Antibiotics and antimycotics in waste water treatment plants: Concentrations, removal efficiency, spatial and temporal variations, prediction, and ecological risk assessment

For investigating the spatial, temporal variations and assessing ecological risk of 10 antibiotics and 6 antimycotics, influent sewage water and treated effluent were collected during three different seasons in 19 waste water treatment plants of Tianjin. High performance liquid chromatography tandem mass spectrometry was used to analyze 16 substances. The concentration range of influent samples was not detected (nd) -547.94 ng/L and the concentration range of effluent samples was nd-52.97 ng/L. By calculating the removal efficiency, it was found that Ciprofloxacin (CIP), Ofloxacin (OFL) and Clotrimazole (CTR) were effectively removed. There were significant spatial and temporal differences, the concentration in the dry season was evidently higher than that in the wet and normal seasons, and the northeast was lower than that in the northwest and southeast. By establishing a data set of influent and effluent, the priority features were extracted by feature engineering, which were temperature and NH₃-N. Under the condition of ensuring the best performance of the models, the influent model with 9 features and the effluent model with 4 features were established, and the quantitative relationship between the above features and concentration was obtained through partial dependence analysis. Except for Moxifloxacin (MOX), Norfloxacin (NOR) and OFL in the influent samples, the RQ values for other antibiotics and antimycotics were less than 0.1. Among the effluent samples, only NOR had an RQ value greater than 0.1, and OFL, MOX, and Pefloxacin (PEF) had RQ values between 0.01 and 0.1. Comparing the observations and predictions individual RQ values, the predictions were ideal and matched the observations. This work effectively assessed environmental impact and provided a valuable reference for evaluating antibiotics and antimycotics ecological toxicity.

Occurrences, transport drivers, and risk assessments of antibiotics in typical oasis surface and groundwater

Intensive use of antibiotics affects biogeochemical cycles and stimulates the evolution of antibiotic resistance, thus threatening global health and social development. The spatiotemporal distributions of antibiotics in single aqueous matrices have been widely documented; however, their occurrence in surface-groundwater systems has received less attention, especially in arid regions that usually have fragile ecosystems. Therefore, we investigated the occurrence of thirty-one antibiotics in the surface water and adjacent groundwater in the Xinjiang Uygur Autonomous Region, China. The results showed that the total concentrations of detected antibiotics varied from 17.37 to 84.09 ng L^-1 and from 16.38 to 277.41 ng L^-1 in surface and groundwater, respectively. The median concentration of antibiotics showed the pattern of norfloxacin (4.86 ng L^-1) > ciprofloxacin (3.93 ng L^-1) > pefloxacin (3.39 ng L^-1) in surface water; whereas in groundwater, this was in the order of pefloxacin (6.30 ng L^-1) > norfloxacin (4.33 ng L^-1) > ciprofloxacin (2.68 ng L^-1). Heatmap analysis indicated that vertical infiltration had limited effects on antibiotic exchange in surface-ground water systems because of the high potential evaporation and low water storage. Redundancy analysis suggested that the oxidation-reduction potential (p < 0.01) and dissolved oxygen (p < 0.05) jointly affected the distribution of antibiotics in surface water. Ecological risk assessment showed that antibiotics in 98.9% of surface water and 99.1% of groundwater did not pose significant risks to aquatic species. The findings of this study will help develop effective mitigation strategies for antibiotics in aquatic environments.

