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).

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 ±â€¯1 °C), both drugs presented moderate stability (t½â€¯= 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, kapp 0.0095 ±â€¯0.0004 and 0.0092 ±â€¯0.001 cm2 mJ-1, respectively. Furthermore, using surface water in hydrolysis experiments, CEF demonstrated significant matrix-dependent stability with a half-life (t½â€¯= 14.7 d) tenfold higher than in buffered solutions. In contrast, CEPA presented a very similar hydrolysis rate in river water (t½â€¯= 4.2 d) and a subtle faster photo-degradation rate in this same matrix (kapp 0.0128 ±â€¯0.001 cm2 mJ-1), highlighting the importance of disinfection radiation for cephalosporin depletion in aqueous environments.

Performance of microwave treatment for disintegration of cephalosporin mycelial dreg (CMD) and degradation of residual cephalosporin antibiotics.

Significant amounts of cephalosporin mycelial dreg (CMD) are still being generated from biopharmaceutical processes, representing both an economic and environmental burden for pharmaceutical factories. This study investigates the microwave (MW) treatment of CMD at a relatively mild temperature (100°C) within 15min. The results reveal that the MW treatment disintegrates the CMD efficiently and that the residual cephalosporin C (CPC) is almost degraded after sufficient irradiation. MW heating temperature strongly influences the polymer's release. SCOD (soluble chemical oxygen demand), soluble proteins and carbohydrates have significant positive correlations to the temperature (r=0.993, 0.983 and 0.992, respectively; p<0.01). 3D-EEM fluorescence spectra indicate that the key organic matters relate to temperature as well as microwave energies. Furthermore, more than 99.9% of the residual antibiotics in CMD are degraded by MW irradiation without antibacterial activities that are proven by the possible degradation pathway we elucidate. These results suggest that microwave irradiation treatment not only disintegrates CMD and destroys mycelial cells but also degrades the residual cephalosporin antibiotics, which implies the possibility for practical applications.

Radiolytic studies of cefozopran hydrochloride in the solid state

Background: The radiation sterilization is one of the best methods for sterilizing vulnerable degradation drugs like cefozopran hydrochloride. Results: Chemical stability of radiosterylized cefozopran hydrochloride, was confirmed by spectrophotometric and chromatographic methods. EPR studies showed that radiation has created some radical defects whose concentration was no more than several dozen ppm. The antibacterial activity of cefozopran hydrochloride irradiated with a dose of 25 kGy was unaltered for Gram-positive bacteria but changed for two Gram-negative strains. The radiation sterilized cefozopran hydrochloride was not in vitro cytotoxic against human CCD39Lu normal lung fibroblast cell line. Conclusions: Cefozopran hydrochloride in solid state is not resistant to radiation sterilization and this method cannot be used for sterilization of this compound.

The radiolytic studies of cefpirome sulfate in the solid state.

The possibility of applying radiation sterilization to cefpirome sulfate was investigated. The lack of changes in the chemical structure of cefpirome sulfate irradiated with a dose of 25 kGy, required to attain sterility, was confirmed by UV, FT-IR, Raman, DSC and chromatographic methods. Some radical defects with concentration no more than over a several dozen ppm were created by radiation. The antibacterial activity of cefpirome sulfate for two Gram-positive and three Gram-negative strains was changed. The radiation sterilised cefpirome sulfate was not in vitro cytotoxic against fibroblast cells.

Sterilization by gamma radiation of antibiotic impregnated polymethylmethacrylate and plaster of Paris beads. A pilot study.

