Impact of Bacillus licheniformis from yaks following antibiotic therapy in mouse model

Gut microorganism (GM) is an integral component of the host microbiome and health system. Abuse of antibiotics disrupts the equilibrium of the microbiome, affecting environmental pathogens and host-associated bacteria alike. However, relatively little research on Bacillus licheniformis alleviates the adverse effects of antibiotics. To test the effect of B. licheniformis as a probiotic supplement against the effects of antibiotics, cefalexin was applied, and the recovery from cefalexin-induced jejunal community disorder and intestinal barrier damage was investigated by pathology, real-time PCR (RT-PCR), and high-throughput sequencing (HTS). The result showed that A group (antibiotic treatment) significantly reduced body weight and decreased the length of jejunal intestinal villi and the villi to crypt (V/C) value, which also caused structural damage to the jejunal mucosa. Meanwhile, antibiotic treatment suppressed the mRNA expression of tight junction proteins ZO-1, claudin, occludin, and Ki67 and elevated MUC2 expression more than the other Groups (P < 0.05 and P < 0.01). However, T group (B. licheniformis supplements after antibiotic treatment) restored the expression of the above genes, and there was no statistically significant difference compared to the control group (P > 0.05). Moreover, the antibiotic treatment increased the relative abundance of 4 bacterial phyla affiliated with 16 bacterial genera in the jejunum community, including the dominant Firmicutes, Proteobacteria, and Cyanobacteria in the jejunum. B. licheniformis supplements after antibiotic treatment reduced the relative abundance of Bacteroidetes and Proteobacteria and increased the relative abundance of Firmicutes, Epsilonbacteraeota, Lactobacillus, and Candidatus Stoquefichus. This study uses mimic real-world exposure scenarios by considering the concentration and duration of exposure relevant to environmental antibiotic contamination levels. We described the post-antibiotic treatment with B. licheniformis could restore intestinal microbiome disorders and repair the intestinal barrier. KEY POINTS: • B. licheniformis post-antibiotics restore gut balance, repair barrier, and aid health • Antibiotics harm the gut barrier, alter structure, and raise disease risk • Long-term antibiotics affect the gut and increase disease susceptibility.

Streamlined fabrication of AuPtRh trimetallic nanoparticles supported on Ti3C2MXene for enhanced photocatalytic activity in cephalosporins degradation

The escalating prevalence of cephalosporin antibiotics in wastewater poses a serious threat to public health and environmental balance. Thus, it is crucial to develop effective methods for removing cephalosporin antibiotics from water sources. Herein, we propose the use of AuPtRh trimetallic nanoparticles supported on Ti3C2MXene as a photocatalyst for the degradation of cephalosporin antibiotics. Initially, AuPtRh nanoparticles were uniformly grown onto Ti3C2MXene sheets using one-step reduction technique. The prepared AuPtRh/Ti3C2MXene exhibited a complete degradation of cefixime and ceftriaxone sodium, while an impressive degradation efficiency of 91.58 % for cephalexin was achieved after 60 min of exposure to visible light, surpassing the performance of its individual AuPtRh nanoparticles and Ti3C2MXene. The enhanced photoactivity of AuPtRh/Ti3C2MXene was resulted from improved light absorption capacity and efficient generation, separation, and transfer of charge carriers driven by the formation of heterojunction between AuPtRh and Ti3C2MXene. Electron paramagnetic resonance and radicals trapping experiments results revealed that •O2- and h+ are the principal reactive species governing the degradation of cephalosporins. The photocatalyst exhibited excellent stability and could be reused four times without significant loss in efficiency. Our study highlights the potential of MXene composites for environmental remediation, offering insights into designing sustainable AuPtRh/Ti3C2MXene photocatalyst for water pollutant degradation.

Doxycycline versus cephalexin treatment of presumed streptococcal skin and soft tissue infection among adults presenting to the emergency department

Among 100 propensity score-matched emergency department patients receiving ≤14 days doxycycline versus cephalexin monotherapy for outpatient treatment of nonpurulent (presumed streptococcal) skin and soft tissue infection, a low rate of 14-day clinical failure was observed [6% each group; odds ratio (OR), 1.34 (0.21-8.69); P = 0.745], defined as hospital admission, i.v. antibiotic therapy, or change in oral antibiotic. Doxycycline may represent a reasonable therapeutic alternative for this indication in regions with low tetracycline resistance.

Quantitative analysis of cephalexin in solid dosage form by Raman spectroscopy and chemometric tools

OBJECTIVE

To use Raman Spectroscopy for qualitative and quantitative evaluation of pharmaceutical formulations of active pharmaceutical ingredient (API) of Cephalexin.

SIGNIFICANCE

Raman Spectroscopy is a noninvasive, nondestructive, reliable and rapid detection technique used for various pharmaceutical drugs quantification. The present study explores the potential of Raman Spectroscopy for quantitative analysis of pharmaceutical drugs.

METHOD

For qualitative and quantitative analysis of Cephalexin API, various standard samples containing less and more concentration of API than commercial tablet was prepared. To study spectral differences, the mean plot of all the samples was prepared. For qualitative analysis, Principal Component Analysis (PCA) and for quantitative analysis Partial Least Square Regression analysis (PLSR) was used. Both of these are Multivariate data analysis techniques and give reliable results as published in previous literature.

RESULTS

PCA model distinguished all the Raman Spectral data related to the various Cephalexin solid dosage formulations whereas the PLSR model was used to calculate the concentration of different unknown formulations. For the PLSR model, RMSEC and RMSEP were determined to be 3.3953 and 3.8972, respectively. The prediction efficiency of this built PLSR model was found to be very good with a goodness of the model value (R2) of 0.98. The PLSR model also predicted the concentrations of Cephalexin formulations in the blind or unknown sample.

CONCLUSION

These findings demonstrate that the Raman spectroscopy coupled to PLSR analysis could be regarded as a fast and effectively reliable tool for quantitative analysis of pharmaceutical drugs.

Condition optimization of eco-friendly RP-HPLC and MCR methods via Box-Behnken design and six sigma approach for detecting antibiotic residues

A precise, Eco-friendly, and highly sensitive RP-HPLC method was employed using quality-by-design principles to concurrently identify cephalexin and cefixime residues in the manufacturing machines using a hypersil BDS C18 column (250 × 4.6 mm, 5 μm) at wavelength 254 nm. The Box-Behnken design was applied to obtain the best chromatographic conditions with the fewest possible trials. Three independent factors viz organic composition, flow rate, and pH were used to assess their effects on the responses' resolution and retention time. Overlay plot and desirability functions were implemented to predict responses of the high resolution and relatively short retention time using a mobile phase composed of acidic water: acetonitrile (85:15, v/v) at pH 4.5 adjusted by phosphoric acid with a flow rate of 2.0 mL/min. The spectral overlapping of the drugs was successfully resolved by the mean centering ratio (MCR) spectra approach at 261 nm and 298 nm for cephalexin and cefixime, respectively. Good linearity results were obtained for the suggested HPLC and MCR methods over the concentration range of (0.05-10 ppm) and (5-30 ppm) with a detection limit of 0.003, 0.004, 0.26, and 0.23 ppm, and quantitation limits of 0.008, 0.013, 0.79, and 0.68 ppm for cephalexin and cefixime, respectively, with a correlation coefficient of ≥ 0.9998 and good swab recovery results of 99-99.5%. A process capability index was accomplished for chemical and micro results, illustrating that both are extremely capable. The suggested method was effectively validated using ICH recommendations.

