research Team [PORT] class II-IV) were randomized 1:1 to receive either intravenous-to-oral solithromycin or moxifloxacin for 7 once-daily doses. All patients received 400 mg intravenously on day 1 and were permitted to switch to oral dosing when clinically indicated. The primary objective was to demonstrate noninferiority (10% margin) of solithromycin to moxifloxacin in achievement of early clinical response (ECR) assessed 3 days after first dose in the intent-to-treat (ITT) population. Secondary endpoints included demonstrating noninferiority in ECR in the microbiological ITT population (micro-ITT) and determination of investigator-assessed success rates at the short-term follow-up (SFU) visit 5-10 days posttherapy. Results. In the ITT population, 79.3% of solithromycin patients and 79.7% of moxifloxacin patients achieved ECR (treatment difference, -0.46; 95% confidence interval [CI], -6.1 to 5.2). In the micro-ITT population, 80.3% of solithromycin patients and 79.1% of moxifloxacin patients achieved ECR (treatment difference, 1.26; 95% CI, -8.1 to 10.6). In the ITT population, 84.6% of solithromycin patients and 88.6% of moxifloxacin patients achieved clinical success at SFU based on investigator assessment. Mostly mild/moderate infusion events led to higher incidence of adverse events overall in the solithromycin group. Other adverse events were comparable between treatment groups. Conclusions. Intravenous-to-oral solithromycin was noninferior to intravenous-to-oral moxifloxacin. Solithromycin has potential to provide an intravenous and oral option for monotherapy for community-acquired bacterial pneumonia. [ABSTRACT FROM AUTHOR]

The fluoroketolide solithromycin is 2-fold more potent in vitro than telithromycin against pneumococci (including macrolide-resistant strains) and Haemophilus influenzae and very active on pathogens causing atypical pneumonia. In contrast, it is a 30-fold less potent inhibitor of nicotinic receptors incriminated in telithromycin toxicity. In Phase II/III trials, oral solithromycin once-daily (800 mg on day 1; 400 mg on days 2-5) proved effective and safe when compared to respiratory fluoroquinolones for the treatment of community-acquired bacterial pneumonia (CABP). A Phase III intravenous trial vs. moxifloxacin has been recently completed for the same indication. Solithromycin may restore interest in ketolides as a first-line therapy for CAPB. Solithromycin safety should nevertheless be confirmed in larger populations allowing for detection of rare adverse events. [ABSTRACT FROM AUTHOR]

The emergence of high-level resistance to ceftriaxone is giving rise to serious concern about absence of effective treatment options to cure gonococcal infections. Increasing the dosage regimen can be applied to ceftriaxone and azithromycin, but the emergence of high-level resistance has already been reported. Spectinomycin is another active drug but has low efficacy in the treatment of pharyngeal gonorrhoea. Conventional antibiotics could be introduced for gonococcal treatment, but they have some limitations, such as the absence of clinical trials and breakpoint. Combining antibiotics is another promising method to cure patients and to prevent the emergence of resistance. The most important strategy to maintain the efficacy of antibiotics is rapid detection and dissemination control of novel resistant isolate. [ABSTRACT FROM PUBLISHER]

Background. Progressive resistance to antimicrobial agents has reduced options for gonorrhea therapy worldwide. Solithromycin (CEM-101) is a novel oral fluoroketolide antimicrobial with substantial in vitro activity against Neisseria gonorrhoeae. Methods. We conducted a phase 2 trial of 2 oral doses of solithromycin (1200 and 1000 mg) for treatment of uncomplicated gonorrhea. Results. A total of 59 participants were enrolled and treated in this trial; 28 participants received 1200 mg of solithromycin and 31 received 1000 mg. Forty-six (78%) participants had positive cultures for N. gonorrhoeae at the time of enrollment: 24 of the 28 persons (86%) who received 1200 mg of oral solithromycin, and 22 of 31 (71%) who received 1000 mg. In addition, 8 participants had positive pharyngeal gonococcal cultures, and 4 had positive rectal cultures. All patients with positive cultures for N. gonorrhoeae were cured at all sites of infection. Chlamydia trachomatis and Mycoplasma genitalium coinfections were evaluated using nucleic acid amplification tests and were negative at 1 week of follow-up in 9 of 11 (82%) participants positive for C. trachomatis and 7 of 10 (70%) participants positive for M. genitalium. Mild dose-related gastrointestinal side effects (nausea, loose stools, vomiting) were common but did not limit therapy. Conclusions. Oral single-dose solithromycin, in doses of 1000 mg and 1200 mg, was 100% effective for treatment of culture-proven gonorrhea at genital, oral, and rectal sites of infection and is a promising new agent for gonorrhea treatment. [ABSTRACT FROM AUTHOR]

There is a strong association between vaginal and/or amniotic fluid Ureaplasma spp. colonisation and risk of preterm birth. The novel fluoroketolide antibiotic solithromycin (CEM-101) is active against Ureaplasma spp. in vitro. Evidence from ex vivo and in vivo models suggests that, unlike most macrolide antibiotics, solithromycin readily crosses the placenta. Solithromycin metabolism varies according to species; in pregnant sheep, the bioactive metabolites CEM-214 and N -acetyl-CEM-101 (NAc-CEM-101) have been shown to accumulate in the amniotic cavity following maternal solithromycin administration, potentially contributing to its antimicrobial effects. To determine the antimicrobial activity of these metabolites against Ureaplasma spp., the effects of solithromycin, CEM-214, NAc-CEM-101 and the comparator azithromycin were tested on a collection of 100 clinical Ureaplasma spp. isolates from the UK and Australia using a modified 96-well broth microdilution method. MIC 90 values observed for the combined cohort were: solithromycin, 0.125 mg/L; CEM-214, 0.5 mg/L; NAc-CEM-101, 0.5 mg/L; and azithromycin, 2 mg/L. Solithromycin showed 34-fold greater activity against Ureaplasma spp. isolates than azithromycin, whilst CEM-214 and NAc-CEM-101 possessed ca. 22% and 17% of the activity of solithromycin, respectively, significantly greater than that of azithromycin. One bacterial isolate showed resistance to azithromycin (MIC = 16 mg/L) but had a much lower MIC for solithromycin (MIC = 0.25 mg/L). In conclusion, the metabolites of solithromycin had reduced, but still potent, activity against 100 clinical Ureaplasma spp. isolates in vitro. This may be important in some instances such as pregnancy, however studies to determine levels of the metabolites in these settings are required. [ABSTRACT FROM AUTHOR]