Discovery of YFJ-36: Design, Synthesis, and Antibacterial Activities of Catechol-Conjugated β-Lactams against Gram-Negative Bacteria

Cefiderocol is the first approved catechol-conjugated cephalosporin against multidrug-resistant Gram-negative bacteria, while its application was limited by poor chemical stability associated with the pyrrolidinium linker, moderate potency against Klebsiella pneumoniae and Acinetobacter baumannii, intricate procedures for salt preparation, and potential hypersensitivity. To address these issues, a series of novel catechol-conjugated derivatives were designed, synthesized, and evaluated. Extensive structure-activity relationships and structure-metabolism relationships (SMR) were conducted, leading to the discovery of a promising compound 86b (Code no. YFJ-36) with a new thioether linker. 86b exhibited superior and broad-spectrum in vitro antibacterial activity, especially against A. baumannii and K. pneumoniae, compared with cefiderocol. Potent in vivo efficacy was observed in a murine systemic infection model. Furthermore, the physicochemical stability of 86b in fluid medium at pH 6-8 was enhanced. 86b also reduced potential the risk of allergy owing to the quaternary ammonium linker. The improved properties of 86b supported its further research and development.

Production of AmpC β-Lactamase and Development of a Competitive Array for Discriminative Determination of Cephalosporins in Milk

In this study, AmpC β-lactamase of Escherichia coli was expressed, and its intermolecular interaction mechanisms with 15 cephalosporins (CPs) were studied by using a molecular docking technique. Results showed that this enzyme mainly interacted with the β-lactam ring of these CPs, and the key contacting amino acids were Ser80 and Ser228. The AmpC β-lactamase was combined with 5 horseradish peroxidase-labeled conjugates to develop a direct competitive array on a microplate for determination of 15 drugs in milk. Due to the use of principal component analysis method to analyze the data, this method could discriminate the 15 drugs at the concentration as low as 10 ng/mL. The detection results for the unknown milk samples were consistent with those obtained by the liquid chromatography-mass spectrometry method. As a general comparison, this method is better than the previous antibody-based and receptor-based detection methods for CPs. This is the first paper reporting a competitive array for discriminative determination of a class of small-molecule substances.

Electrochemical fingerprinting of cephalosporin antibiotics and its applications for investigations of hydrolysis behavior

Cephalosporin, as one of the most widely used antibiotics, study of its hydrolysis process is important for predicting their environmental persistence. Two critical factors are considered has the first priority, which are hydrolysis rate constant (k_h) and half-life (t_1/2). To date, many efforts have been made by using various analytical techniques to obtain the data for calculating k_h and t_1/2. However, the typical techniques such as UV/vis spectrophotometry and liquid chromatography are of significant challenges like low accuracy and timely operations. Herein, we explored an electrochemical method by identifying the characteristic peaks with the same parent nuclear structure through square wave voltammetry (SWV). This proposed electrochemical fingerprinting was able to track the hydrolysis of intact cephalosporin molecules, β-lactam ring, and transformation product. The k_h and t_1/2 of cefadroxil (CDX) under pH = 7 and 25 °C by electrochemical (0.0640 d^-1 and 11.0 d) were consistent with those of high-performance liquid chromatography-UV/vis (HPLC-UV/vis) (0.0660 d^-1 and 10.7 d). The t_1/2 ranged from 3.40 to 36.2 d, 7.33 d-43.7 d and 9.63 d-45.3 d for base-catalyzed, neutral pH and acid-catalyzed hydrolysis hydrolyzed, respectively, indicating that base-catalyzed hydrolysis rates were the greatest under alkaline conditions. Meanwhile, hydrolysis rates increased 2.50-3.60-fold for every 10 °C raise in temperature. Besides, the electrochemical fingerprinting could realize cephalosporin and β-lactam ring hydrolysis rates close to 100% in-situ hydrolysis process monitoring. This present work provides a powerful technology for understanding the environmental fate and predicting the environmental behavior of antibiotics with fast, high accuracy, specific recognition, and in situ monitoring.

A computational drug repurposing approach in identifying the cephalosporin antibiotic and anti-hepatitis C drug derivatives for COVID-19 treatment

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused over 1.4 million deaths worldwide. Repurposing existing drugs offers the fastest opportunity to identify new indications for existing drugs as a stable solution against coronavirus disease 2019 (COVID-19). The SARS-CoV-2 main protease (Mpro) is a critical target for designing potent antiviral agents against COVID-19. In this study, we identify potential inhibitors against COVID-19, using an amalgam of virtual screening, molecular dynamics (MD) simulations, and binding-free energy approaches from the Korea Chemical Bank drug repurposing (KCB-DR) database. The database screening of KCB-DR resulted in 149 binders. The dynamics of protein-drug complex formation for the seven top scoring drugs were investigated through MD simulations. Six drugs showed stable binding with active site of SARS-CoV-2 Mpro indicated by steady RMSD of protein backbone atoms and potential energy profiles. Furthermore, binding free energy calculations suggested the community-acquired bacterial pneumonia drug ceftaroline fosamil and the hepatitis C virus (HCV) protease inhibitor telaprevir are potent inhibitors against Mpro. Molecular dynamics and interaction analysis revealed that ceftaroline fosamil and telaprevir form hydrogen bonds with important active site residues such as Thr24, Thr25, His41, Thr45, Gly143, Ser144, Cys145, and Glu166 that is supported by crystallographic information of known inhibitors. Telaprevir has potential side effects, but its derivatives have good pharmacokinetic properties and are suggested to bind Mpro. We suggest the telaprevir derivatives and ceftaroline fosamil bind tightly with SARS-CoV-2 Mpro and should be validated through preclinical testing.

Separation and characterization of impurities and isomers in cefpirome sulfate by liquid chromatography/tandem mass spectrometry and a summary of the fragmentation pathways of oxime-type cephalosporins

RATIONALE

Although the identification of degradation products of cefpirome sulfate has been reported, there has been no report concerning the impurities in bulk samples of this compound. To meet the requirements of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, the structures of impurities whose content are over 0.1% need to be confirmed. Thus, characterization of the impurities in cefpirome sulfate bulk samples is critical for controlling the production of this drug.

METHODS

The structures of cefpirome sulfate impurities were investigated using two-dimensional liquid chromatography (LC) coupled to electrospray ionization tandem mass spectrometry. In the first LC dimension, a Kromasil 100-5C18 column (4.6 mm × 250 mm, 5 μm) was used, and the mobile phases were 0.03 M ammonium dihydrogen phosphate solution and acetonitrile. In the second dimension, the column was a Shimadzu Shim-pack GISS C18 column (50 mm × 2.1 mm, 1.9 μm), and the mobile phases were 10 mM ammonium formate solution and methanol. An ion trap time-of-flight mass spectrometer operated in both positive and negative ion mode was employed in this study.

RESULTS

Nine impurities and isomers in cefpirome sulfate, eight of which were previously unknown, were separated and characterized. Structures were proposed for the eight unknown compounds based on the MSn fragmentation data. The degradation behavior of cefpirome sulfate was also studied.

CONCLUSIONS

Based on the characterization of impurities and isomers, this study could be used to improve the quality control of the cefpirome sulfate drug recommended in pharmacopoeias. The degradation behavior of cefpirome sulfate provides a basis for the selection of storage conditions.

Cefiderocol: A Siderophore Cephalosporin

OBJECTIVE

This article reviews the available data on the chemistry, spectrum of activity, pharmacokinetic and pharmacodynamic properties, clinical efficacy, and potential place in therapy of cefiderocol.

DATA SOURCES

A literature search through PubMed, Google Scholar, and ClinicalTrials.gov was conducted (2009 to March 2020) using the search terms cefiderocol and S-649266. Abstracts presented at recent conferences, prescribing information, and information from the US Food and Drug Administration (FDA) and the manufacturer's website were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All relevant published articles, package inserts, and unpublished meeting abstracts on cefiderocol were reviewed.