Phage-antibiotic synergy: Cell filamentation is a key driver of successful phage predation

Phages are promising tools to fight antibiotic-resistant bacteria, and as for now, phage therapy is essentially performed in combination with antibiotics. Interestingly, combined treatments including phages and a wide range of antibiotics lead to an increased bacterial killing, a phenomenon called phage-antibiotic synergy (PAS), suggesting that antibiotic-induced changes in bacterial physiology alter the dynamics of phage propagation. Using single-phage and single-cell techniques, each step of the lytic cycle of phage HK620 was studied in E. coli cultures treated with either ceftazidime, cephalexin or ciprofloxacin, three filamentation-inducing antibiotics. In the presence of sublethal doses of antibiotics, multiple stress tolerance and DNA repair pathways are triggered following activation of the SOS response. One of the most notable effects is the inhibition of bacterial division. As a result, a significant fraction of cells forms filaments that stop dividing but have higher rates of mutagenesis. Antibiotic-induced filaments become easy targets for phages due to their enlarged surface areas, as demonstrated by fluorescence microscopy and flow cytometry techniques. Adsorption, infection and lysis occur more often in filamentous cells compared to regular-sized bacteria. In addition, the reduction in bacterial numbers caused by impaired cell division may account for the faster elimination of bacteria during PAS. We developed a mathematical model to capture the interaction between sublethal doses of antibiotics and exposition to phages. This model shows that the induction of filamentation by sublethal doses of antibiotics can amplify the replication of phages and therefore yield PAS. We also use this model to study the consequences of PAS on the emergence of antibiotic resistance. A significant percentage of hyper-mutagenic filamentous bacteria are effectively killed by phages due to their increased susceptibility to infection. As a result, the addition of even a very low number of bacteriophages produced a strong reduction of the mutagenesis rate of the entire bacterial population. We confirm this prediction experimentally using reporters for bacterial DNA repair. Our work highlights the multiple benefits associated with the combination of sublethal doses of antibiotics with bacteriophages.

Drug-Induced Liver Injury with Commonly Used Antibiotics in the All of Us Research Program

Antibiotics are a known cause of idiosyncratic drug-induced liver injury (DILI). According to the Centers for Disease Control and Prevention, the five most commonly prescribed antibiotics in the United States are azithromycin, ciprofloxacin, cephalexin, amoxicillin, and amoxicillin-clavulanate. We quantified the frequency of acute DILI for these common antibiotics in the All of Us Research Program, one of the largest electronic health record (EHR)-linked research cohorts in the United States. Retrospective analyses were conducted applying a standardized phenotyping algorithm to de-identified clinical data available in the All of Us database for 318,598 study participants. Between February 1984 and December 2022, more than 30% of All of Us participants (n = 119,812 individuals) had been exposed to at least 1 of our 5 study drugs. Initial screening identified 591 potential case patients that met our preselected laboratory-based phenotyping criteria. Because DILI is a diagnosis of exclusion, we then used phenome scanning to narrow the case counts by (i) scanning all EHRs to identify all alternative diagnostic explanations for the laboratory abnormalities, and (ii) leveraging International Classification of Disease 9th revision (ICD)-9 and ICD 10th revision (ICD)-10 codes as exclusion criteria to eliminate misclassification. Our final case counts were 30 DILI cases with amoxicillin-clavulanate, 24 cases with azithromycin, 24 cases with ciprofloxacin, 22 cases with amoxicillin alone, and < 20 cases with cephalexin. These findings demonstrate that data from EHR-linked research cohorts can be efficiently mined to identify DILI cases related to the use of common antibiotics.

Fabrication and characterization of Ti/polyaniline-Co/PbO2-Co for efficient electrochemical degradation of cephalexin in secondary effluents

The traditional interlayer of PbO₂ electrode possessed many problems, such as short service lifetime and limited specific surface area. Herein, a novel and efficient Ti/polyaniline-Co/PbO₂-Co electrode was conctructed employing cyclic voltammetry to introduce a Co-doped polyaniline interlayer and anodic electrodeposition to synthetize a β-PbO₂-Co active layer. Compared with pristine PbO₂ electrode, Ti/polyaniline-Co/PbO₂-Co exhibited more compact crystalline shape and higher active sites amounts. Pratically, the electrochemical degradation of 5 mg L^-1 cephalexin in real secondary effluents was effectively achieved by the novel anode with 87.42% cephalexin removal and 71.8% COD mineralization after 120 min of 15 mA cm^-2 electrolysis. The hydroxyl radical production and electrochemical stability were increased by 3.16 and 3.27 times respectively. The cephalexin degradation pathway was investigated by combining a density functional theory-based theoretical approach and LC-QTrap-MS/MS. The most likely cleavage point of the β-lactam ring was the O=C-N bond, whose attack would produce small molecular compounds containing the thiazole and 4, 6-thiazine rings. Further oxidation produced inorganic ions; quantitative investigations indicated the amino groups to undergo decomposition to form aqueous NH₄⁺, which was further oxidized to NO₃^-. The accumulation of NO₃^- and SO₄^2-, combined with a decrease in toxicity toward Escherichia coli, demonstrated the efficient mineralization of cephalexin on the Ti/polyaniline-Co/PbO₂-Co electrode.

WO3/Ag/ZnO S-scheme heterostructure thin film spinning disc photoreactor for intensified photodegradation of cephalexin antibiotic

The presence of antibiotics in wastes and drinking water has led to serious environmental and health concerns, further necessitating the development of an advanced sustainable strategy to eliminate antibiotics from aquatic media. In this context, the present research reports the successful fabrication of a spinning disc photoreactor (SDPR) supported ZnO/Ag/WO₃ S-scheme visible-light-driven thin-film photocatalyst to study the degradation of cephalexin (CPX) as a target pollutant under blue light irradiation. The optical, electrochemical and physicochemical characterization of the as-prepared thin-film samples were carried out by XRD, top-view FE-SEM, EDS-mapping, UV-Vis-DRS, contact angle, EIS, transient photocurrent, mott Schottky and AFM techniques. The rod shape morphology of the samples with moderate surface roughness, desirable hydrophobicity, low bandgap and remarkable band structure alignment confirmed the applicability of as-prepared thin-film with an average photon flux of 1.94 × 10^-4-8.61 × 10^-5 E's m^-2 s^-1. The use of a rotating catalytic disc impressively declined the photon propagation distance, decremented the probability of light absorption by the solution, and intensified the mass transfer rate. The maximum throughputs of 98.8% efficiencies for CPX degradation were achieved at a rotational speed of 180 rpm, the solution flow rate of 1.0 L min^-1, the light intensity of 11 mW cm^-2, and initial CPX concentration of 40 mg L^-1, illumination time of 80 min, and pH of 6. Damkohler number (Da) value was found to be 1.23 × 10^-2 at the optimum conditions, indicating the negligibility of the external mass transfer resistance in the SDPR. The photocatalytic mechanism was elucidated for finding the most operative radical species, suggesting the crucial role of ·O₂^- in photodegradation of CPX and a drastic improvement of the charge separation by S-scheme heterostructure and facilitation by Ag mediator. Findings indicated that the developed reusable and robust SDPR benefited from an s-scheme photocatalyst can be a promising technology for degradation of the organic compounds.