INTRODUCTION: Ethylene oxide is currently recommended for sterilization of antibiotic impregnated beads; however this method carries health risks to personnel and is becoming less available. OBJECTIVE: To perform a pilot study of the effect of radiation for sterilization of polymethylmethacrylate (PMMA) and plaster of Paris (POP) beads impregnated with amikacin, enrofloxacin, and ceftiofur. HYPOTHESIS: Radiation would effectively sterilize the beads without affecting the efficacy of the antibiotic. MATERIALS AND METHODS: Beads of PMMA and POP were prepared in a clean but non-sterile manner with one of the three antibiotics (amikacin, enrofloxacin, ceftiofur) or no antibiotic. Beads were then exposed to radiation for a total dose of 0 kiloGray (kGy), 10 kGy and 25 kGy. Beads were incubated on Mueller-Hinton agar plates seeded with Escherichia coli, Staphylococcus aureus or Pseudomonas aeruginosa for 24 hours or cultured in brain-heart infusion broth for 48 hours. Zones of inhibition were measured on the agar plates and statistics were performed on the diameters of the zones of inhibition using an analysis of variance. RESULTS: There were no differences in the diameters of inhibition for all levels of radiation for all PMMA beads. The same was true with POP beads with the exception of enrofloxacin which had a significantly decreased zone of inhibition with increased levels of radiation, though the clinical significance of this finding was not assessed. Only beads without antibiotics and not exposed to radiation had bacterial growth. CLINICAL SIGNIFICANCE: Radiation may be an effective method of sterilization for antibiotic impregnated beads.

Radiosterilization of fluoroquinolones and cephalosporins: assessment of radiation damage on antibiotics by changes in optical property and colorimetric parameters.

A most common problem encountered in radiosterilization of solid drugs is discoloration or yellowing. By pharmacopoeia method, discoloration can be assessed by measuring absorbance of solutions of irradiated solid samples at 450 nm. We propose to evaluate discoloration of solid samples directly by recording their diffuse reflectance spectra. Further, the reflectance spectrum is used to compute various color parameters: CIE XYZ tristimulus value, CIE Lab, DeltaE*(ab) (color difference), yellowness index (YI), dominant wavelength, and excitation purity by CIE method. The investigation of difference reflectance spectra and color parameters revealed that for fluoroquinolones, e-beam was more damaging than gamma radiation, whereas for cephalosporins, trend was reversed. The quantum of discoloration with gamma radiation and e-beam is found to be nearly equal when assessed by pharmacopeia method, and it is therefore inadequate to assess small color differences. The color parameters DeltaE*(ab) and DeltaYI are found to be reliable indicators of discoloration. The tolerance limits proposed in terms of DeltaE*(ab) and DeltaYI are +/-2 and +/-10 U, respectively. The dominant wavelength for all compounds has shifted to higher values indicating change in hue but defining color tolerance limit with this parameter requires adjunct excitation purity value.

Radiosterilization of cefotaxime: investigation of potential degradation compounds by liquid chromatography-electrospray mass spectrometry.

The nonvolatile radiolytic compounds produced by irradiation of cefotaxime were studied by a liquid chromatography-electrospray mass spectrometry method. Full scan LC-MS was first performed in order to obtain the m/z value of the protonated molecules of all detected peaks. LC-MS-MS was then carried out on the compounds of interest. A comparison between the MS-MS spectrum of cefotaxime and those of the radiolytic compounds showed that their fragmentation patterns were very similar suggesting that they were structural analogues of the main drug. The examination of the two main fragmentation pathways also permitted the location of the modified substructures. Moreover, it was shown that some stereoisomers appeared with the irradiation process. The complete fragmentation pattern of cefotaxime was studied by MSn and used to obtain information about the structure of the radiolytic compounds. A complete structure was proposed for four of these.

Stability of a second-generation cephalosporin veterinary mastitis formulation after electron beam irradiation.

This study focused on the chemical stability of the cephalosporin (6R, 7R)-7-(1-pentafluorophenoxyacetamido)-3-[2-(5-methyl-1,3,4-thiodiazolyl)thiomethyl]-Delta(3)-cephem-4-carboxylic acid, sodium salt (cephem 1) formulation after electron beam (e-beam) irradiation. The cephem 1 concentrations of samples irradiated at 5, 10, and 15 kilograys for glass vials and low-density polyethylene (LDPE) cannula syringes were not statistically different from the concentrations of the nonirradiated control samples. Samples from each irradiation dose stored in controlled-temperature chambers at 5 degrees C and 30 degrees C for 24 months did not show any concentration changes within statistical limits compared with the nontreated samples. Samples from each irradiation dose stored at 40 degrees C for 12 months also did not show any concentration changes within statistical limits compared with the nontreated samples. The percentage of related substances increased slightly with the increase in e-beam irradiation level and storage temperature, but this increase was within the proposed label claim of 90% to 110% (45-55 mg/g). In conclusion, e-beam sterilization did not affect the chemical stability of cephem 1 intramammary formulation in LDPE cannula syringes, suggesting that e-beam irradiation may be a feasible method for terminal sterilization of this cephem 1 formulation.