DATA SYNTHESIS

Cefiderocol is the first siderophore antibiotic to be approved by the FDA. It was shown to be active against a wide range of resistant Gram-negative pathogens, including multidrug-resistant (MDR) Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacteriaceae, and Stenotrophomonas maltophilia. Cefiderocol was studied in the treatment of adult patients with complicated urinary tract infections (cUTIs) and nosocomial pneumonia and was well tolerated. In a recently completed prospective study, higher mortality was observed with cefiderocol in the treatment of serious infections caused by carbapenem-resistant (CR) Gram-negative pathogens.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The approval of cefiderocol provides a new option in the treatment of cUTIs and potentially treatment of nosocomial pneumonia caused by resistant Gram-negative pathogens. Given the higher mortality observed with cefiderocol, its use in the treatment of CR Gram-negative infections should be carefully considered.

CONCLUSION

Cefiderocol shows promising activity against MDR Gram-negative pathogens. Its use in the treatment of serious infections caused by CR Gram-negative bacteria needs further evaluation in phase III clinical studies.

β-Lactamase triggered visual detection of bacteria using cephalosporin functionalized biomaterials

We report the conjugation of a chromogenic cephalosporin β-lactamase (βL) substrate to polymers and integration into biomaterials for facile, visual βL detection. Identification of these bacterial enzymes, which are a leading cause of antibiotic resistance, is critical in the treatment of infectious diseases. The βL substrate polymer conjugate undergoes a clear to deep yellow color change upon incubation with common pathogenic Gram-positive and Gram-negative bacteria species. We have demonstrated the feasibility of formulating hydrogels with the βL substrate covalently tethered to a poly(ethylene glycol) (PEG) polymer matrix, exhibiting a visible color change in the presence of βLs. This approach has the potential to be used in diagnostic biomaterials for point-of-care detection of βL-producing bacteria, helping combat the spread of drug resistant microbes.

Two novel drugs as bio-functional inhibitors for copper performing excellent anticorrosion and antibacterial properties

Two drugs (cefpirome, cefixime) as dual-action inhibitors could self-organize on copper surface forming bio-functional protective film, which effectively prevents copper corrosion in the picking process with an excellent performance on the resistance of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) results showed that studied drugs can self-organize on copper surface successfully forming adsorption film to protect copper. The results also indicated that N/S atoms with the lone pair electrons in the drugs donated electrons to the vacant orbital of Cu occupying the active sites of copper surface. Electrochemistry and surface morphology study revealed that the corrosion inhibition efficiency of cefixime was better than cefpirome. Furthermore, adsorption isotherm study suggested that the adsorption was spontaneous chemical and physical adsorption, obeying Langmuir adsorption.

Enhancement of ionizing radiation-induced catalytic degradation of antibiotics using Fe/C nanomaterials derived from Fe-based MOFs

In present work, we studied a novel Fe/C nanomaterial fabricated using Fe-based metal organic frameworks (MOFs) as precursors through thermal pyrolysis to catalyze gamma irradiation-induced degradation of antibiotics, cephalosporin C (CEP-C) and sulfamethazine (SMT) in aqueous solution. The MOFs-derived Fe/C nanomaterials (DMOFs) had the regular octahedrons structure of MOFs and contained element C, Fe and O, while Fe° with a fraction of Fe₃O₄ and Fe₂O₃ were identified. Results showed that DMOFs addition could accelerate the generation of OH during gamma irradiation, while the intermediates of bonds cleavages of antibiotic molecules and OH addition were identified. DMOFs were more effective to improve the decomposition of antibiotic having the higher adsorption capacity like SMT. The degradation rate of CEP-C and SMT increased by 1.3 times and 1.8 times, and TOC reduction at 1.0 kGy reached 42 % and 51 %, respectively by gamma/DMOFs treatment, while only 20.2 % (CEP-C) and 4.5 % (SMT) of TOC reduction were obtained by γ-irradiation alone. The crystal structure, functional groups and magnetism of DMOFs changed slightly after gamma irradiation, which made it possible to be reused. DMOFs were promising to enhance the degradation of antibiotics during gamma irradiation.

Enhanced performance of anaerobic digestion of cephalosporin C fermentation residues by gamma irradiation-induced pretreatment

Antibiotic fermentation residues is a hazardous waste due to the existence of residual antibiotics and antibiotic resistance genes (ARGs), probably leading to the induction and spread of antibiotic resistant bacteria (ARB) in the environment, which could pose potential harm to the ecosystem and human health. It is urgent to develop an effective technology to remove the residual antibiotics and ARGs. In this study, the anaerobic digestion combined with gamma irradiation was applied for the disposal and utilization of cephalosporin C fermentation residues. The experimental results showed that the antibacterial activities of cephalosporin C against Staphylococcus aureus were significantly decreased after anaerobic digestion. The removal of tolC, a multidrug resistant gene, was improved up to 100% by the combination of gamma irradiation and anaerobic digestion compared to solely anaerobic digestion process, which may be due to the changes of microbial community structures induced by gamma irradiation.

Degradation of antibiotics and inactivation of antibiotic resistance genes (ARGs) in Cephalosporin C fermentation residues using ionizing radiation, ozonation and thermal treatment

In present work, the degradation of antibiotic and inactivation of antibiotic resistance genes (ARGs) in cephalosporin C fermentation (CEPF) residues were performed using ionizing radiation, ozonation and thermal treatment. The results showed that the three treatment methods could degrade cephalosporin C effectively, with the removal efficiency of 85.5% for radiation at dose of 100 kGy, 79.9% for ozonation at dosage of 5.2 g O₃/L, and 71.9% and 87.3% for thermal treatment at 60 °C and 90 °C for 4 h. The cephalosporin resistance gene tolC was detected in the raw CEPF residues, and its abundance was decrease 74.2% by radiation, 64.6% by ozonation and 26.9%-37.1% by thermal treatment respectively. The presence of protein, glucose and acetate in the CEPF residues had inhibitive influence on the degradation of cephalosporin C by ionizing radiation, and the effect was more significant when the antibiotic concentration was lower. The total content of COD, polysaccharides and protein changed slightly after radiation and thermal treatment, while they were decreased greatly by ozonation. The primary techno-economic analysis showed that the operational cost of ionizing radiation by electron beam at 50 kGy ($5.2/m³) was comparable to thermal treatment ($4.3-7.9/m³), which was more economical than ozonation ($14.6/m³).

Review on the Characteristic, Properties and Analytical Methods of Cefquinomesulphate: ß-lactam Veterinary Drug

BACKGROUND

Chemotherapy as a science began within the 1st decade of the twentieth century with understanding of the principles of selective toxicity, the particular chemical relationships between microorganism pathogens and medicines, the event of drug resistance, and also the role of combined medical aid.

OBJECTIVES

This review aims to highlight the characteristics, specifically the pharmacokinetic parameters and the analytical methods reported in literature for the determination of Cefquinome, a fourth generation cephalosporine used to treat Gram-positive and Gram-negative caused infections.

CONCLUSION

Analysis of such drugs, whether used for the treatment of human or animal illness, is essential in understanding the bioavailability and therapeutic control which will ensure their activity and safety.

An Overview of the Activities of Cefiderocol Against Sensitive and Multidrug- Resistant (MDR) Bacteria

The need for new therapeutics and drug delivery systems has become necessary owing to the public health concern associated with the emergence of multidrug-resistant microorganisms. Among the newly discovered therapeutic agents is cefiderocol, which was discovered by Shionogi Company, Japan as an injectable siderophore cephalosporin. Just like the other β-lactam antibiotics, cefiderocol exhibits antibacterial activity via cell wall synthesis inhibition, especially in Gram negative bacteria (GNB); it binds to the penicillin-binding proteins, but its unique attribute is that it crosses the periplasmic space of bacteria owing to its siderophore-like attribute; it also resists the activity of β-lactamases. Among all the synthesized compounds with the modified C-7 side chain, cefiderocol (3) presented the best and well-balanced activity against multi-drug resistant (MDR) Gram negative bacteria, including those that are resistant to carbapenem. İn this article, an overview of the recent studies on cefiderocol was presented.