Reduced incidence of CIED infections with peri- and post-operative antibiotic use in CRT-P/D and ICD procedures

Higher cardiac implantable electronic device (CIED) infection incidence has been observed with cardiac resynchronization therapy pacemaker/defibrillator (CRT-P/D) and implantable cardioverter defibrillator (ICD) devices compared to traditional pacemakers with a 1.2% rate reported at 1 year. CIED infection management has high morbidity/mortality. A previous study from this institution demonstrated significantly reduced CIED infection rate when peri/post-operative antibiotics were given for traditional pacemaker procedures. The present study examines CIED infection incidence following peri/post-operative antibiotics during CRT-P/D and ICD procedures. All patients who underwent CRT-P/D and ICD procedures from 1996 to 2015 received IV cephalexin/clindamycin pre- and 8-hours post-procedure followed by 5 days of oral therapy. There were 427 procedures (CRT-P = 146 (34.2%); CRT-D = 142 (33.3%); ICD = 139 (32.6%)). Mean age at time of procedure was 61.6 years. Mean follow-up duration was 4.26 years. CIED infection occurred in 6 patients (ICD = 4, CRT-P = 1, CRT-D = 1), amounting to a rate of 4.96/1000 device-years in total. Times to CIED infection from procedure were: 1.7, 3.5, 6.7, 7.3, 7.9 and 9.2 years. Five out of 6 infections occurred in patients with repeat procedures. This study demonstrates that administration of peri- followed by post-operative antibiotics during CRT-P/D and ICD procedures is associated with a very low rate of CIED infection. This rate of 4.96 infections per 1000 device-years compares favorably to contemporary rates of 8.9 infections per 1000 device-years. Most CIED infections occur late and well-beyond the 1-year follow-up of the Prevention of Arrhythmia Device Infection Trial, the largest trial on this question. This approach should be considered pending a definitive trial.

Synergistic catalysis of ozonation and photooxidation by sandwich structured MnO2-NH2/GO/p-C3N4 on cephalexin degradation

Antibiotics such as cephalexin (CLX) are often detected in water and sewage, and advanced oxidation processes (AOPs) are usually the most effective method to degrade them. Currently, the synergy of AOPs has raised lively interest in water and wastewater treatment. Here the sandwiched catalyst of MnO₂-NH₂/GO/p-C₃N₄ (MN/GO/CN) is synthesized, in which graphene oxide (GO) acts as "core layer" connecting aminated MnO₂ (MnO₂-NH₂) for catalytic ozonation and proton-functionalized g-C₃N₄ (p-C₃N₄) for photocatalysis. The MN/GO/CN combines the AOPs of catalytic ozonation and photocatalysis, initiates hydroxyl radicals 4.2 times the sum of catalytic ozonation and photocatalysis, and achieves the first order kinetics constant of 2.4 × 10^-2/s, which is 2.7, 8.1 and 20.1 times that of catalytic ozonation, photo ozonation, and photocatalysis, respectively, and consequently reduces CLX from 1.0 mg/L to below the detection limit within 2.5 min, demonstrating the strong synergism between the AOPs. The sandwich structure enables GO to mediate the electron transfer between p-C₃N₄ and MnO₂-NH₂, which not only hinders electron-hole recombination on p-C₃N₄, but also speeds redox electron cycle on MnO₂ to promote the catalytic activity. The simultaneous catalytic ozonation and photocatalysis by sandwiched bifunctional catalyst to obtain synergistic effect will find its broad prospect in water and wastewater treatment.

Peroxydisulfate activation by CuO pellets in a fixed-bed column, operating mode and assessments for antibiotics degradation and urban wastewater disinfection

A fixed-bed column packed with copper oxide pellets (FBC-CuO) combined with peroxydisulfate (PDS) as a primary oxidant was assessed as an option for simultaneously wastewater decontamination (antibiotics) and disinfection (bacteria, viruses, and protozoa). Preliminary to these experiments, phenol was used as the target molecule to investigate the working mode of FBC-CuO under various operating conditions, such as varying flow rates, initial persulfate, and phenol concentrations. Then, the removal of a mix of five representative antibiotics (amoxicillin (AMX), cefalexin (CFX), ofloxacin (OFL), sulfamethoxazole (SMX), and clarithromycin (CLA)) in secondary treated urban wastewater (STWW) was evaluated. AMX, CFX, and OFL were effectively removed by simply flowing through the FBC-CuO, and the addition of PDS (500 µM) systematically enhanced the degradation of all targeted antibiotics, which is also the necessary condition for the removal of SMX and CLA. Urban wastewater disinfection was evaluated by monitoring targeted pathogens originally in the STWW. A significant reduction of Escherichia coli, Enterococcus, F-specific RNA bacteriophages was observed after the treatment by FBC-CuO with 500 µM PDS. X-ray diffraction measurement and scanning electron microscopy performed on CuO pellets before and after treatment confirmed that the structure of the catalyst was preserved without any phase segregation. Finally, quantification of Cu(II) at the outlet of FBC-CuO indicate a non-negligible but limited released. All these results underline the potential of the FBC-CuO combined with PDS at the field scale for the degradation of micropollutants and inactivation of pathogens in wastewater.

Assessing the Variability of Antibiotic Management in Patients With Open Hand Fractures Presenting to the Pediatric Emergency Department

OBJECTIVES

Open hand fractures may be difficult to recognize and treat. There is variability in management and administration of antibiotics for these types of injuries. Unlike open long bone fractures, there is no standardized protocol for antibiotic administration for open hand fractures in children. The objective of this study is to assess the variability of antibiotic management of open hand fractures in children.

METHODS

We performed a retrospective chart review at a tertiary hospital in New York of patients with hand injuries between ages 0 and 18 years presenting to the emergency department during January 2019 and December 2020. Patient encounters were reviewed for open fractures of the hand. Descriptive statistics were included for demographic and physical characteristics.

RESULTS

There were 80 encounters with open hand fractures, of which the most common being tuft fractures (77.5%). The mean age was 7.6 years (SD, 4.7 years) with male predominance (58.8%). Crush injuries were the most common mechanism of injury (78.8%). Bedside repair was performed on 62 encounters (77.5%), of which 45 (72.5%) required nail bed repair, 56 (90.3%) required suturing, and 24 (38.7%) required reduction. Antibiotics were given to 62 (77.5%) encounters, most commonly oral cefalexin (45.2%), oral amoxicillin-clavulanic acid (27.4%), and intravenous cefazolin (14.5%). Median time to antibiotics from emergency department registration to administration was 150 minutes (interquartile range, 92-216 minutes). Antibiotic prescriptions were sent for 71 encounters (88.8%). Seventy seven (96.3%) of the encounters were discharged home.

CONCLUSIONS

Pediatric open hand fractures have a variability of type and timing to antibiotics. Future initiatives should attempt to create standardized guidelines for management of open hand fractures.

Cephalexin degradation initiated by OH radicals: theoretical prediction of the mechanisms and the toxicity of byproducts

In this work, the density functional theory is used to study the local reactivity of cephalexin (CLX) to radical attack and explain the mechanism of the reaction between CLX and hydroxyl radical attack leading to degradation byproducts. The reaction between •OH and CLX is supposed to lead to either an addition of a hydroxyl radical or an abstraction of a hydrogen. The results showed that the affinity of cephalexin for addition reactions increases as it passes from the gas to the aqueous phase and decreases as it passes from the neutral to the ionized form. Thermodynamic data confirmed that OH addition radicals (R_add) are thermodynamically favored over H abstraction radicals (R_abs). The ecotoxicity assessments of CLX and its byproducts are estimated from the acute toxicities toward green algae, Daphnia, and fish. The formation of byproducts is safe for aquatic organisms, and only one byproduct is harmful to Daphnia.