Simplex optimization of the variables influencing the determination of pefloxacin by time-resolved chemiluminescence

A new chemiluminescence (CL) detection system combined with flow injection analysis (FIA) for the determination of Pefloxacin is proposed. The determination is based on an energy transfer from Pefloxacin to terbium (III). The metal ion enhances the weak CL signal produced by the KMnO₄/H₂SO₃/Pefloxacin system. A modified simplex method was used to optimize chemical and instrumental variables. The influence of the interaction of the permanganate, Tb (III), sodium sulphite and sulphuric acid concentrations, flow rate and injected sample volume was thoroughly investigated by using a modified simplex optimization procedure. The results revealed a strong direct relationship between flow rate and CL intensity throughout the studied range that was confirmed by a gamma test. The response factor for the CL emission intensity was used to assess performance in order to identify the optimum conditions for maximization of the response. Under such conditions, the CL response was proportional to the Pefloxacin concentration over a wide range. The detection limit as calculated according to Clayton's criterion 13.7μgL^-1. The analyte was successfully determined in milk samples with an average recovery of 100.6±9.8%.

Near-infrared spectroscopy quantitative determination of pefloxacin mesylate concentration in pharmaceuticals by using partial least squares and principal component regression multivariate calibration

Pefloxacin mesylate, a broad-spectrum antibacterial fluoroquinolone, has been widely used in clinical practice. Therefore, it is very important to detect the concentration of Pefloxacin mesylate. In this research, the near-infrared spectroscopy (NIRS) has been applied to quantitatively analyze on 108 injection samples, which was divided into a calibration set containing 89 samples and a prediction set containing 19 samples randomly. In order to get a satisfying result, partial least square (PLS) regression and principal components regression (PCR) have been utilized to establish quantitative models. Also, the process of establishing the models, parameters of the models, and prediction results were discussed in detail. In the PLS regression, the values of the coefficient of determination (R(2)) and root mean square error of cross-validation (RMSECV) of PLS regression are 0.9263 and 0.00119, respectively. For comparison, though applying PCR method to get the values of R(2) and RMSECV we obtained are 0.9685 and 0.00108, respectively. And the values of the standard error of prediction set (SEP) of PLS and PCR models are 0.001480 and 0.001140. The result of the prediction set suggests that these two quantitative analysis models have excellent generalization ability and prediction precision. However, for this PFLX injection samples, the PCR quantitative analysis model achieved more accurate results than the PLS model. The experimental results showed that NIRS together with PCR method provide rapid and accurate quantitative analysis of PFLX injection samples. Moreover, this study supplied technical support for the further analysis of other injection samples in pharmaceuticals.

Simultaneous determination of 13 quinolones in eggs using column high-performance liquid chromatography/electrospray ionization-tandem mass spectrometry and depletion of pefloxacin methanesulfonate in eggs

An efficient method was developed for simultaneous determination of 13 quinolones--namely, enoaxacin (ENO), marbofloxacin (MAR), ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OFL), pefloxacin methanesulfonate (PEF), danofloxacin (DAN), enrofloxacin (ENR), lomefloxacin (LOM), difloxacin (DIF), sarafloxacin (SAR), oxolinic acid (OXO), and flumequine (FLU)--in eggs by column liquid chromatography/electrospray ionization-tandem mass spectrometry. Samples were extracted with a phosphoric acid-phosphate buffer followed by purification with a solid-phase extraction cartridge. Recoveries for the 13 quinolones were 67-93% with intraday and interday coefficients of variation ranging from 4 to 9% and 2 to 18%, respectively. The limit of determination was 0.05 microg/kg for OXO and FLU; 0.1 microg/kg for MAR, OFL, CIP, LOM, DAN, SAR, DIF, NOR, and ENR; and 0.2 microg/kg for ENO and PEF. The method was also applied to study the depletion of PEF in eggs. The concentration of PEF increased and reached a maximum value on the third day, and then decreased rapidly until it could not be detected on day 32; its metabolite NOR was detectable on the second day, and then reached a maximum on the sixth day, after which it could not be detected until day 15.