Development of Neutropenic Murine Models of Iron Overload and Depletion To Study the Efficacy of Siderophore-Antibiotic Conjugates

Siderophore-antibiotic conjugates have increased in vitro activity in low-iron environments where bacteria express siderophores and associated transporters. The host immune hypoferremic response reduces iron availability to bacteria; however, patients with iron overload or deficiency may have altered ability to restrict iron, which may affect the efficacy of siderophore-antibiotic conjugates. In vivo models of infection with iron overload and deficiency are needed to perform this assessment. The standard neutropenic murine thigh infection model was supplemented with iron-altering treatments: iron dextran at 100 mg/kg of body weight daily for 14 days to load iron or deferoxamine at 100 mg/kg daily plus a low-iron diet for up to 30 days to deplete iron. Human-simulated regimens of cefiderocol and meropenem were administered in both models to assess any impact of iron alteration on plasma pharmacokinetics. Median iron in overloaded mice was significantly higher than that of controls in plasma (1,657 versus 336 μg/dl; P < 0.001), liver (2,133 versus 11 μg/g; P < 0.001), and spleen (473 versus 144 μg/g; P < 0.001). At 30 days, depleted mice had significantly lower iron than controls in liver (2.4 versus 6.5 μg/g; P < 0.001) and spleen (72 versus 133 μg/g; P = 0.029) but not plasma (351 versus 324 μg/dl; P = 0.95). Cefiderocol and meropenem plasma concentrations were similar in iron overloaded and control mice but varied in iron-depleted mice. The iron-overloaded murine thigh infection model was established, and human-simulated regimens of cefiderocol and meropenem were validated therein. While deferoxamine successfully reduced liver and splenic iron, this depleting treatment altered the pharmacokinetics of both antimicrobials.

Sorption of antibiotics onto aged microplastics in freshwater and seawater

Microplastics in environments undergo aging processes and may sorb antibiotics from surrounding water. Understanding the interaction between aged microplastics and antibiotics is important to assess the impact of microplastics on environments. In this paper, the sorption of three typical antibiotics, i.e., sulfamethoxazole (SMX), sulfamethazine (SMT), and cephalosporin C (CEP-C) onto the naturally aged microplastics (polystyrene (PS) and polyethylene (PE)) derived from aged plastics samples from the coast of East China Sea and Yellow Sea, China in freshwater and simulated seawater systems were studied. The results indicated that the mixed order (MO) model provided good prediction for the kinetics data. The linear isotherm represented adequately the sorption equilibrium data in freshwater. The K_d values ranged from 0.0236 L·g^-1 to 0.0383 L·g^-1. In simulated seawater, only CEP-C could be sorbed onto the microplastics. The main sorption mechanisms are hydrophobic, van der Waals, and electrostatic interactions.

The latest advances in β-lactam/β-lactamase inhibitor combinations for the treatment of Gram-negative bacterial infections

Introduction: Antimicrobial resistance in Gram-negative pathogens is a significant threat to global health. β-Lactams (BL) are one of the safest and most-prescribed classes of antibiotics on the market today. The acquisition of β-lactamases, especially those which hydrolyze carbapenems, is eroding the efficacy of BLs for the treatment of serious infections. During the past decade, significant advances were made in the development of novel BL-β-lactamase inhibitor (BLI) combinations to target β-lactamase-mediated resistant Gram-negatives.Areas covered: The latest progress in 20 different approved, developing, and preclinical BL-BLI combinations to target serine β-lactamases produced by Gram-negatives are reviewed based on primary literature, conference abstracts (when available), and US clinical trial searches within the last 5 years. The majority of the compounds that are discussed are being evaluated as part of a BL-BLI combination.Expert opinion: The current trajectory in BLI development is promising; however, a significant challenge resides in the selection of an appropriate BL partner as well as the development of resistance linked to the BL partner. In addition, dosing regimens for these BL-BLI combinations need to be critically evaluated. A revolution in bacterial diagnostics is essential to aid clinicians in the appropriate selection of novel BL-BLI combinations for the treatment of serious infections.

Cefiderocol: Discovery, Chemistry, and In Vivo Profiles of a Novel Siderophore Cephalosporin

The emergence of antimicrobial resistance is a significant public health issue worldwide, particularly for healthcare-associated infections caused by carbapenem-resistant gram-negative pathogens. Cefiderocol is a novel siderophore cephalosporin targeting gram-negative bacteria, including strains with carbapenem resistance. The structural characteristics of cefiderocol show similarity to both ceftazidime and cefepime, which enable cefiderocol to withstand hydrolysis by β-lactamases. The unique chemical component is the addition of a catechol moiety on the C-3 side chain, which chelates iron and mimics naturally occurring siderophore molecules. Following the chelation of iron, cefiderocol is actively transported across the outer membrane of the bacterial cell to the periplasmic space via specialized iron transporter channels. Furthermore, cefiderocol has demonstrated structural stability against hydrolysis by both serine- and metallo-β-lactamases, including clinically relevant carbapenemases such as Klebsiella pneumoniae carbapenemase, oxacillin carbapenemase-48, and New Delhi metallo-β-lactamase. Cefiderocol has demonstrated promising in vitro antibacterial and bactericidal activity, which correlates with its in vivo efficacy in several animal models. This article reviews the discovery and chemistry of cefiderocol, as well as some of the key microbiological and in vivo findings on cefiderocol from recently conducted investigations.

The Role of Iron and Siderophores in Infection, and the Development of Siderophore Antibiotics

Iron is an essential nutrient for bacterial growth, replication, and metabolism. Humans store iron bound to various proteins such as hemoglobin, haptoglobin, transferrin, ferritin, and lactoferrin, limiting the availability of free iron for pathogenic bacteria. However, bacteria have developed various mechanisms to sequester or scavenge iron from the host environment. Iron can be taken up by means of active transport systems that consist of bacterial small molecule siderophores, outer membrane siderophore receptors, the TonB-ExbBD energy-transducing proteins coupling the outer and the inner membranes, and inner membrane transporters. Some bacteria also express outer membrane receptors for iron-binding proteins of the host and extract iron directly from these for uptake. Ultimately, iron is acquired and transported into the bacterial cytoplasm. The siderophores are small molecules produced and released by nearly all bacterial species and are classified according to the chemical nature of their iron-chelating group (ie, catechol, hydroxamate, α-hydroxyl-carboxylate, or mixed types). Siderophore-conjugated antibiotics that exploit such iron-transport systems are under development for the treatment of infections caused by gram-negative bacteria. Despite demonstrating high in vitro potency against pathogenic multidrug-resistant bacteria, further development of several candidates had stopped due to apparent adaptive resistance during exposure, lack of consistent in vivo efficacy, or emergence of side effects in the host. However, cefiderocol, with an optimized structure, has advanced and has been investigated in phase 1 to 3 clinical trials. This article discusses the mechanisms implicated in iron uptake and the challenges associated with the design and utilization of siderophore-mimicking antibiotics.

Ceftiofur formulation differentially affects the intestinal drug concentration, resistance of fecal Escherichia coli, and the microbiome of steers

Antimicrobial drug concentrations in the gastrointestinal tract likely drive antimicrobial resistance in enteric bacteria. Our objective was to determine the concentration of ceftiofur and its metabolites in the gastrointestinal tract of steers treated with ceftiofur crystalline-free acid (CCFA) or ceftiofur hydrochloride (CHCL), determine the effect of these drugs on the minimum inhibitory concentration (MIC) of fecal Escherichia coli, and evaluate shifts in the microbiome. Steers were administered either a single dose (6.6 mg/kg) of CCFA or 2.2 mg/kg of CHCL every 24 hours for 3 days. Ceftiofur and its metabolites were measured in the plasma, interstitium, ileum and colon. The concentration and MIC of fecal E. coli and the fecal microbiota composition were assessed after treatment. The maximum concentration of ceftiofur was higher in all sampled locations of steers treated with CHCL. Measurable drug persisted longer in the intestine of CCFA-treated steers. There was a significant decrease in E. coli concentration (P = 0.002) within 24 hours that persisted for 2 weeks after CCFA treatment. In CHCL-treated steers, the mean MIC of ceftiofur in E. coli peaked at 48 hours (mean MIC = 20.45 ug/ml, 95% CI = 10.29–40.63 ug/ml), and in CCFA-treated steers, mean MIC peaked at 96 hours (mean MIC = 10.68 ug/ml, 95% CI = 5.47–20.85 ug/ml). Shifts in the microbiome of steers in both groups were due to reductions in Firmicutes and increases in Bacteroidetes. CCFA leads to prolonged, low intestinal drug concentrations, and is associated with decreased E. coli concentration, an increased MIC of ceftiofur in E. coli at specific time points, and shifts in the fecal microbiota. CHCL led to higher intestinal drug concentrations over a shorter duration. Effects on E. coli concentration and the microbiome were smaller in this group, but the increase in the MIC of ceftiofur in fecal E. coli was similar.

