Development, synthesis, and application of magnetic layered double hydroxides (Fe3O4@SiO-LDH/DS-) as an efficient adsorbent for the removal of tetracyclines from milk samples.

This work presents the development, synthesis, and application of a layered double hydroxide (LDH) coupled to magnetic particles for the removal of antibiotics as tetracyclines (TC´s): tetracycline (TC), chlortetracycline (CT), oxytetracycline (OT), and doxycycline (DT) from milk samples. The LDH synthesis conditions, reaction time (30-90 min), molar ratios Mg2+/Al3+ (7:1-1:7), interlayer anion (NO3-, Cl-, CO32-, and dodecyl sulphate (DS-)) were evaluated. Under synthesis conditions (reaction time of 30 min, Mg2+/Al3+ molar ratio of 7:1, and DS- as interlayer anion), the LDH was coupled in a magnetic solid phase microextraction (MSPµE) methodology. At the optimal extraction conditions (pH 6, 5 min of contact time, 10 mg of adsorbent), a removal percentage of 99.0 % was obtained for each tetracycline. FTIR, TGA, SEM, and adsorption isotherms were employed to characterize the optimal adsorbent. Each experiment was corroborated by large-volume sample stacking capillary electrophoresis (LVSS-CE). The adsorbent was applied directly to positive milk samples (previously tested) for TC´s removal.

Evaluation of Antibiotic Biodegradation by a Versatile and Highly Active Recombinant Laccase from the Thermoalkaliphilic Bacterium Bacillus sp. FNT.

Laccases are industrially relevant enzymes that have gained great biotechnological importance. To date, most are of fungal and mesophilic origin; however, enzymes from extremophiles possess an even greater potential to withstand industrial conditions. In this study, we evaluate the potential of a recombinant spore-coat laccase from the thermoalkaliphilic bacterium Bacillus sp. FNT (FNTL) to biodegrade antibiotics from the tetracycline, ß-lactams, and fluoroquinolone families. This extremozyme was previously characterized as being thermostable and highly active in a wide range of temperatures (20-90 °C) and very versatile towards several structurally different substrates, including recalcitrant environmental pollutants such as PAHs and synthetic dyes. First, molecular docking analyses were employed for initial ligand affinity screening in the modeled active site of FNTL. Then, the in silico findings were experimentally tested with four highly consumed antibiotics, representatives of each family: tetracycline, oxytetracycline, amoxicillin, and ciprofloxacin. HPLC results indicate that FNTL with help of the natural redox mediator acetosyringone, can efficiently biodegrade 91, 90, and 82% of tetracycline (0.5 mg mL-1) in 24 h at 40, 30, and 20 °C, respectively, with no apparent ecotoxicity of the products on E. coli and B. subtilis. These results complement our previous studies, highlighting the potential of this extremozyme for application in wastewater bioremediation.

Doxycycline treatment modulates the immune response of tilapia and controls Aeromonas hydrophila infection

The objective of this study was to evaluate the immunopharmacological activity of doxycycline, administered orally in Nile tilapia (Oreochromis niloticus), during experimental infection by Aeromonas hydrophila, through the correlation between therapeutic efficacy and fish immune response. 160 Nile tilapia (±100 g) from the same spawning were distributed in 16 tanks (100 L, n = 10), constituting four treatments: control (infected and untreated); Infected and Treated with 20, 40 and 80 mg of doxycycline/Kg of b.w. Control fish and treated with the lowest dose of doxycycline (20 mg) exhibited typical signs of aeromonosis, including exophthalmos, fin erosion, hemorrhagic septicemia, corneal opacity and ascites. No clinical signs were observed in animals treated with 40 and 80 mg of doxycycline. There was a dose-response effect to the treatment with this tetracycline with relative percentage of survival (RPS) of 60, 73.3 and 93.3% for the treatments with 20, 40 and 80 mg/kg of b.w. when compared to control animals, as well as increased in the production of antibodies anti-A. hydrophila. Doxycycline treatment decreased monocytosis and reactive oxygen species (ROS) production observed in tilapia during A. hydrophila infection. Therefore, doxycycline administered orally to O. niloticus revealed the potential of this antimicrobial for use in tilapia farming, providing convincing results of the therapeutic efficacy against A. hydrophila. These results confirm the hypothesis that the antimicrobial action of doxycycline favored the defense mechanisms of tilapia treated mainly at a dose of 80 mg/kg. Although the exact mechanism of increased antibody response remains to be elucidated, the present observations demonstrate important practical significance for the sanitary management of tilapia farming.

Assessing the transformation products and fate of Oxytetracycline by simulated aerobic degradation tests.