Cephalexin removal by persulfate activation using simulated sunlight and ferrous ions

This study presents the main results related to the use of activated persulfate (PS) in the elimination of the beta-lactam antibiotic cephalexin (CPX). Experiments were done using K₂S₂O₈ and simulated sunlight. A face-centered central composite experimental design was used to analyze the effects of the solution pH and the PS concentration on the reaction, and to determine the optimized conditions that favor the CPX elimination. The results indicated that the removal of CPX is promoted by an acidic pH and under the higher evaluated PS dose (7.5 mg L^-1). CPX total removal was achieved in 30 min. The analysis of the effect of the pollutant initial concentration indicated that a pseudo-first-order kinetics model can be used to describe the reaction. Likewise, the use of Fe²⁺ ions for PS activation (in the dark) was evaluated and established that a higher concentration of ions favors the pollutant removal. Control tests and under the presence of scavenger agents indicated that both HO• and SO₄^-• radicals would be present in the solution and promote the CPX elimination. The assessment of the solution dissolved organic carbon, nitrates and sulfates was also carried out, and indicated that a portion of the organic matter was mineralized.

A ratiometric fluorescent probe based on carbon dots and gold nanocluster encapsulated metal-organic framework for detection of cephalexin residues in milk

Herein, we report a ratiometric fluorescent probe based on in situ incorporation of both Gold nanoclusters (AuNCs) and Green emitting carbon dots (gCDs) into zeolitic imidazolate framework-8 (ZIF-8) to analysis of Cephalexin (CFX). Under a single excitation wavelength of 400 nm, the sensor exhibits dual-emissions centered at 520 and 630 nm. The fluorescence of AuNCs (630 nm) is selectively quenched by CFX, whereas the fluorescence of gCDs (520 nm) remainsalmostconstant. The ratiometric fluorescence signal (F₅₂₀/F₆₃₀) of the prepared composite (gCDc/AuNCs @ ZIF-8) is linearly proportional to the concentration of CFX from 0.1 to 6 ng/mL with a low detection limit (LOD) of 0.04 ng/mL, which is below the maximum residues limit (MRL) of 100 ng/mL set by the Food and Drug Administration (FDA). Moreover, the designed sensing platform was successfully applied to detect CFX in the milk samples.

Photocatalyst production from wasted sediment and quality improvement with titanium dioxide to remove cephalexin in the presence of hydrogen peroxide and ultrasonic waves: A cost-effective technique

In this study, wasted sediment (sludge waste from shipping docks) was coupled with titanium isopropoxide by the thermal and sol-gel method as a new photocatalyst. The sediment-titanate catalyst alongside ultrasonic and UV was activated hydrogen peroxide to produce OH radicals and decompose cephalexin (CEP). The photocatalyst was crystalline with 52.29 m²/g BET area. The best destruction rate of 87.01% based on COD test was achieved at optimal conditions (pH: 8, cephalexin concentration: 100 mg/L, H₂O₂: 1.63 mg/L, UV: 15 W/m², ultrasonication time: 100 min at 40 kHz, photocatalyst quantity: 1.5 g/L). The trend of anions effect was NO₃^- ≤ SO₄^2- ≤ Cl^-. Decomposition of cephalexin in water solution followed the first-order kinetics (k > 0.01 min^-1, R² > 0.9). The percentage of cephalexin removal from urban water (76%) and hospital wastewater (63%) has decreased compared to the distilled water solution (87%), which is probably due to the presence of radical inhibitors. The consumed electrical energy of the studied system was calculated by 0.031 kW/h. The developed system is a promising and economical method to remove cephalexin.

Insights into the degradation mechanisms and pathways of cephalexin during homogeneous and heterogeneous photo-Fenton processes

The widespread occurrence of antibiotics in the environment poses a potential threat to human health. The photo-Fenton process has demonstrated better degradation performance compared with the conventional wastewater treatment processes. In this study, the degradation of cephalexin was evaluated comparatively by homogeneous (Fe²⁺/H₂O₂/UV) and heterogeneous (MoS₂@Fe/H₂O₂/UV) photo-Fenton processes. Key influencing factors affecting photo-Fenton performance were assessed, confirming the optimum Fe²⁺ concentration at 0.2016 mg L^-1 and H₂O₂/Fe²⁺ molar ratio at 6. Higher degradation efficiency (73.10%) and pseudo-first-order degradation rate constant (0.0078 min^-1) were achieved with the assistance of MoS₂@Fe as the heterogeneous catalyst. Completely different degradation products were identified in the homogeneous and heterogeneous photo-Fenton processes, with main degradation pathways proposed as β-lactam ring-opening, sulfoxide formation, demethylation, N-dealkylation, decarbonylation, hydroxylation and deamination in the Fe²⁺/H₂O₂/UV system and β-lactam ring-opening, hydroxylation, dehydration, amide hydrolysis, and demethylation and ring contraction in the MoS₂@Fe/H₂O₂/UV system, respectively. The formation of newly identified products might root in the attack on cephalexin from active species (i.e., OH, h⁺, e^-, O₂^-) photoinduced by the MoS₂@Fe catalyst. Results also indicated the importance of understanding the underlying mechanisms and pathways to eliminate the antimicrobial activities of antibiotics in the future.

Removal of cephalexin and erythromycin antibiotics, and their resistance genes, by microalgae-bacteria consortium from wastewater treatment plant secondary effluents

Antibiotics have become a concern in the aquatic environments owing to the potential development of bacterial resistances. Thus, this study evaluated the removal of cephalexin (CEP) and erythromycin (ERY) from a local wastewater treatment plant (WWTP) effluent, mediated by microalgae-bacteria consortium. Likewise, the removal of correlated antibiotics resistance genes bla_TEM and ermB was also assessed. The incubation results showed that the added concentrations of selected antibiotics did not restrain the consortium growth. Moreover, CEP and ERY were almost completely removed after the cultivation period, reaching total removals of 96.54% and 92.38%, respectively. The symbiotic interaction between microalgae and bacteria plays a role in the kinetics removal of CEP and ERY. The abundance of bla_TEM and ermB was reduced by 0.56 and 1.75 logs, respectively. Lastly, our results suggest that technology based on natural microalgae-bacteria consortium could be a potential alternative to improve the quality of WWTP effluents.

Cephalexin removal by a novel Cu-Zn bionanocomposite biosynthesized in secondary metabolic products of Aspergillus arenarioides EAN603 with pumpkin peels medium: Optimization, kinetic and artificial neural network models

The present study aimed to investigate the removal efficiency of cephalexin (CFX) by a novel Cu-Zn bionanocomposite biosynthesized in the secondary metabolic products of Aspergillus arenarioides EAN603 with pumpkin peels medium (CZ-BNC-APP). The optimization study was performed based on CFX concentrations (1, 10.5 and 20 ppm); CZ-BNC-APP dosage (10, 55 and 100 mg/L); time (10, 55 and 100 min), temperature (20, 32.5 and 45 °C). The artificial neural network (ANN) model was used to understand the CFX behavior for the factors affecting removal process. The CZ-BNC-APP showed an irregular shape with porous structure and size between 20 and 80 nm. The FTIR detected CC, C-O and OH groups. ANN model revealed that CZ-BNC-APP dosage exhibited the vital role in the removal process, while the removal process having a thermodynamic nature. The CFX removal was optimized with 12.41 ppm CFX, 60.60 mg/L of CZ-BNC-APP, after 97.55 min and at 35 °C, the real maximum removal was 95.53% with 100.52 mg g^-1 of the maximum adsorption capacity and 99.5% of the coefficient. The adsorption of CFX on CZ-BNC-APP was fitted with pseudo-second-order model and both Langmuir and Freundlich isotherms models. These findings revealed that CZ-BNC-APP exhibited high potential to remove CFX.