Metabolism, Excretion, and Pharmacokinetics of [14 C]-Cefiderocol (S-649266), a Siderophore Cephalosporin, in Healthy Subjects Following Intravenous Administration

The objectives of this study were to characterize the concentration-time profiles of total radioactivity equivalent and unchanged cefiderocol, the route(s) of elimination and mass balance, and safety of cefiderocol after intravenous administration of a single 1000-mg (100 μCi) dose of [14 C]-cefiderocol as a 1-hour infusion in healthy adult male subjects. Unchanged cefiderocol accounted for the majority of total radioactivity in plasma, and the partitioning of total radioactivity into red blood cells was negligible. The recovery of total radioactivity was complete in all subjects within 120 hours after initiation of the infusion (101.5% of the administered dose). Cefiderocol-related material was primarily excreted into urine, with 98.7% of the administered dose of [14 C]-cefiderocol excreted as total radioactivity into urine and negligible excretion into feces. Based on the results of metabolite profiling, cefiderocol accounted for 92.3% of area under the concentration-time curve of total radioactivity in plasma and accounted for 90.6% of the administered dose excreted into urine. Metabolism was a minor route of elimination for cefiderocol. Cefiderocol was generally safe and well tolerated in healthy adult male subjects. In conclusion, unchanged cefiderocol represents the majority of total radioactivity in plasma. Cefiderocol is primarily excreted as unchanged drug into urine. This study indicates that cefiderocol and drug-related material did not remain in the body.

The effects of some cephalosporins on acetylcholinesterase and glutathione S-transferase: an in vivo and in vitro study

BACKGROUND

Glutathione S-transferase (GST) and acetylcholinesterase (AChE) are important enzymes in the metabolism. GSTs are primarily available in phase II metabolism. AChE is vital for neurodegenerative disorders.

SUBJECTS AND METHODS

The in vitro and in vivo effects of cefoperazone sodium (CFP), cefuroxime (CXM), and cefazolin (CZO) were investigated on GST and AChE activity in the present study. GST was purified using Glutathione-Agarose affinity chromatography.

RESULTS

K_i constants of CFP, CXM, and CZO were 0.1392 ± 0.02, 1.5179 ± 0.33, and 1.006 ± 0.11 mM for GST and 0.3010 ± 0.07, 0.3561 ± 0.09, and 0.3844 ± 0.04 mM, for AChE, respectively. The most effective inhibitor was CFP for both enzymes in in vitro. CZO (50 mg/kg), CXM (25 mg/kg), and CFP (100 mg/kg) inhibit in vivo GST and AChE activities. CXM had the most effective in vivo inhibition on AChE and GST.

CONCLUSIONS

CZO, CXM, and CFP are effective AChE and GST inhibitors in both in vitro and in vivo.

Effect of environmental factors on the oxidative transformation of cephalosporin antibiotics by manganese dioxides

This study aimed to explore the oxidation and transformation of the cephalosporins cefotaxime (CTX), cephalexin (CFX), cephradine (CFD), cephapirin (CFP) and cefazolin (CFZ) by δ-MnO2. The results showed that the MnO2 oxidation rate was promoted by environmental factors such as higher MnO2 loading, lower initial cephalosporin concentration and lower solution pH. The inhibitory effect occurred in the presence of dissolved organic matter and dissolved cations (inhibitory capacity: Mn2+ > Ca2+ > Mg2+ > Fe3+). Total organic carbon analysis indicated that the transformation byproducts of the cephalosporins are less reactive and persistent under MnO2 oxidation. Twelve transformation byproducts (9 CFP byproducts and 3 CTX byproducts) were identified, and two oxidative transformation pathways were proposed: one occurred in the cephem for CFP, and the other occurred at the substituent at the amine position for CTX. The effect of solar light on the oxidation of the five cephalosporin antibiotics by δ-MnO2 was also investigated, and the results indicated that the initial dissolution rate of δ-MnO2 under sunlight was approximately eight times faster than that in the dark in the presence of CFP.

Cefquinome-loaded microsphere formulations against Klebsiella pneumonia infection during experimental infections

The aim of this study was to prepare cefquinome-loaded polylactic acid microspheres and to evaluate their in vitro and in vivo characteristics and pharmacodynamics for the therapy of pneumonia in a rat model. Microspheres were prepared using a 0.7 mm two-fluid nozzle spray drier in one step resulting in spherical and smooth microspheres of uniform size (9.8 ± 3.6 μm). The encapsulation efficiency and drug loading of cefquinome were 91.6 ± 2.6% and 18.7 ± 1.2%, respectively. In vitro release of cefquinome from the microspheres was sustained for 36 h. Cefquinome-loaded polylactic acid microspheres as a drug delivery system was successful for clearing experimental Klebsiella pneumonia lung infections. A decrease in inflammatory cells and an inhibition of inflammatory cytokines TNF-α, IL-1β and IL-8 after microspheres treatment was found. Changes in cytokine levels and types are secondary manifestations of drug bactericidal effects. Rats were considered to be microbiologically cured because the bacterial load was less than 100 CFU/g. These results also indicated that the spray-drying method of loading therapeutic drug into polylactic acid microspheres is a straightforward and safe method for lung-targeting therapy in animals.

Measurement of ceftolozane and tazobactam concentrations in plasma by UHPLC-MS/MS. Clinical application in the management of difficult-to-treat osteoarticular infections

BACKGROUND

Ceftolozane, in combination with the β-lactamase inhibitor tazobactam, is a new option in the pipeline against multidrug-resistant Gram-negative bacilli. As for other β-lactam antibiotics, optimizing the use of ceftolozane-tazobactam is advisable, especially in difficult-to-treat infections. In this regard, therapeutic drug monitoring would be required to guide the treatment of ceftolozane-tazobactam. Thus, we aimed to develop and validate procedures based on UHPLC-MS/MS for measurement of ceftolozane and tazobactam plasma concentrations in clinical practice.

MATERIAL AND METHODS

Analyses were conducted using an Acquity® UPLC® integrated system coupled to an Acquity® TQD® tandem-quadrupole mass spectrometer. Ceftolozane, tazobactam and their internal standards (ceftazidime-D₅ and sulbactam) were detected by electrospray ionization mass spectrometry in positive and negative ion multiple reaction monitoring modes, using transitions of 667.2 → 199.3/139.0 and 551.9 → 467.9 for ceftolozane and ceftazidime-D₅, and 299.0 → 138/254.9 and 232.0 → 140.0 for tazobactam and sulbactam. Measurement procedures developed were used for guiding the treatment and adjusting daily dose of ceftolozane-tazobactam in patients with osteoarticular infections.

RESULTS

Coefficients of variation and absolute relative biases were <7.9% and 6.5% in all cases. The lower limit of quantification, linearity, normalized-recoveries, normalized-matrix effects and measurement uncertainties for ceftolozane were: 0.97 mg/L, (0.97-125) mg/L, ≤113.6%, ≤108.7%, and ≤ 18.7%, respectively; and for tazobactam: 1.04 mg/L, (1.04-125) mg/L, ≤103.6%, ≤101.9%, and ≤ 20.0%. No interferences and carry-over were observed. Patients plasma concentrations were higher than the recommended 3-4 times the minimal inhibitory concentrations.

CONCLUSIONS

Our measurement procedures are suitable for therapeutic drug monitoring of ceftolozane-tazobactam in patients with osteoarticular infections.