Oxytetracycline (OTC) is a widely used broad-spectrum antibiotic, whose presence in water and sediments was reported in various regions of the world. The effects of OTC and other tetracyclines on the environment have been intensively studied although many of their transformation products (TPs) formed in the environment and their impact have not been yet fully characterized. Abiotic and biotic degradation tests under aerobic conditions at two pH values were carried out using OTC in artificial water/sediment systems to assess the effect of these variables on the environmental fate of the pollutant. HPLC-MSn was employed to detect and identify the main degradation products and pathways. Several transformations involved in the process were identified including alcohol oxidation, decarbonylation and hydroxylation. Differences in TPs and kinetics were found among degradation conditions, remarking a faster degradation of both OTC and TPs in the presence of microorganisms and at lower pH values. In summary, a total of 44 TPs were detected and structures were proposed for 20 of them, none of them having been previously reported. Furthermore, OTC degradation generated 24 TPs which remained in either solution or sediment, although none of them displayed higher algae toxicity than OTC. These results might be useful for planning future remediation and monitoring strategies.

Doxycycline attenuates l-DOPA-induced dyskinesia through an anti-inflammatory effect in a hemiparkinsonian mouse model.

The pharmacological manipulation of neuroinflammation appears to be a promising strategy to alleviate l-DOPA-induced dyskinesia (LID) in Parkinson's disease (PD). Doxycycline (Doxy), a semisynthetic brain-penetrant tetracycline antibiotic having interesting anti-inflammatory properties, we addressed the possibility that this compound could resolve LID in l-DOPA-treated C57BL/6 mice presenting either moderate or intermediate lesions of the mesostriatal dopaminergic pathway generated by intrastriatal injections of 6-OHDA. Doxy, when given subcutaneously before l-DOPA at doses of 20 mg kg-1 and 40 mg kg-1, led to significant LID reduction in mice with moderate and intermediate dopaminergic lesions, respectively. Importantly, Doxy did not reduce locomotor activity improved by l-DOPA. To address the molecular mechanism of Doxy, we sacrificed mice with mild lesions 1) to perform the immunodetection of tyrosine hydroxylase (TH) and Fos-B and 2) to evaluate a panel of inflammation markers in the striatum, such as cyclooxygenase-2 and its downstream product Prostaglandin E2 along with the cytokines TNF-α, IL-1ß and IL-6. TH-immunodetection revealed that vehicle and Doxy-treated mice had similar striatal lesions, excluding that LID improvement by Doxy could result from neurorestorative effects. Importantly, LID inhibition by Doxy was associated with decreased Fos-B and COX-2 expression and reduced levels of PGE2, TNF-α, and IL-1ß in the dorsolateral striatum of dyskinetic mice. We conclude 1) that Doxy has the potential to prevent LID regardless of the intensity of dopaminergic lesioning and 2) that the anti-inflammatory effects of Doxy probably account for LID attenuation. Overall, the present results further indicate that Doxy might represent an attractive and alternative treatment for LID in PD.

Prevalence, Tetracycline Resistance and Tet(O) Gene Identification in Pathogenic Campylobacter Strains Isolated from Chickens in Retail Markets of Lima, Peru.

Background: In this study, we aimed to estimate the prevalence, tetracycline resistance and presence of Tet(O) in Campylobacter strains isolated from chicken in markets of Lima, Peru. Methods: A total of 250 chicken samples were obtained from traditional markets (skin, n = 120) and supermarkets (meat, n = 130). Samples were subjected to microbiological assays for identification of Campylobacter spp. according to ISO 10272-2017, and the isolates were then submitted to species identification by PCR. Phenotypic resistance to tetracyclines was assessed by the Kirby−Bauer test, and the presence of the Tet(O) gene was determined by PCR. Results: A significantly higher prevalence (p < 0.0001) of Campylobacter coli in skin samples from traditional markets (97.5%) than in meat samples from supermarkets (36.2%) was observed. On the other hand, Campylobacter jejuni was confirmed only in 3.1% of meat samples. All Campylobacter species isolated from skin and meat samples were phenotypically resistant to tetracyclines; however, the presence of the Tet(O) gene in C. coli was identified in 76.9% and 66.0% of skin and meat samples, no significant statistical difference (p = 0.1488) was found between these prevalence. All C. jejuni isolated from chicken meat samples from supermarkets were positive for Tet(O) gene. Conclusions: This study confirms the high prevalence of C. coli isolated from chicken sold in traditional markets and supermarkets in Lima, Peru, and in more than 70% of these strains, phenotypic resistance to tetracyclines could be linked with expression of the Tet(O) gene. It is necessary to evaluate other genes involved in resistance to tetracyclines and other groups of antibiotics in campylobacter strains isolated from chicken meat.

Antimicrobial resistance in the globalized food chain: a One Health perspective applied to the poultry industry.