[Determination of 16 quinolone residues in animal tissues using high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry]

A confirmative method was developed with high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-MS/MS) to simultaneously detect 16 quinolone residues in animal tissues, which included nalidixinic acid, oxolinic acid, flumequine, norfloxacin, enoxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, ofloxacin, sarafloxacin, difloxacin, marbofloxacin, pefloxacin, sparfloxacin and orbifloxacin. In the method, the 16 residues were extracted with acidified acetonitrile, cleaned-up with hexane, and concentrated with a rotary evaporator. Then the reconstituted sample solution was analyzed using HPLC-MS/MS in positive mode, with a Inertsil C8-3 column as the analytical column. The method was validated at 10, 50 and 100 microg/kg. The validation results were as follows: the linear ranges were from 10 to 100 microg/kg; the overall recoveries were from 62.4% to 102% with the relative standard deviations of 1.4%-11.9%. The method is simple, rapid, and accurate, and its performance could meet the requirements of the domestic and international legislation. The method is applicable to simultaneously confirm multi-residues of quinolones in animal tissues such as chicken muscle, chicken liver and fish muscle.

Spectrophotometric determination of pefloxacin mesylate in pharmaceuticals

A spectrophotometric method is described for assay of pefloxacin mesylate (PFM) in bulk drug and in tablets. The method is based on back extraction of the bromophenol blue dye at pH 5.2 from the dye-drug ion pair followed by measurement of the dye absorbance at 590 nm. The working conditions of the method were investigated and optimized. Beer's law plot showed a good correlation in the concentration range of 0.15-1.25 microg mL(-1). Sensitivity indices such as molar absorptivity, limits of detection and quantification are reported. Intra-day and inter-day precision, and accuracy of the methods were established according to the ICH guidelines, and the er values were in the range of -1.7 to 1.8% with RSD values ranging from 1.0 to 1.1%. The method was successfully applied to the assay of PFM in tablet preparations with recoveries varying from 97.5 to 101.9%, with standard deviation in the range of 0.6 to 1.9. The results were statistically compared with those of the reference method by applying Student's t-test and F-test. Accuracy evaluated by means of the spike recovery method, range from 97.0 to 106.0%, with precision better than 3%.

Preparation of anti-pefloxacin antibody and development of an indirect competitive enzyme-linked immunosorbent assay for detection of pefloxacin residue in chicken liver

Pefloxacin has been increasingly used in veterinary medicine to treat microbial infections. To avoid using a labor-intensive instrumental method to detect the residue of pefloxacin in food, a simple and convenient indirect competitive enzyme-linked immunosorbent assay method has been developed in this study. The antibody generated from immunogen cationized bovine serum albumin-pefloxacin showed high sensitivity toward pefloxacin with an IC50 value of 6.7 ppb in buffer and was suitable for a screening assay to detect the residue of pefloxacin in food products. The antibody has been assessed using rapid enzyme immunoassays to exploit its specificity. The antibody prepared shows cross-reactivity with a few other (fluoro)quinolones including fleroxacin (116%), enrofloxacin (88%), and ofloxacin (10%). The assay measured drug residue in chicken liver spiked with pefloxacin with an interassay coefficient of variation of 13.6% or less and an intra-assay coefficient of variation of 10.9% or less. The average recovery rates at 0.5, 5, 10, 50, and 100 ppb were in the range of 86-106% for interassay and in the range of 87-103% for intra-assay, respectively.

Quantitative determination of gatifloxacin, levofloxacin, lomefloxacin and pefloxacin fluoroquinolonic antibiotics in pharmaceutical preparations by high-performance liquid chromatography

The objective of this research was to develop and validate analytical methods for quantitative determination of fluoroquinolones of third generation. Simple and rapid chromatographic method was developed and validated for quantitative determination of four quinolone antibiotics in tablets and injection preparations. The fluoroquinolones studied were gatifloxacin (GAT), levofloxacin (LEV), lomefloxacin (LOM) and pefloxacin (PEF). The quinolones were analyzed by using a LiChrospher 100 RP-18 column (5 microm, 125 mm x 4 mm) and a mobile phase constituted of water:acetonitrile (80:20, v/v) with 0.3% of triethylamine and pH adjusted to 3.3 with phosphoric acid. The flow rate was 1.0 mL/min and the analyses were performed using UV detector with wavelengths varying from 279 to 295 nm. The analyses were performed at room temperature (24 +/- 2 degrees C). All fluoroquinolones were separated within 5 min. The calibration curves were linear (r>or=0.9999) over a concentration range from 4.0 to 24.0 microg/mL. The relative standard deviation (R.S.D.) was < 1.0% and average recovery was above 99.54%.