Quantitative analysis of cefquinome considering different matrix compositions of bovine colostrum and raw milk

A robust liquid chromatography-tandem mass spectrometry method was developed and comprehensively validated for the quantification of cefquinome considering the changing matrix composition from bovine colostrum to raw milk. Sample preparation consisted of addition of isotopically labeled cefquinome internal standard prior to protein precipitation of 2 g colostrum or milk followed by solid-phase extraction. A wide concentration range from 1 to 5000 ng cefquinome per gram of colostrum or milk was quantified using a 3200 QTRAP tandem mass spectrometer in positive ionization mode with electrospray ionization. Validation was performed according to the European Commission Decision 2002/657/EC guidelines. Matrix-comprehensive in-house validation included analytical limits CC_α and CC_β, recovery, precision and calibration curves with prediction intervals, storage conditions, and evaluation of robustness based on factorial effect analysis. The detection limit was 0.2 ng cefquinome per gram of colostrum or milk. Recovery was between 98.4 and 99.4% for cefquinome concentrations from 4 to 240 ng/g. None of the investigated validation factors (matrix, storage of extracts, lot of SPE cartridges, and operators) exerted an influence higher than ± 3.2%, indicating that these factors make relatively low contributions to the respective combined measurement uncertainties. The comprehensively validated method enables routine residue control purposes and to monitor the pharmacokinetics of cefquinome in bovine colostrum and raw milk. In particular, residue depletion curves of cefquinome from high concentrations in first milking after treatment to concentrations far below the maximum residue limit can be measured.

Cefiderocol (S-649266), A new siderophore cephalosporin exhibiting potent activities against Pseudomonas aeruginosa and other gram-negative pathogens including multi-drug resistant bacteria: Structure activity relationship

The structure-activity relationship (SAR) for a novel series of catechol conjugated siderophore cephalosporins is described with their in vitro activities against multi-drug resistant Gram-negative pathogens including Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia and Enterobacteriaceae. Cefiderocol (3) was one of the best molecules which displayed well-balanced and potent activities against multi-drug resistant Gram-negative pathogens including carbapenem resistant bacteria among the prepared compounds with the modified C-7 side chain and the modified C-3 side chain. Cefiderocol (3) is a highly promising parenteral cephalosporin for the treatment of multi-drug resistant Gram-negative infection.

Base-catalyzed hydrolysis and speciation-dependent photolysis of two cephalosporin antibiotics, ceftiofur and cefapirin

Lately, special attention has been given to veterinary cephalosporin antibiotics due to their broad activity spectrum and significant consumption. Indeed, the determination of hydrolytic and photolytic kinetics provides a better comprehension of the undesired persistence of cephalosporins in aqueous matrices. In this work, the two widely used veterinary antibiotics ceftiofur (CEF) and cefapirin (CEPA) showed high instability under alkaline conditions, degrading in few minutes at pH > 11. In buffered solutions at neutral pH and natural temperature (T = 22 ± 1 °C), both drugs presented moderate stability (t½ = 3 d, CEPA and 1.4 d, CEF). Our study also demonstrated that CEPA and CEF speciation did not significantly influence the direct photolysis rates. Using a simulated water disinfection set-up (λ = 254 nm), all ionic species of CEF and CEPA presented fast and similar pseudo-first order degradation rates, k^app 0.0095 ± 0.0004 and 0.0092 ± 0.001 cm² mJ^-1, respectively. Furthermore, using surface water in hydrolysis experiments, CEF demonstrated significant matrix-dependent stability with a half-life (t½ = 14.7 d) tenfold higher than in buffered solutions. In contrast, CEPA presented a very similar hydrolysis rate in river water (t½ = 4.2 d) and a subtle faster photo-degradation rate in this same matrix (k^app 0.0128 ± 0.001 cm² mJ^-1), highlighting the importance of disinfection radiation for cephalosporin depletion in aqueous environments.

The interactions of cephalosporins on polyol pathway enzymes from sheep kidney

CONTEXT

Cephalosporins are derived from the fungus Acremonium. Due to their strong bactericidal ability, these drugs have to a wide usage in medicine.

OBJECTIVE

An investigation of the effects on sheep renal aldose reductase (AR) and sorbitol dehydrogenase (SDH) of cefoperazone, cefazolin, cefuroxime, ceftazidime and ceftriaxone as cephalosporin drugs was carried out in the present study.

METHODS

AR and SDH were purified from sheep kidney by ion exchange, gel filtration and affinity methods with approximately 219- and 484-fold, respectively. Some kinetic properties of the enzymes were determined such as optimal pH, optimal ionic strength, optimal temperature, stable pH, K_m and V_max. IC₅₀ values of the drugs were found for each enzyme.

RESULTS

While the AR was inhibited by all drugs, SDH enzyme was inhibited by only CXM (IC₅₀ 8.10 mM). Interestingly, CZO activated SDH enzyme. This result was evaluated as important for the flow of the polyol reactions. K_i values and inhibition types were determined for AR. However, these values could not have determined for SDH, due to insufficient inhibition.

CONCLUSIONS

From these results, it was concluded that cephalosporins may have an important effect on flow of the polyol metabolism.

Analytical method development and validation of spectrofluorimetric and spectrophotometric determination of some antimicrobial drugs in their pharmaceuticals

In this study, three novel, sensitive, simple and validated spectrophotometric and spectrofluorimetric methods have been proposed for estimation of some important antimicrobial drugs. The first two methods have been proposed for estimation of two important third-generation cephalosporin antibiotics namely, cefixime and cefdinir. Both methods were based on condensation of the primary amino group of the studied drugs with acetyl acetone and formaldehyde in acidic medium. The resulting products were measured by spectrophotometric (Method I) and spectrofluorimetric (Method II) tools. Regarding method I, the absorbance was measured at 315nm and 403nm with linearity ranges of 5.0-140.0 and 10.0-100.0μg/mL for cefixime and cefdinir, respectively. Meanwhile in method II, the produced fluorophore was measured at λ_em 488nm or 491nm after excitation at λ_ex 410nm with linearity ranges of 0.20-10.0 and 0.20-36.0μg/mL for cefixime and cefdinir, respectively. On the other hand, method III was devoted to estimate nifuroxazide spectrofluorimetrically depending on formation of highly fluorescent product upon reduction of the studied drug with Zinc powder in acidic medium. Measurement of the fluorescent product was carried out at λ_em 335nm following excitation at λ_ex 255nm with linearity range of 0.05 to 1.6μg/mL. The developed methods were subjected to detailed validation procedure, moreover they were used for the estimation of the concerned drugs in their pharmaceuticals. It was found that there is a good agreement between the obtained results and those obtained by the reported methods.

Synthesis and biological evaluation of the progenitor of a new class of cephalosporin analogues, with a particular focus on structure-based computational analysis

We present the synthesis and biological evaluation of the prototype of a new class of cephalosporins, containing an additional isolated beta lactam ring with two phenyl substituents. This new compound is effective against Gram positive microorganisms, with a potency similar to that of ceftriaxone, a cephalosporin widely used in clinics and taken as a reference, and with no cytotoxicity against two different human cell lines, even at a concentration much higher than the minimal inhibitory concentration tested. Additionally, a deep computational analysis has been conducted with the aim of understanding the contribution of its moieties to the binding energy towards several penicillin-binding proteins from both Gram positive and Gram negative bacteria. All these results will help us developing derivatives of this compound with improved chemical and biological properties, such as a broader spectrum of action and/or an increased affinity towards their molecular targets.

Role of inducers in detection of blaPDC-mediated oxyimino-cephalosporin resistance in Pseudomonas aeruginosa

BACKGROUND & OBJECTIVES

Pseudomonas aeruginosa possessing chromosomally inducible blaPDCalong with other intrinsic mechanism causes infection with high mortality rate. It is difficult to detect inducible AmpC enzymes in this organism and is usually overlooked by routine testing that may lead to therapeutic failure. Therefore, three different inducers were evaluated in the present study to assess their ability of induction of blaPDCin P. aeruginosa.

METHODS

A total of 189 consecutive Pseudomonas isolates recovered from different clinical specimens (November 2011-April 2013) were selected for the study. Isolates were screened with cefoxitin for AmpC β-lactamases and confirmed by modified three-dimensional extract test (M3DET). Inductions were checked using three inducers, namely, clavulanic acid, cefoxitin and imipenem along with ceftazidime. Molecular screening of AmpC β-lactamase genes was performed by PCR assay. Antimicrobial susceptibility and minimum inhibitory concentrations (MICs) were determined, and repetitive extragenic palindromic-PCR of all blaPDCharbouring isolates was performed.