Sustainable approaches for removal of cephalexin antibiotic from non-clinical environments: A critical review

In this article, the removal of cephalexin (CFX) antibiotic from non-clinical environment is reviewed. Adsorption and photocatalytic degradation techniques are widely used to remove CFX from waters and wastewaters, the combination of these methods is becoming more common for CFX removal. The treatment methods of CFX has not been reviewed before, the present article aim is to organize the scattered available information regarding sustainable approaches for CFX removal from non-clinical environment. These include adsorption by nanoparticles, bacterial biomass, biodegradation by bacterial enzymes and the photocatalysis using different catalysts and Photo-Fenton photocatalysis. The metal-organic frameworks (MOFs) appeared to have high potential for CFX degradation. It is evident from the recently papers reviewed that the effective methods could be used in place of commercial activated carbon. The widespread uses of photocatalytic degradation for CFX remediation are strongly recommended due to their engineering applicability, technical feasibility, and high effectiveness. The adsorption capacity of the CFX is ranging from 7 mg CFX g^-1 of activated carbon nanoparticles to 1667 mg CFX g^-1 of Nano-zero-valent iron from Nettle. In contrast, the photo-degradation was 45% using Photo-Fenton while has increased to 100% using heterogeneous photoelectro-Fenton (HPEF) with UVA light using chalcopyrite catalyst.

Pyrolyzed carbon derived from red soil as an efficient catalyst for cephalexin removal

Red soil, a typical soil type in southern China, has been deemed infertile or nutrient-deficient. In this study, red soil was firstly utilized as a substrate for preparing catalysts, which were then successfully applied to the catalytic wet peroxide oxidation (CWPO) of cephalexin. The highest cephalexin removal was 95.23% and TOC removal was 60.58%, with the catalyst pyrolyzed at 500 °C (RC500). The high iron content and proportion of Fe(II) on the surface of RC500 was responsible for the decomposition of H₂O₂ into· OH. Moreover, the porous structure and existence of other minerals (such as SiO₂ and Al₂O₃) in the catalyst were also significant for enhancing the catalytic activity of RC500. Afterwards, the influencing parameters, including temperature, pH, the dose of H₂O₂, and catalyst, were examined for cephalexin degradation. It was noteworthy that RC500 was efficient in treating hospital wastewater when using a self-design pilot device. A density functional theory analysis of cephalexin was conducted to establish the possible position attacked by ·OH, and the possibly ruptured one. Meanwhile, the intermediates generated during CWPO were identified. Finally, a reliable degradation pathway of cephalexin was proposed on the basis of the results.

Degradation of micropollutant cephalexin by ultraviolet (UV) and assessment of residual antimicrobial activity of transformation products

Cephalexin (CEX) is an antibiotic commonly used to treat bacterial infections in humans and animals. However, it is also a micropollutant. Thus, this study evaluated the degradation of CEX using ultraviolet irradiation (UV-C) and analyzed the by-products as well as their residual antimicrobial activity. A reactor with a mercury vapor lamp was used for the degradation. Irradiated CEX solutions were collected over a period of 4 hours and analyzed using high-performance liquid chromatography coupled with mass spectrometry. For the residual antimicrobial activity the susceptibility test was performed using Staphylococcus aureus and Escherichia coli microorganisms by broth microdilution. It was found that CEX, after treatment, generated a metabolite with a mass of 150 m/z in 15 min. A four- and eightfold increase in the minimum inhibitory concentration of the drug against S. aureus and E. coli could be observed, respectively, after 20 min. Therefore, this treatment proved to be effective in the degradation of CEX, being able to degrade 81% of the initial molecule of the drug in 20 min. Furthermore, the antimicrobial activity of the CEX solution decreased as the irradiation time increased, indicating loss of antimicrobial function of the initial CEX molecule and the resulting by-products.

Cerium-modified iron oxides applied as catalysts in the heterogeneous Fenton system for degradation of cephalexin

The effect of incorporation of different amounts of cerium on iron oxides and different heat treatment temperatures was evaluated for the degradation of cephalexin (CEX) using heterogeneous Fenton and photo-Fenton processes. The materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), specific area (BET), and zeta potential (ZP). The conversion of magnetite to maghemite was observed when a 140 °C thermal treatment was applied. The insertion of cerium resulted in a loss of the uniform spherical shape of the particles. The material containing the lowest amount of cerium (0.5% w/w) presented an increase in the specific area from 91.2 to 171.6 m² g^-1 relative to the pure iron oxide, while with 2% (w/w) a decrease to 99.2 m² g^-1 was observed for the materials treated at 70 °C. The same behavior was observed for materials treated at 140 °C, however, with smaller areas. At pH 6.0, a low catalytic activity was observed contrasting to the high consumption of H₂O₂, suggesting its catalytic decomposition into water and oxygen. This was confirmed by the very low production of HO• in the degradation system. On the other hand, the high production of HO• was observed at pH 3.5, which was chosen as a working pH. The material treated at 140 °C and containing 1% Ce (w/w) was the highlight, promoting degradation of 0.052 mg of CEX per m² area of the catalyst after 150 min using 1.0 mmol L^-1 of H₂O₂. The CEX intermediates identified indicated hydroxylation as the major route of degradation.

Tin dioxide decorated on Ni-encapsulated nitrogen-doped carbon nanotubes for anodic electrolysis and persulfate activation to degrade cephalexin: Mineralization and degradation pathway

In this study, bamboo-shaped carbon nanotubes exhibiting high nitrogen content and Ni encapsulation (Ni@NCNT) were effectively synthesized by a simple pyrolysis method. The catalytic peroxydisulfate activation for cephalexin (CPX) degradation was investigated using the prepared material. SnO₂ was further decorated and fabricated on the anode material (SnO₂/Ni@NCNT) for electrochemical degradation of CPX in an aqueous solution. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that the SnO₂ nanoparticles were uniformly distributed on the surface of Ni@NCNT. Electrochemical characterization employing cyclic voltammetry and linear sweep voltammetry demonstrated that SnO₂/Ni@NCNT displayed higher oxygen evolution potential and electrocatalytic activity than Ni@NCNT. Mineralization of CPX in wastewater was performed using electrolysis coupled with persulfate oxidation. The analysis revealed a synergistic strengthening effect. The electropersulfate oxidation resulted in higher total organic carbon (TOC) removal (70.3%) than the sum of electrooxidation (48.1%) and persulfate oxidation (9.2%) toward CPX. This phenomenon might result from the regeneration of sulfate radicals (SO₄^•-) on the anode and complementary oxidation by SO₄^•- and OH. Persulfate oxidation alone was shown to result in low TOC removal, although CPX was mostly degraded. Additionally, the CPX degradation pathway involving electropersulfate oxidation was proposed and it is indicated that CPX molecules were completed decomposed by the examination of short chain acids, mineralized ions, and ecotoxicity evolution indicated that the antibiotic was completely degraded. This study provides a new approach for the design and preparation of novel electrode materials and electrochemical degradation facilities for the removal of pollutants via persulfate activation.

A smartphone-combined ratiometric fluorescence probe for specifically and visibly detecting cephalexin

A smartphone-combined dual-emission ratiometric fluorescence probe for specifically and visibly detecting cephalexin was first designed. In the probe, blue-emitting fluorescent carbon dots (CDs) was synthesized and covered with a layer of silica spacer. Red-emitting fluorescent CdTe QDs (r-QDs) was grafted onto the silica nanospheres as an analytical probe. Then, the cephalexin antibody was covalent grafted to the ratio sensor to increase the selectivity. The ratio of fluorescence intensity (FL) of r-QDs and CDs was quenched with the increasing concentration of cephalexin. The detection method has good linear response in the range of 1-500 μM and the detection limit was 0.7 μM. Then portable device based on smartphone detection was constructed according to the color change under UV lamp. The detection image was obtained through the smartphone camera, and the color picker APP installed in the smartphone captured the RGB value of the image. In addition, this method was also used to determine the amount of cephalexin in milk samples with recovery of 94.1%-102.2%. These results showed that it was a portable, simple and visible method to detect cephalexin in food analysis and environmental monitoring.