A light-inactivated antibiotic.

Sodium 7beta-[(R)-2-(N(b)()-o-nitrobenzyloxycarbonyl)hydrazino-3-pheny lpropa namido]cephalosporanate (1) is described as a new type of beta-lactam antibiotic, which undergoes light-induced destruction of its beta-lactam moiety and hence becomes biologically inactive. This type of antibiotic holds the promise of self-destruction over a number of hours of exposure to light, so that it would not allow selection of resistance in the environment.

Radiation induced effects on cephalosporins: an ESR study.

PURPOSE: This paper reports experimental data on the ESR identification of four irradiated cephalosporins (cefpodoxime, cefsulodin, cefixime and ceftizoxime). MATERIALS AND METHODS: Equations to describe the ESR curves versus the dose and storage time were developed using mathematical procedures. RESULTS: Limits of detection (LOD) and limits of quantification (LOQ), estimated on the basis of the S/N ratios are 1.0+/-0.5 kGy and 2.5+/-0.5 kGy respectively. The yield of free radicals are in the range 4.6 10(19) - 2.2 10(20) radicals mol(-1) (G values from 0.1 to 0.4). Besides a very unstable situation (cefsulodin), the time limit of detection of free radicals after storage ranges from about 1 year to over 2 years. These time intervals are comparable with the shelf-life of the antibiotics and to the time limits found for 10 other cephalosporins described previously. Apart from qualitative detection, ESR spectrometry can be used for dose estimation. Exponential loss of ESR signal (first-order reaction) correlates well with the data. CONCLUSION: Given the sensitivity of ESR spectrometry, this experimental technique is promising for identification of irradiated cephalosporins.

ESR spectroscopy applied to the study of pharmaceuticals radiosterilization: cefoperazone.

As an alternative to heat and gas exposure sterilization, ionizing radiation is gaining interest as a sterilization process for medicinal products. Nevertheless, essentially for economic profits, an unauthorized and uncontrolled use of radiation process may be expected. In this context, it is necessary to find methods distinguishing between irradiated and unirradiated pharmaceuticals and, in the absence of suitable detection methods, our attention was focused on ESR spectrometry. In this paper, we examine the potential of ESR as an analytical tool in cefoperazone radiosterilization; this cephalosporin is a potential candidate for radiation treatment due to its thermosensitivity. While the ESR spectra of unirradiated sample present no intensity, a signal, dependent of the irradiation dose, is found exclusively in irradiated samples. The number of free radicals (2 x 10(17) radicals per g at 25 kGy) was estimated by comparison of the second integral from radiosterilized samples and DPPH. From this, the G-value could be estimated to 0.3. Limit of detection and limit of quantification are 0.5 kGy and 1 kGy, respectively. Aside from qualitative detection, ESR can be used for dose estimation. The dose-ESR response curves can be simulated by bi-exponential or power functions and the linear function can't be used for simulation even for low doses. Decay of radicals upon storage were simulated using bi-exponential function. The limit of detection of free radicals after irradiation at 25 kGy is 140 days.

Syn/anti isomerization of cefuroxime by ultraviolet light.

Cefuroxime, like all the oximino cephalosporins on the market, has the methoxyimino group in the syn (Z) configuration. By U.V. light irradiation of cefuroxime, a syn/anti isomerization occurs until equilibration of the two isomers is reached. Measurement of the 1H-N.M.R. chemical shift differences of the two isomers allows the assignment of methoxyimine stereochemistry.