RESULTS

Inducible phenotype was observed in 42 (24.3%) of 97 (56%) isolates confirmed by M3DET. Among these, 22 isolates harboured chromosomal blaPDCgene, and cocarriage of both chromosomal and plasmid-mediated blaAmpC genes was observed in seven isolates. Cefoxitin-ceftazidime-based test gave good sensitivity and specificity for detecting inducible AmpC enzymes. Isolates harbouring blaPDCshowed high MIC against all tested cephalosporins and monobactam. DNA fingerprinting of these isolates showed 22 different clones of P. aeruginosa.

INTERPRETATION & CONCLUSIONS

P. aeruginosa harbouring inducible (chromosomal) and plasmid-mediated AmpC β-lactamase is a matter of concern as it may limit therapeutic option. Using cefoxitin-ceftazidime-based test is simple and may be used for detecting inducible AmpC β-lactamase amongst P. aeruginosa.

Inhibition by Avibactam and Clavulanate of the β-Lactamases KPC-2 and CTX-M-15 Harboring the Substitution N132G in the Conserved SDN Motif

The substitution N132G in the SDN motif of class A β-lactamases from rapidly growing mycobacteria was previously shown to impair their inhibition by avibactam but to improve the stability of acyl-enzymes formed with clavulanate. The same substitution was introduced in KPC-2 and CTX-M-15 to assess its impact on β-lactamases from Enterobacteriaceae and evaluate whether it may lead to resistance to the ceftazidime-avibactam combination. Kinetic parameters for the inhibition of the β-lactamases by avibactam and clavulanate were determined by spectrophotometry using nitrocefin as the substrate. The substitution N132G impaired (>1,000-fold) the efficacy of carbamylation of KPC-2 and CTX-M-15 by avibactam. The substitution improved the inhibition of KPC-2 by clavulanate due to reduced deacylation, whereas the presence or absence of N132G resulted in the inhibition of CTX-M-15 by clavulanate. The hydrolysis of amoxicillin and nitrocefin by KPC-2 and CTX-M-15 was moderately affected by the substitution N132G, but that of ceftazidime, ceftaroline, and aztreonam was drastically reduced. Isogenic strains producing KPC-2 and CTX-M-15 were constructed to assess the impact of the substitution N132G on the antibacterial activities of β-lactam-inhibitor combinations. For amoxicillin, the substitution resulted in resistance and susceptibility for avibactam and clavulanate, respectively. For ceftazidime, ceftaroline, and aztreonam, the negative impact of the substitution on β-lactamase activity prevented resistance to the β-lactam-avibactam combinations. In conclusion, the N132G substitution has profound effects on the substrate and inhibition profiles of class A β-lactamases, which are largely conserved in distantly related enzymes. Fortunately, the substitution does not lead to resistance to the ceftazidime-avibactam combination.

Cefdinir Solid Dispersion Composed of Hydrophilic Polymers with Enhanced Solubility, Dissolution, and Bioavailability in Rats

The aim of this work was to develop cefdinir solid dispersions (CSDs) prepared using hydrophilic polymers with enhanced dissolution/solubility and in vivo oral bioavailability. CSDs were prepared with hydrophilic polymers such as hydroxypropyl-methylcellulose (HPMC; CSD1), carboxymethylcellulose-Na (CMC-Na; CSD2), polyvinyl pyrrolidone K30 (PVP K30; CSD3) at the weight ratio of 1:1 (drug:polymer) using a spray-drying method. The prepared CSDs were characterized by aqueous solubility, differential scanning calorimetry (DSC), powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), aqueous viscosity, and dissolution test in various media. The oral bioavailability of CSDs was also evaluated in rats and compared with cefdinir powder suspension. The cefdinir in CSDs was amorphous form, as confirmed in the DSC and p-XRD measurements. The developed CSDs commonly resulted in about 9.0-fold higher solubility of cefdinir and a significantly improved dissolution profile in water and at pH 1.2, compared with cefdinir crystalline powder. Importantly, the in vivo oral absorption (represented as AUC_inf) was markedly increased by 4.30-, 6.77- and 3.01-fold for CSD1, CSD2, and CSD3, respectively, compared with cefdinir suspension in rats. The CSD2 prepared with CMC-Na would provide a promising vehicle to enhance dissolution and bioavailability of cefdinir in vivo.

Determination of acid dissociation constants (pKa) of cephalosporin antibiotics: Computational and experimental approaches

Cefapirin (CEPA) and ceftiofur (CEF) are two examples of widely used veterinarian cephalosporins presenting multiple ionization centers. However, the acid dissociation constants (pK_a) of CEF are missing and experimental data about CEPA are rare. The same is true for many cephalosporins, where available data are either incomplete or even wrong. Environmentally relevant biotic and abiotic processes depend primordially on the antibiotic pH-dependent speciation. Consequently, this physicochemical parameter should be reliable, including the correct ionization center identification. In this direction, two experimental techniques, potentiometry and spectrophotometry, along with two well-known pK_a predictors, Marvin and ACD/Percepta, were used to study the macro dissociation constants of CEPA and CEF. Additionally, the experimental dissociation constants of 14 cephalosporins available in the literature were revised, compiled and compared with data obtained in silico. Only one value was determined experimentally for CEF (2.68 ± 0.05), which was associated to the carboxylic acid group deprotonation. For CEPA two values were obtained experimentally: 2.74 ± 0.01 for the carboxylic acid deprotonation and 5.13 ± 0.01 for the pyridinium ring deprotonation. In general, experimentally obtained values agree with the in silico predicted data (ACD/Percepta RMSE: 0.552 and Marvin RMSE: 0.706, n = 88). However, for cephalosporins having imine and aminothiazole groups structurally close, Marvin presented problems in pK_a predictions. For the biological and environmental fate and effect discussion, it is important to recognize that CEPA and CEF, as well as many other cephalosporins, are present as anionic species in the biologic and environmentally relevant pH values of 6-7.5.

Comparative pharmacokinetics of ceftiofur hydrochloride and ceftiofur sodium after administration to water buffalo (Bubalus bubalis)

OBJECTIVE To evaluate pharmacokinetics and bioavailability after administration of ceftiofur hydrochloride and ceftiofur sodium to water buffalo (Bubalus bubalis). ANIMALS 5 healthy adult water buffalo (3 males and 2 nonlactating females). PROCEDURES All animals received a dose (2.2 mg/kg) of 3 ceftiofur products (2 commercially available suspensions of ceftiofur hydrochloride [CEF1 and CEF2, IM] and ceftiofur sodium [CEF3, IV]). Blood samples were collected for up to 196 hours. Concentrations of ceftiofur in plasma were determined by use of high-performance liquid chromatography, and pharmacokinetic parameters were calculated on the basis of noncompartmental methods. RESULTS Most of the pharmacokinetic parameters, except for bioavailability and the area under the concentration-time curve extrapolated to infinity, were significantly different between the 2 products administered IM. Mean ± SD bioavailability of CEF1 and CEF2 was 89.57 ± 32.84% and 86.28 ± 11.49%, respectively, which indicated good absorption of both products. In addition, there was a longer drug residence time for CEF1 than for CEF2. Data analysis for CEF1 revealed a flip-flop phenomenon. CONCLUSIONS AND CLINICAL RELEVANCE In this study, there was good absorption of CEF1, and CEF1 had a longer drug residence time in vivo than did CEF2. On the basis of pharmacokinetic parameters and the in vitro antimicrobial susceptibility, a dosage regimen of 2.2 mg/kg administered at 48- and 36-hour intervals for CEF1 and CEF2, respectively, could be an appropriate choice for the treatment of buffalo with infectious diseases.