Photocatalytic degradation of cephalexin by g-C3N4/Zn doped Fe3O4 under visible light

In this work, we reported synthesis of a novel magnetically separable g-C₃N₄/Zn doped Fe₃O₄ composite (g-CN/ZnFe) by a simple polyol thermal method. The characteristics of the as-prepared composite was checked by XRD, SEM, TEM, XPS, PL technologies. The optimized weight ratio of g-C₃N₄ and Zn doped Fe₃O₄ was investigated. In addition, the photocatalytic activities of the composite products were checked by degradation of Cephalexin (CEX) under visible light. The results showed that g-CN/ZnFe composite with an added 20% g-C₃N₄ exhibited the highest photocatalytic activity for cephalexin under visible light irradiation. The improved photocatalytic activity of 20% g-CN/ZnFe can be ascribed to the low combination rate of photoinduced electron/hole pairs. Especially, g-CN/ZnFe can be recovered easily by using an external magnetic field and has the high stability after six runs. These properties of the g-CN/ZnFe as-prepared composite could be a promising photocatalyst for the degradation of pharmaceutical contaminants.

Reponses of microbial community and antibiotic resistance genes to the selection pressures of ampicillin, cephalexin and chloramphenicol in activated sludge reactors

High concentrations of antibiotics can exert strong selection pressures on the microbial community and promote the emergence and dissemination of antibiotic resistance genes (ARGs). The activated sludge reactors treating ampicillin, cephalexin and chloramphenicol production wastewater were established to investigate the responses of microbial community, ARGs and mobile genetic elements (MGEs) to antibiotics. Antibiotic selection pressures significantly declined the microbial diversity and changed microbial community structures. Based on metagenomic analysis, a total of 500 ARG subtypes affiliated with 18 ARG types were identified and 63 ARGs were shared by all samples. The substantial increase of ARG abundance and the shifts of ARG profiles were significantly correlated with antibiotic types and concentrations. The evident enrichment of non-corresponding ARG types suggested the strong co-selection effects of the target antibiotics. Additionally, metagenomic analysis revealed the occurrence of 104 MGEs belonging to various types and the five dominant MGEs were tnpA, intI1, tniA, tniB and IS91. The ARG-MGE co-occurrence associations implied the potential mobility of ARGs. Network analysis also demonstrated that five ARG types (aminoglycoside, beta-lactam, chloramphenicol, multidrug and tetracycline resistance genes) tended to co-occur internally and the obvious co-occurrence patterns among different ARG types indicated the potential for resistance co-selection. Moreover, 15 bacterial genera were speculated as the hosts of diverse ARGs. This study provides a comprehensive overview of the occurrence of ARGs and MGEs and is valuable for the risk assessment and management of antibiotic resistance.

Uptake of cephalexin by lettuce, celery, and radish from water

The introduction of pharmaceuticals into agricultural lands from the application of biosolids and animal manure, and irrigation with treated wastewater has led to concern for animal and human health after the ingestion of pharmaceutical-tainted agricultural products. In this study, the uptake and accumulation of cephalexin, a commonly prescribed antibiotic, was compared in three common vegetables (lettuce, celery, and radish) grown in nutrient solution for 144 h. During the uptake experiments, cephalexin concentration in the nutrient solution decreased in the order of radish > celery > lettuce, while the accumulation of cephalexin in vegetable roots followed the rank of lettuce > celery > radish. The accumulation of cephalexin was below the limit of detection in radish roots. No accumulation of cephalexin was observed in the shoots of all three vegetables. The behaviors of cephalexin in vivo were further elucidated using in vitro measurements of cephalexin sorption by vegetable roots and transformation in plant enzyme extracts. The affinity of cephalexin to lettuce > celery > radish roots, and the respective sorption coefficients of 687, 303, and 161 mL g-1, coupled to the transformation of cephalexin in root enzyme extracts with estimated reaction rate constants of 0.020, 0.027 and 0.024 hr-1 for lettuce, celery and radish, could help elucidate the accumulation observed in the in vivo experiments. Overall, sorption by plant roots (affinity) and reaction with plant enzymes could collectively influence the uptake and accumulation of cephalexin in vegetables.

Enhanced removal of cephalexin and sulfadiazine in nitrifying membrane-aerated biofilm reactors

Nitrification process has been reported to be capable of degrading various pharmaceuticals due to the cometabolism of ammonia-oxidizing bacteria (AOB). The membrane aerated biofilm reactor (MABR) is an emerging configuration in wastewater treatment with advantages of high nitrification rate and low energy consumption. However, there are very few studies investigating the degradation of antibiotics at environmentally relevant levels in nitrifying MABR systems. In this study, the removal of two widely used antibiotics, cephalexin (CFX) and sulfadiazine (SDZ), was evaluated in two independent MABRs with nitrifying biofilms. The impacts of CFX and SDZ exposure on the nitrification performance and microbial community structure within biofilms were also investigated. The results showed that nitrifying biofilms were very efficient in removing CFX (94.6%) and SDZ (75.4%) with an initial concentration of 100 μg/L when hydraulic retention time (HRT) was 4 h in the reactors. When HRT decreased from 4 h to 3 h, the removal rates of CFX and SDZ increased significantly from 23.4 ± 1.0 μg/(L·h) and 18.7 ± 1.1 μg/(L·h), respectively, to 27.7 ± 1.3 μg/(L·h) (p＜0.01) and 20.8 ± 2.4 μg/(L·h) (p＜0.05), while the removal efficiencies decreased to 86.0% and 61.5%, respectively. Despite the exposure to CFX and SDZ, the nitrification performance was not affected, and microbial community structure within biofilms also remained relatively stable. This study shows that nitrifying MABR process is a promising option for the efficient removal of antibiotics from domestic wastewater.

Efficient removal of diclofenac and cephalexin from aqueous solution using Anthriscus sylvestris-derived activated biochar

The objective of this study was to investigate the adsorption of diclofenac (DF) and cephalexin (CPX) by Anthriscus sylvestris-derived activated biochar. The raw biochar (R-BC) and activated biochar (ACT-B) were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and elemental analyses techniques to obtain information regarding the morphology, functional groups and elements of the adsorbents. Batch studies were carried out to examine the effect of various operational parameters. The maximum adsorption capacity of ACT-B was 392.94 mg g^-1 for DF and 724.54 mg g^-1 for CPX. The removal of DF and CPX was influenced by temperature and the co-existing ions. The kinetic data fitted well with the pseudo-second-order kinetic model, whereas the isotherm data showed the best correlation with Langmuir isotherm model. Electrostatic adsorption, hydrophobic interaction and π-π bonding play a key role in adsorption of both adsorbates by ACT-B. Additionally, column studies were conducted using ACT-B at different flow rates and different concentrations of DF and CPX to investigate the practical applicability of ACT-B in removal of the target contaminants. Thus, this study provides a feasible approach to synthesize activated biochar that can minimize pharmaceuticals pollution in water bodies.