Multiresidue determination of eleven quinolones in milk by liquid chromatography with fluorescence detection

A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69-88% with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 microg/L for enrofloxacin, and 1-9 microg/L for the other 10 quinolones.

[The fluorescence characteristics of micelle inclusion of pefloxacin and its application]

A new highly sensitive fluorescence spectrophotometic method for the determination of pefloxacin (PEFX) has been developed based on micella enhancement. The fluorescence characteristic of micelle inclusion complex formed between PEFX and sodium dodecyl sulfate (SDS) was studied. Different variables and parameters affecting the fluorescence were studied and optimized. Experiments show that sodium dodecyl sulfate can enhance greatly the fluorescence signal for pefloxacin in pH 5 Britton Robinson(BR) buffer solution. The fluorimetric method allows the determination of 0.06-1.20 microg x mL(-1) of pefloxacin with SDS in aqueous solution with lambda ex = 278 nm and lambda em = 432 nm, respectively. The detection limit for PEFX is 0.06 microg x mL(-1), The recoveries are 98.5%-100.8% and the RSDs are 1.4%-2.3%. The proposed procedures could be applied successfully to the determination of the pefloxacin drugs in tablets and human plasma with good recovery. In this paper we determined pefloxacin in human plasma by synchronization-derivative fluorescence spectroscopic techniques with good analytical selectivity, high sensitivity, high capability of eliminating blank interference and improving the limit of detection.

Spectrophotometric determination of enrofloxacin and pefloxacin through ion-pair complex formation

Two simple, quick and sensitive spectrophotometric methods are described for the determination of enrofloxacin and Pefloxacin. The methods are based on the reaction of these drugs with bromophenol blue (BPB) and methyl orange (MO) in buffered aqueous solution at pH 2.3-2.5 in case of bromophenol blue and at pH 3.6 with MO to give highly coloured complex species, extractable with chloroform. The coloured products are quantitated spectrophotometrically at 420 and 424 nm for BPB and MO, respectively. Optimisation of the different experimental conditions is described. Beer's law is obeyed in the concentration ranges 2-12 and 2-18 microg ml(-1) with BPB and in the ranges 1-12 and 4-40 microg ml(-1)with MO for enrofloxacin and pefloxacin, respectively. The proposed methods are applied for determination of Enroxil oral solution, Peflacine tablets and Peflacine ampoules with mean percentage accuracies 99.5+/-0.99, 99.39+/-1.05 and 100.02+/-0.895, respectively, with BPB and 100.30+/-0.89, 100.25+/-0.98 and 100.20+/-0.72, respectively, with MO.

Spectrophotometric determination of ciprofloxacin, enrofloxacin and pefloxacin through charge transfer complex formation

A spectrophotometric method was described for the determination of the antibacterial quinolone derivatives, ciprofloxacin, enrofloxacin and pefloxacin through charge transfer complex formation with three different acceptors. Chloranilic acid (CL) was utilized for their determination, forming charge transfer complex with lambdamax 520 nm. The proposed method was applied for determination of Ciprocin tablets, Enroxil oral solution, Peflacin ampoules and Peflacin tablets, with mean percentage accuracies, 99.58+/-1.25,99.94+/-0.96,100.91+/-1.59 and 99.86+/-1.003. Also, tetracyanoethylene (TCNE) was utilized in the determination of the concerned compounds forming charge transfer complexes with maximum absorbances at lambdamax 335 nm for ciprofloxacin and at lambdamax 290 nm for both enrofloxacin and pefloxacin. The procedure was applied for determination of Ciprocin tablets, Enroxil 10% oral solution, Peflacine tablets and Peflacine ampoules with mean percentage accuracies 99.40+/-1.27,99.95+/-0.90,98.98+/-1.565 and 99.88+/-0.998, respectively. Also, 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) was utilized for determination of pefloxacin forming charge transfer complex with maximum absorbance at lambdamax 460 nm. The procedure was applied for determination of peflacine tablets and peflacine ampoules with mean percentage accuracies 100.40+/-0.76 and 99.91+/-0.623, respectively. Statistical analysis of the obtained results showed no significant difference between the proposed method and other official and reported methods as evident from the t-test and variance ratio.