Siderophore Cephalosporin Cefiderocol Utilizes Ferric Iron Transporter Systems for Antibacterial Activity against Pseudomonas aeruginosa

Cefiderocol (S-649266) is a novel parenteral siderophore cephalosporin conjugated with a catechol moiety at the third-position side chain. The in vitro activity of cefiderocol against Pseudomonas aeruginosa was enhanced under iron-depleted conditions, whereas that of ceftazidime was not affected. The monitoring of [thiazole-14C]cefiderocol revealed the increased intracellular accumulation of cefiderocol in P. aeruginosa cells incubated under iron-depleted conditions compared with those incubated under iron-sufficient conditions. Cefiderocol was shown to have potent chelating activity with ferric iron, and extracellular iron was efficiently transported into P. aeruginosa cells in the presence of cefiderocol as well as siderophores, while enhanced transport of extracellular ferric iron was not observed when one of the hydroxyl groups of the catechol moiety of cefiderocol was replaced with a methoxy group. We conclude that cefiderocol forms a chelating complex with iron, which is actively transported into P. aeruginosa cells via iron transporters, resulting in potent antibacterial activity of cefiderocol against P. aeruginosa.

Physical compatibility of tedizolid phosphate with selected i.v. drugs during simulated Y-site administration

PURPOSE

The physical compatibility of commonly used agents that could be coadministered in the clinical setting with tedizolid phosphate during Y-site administration was evaluated.

METHODS

Tedizolid phosphate vials were reconstituted to a final concentration of 0.8 mg/mL. All other drugs were prepared according to manufacturers' recommendations and diluted with 0.9% sodium chloride injection (where applicable) to the highest standard concentrations used clinically. Y-site conditions were simulated in culture tubes by mixing 5 mL of tedizolid phosphate solution with 5 mL of the test drug solutions. The physical characteristics, turbidity, and pH of all admixtures were examined immediately after mixing and at 15, 60, and 120 minutes. Incompatibility was defined as gross precipitation, a positive Tyndall beam test, color changes, or increases in turbidity.

RESULTS

With simulated Y-site administration, tedizolid phosphate was compatible with 69 of 86 drugs in 0.9% sodium chloride injection, including 24 of 31 antimicrobial agents. Of note, incompatibility was observed immediately after mixing except with ceftaroline and diphenhydramine, whose incompatibility with tedizolid phosphate was apparent after 15 and 60 minutes, respectively. Among the drug classes tested, tedizolid phosphate was compatible only with 1 aminoglycoside (amikacin) and incompatible with 1 echinocandin (caspofungin) and 1 cephalosporin (ceftaroline). In addition, tedizolid phosphate was incompatible with divalent cations (calcium chloride, calcium gluconate, and magnesium sulfate), probably due to precipitation with the phosphate component. A pH change of >1 unit occurred only with epinephrine (at 120 minutes).

CONCLUSION

Tedizolid phosphate 0.8 mg/mL in 0.9% sodium chloride injection was physically compatible with 69 of 86 study drugs during simulated Y-site administration.

Safe use of selected cephalosporins in penicillin-allergic patients: A meta-analysis

Background

Recent analysis of clinical data and a clearer understanding of the role of chemical structure in the development of cross-reactivity indicate that the increased risk of an allergic reaction to a cephalosporin in penicillin-allergic patients is smaller than previously postulated.

Method

Medline and EMBASE databases were searched with the keywords: cephalosporin, penicillin, allergy, and crosssensitivity for the years 1960 through 2005. Among 219 articles retrieved, 9 served as source material for this evidence-based meta-analysis.

Results

A significant increase in allergic reactions to cephalothin (odds ratio [OR] = 2.5; 95% confidence interval [CI] = 1.1 to 5.5), cephaloridine (OR = 8.7; CI = 5.9 to 12.8), and cephalexin (OR = 5.8; CI = 3.6 to 9.2), and all first generation cephalosporins plus cefamandole (OR = 4.8; CI = 3.7 to 6.2) were observed in penicillin allergic patients; no increase was observed with second generation cephalosporins (OR = 1.1; CI, 0.6 to 2.1) or third generation cephalosporins (OR = 0.5; CI = 0.2 to 1.1). Clinical challenges, skin testing, and monoclonal antibody studies point to the paramount importance of similarities in side chain structure to predict cross-allergy between cephalosporins and penicillins.

Conclusion

First-generation cephalosporins have cross-allergy with penicillins, but cross-allergy is negligible with second-and third-generation cephalosporins. Particular emphasis should be placed on the role of chemical structure in determining the risk of cross-reactivity between specific agents. 2007 American Academy of Otolaryngology-Head and Neck Surgery Foundation. All rights reserved.

Cephalosporins inhibit human metallo β-lactamase fold DNA repair nucleases SNM1A and SNM1B/apollo

Bacterial metallo-β-lactamases (MBLs) are involved in resistance to β-lactam antibiotics including cephalosporins. Human SNM1A and SNM1B are MBL superfamily exonucleases that play a key role in the repair of DNA interstrand cross-links, which are induced by antitumour chemotherapeutics, and are therefore targets for cancer chemosensitization. We report that cephalosporins are competitive inhibitors of SNM1A and SNM1B exonuclease activity; both the intact β-lactam and their hydrolysed products are active. This discovery provides a lead for the development of potent and selective SNM1A and SNM1B inhibitors.

Alkaline thermal pretreatment at mild temperatures for biogas production from anaerobic digestion of antibiotic mycelial residue

This paper aims at lowering the temperature for thermal pretreatment (TPT) of antibiotic mycelial residue (AMR) by alkali addition but without significantly worsening subsequent anaerobic digestion (AD) for biogas. Batch TPT and AD experiments were conducted in a bench-scale autoclave and several bench-scale anaerobic digesters, respectively. The results showed that the methane yield (<200 ml·(g VS)(-1)) was visibly lower with lowering pretreatment temperature, compared to that (290 ml·(g VS)(-1)) for TPT at the optimal temperature of 120°C, while it rebounded to 231 ml·(g VS)(-1) when proper amounts of alkali were employed (to adjust the pH of the AMR to 12) for TPT at 80°C. Further analysis indicated that low-temperature alkaline TPT was significantly less energy-consumption compared to only TPT, at cost of small amounts of alkali. It was more convenient and economical to implement AD of AMR in combination with alkaline TPT at mild temperatures for biogas.

Stability indicating methods for the analysis of cefprozil in the presence of its alkaline induced degradation product

Three simple, specific, accurate and precise spectrophotometric methods were developed for the determination of cefprozil (CZ) in the presence of its alkaline induced degradation product (DCZ). The first method was the bivariate method, while the two other multivariate methods were partial least squares (PLS) and spectral residual augmented classical least squares (SRACLS). The multivariate methods were applied with and without variable selection procedure (genetic algorithm GA). These methods were tested by analyzing laboratory prepared mixtures of the above drug with its alkaline induced degradation product and they were applied to its commercial pharmaceutical products.

A Liquid Chromatography-Tandem Mass Spectrometry Method for the Detection of Antimicrobial Agents from Seven Classes in Calf Milk Replacers: Validation and Application

Calf milk replacers are low-cost feeds that contain available, digestible protein. During their reconstitution, however, the addition of drugs, such as antibiotics, could make them a very simple route for illicit treatment for therapeutic, preventive, or growth-promoting purposes. We developed an HPLC-MS/MS method, preceded by a unique extraction step, able to identify 17 antibiotics from seven classes (penicillins, tetracyclines, fluoroquinolones, sulfonamides, cephalosporins, amphenicols, and lincosamides) in this matrix. Prior to solid phase extraction (SPE), the sample underwent deproteinization and defatting. The method was fully validated according to Commission Decision 2002/657/EC. Decision limits (CCα) and detection capability (CCβ) were in the ranges of 0.13-1.26 and 0.15-1.47 ng/mL, respectively. Thirty-eight samples were finally analyzed, showing the occasional presence of marbofloxacin (six samples) and amoxicillin (one sample).