Treatment of antibiotic cephalexin by heterogeneous electrochemical Fenton-based processes using chalcopyrite as sustainable catalyst

The development of heterogeneous Fenton-based electrochemical advanced oxidation processes is important for the removal of organic pollutants at industrial level in the near future. This work reports the application of heterogeneous photoelectro-Fenton (HPEF) with UVA light as an enhanced alternative to the more widespread heterogeneous electro-Fenton (HEF) process. The treatment of the antibiotic cephalexin using chalcopyrite as a sustainable catalyst was studied using an undivided IrO₂/air-diffusion cell. XPS analysis showed the presence of Fe(III), Cu(I) and Cu(II) species on the surface. The amount of Fe²⁺ ions dissolved upon chalcopyrite exposure to continuous stirring and air bubbling was proportional to chalcopyrite content. In all cases, the occurrence of pH self-regulation to an optimum value near 3 was observed. The HEF and HPEF treatments of 100 mL of 50 mg L^-1 cephalexin solutions with 0.050 M Na₂SO₄ have been studied with 1.0 g L^-1 chalcopyrite at 50 mA cm^-2. Comparative homogeneous EF and PEF with dissolved Fe²⁺ and Cu²⁺ catalysts were also performed. HPEF was the most effective process, which can be mainly explained by the larger production of homogeneous and heterogeneous OH and the photodegradation of the complexes formed between iron and organics. The effect of applied current and catalyst concentration on HPEF performance was assessed. Recycling experiments showed a long-term stability of chalcopyrite. Seven initial aromatics and six cyclic by-products of cephalexin were identified, and a plausible degradation route that also includes five final carboxylic acids is proposed.

Simultaneous Quantification of Cephalexin and Sodium Benzoate in their Dosage forms by high analytical technique. Application of Lean Six Sigma and In-Vitro Dissolution studies

OBJECTIVES

The aim of the present work is to develop and validate a novel and simple Chromatographic and MCR methods for simultaneous quantification of cephalexin (CPH) and sodium benzoate (SDM) in their dosage form and application of Lean Six Sigma (LSS) to reduce variation and improve quality.

METHODS

Isocratic separation is performed using Agilent XDB-C8 (4.6mm×250mm) 5μm, with a mobile phase consisting of acetonitrile: water (30: 70, v/v) containing 0.1% orthophosphoric acid (OPA) at flow rate of 1.5mL/min and wavelength 254nm with injection volume of 20μL for HPLC and Agilent ZORBAX SB-C18 column (50mm×2.1mm, 1.8μm particle size) at flow rate 0.25mL/min, injection volume 0.8μL for UPLC. MCR spectrophotometric method is successfully applied for resolving spectral overlap of drugs at 240nm and 250nm for CPH and SDM, respectively. Comparative invitro dissolution studies are established on Generic product; Rivalexin and Lexin 250mg/5mL, consequently it had been considered equivalent and like the innovator product; Cephalexin USP 250mg/5mL using different USP media.

RESULTS

Good Linearity and recovery are achieved over the concentration range of 10-300, and 5-50μg/mL for the studied drugs. Process Capability Index (Cpk) is >1.33 and still capable during all stages of the product release.

CONCLUSION

The proposed method is accurate and could be applied to dosage form and LSS to interpret the data of quality attributes.

Unravelling kinetic and microbial responses of enriched nitrifying sludge under long-term exposure of cephalexin and sulfadiazine

Wastewater treatment plants (WWTPs) have been identified as one of the reservoirs of antibiotics. Although nitrifying bacteria have been reported to be capable of degrading various antibiotics, there are very few studies investigating long-term effects of antibiotics on kinetic and microbial responses of nitrifying bacteria. In this study, cephalexin (CFX) and sulfadiazine (SDZ) were selected to assess chronic impacts on nitrifying sludge with stepwise increasing concentrations in two independent bioreactors. The results showed that CFX and SDZ at an initial concentration of 100 μg/L could be efficiently removed by enriched nitrifying sludge, as evidenced by removal efficiencies of more than 88% and 85%, respectively. Ammonia-oxidizing bacteria (AOB) made a major contribution to the biodegradation of CFX and SDZ via cometabolism, compared to limited contributions from heterotrophic bacteria and nitrite-oxidizing bacteria. Chronic exposure to CFX (≥30 μg/L) could stimulate ammonium oxidation activity in terms of a significant enhancement of ammonium oxidation rate (p < 0.01). In contrast, the ammonium oxidation activity was inhibited due to exposure to 30 μg/L SDZ (p < 0.01), then it recovered after long-term adaption under exposure to 50 and 100 μg/L SDZ. In addition, 16S rRNA gene amplicon sequencing revealed that the relative abundance of AOB decreased distinctly from 23.8% to 28.8% in the control phase (without CFX or SDZ) to 14.2% and 10.8% under exposure to 100 μg/L CFX and SDZ, respectively. However, the expression level of amoA gene was up-regulated to overcome this adverse impact and maintain a stable and efficient removal of both ammonium and antibiotics. The findings in this study shed a light on chronic effects of antibiotic exposure on kinetic and microbial responses of enriched nitrifying sludge in WWTPs.

Bioremediation of Cephalexin with non-living Chlorella sp., biomass after lipid extraction

In this work, the removal of the Cephalexin by Chlorella sp., nonliving modified by extraction of lipids was evaluated. First, the microalga was grown to completing 20 days and later, the biomass of crop was centrifuged and the extraction of lipids was performed. Two adsorption experiments were performed: (1) with nonliving Chlorella sp. (control), and (2) the obtained biomass after lipid extraction. The high antibiotic removal, 71.19% and 82.77% (control), were obtained at the lowest initial concentration. The contact time between the biosorbent and the antibiotic was 2 h. The adsorption isotherm follows the Freundlich model and the obtained maximum absorption capacity was 63.29 mg of antibiotic/g of biosorbent for lipid-extracted biomass, while the control follows best to the Langmuir model with 129.87 mg/g in maximum absorption capacity. In summary, this biosorbent provides a potential alternative in the removal of Cephalexin.

[Validation of dissolution testing: evaluation of vibration levels of dissolution apparatuses]

The collaborative study participated by seven laboratories was carried out to develop a dissolution standard for evaluating vibration levels of dissolution apparatuses using enteric-coated granules of cefalexin (EG). Dissolution apparatuses could be divided into two groups according to their vibration levels and the dissolution test results of EG by the rotating basket method at 50 rpm. The critical value of acceleration was about 0.05 m/s2. The upper limit of normal dissolution rates of EG was calculated from the results of the rotating basket method at 50 rpm obtained from low vibration apparatuses. All high vibration apparatuses used in this study were distinguished by the limit from low vibration apparatuses, although most of them were not distinguished by current USP calibrators. These results suggest that EG would be useful as a calibrator for detection of apparatuses on high vibration levels.

In vitro drug release of antibiotic-loaded porous hydroxyapatite cement

A model was proposed for describing the observed in vitro release behavior of drugs from porous HAPs. The model consists of three successive stages; during the first stage, the dissolution medium penetrating into the porous HAP, the amount of the drug released is proportional to the square root of release time. During the second stage, after the pores in the HAP are filled out by the dissolution medium, the drug release being proceeded by dissolution into the dissolution medium outside of the HAP, the amount of the drug released is proportional to release time. During the third stage, after the drug concentration is decreased and below the solubility limit of the drug in the dissolution medium, the drug diffusing to the stirred dissolution medium outside of the HAP, the release rate is markedly slowed and the release amount approaches a plateau value.