Selective separation and simultaneous determination of trace levels of five types of fluorinated quinolone drugs by thin-layer chromatography/fluorescence densitometry

This paper reports the determination of trace levels of 5 types of fluorinated quinolone drugs, i.e., ciprofloxacin, norfloxacin, enoxacin, pefloxacin, and ofloxacin, by thin-layer chromatography (TLC)/fluorescence densitometry. The new analytical method uses 2-step TLC development, selective separation, and simultaneous determination of the 5 drugs. The method was also applied to the determination of recoveries of standards of the 5 drugs in plasma and urine samples. The results show that the method has a wide linear range, high repeatability, and good stability.

Pefloxacin penetration into human necrotic pancreatic tissue

Antibiotic prophylaxis may be useful in acute necrotising pancreatis, a disease associated with a considerable incidence of infectious complications. The aim of this study was to assess pefloxacin penetration into necrotic pancreatic tissue during human necrotic pancreatitis. Ten patients (mean age 53.2 +/- 17.4 years) with severe acute pancreatitis (mean Ranson score 4.3) were studied. Pefloxacin was administered at a dose of 400 mg bd every 12 h by i.v. infusion (bolus, 15 min). Intraoperative samples of necrotic pancreatic tissue and blood were collected simultaneously 1, 2, 4.5, 6, 8.5 or 10 h after the last pefloxacin administration in patients treated for 1, 3, 4, 7, 8, 17 or 20 days. Drug concentrations were determined by the microbiological agar-well diffusion method (Escherichia coli Kp 05124 as test micro-organism in Isosensitest Agar). Levels in serum ranged from 2.0 to 9.0 mg/L (at 2 and 6 h, respectively), in necrotic pancreatic tissue from 2.0 to 29.0 micrograms/g depending on different sampling time. Maximum tissue peak concentrations appeared between 4 and 6 h. The necrotic pancreatic tissue/serum concentration ratio ranged from 0.9 to 5.1, values depending on tissue sample collection. Therapeutic concentrations (20.6 micrograms/g) above the MIC of potentially pathogenic enteric microorganisms were still present in necrotic pancreatic tissue 10 h after the last drug administration. Pefloxacin appeared to concentrate in necrotic pancreatic tissue, without appreciable accumulation after multiple-dose administration. The pefloxacin concentrations in necrotic pancreatic tissue showed high variability, depending on the degree of necrosis, inflammation and sample vascularization. Our results provided evidence of good, prompt penetration of pefloxacin into necrotic pancreatic tissue. Pefloxacin seems to exhibit favourable pharmacokinetic and pharmacodynamic properties for pancreatic infections.

Ventriculitis caused by Klebsiella pneumoniae successfully treated with pefloxacin in a neonate

Pefloxacin was applied to a newborn suffering from ventriculitis caused by Klebsiella pneumoniae after failure of routine antibiotics. Treatment was successful. Blood and CSF levels were high, thus documenting good CSF penetration. In addition to this case report, a review of the literature regarding seven neonates with CNS infection treated with fluoroquinolones and from whom CSF levels were obtained, is presented. In conclusion, due to their excellent activity against gram-negative microorganisms, fluoroquinolones may be considered in the treatment of neonatal CNS infections if the pathogen is resistant to routinely used antibiotics. Only limited experience is available with fluoroquinolones in pediatric patients given their potential for cartilage toxicity in young animals.