Investigation on the interaction of cefpirome sulfate with lysozyme by fluorescence quenching spectroscopy and synchronous fluorescence spectroscopy

The reaction mechanism of cefpirome sulfate with lysozyme at different temperatures (298, 310 and 318 K) was investigated using fluorescence quenching and synchronous fluorescence spectroscopy under simulated physiological conditions. The results clearly demonstrated that cefpirome sulfate caused strong quenching of the fluorescence of lysozyme by a static quenching mechanism. The binding constants obtained using the above methods were of the same order of magnitude and very similar. Static electric forces played a key role in the interaction between cefpirome sulfate and lysozyme, and the number of binding sites in the interaction was close to 1. The values of Hill's coefficients were > 1, indicating that drugs or proteins showed a very weakly positive cooperativity in the system. In addition, the conclusions obtained from the two methods using the same equation were consistent. The results indicated that synchronous fluorescence spectrometry could be used to study the binding mechanism between drug and protein, and was a useful supplement to the fluorescence quenching method. In addition, the effect of cefpirome sulfate on the secondary structure of lysozyme was analyzed using circular dichroism spectroscopy.

Bioactive ZnO Coatings Deposited by MAPLE-An Appropriate Strategy to Produce Efficient Anti-Biofilm Surfaces

Deposition of bioactive coatings composed of zinc oxide, cyclodextrin and cefepime (ZnO/CD/Cfp) was performed by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The obtained nanostructures were characterized by X-ray diffraction, IR microscopy and scanning electron microscopy. The efficient release of cefepime was correlated with an increased anti-biofilm activity of ZnO/CD/Cfp composites. In vitro and in vivo tests have revealed a good biocompatibility of ZnO/CD/Cfp coatings, which recommend them as competitive candidates for the development of antimicrobial surfaces with biomedical applications. The release of the fourth generation cephalosporin Cfp in a biologically active form from the ZnO matrix could help preventing the bacterial adhesion and the subsequent colonization and biofilm development on various surfaces, and thus decreasing the risk of biofilm-related infections.

New valid spectrofluorimetric method for determination of selected cephalosporins in different pharmaceutical formulations using safranin as fluorophore

A new validated spectrofluorimetric method has been developed for the determination of some cephalosporins namely; cefepime, cefaclor, cefadroxil, cefpodoxime and cefexime. The method was based on the reaction of these drugs with safranin in slightly alkaline medium (pH 8.0), to form ion-association complexes. The fluorescent products were extracted into chloroform and their fluorescence intensities were measured at 544-565 nm after excitation at 518-524 nm. The reaction conditions influencing the product formation and stability were investigated and optimized. The relative fluorescence intensity was proportional to the drug concentration in the linear ranges of 0.15-1.35, 0.35-1.25, 0.35-1.25, 0.20-1.44 and 0.20-1.25 μg/mL for cefepime, cefaclor, cefadroxil, cefpodoxime proxetil and cefexime, respectively. The detection limits were 40, 100, 100, 60 and 70 ng/mL, respectively. The performance of the developed method was evaluated in terms of Student's t-test and variance ratio F-test to find out the significance of proposed methods over the reference spectrophotometric method. Various pharmaceutical formulations were successfully analyzed using the proposed method and the results were in good agreement with those of the previously reported methods.

Ratio manipulating spectrophotometry versus chemometry as stability indicating methods for cefquinome sulfate determination

Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photo-degradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.0-40.0 μg mL(-1). Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photo-degradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and cost-effective compared with the manufacturer's RP-HPLC method.

STABILITY OF CEFPIROME SULFATE IN AQUEOUS SOLUTIONS

The influence of pH on the stability of cefpirome sulfate was investigated in the pH range of 0.44 - 13.00. The degradation of cefpirome sulfate as a result of hydrolysis was a pseudo-first-order reaction. General acid-base hydrolysis of cefpirome sulfate was not observed. In the solutions of hydrochloric acid, sodium hydroxide, acetate, borate and phosphate buffer, k(obs) = k(pH) because specific acid-base catalysis was observed. Specific acid-base catalysis of cefpirome sulfate consisted of the following reactions: hydrolysis of cefpirome sulfate catalyzed by hydrogen ions (kH+), hydrolysis of dications (k₁H₂O) monocations (k₂ H₂O), zwitter ions (k₃H₂O) and monoanions (k₄ H₂O) of cefpirome sulfate under the influence of water. The total rate of the reaction was equal to the sum of partial reactions k(pH) = kH+ x aH+ + kH₂O x f₁ + k₂H₂O x f₂ + k₃H₂O x f₃ + k₄ H₂O x f₄. Based on the dependence k(pH) = f(pH) it was found that cefpirome sulfate was the most stable in aqueous solutions in the pH range of 4-6.

In-use Stability of Ceftaroline Fosamil in Elastomeric Home Infusion Systems and MINI-BAG Plus Containers

The objective of this study was to determine in-use stability of ceftaroline fosamil infusion solution of concentrations up to 12 mg/mL in elastomeric home infusion system prefilled with 0.9% Sodium Chloride Injection USP or 5% Dextrose Injection USP and MINI-BAG Plus Container delivery devices prefilled with 0.9% sodium chloride injection. In-use ceftaroline fosamil infusion solution (12 mg/mL) was prepared for elastomeric home infusion systems (Homepump Eclipse, Baxter Intermate, and AccuRx Elastomeric Pump) pre-filled with either 0.9% sodium chloride injection or 5% dextrose; or Baxter MINI-BAG Plus Containers pre-filled with 0.9% Sodium Chloride Injection USP (4 mg/mL to 12 mg/mL ceftaroline fosamil in final solution). The systems were stored refrigerated for 24 hours followed by up to 6 hours of storage at room temperature. Samples were analyzed at various time points for assay and degradation product by a validated stability-indicating high-performance liquid chromatography method. In-use ceftaroline fosamil infusion solution, ranging from 4-mg/mL to a maximum of 12-mg/mL concentration, in elastomeric home infusion systems prefilled with 0.9% sodium chloride injection or 5% dextrose, and MINI-BAG Plus Containers prefilled with 0.9% sodium chloride injection were chemically stable for up to 24 hours refrigerated at 2°C to 8°C (36°F to 46°F) and up to 6 hours at room temperature and had acceptable compatibility with material used. Ceftaroline fosamil (4 mg/mL to 12 mg/mL) maintains its potency for up to 24 hours refrigerated at 2°C to 8°C (36°F to 46°F) and up to 6 hours of storage at room temperature upon reconstitution in infusion solution with 0.9% sodium chloride or 5% dextrose when used in elastomeric home infusion system and MINI-BAG Plus Containers delivery devices prefilled with 0.9% sodium chloride injection.

[Construction of the quantitative structure retention relationship of cefdinir related substances]

The molecular descriptors of impurities with known structure in cefdinir were calculated, selected and associated with the chromatographic retention behavior to establish a model. This quantitative structure retention relationships (QSRR) model for the related substances of cefdinir was established under specific chromatographic condition and verified by other impurities. 12 molecular descriptors were used to establish the QSRR model, F_AFRBWF, Blbn_J, SsCH3, SssCH2, SsNH2, SssNH, SssS, SHdCH2, EEM_AFc, EEM_AFpl, EEM_XFpl and Pi_MaxQ. The relativity between true values and predictions in QSRR of cefdinir is R2 = 0.9836 (n = 18), ΔRRT is no more than 0.154, as 10.17% in RRT. The results indicate that the QSRR model for the related substances of cefdinir can be used to evaluate the analysis methods for related substances and predict the chromatographic behavior of new impurities, which will provide a new way for the evaluation of the effectiveness for drug quality control.

A model assessment of the importance of direct photolysis in the photo-fate of cephalosporins in surface waters: Possible formation of toxic intermediates

The direct and indirect photodegradation of six cephalosporins was predicted using a photochemical model, on the basis of literature values of photochemical reactivity. Environmental photodegradation would be important in surface water bodies with depth ⩽ 2-3m, and/or in deeper waters with low values of the dissolved organic carbon (DOC ⩽ 1 mg C L(-1)). The half-life times would range from a few days to a couple of weeks in summertime. In deeper and higher-DOC waters and/or in different seasons, hydrolysis could prevail over photodegradation. The direct photolysis of cephalosporins is environmentally concerning because it is known to produce toxic intermediates. It would be a major pathway for cefazolin, an important one for amoxicillin and cefotaxime and, at pH<6.5, for cefapirin as well. In contrast, direct photolysis would be negligible for cefradine and cefalexin. The DOC values would influence the fraction of photodegradation accounted for by direct photolysis in shallow water, to a different extent depending on the role of sensitisation by the triplet states of chromophoric dissolved organic matter.