Use of cephalexin-aztreonam-arabinose agar for selective isolation of Enterococcus faecium

Cephalexin-aztreonam-arabinose agar (CAA), a new selective agar, was examined in comparison with nalidixic acid-colistin agar for the differentiation of Enterococcus faecium from other enterococci and the ability to isolate the organism from feces. Two hundred sixteen enterococcus isolates and a variety of gram-positive and gram-negative control strains were inoculated onto both media. All control strains of E. faecium were easily differentiated from Enterococcus faecalis and Enterococcus durans on the basis of arabinose fermentation on CAA. Differentiation of E. faecium from other enterococci or Streptococcus bovis was not possible on nalidixic acid-colistin agar. Increased isolation of E. faecium was demonstrated on CAA when both media were compared for the isolation of the organism from feces. CAA has been shown to possess excellent differential and selective features allowing the simple and effective isolation of E. faecium from heavily contaminated sites.

Fluorescent spot test method for specific detection of beta-lactamases

A simple, sensitive fluorescent spot test method for specific detection of microbial beta-lactamases has been developed, based on the modification of a previously disclosed method (K. C. S. Chen, October 23, 1990, U.S. Patent 4,965,193). The new fluorescence developer used in the present study consisted of 0.5 mM HgCl2, in 0.5 M sodium citrate buffer, pH 4.5, prepared in 0.5% formaldehyde aqueous solution. A beta-lactam substrate solution consisting of a beta-lactam antibiotic with an acyl side chain containing an alpha-amino group and an alpha-phenyl group, or its derivatives, was incubated with a beta-lactamase-producing organism. One volume of the fluorescence developer was added to 4 vol of the incubated beta-lactam substrate solution, followed by heating the mixture at 45 degrees C for 10 min. The mixture was spotted on filter paper. Production of fluorophore indicated beta-lactamase activity. Each fluorophore was analyzed by TLC and its chemical identity was determined. Using ampicillin as the penicillinase substrate and cephalexin as the cephalosporinase substrate, the new method can be conveniently carried out by using dropping bottles for storing and dispensing the substrate solutions and the fluorescence developer. This modified method also provided more favorable conditions for the penicillinases to remain active during fluorescence development. Therefore, the sensitivity of the test was increased.

Methods for isolation of Bordetella pertussis from patients with whooping cough

Culture remains the standard method for diagnosis of whooping cough. While in the past attempts at isolating Bordetella pertussis from patients with suspected whooping cough were often unsuccessful, new methods have recently been developed which are suitable for use in routine microbiology laboratories. Recent advances include the use of calcium alginate tipped swabs for taking nasopharyngeal swabs, use of charcoal horse blood agar for transport and culture, and the inclusion of cephalexin as a selective agent in agar media. Experience shows that careful application of these new methods often enables Bordetella pertussis to be isolated from clinical specimens, thereby permitting a diagnosis to be made at an early stage of the disease.

Coordinating behavior of the cephalexin towards Zn(II) and Cd(II) ions

The complex formation equilibria of Zn(II) and Cd(II) with cephalexin have been studied through potentiometric titrations. Experimental data were analyzed using the least squares computer program SUPERQUAD. The stability constants were 1g beta ZnCEX+ = 2.40, 1g beta Zn(CEX)(OH) = -4.54, 1g beta CdCEX+ = 2.18, and 1g beta Cd(CEX)(OH) = -5.18 (I = 0.1 M NaNO3), CEX complexes of formulae Zn(CEX)2(3)H2O and Cd(CEX)(OH)H2O have been synthesized and characterized by elemental analysis, IR spectra, conductivity measurements, and electronic and NMR spectra. The thermal behavior of the synthesized compounds were studied by TGA and DTA. We conclude that the metal ion interacts with the amido group of CEX.

Two-dimensional thin-layer chromatography for simultaneous detection of bacterial beta-lactam acylases and beta-lactamases

A rapid and specific procedure was developed for the simultaneous detection of bacterial acylases and beta-lactamases, using ampicillin and cephalexin as substrates. Bacterial suspensions from agar plates were incubated separately with each beta-lactam substrate for 1 h at 37 degrees C. The supernatant of the reaction mixture was dansylated, and the dansyl derivatives were separated by two-dimensional thin-layer chromatography on polyamide sheets. The end products resulting from acylase hydrolysis, including the intact beta-lactam nucleus, 6-aminopenicillanic acid or 7-aminodeacetoxycephalosporanic acid, and the acyl side chain acid, D-(-)-alpha-aminophenylacetic acid, and the end product resulting from beta-lactamase hydrolysis (D-phenylglycylpenicilloic acid or D-phenylglycyldeacetoxycephalosporoic acid) were separated from each unhydrolyzed substrate and amino acids by this procedure. The presence of the intact beta-lactam nucleus in the reaction mixture is the indication of acylase activity. This method is sensitive and reproducible and has been successfully applied to screening for acylase activity in a variety of bacteria. It may be pharmaceutically useful for identifying organisms capable of removing the acyl side chain from naturally occurring beta-lactam antibiotics such as penicillin G, penicillin V, and cephalosporin C for production of the beta-lactam nuclei which serve as the starting materials for semisynthetic beta-lactam antibiotics.

Comparison of blood-free medium (cyclodextrin solid medium) with Bordet-Gengou medium for clinical isolation of Bordetella pertussis

Cyclodextrin solid medium (CSM) developed by us was evaluated to be a suitable synthetic medium for the clinical isolation of Bordetella pertussis when compared with Bordet-Gengou (BG) medium. The addition of 5 micrograms of cephalexin (CEX) per ml to CSM not only supported the good growth of B. pertussis but also sufficiently suppressed the growth of nasopharyngeal flora. During period 1 of this study, nasopharyngeal specimens from 60 patients with clinical pertussis were inoculated on CSM supplemented with 5 micrograms of CEX per ml. The isolation rate was 70% (42 of 60). To confirm the efficacy of CSM, another study was performed. During period 2 of this study, nasopharyngeal specimens were cultured on both CSM and BG medium, each with 5 micrograms of CEX per ml. The comparative isolation rates were 100% (40 of 40 specimens from 29 patients) on CSM with 5 micrograms of CEX and 65% (26 out of 40) on BG medium with 5 micrograms of CEX. The excellent efficacy of CSM as measured by the isolation rate was thought to be due to the poor nutrition of this medium for the growth of nasopharyngeal bacteria. CSM retained its efficacy in clinical isolations even after 3 months of storage in a refrigerator. These data led us to conclude that CSM with 5 micrograms of CEX was much better than BG medium with 5 micrograms of CEX, determined by both the isolation rate and preservativity considerations, and that CSM with 5 micrograms of CEX per ml can be successfully used instead of BG medium as a medium for the clinical isolation of B. pertussis.

Improving drug-therapy decisions through educational outreach. A randomized controlled trial of academically based "detailing"

Improving precision and economy in the prescribing of drugs is a goal whose importance has increased with the proliferation of new and potent agents and with growing economic pressures to contain health-care costs. We implemented an office-based physician education program to reduce the excessive use of three drug groups: cerebral and peripheral vasodilators, an oral cephalosporin, and propoxyphene. A four-state sample of 435 prescribers of these drugs was identified through Medicaid records and randomly assigned to one of three groups. Physicians who were offered personal educational visits by clinical pharmacists along with a series of mailed "unadvertisements" reduced their prescribing of the target drugs by 14 per cent as compared with controls (P = 0.0001). A comparable reduction in the number of dollars reimbursed for these drugs was also seen between the two groups, resulting in substantial cost savings. No such change was seen in physicians who received mailed print materials only. The effect persisted for at least nine months after the start of the intervention, and no significant increase in the use of expensive substitute drugs was found. Academically based "detailing" may represent a useful and cost-effective way to improve the quality of drug-therapy decisions and reduce unnecessary expenditures.