Penetration of pefloxacin into maxillary sinus cavity and nasal secretions

The ability of oral pefloxacin to penetrate into maxillary sinus cavity and nasal secretions was studied in 39 patients suffering from an exacerbation of chronic maxillary sinusitis. The mean levels of pefloxacin in sinus aspirate fluid 0, 3, 6, 9 and 12 h after the second oral dose of 400 mg were 2.30, 6.92, 3.74, 3.47 and 2.82 mg/l respectively. In sinus cystic fluid (macroscopically non-purulent) the mean pefloxacin levels were 2.30, 7.15, 4.20 and 4.15 mg/l respectively, and in nasal secretion 1.90, 9.05, 3.71, 3.20 and 2.85 mg/l respectively. The mean pefloxacin levels in serum obtained simultaneously were 1.50, 5.00, 3.10, 2.70 and 2.20 mg/l respectively. It is concluded that pefloxacin accumulates in inflamed sinus fluid at concentrations exceeding blood levels.

Decontamination of the bowel by intravenous administration of pefloxacin

Intravenous administration of pefloxacin 400 mg twice daily rapidly decontaminated the bowel from Gram-negative bacilli in ten healthy volunteers. The faecal concentrations of enterococci and yeasts did not change significantly. Further, pefloxacin did not facilitate colonization of the bowel by a highly resistant challenge strain (Klebsiella pneumoniae, MIC = 56 mg/l). The diffusible faecal concentration of pefloxacin was between 110 and 260 mg/l in all samples from day 3 of treatment onwards. It is concluded that parenteral administration of pefloxacin is very effective for decontamination of the bowel from Gram-negative bacilli and provides reliable prophylaxis against colonization of the bowel by highly resistant Gram-negative bacilli ingested with food.

Spectrophotometric determination of pefloxacin in pharmaceutical preparations

It has been established that the antibiotic pefloxacin (Abaktal) methanesulphonate reacts with Fe(III) at pH 1.00-8.00 to form a water-soluble complex with maximum absorbance at 360 nm. The composition of the complex, determined spectrophotometrically by the application of Job's, molar-ratio and Bent-French's methods, was pefloxacin: Fe(III) = 1:1 (pH = 2.50; lambda = 360 nm; mu = 0.1 M). The relative stability constant, obtained by the methods of Sommer and Asmus was 10(5.02) (pH = 2.50; lambda = 360 nm; mu = 0.1 M). The molar absorptivity of the complex at 360 nm was found to be 4.8 x 10(3) l mol-1 cm-1. Beer's law was followed for pefloxacin concentrations of 2.15-85.88 micrograms ml-1. The lower sensitivity limit of the method was 2.15 micrograms ml-1. The relative standard deviation (n = 10) was 0.57-1.07%. The method can be applied to the rapid and simple determination of pefloxacin in aqueous solutions and tablets.

[Kinetics of pefloxacin diffusion in human bone tissue following a single infusion of 800 mg. Evaluation of an extraction technic using chloroform]

A better understanding of the pharmacokinetics of pefloxacin in human bone is warranted by the efficacy of this drug in the treatment of bone and joint infections. Surgical bone samples were taken at 30 mn, 1h, 6h, 12h and 24 h after the administration of a single 800 mg intravenous dose of pefloxacin over 1 hour for 26 patients who underwent surgery in an orthopedic surgery ward. Drug concentration was measured by a microbiological method (extraction of the antibiotic in buffer or with chloroform). Up until the 24th hour, in 25/26 cases, the bone levels were superior to 2 mg/l (the critical concentration of pefloxacin) in cortical as well as in spongy bone. Our study reveals a good diffusion of pefloxacin in bone, results which support the idea that this antibiotic may be prophylactically effective in orthopedic surgery.