Antimicrobial resistance (AMR) remains a major global public health crisis. The food animal industry will face escalating challenges to increase productivity while minimizing AMR, since the global demand for animal protein has been continuously increasing and food animals play a key role in the global food supply, particularly broiler chickens. As chicken products are sources of low-cost, high-quality protein, poultry production is an important economic driver for livelihood and survival in developed and developing regions. The globalization of the food supply, markedly in the poultry industry, is aligned to the globalization of the whole modern society, with an unprecedented exchange of goods and services, and transit of human populations among regions and countries. Considering the increasing threat posed by AMR, human civilization is faced with a complex, multifaceted problem compromising its future. Actions to mitigate antimicrobial resistance are needed in all sectors of the society at the human, animal, and environmental levels. This review discusses the problems associated with antimicrobial resistance in the globalized food chain, using the poultry sector as a model. We cover critical aspects of the emergence and dissemination of antimicrobial resistance in the poultry industry and their implications to public health in a global perspective. Finally, we provide current insights using the multidisciplinary One Health approach to mitigate AMR at the human-animal-environment interface.

Safety of oral doxycycline treatment in Nile tilapia, Oreochromis niloticus / Segurança do tratamento oral com doxiciclina em tilapia do Nilo, Oreochromis niloticus

This study aimed to evaluate the clinical safety of doxycycline treatment (Sandoz Pharmacetical Industry from Brazil Ltd.), administered orally incorporated into the feed of Nile tilapia, Oreochromis niloticus. For this purpose, 75 Nile tilapia (±300g) from the same spawning were randomly distributed in 15 tanks (n=5), containing 100 L of water each, supplied with running water free from chlorine, to establish the following treatments: TO (Control - not treated with doxycycline); T1, T2, T3 and T4 (treated with 10, 20, 40 and 80mg of doxycycline/kg of body weight, respectively), in which 5 animals per treatment were sampled in 3 periods: 2, 4 and 8 days post-treatment (DPT). Blood samples were collected for hemogram determination and serum biochemical evaluation, as well as spleen, liver and kidneys (cranial and caudal) for somatic and histopathological evaluation. The results showed no significant difference among treatments in the serum values of creatinine, total protein, cholesterol, triglycerides, globulin, glycemia and alkaline phosphatase enzyme activity. However, serum levels of AST (aspartate aminotransferase) were significantly higher (P<0.05) in animals treated with 80 mg of doxycycline in the longest period of treatment (8 days). In the hematological evaluation of tilapia treated with doxycycline, no significant changes (P>0.05) were observed in erythrocyte counts, hematocrit, MCV, HCM and CHCM values. Doxycycline-treated tilapia did not present significant difference in the somatic analysis of spleen, liver and kidney when compared to control group. Therefore, the results demonstrated the clinical safety of oral treatment with doxycycline at doses of 10, 20, 40 and 80 mg/kg of b.w., although transient changes in liver functionality were observed after eight days of treatment with the dose of 80mg/kg.

Este estudo teve por objetivo avaliar a segurança clínica do tratamento com doxiciclina (Sandoz do Brasil Indústria Farmacêutica Ltda.), administrada via oral incorporada à ração em tilápias do Nilo, Oreochromis niloticus. Para tal, foram utilizadas 75 tilápias no Nilo (±300g) oriundas da mesma desova foram distribuídas aleatoriamente em 15 tanques (n=5), contendo 100 L de água cada, abastecidos com água corrente desprovida de cloro, para constituir os seguintes tratamentos: TO (Controle - não tratado com doxiciclina); T1, T2, T3 e T4 (tratados com 10, 20, 40 e 80mg de doxiciclina/kg de p.v., respectivamente. 5 animais por tratamento foram amostrados em 3 períodos: 2, 4 e 8 dias pós-tratamento (DPT). Foram coletadas amostras de sangue para determinação do hemograma e avaliação do bioquímico sérico, além de órgãos como baço, fígado e rins (cranial e caudal) para avaliação somática e histopatológica. Os resultados não mostraram diferença significativa entre os tratamentos nos valores séricos de creatinina, proteína total, colesterol, triglicerídeos, globulina, glicemia e atividade da enzima fosfatase alcalina. No entanto, os níveis séricos de AST (aspartato aminotransferase) foram significativamente maiores (P<0,05) nos animais tratados com 80 mg de doxiciclina no período mais longo de tratamento (8 dias). Na avaliação hematológica de tilápias tratadas com doxiciclina, não foram observadas alterações significativas (P>0,05) nas contagens de eritrocitos, valores de hematocrito, VCM, HCM e CHCM. Tilápias tratadas com doxiciclina não apresentaram diferença significativa na análise somática do baço, fígado e rim quando comparadas aos animais do grupo controle. Portanto, os resultados demonstraram a segurança clínica do tratamento oral com doxiciclina nas doses de 10, 20, 40 e 80 mg/kg de peso corporal, embora alterações transitórias na funcionalidade hepática tenham sido observadas após oito dias de tratamento com a dose de 80mg/kg.

Hipomelanosis macular progresiva: respuesta al tratamiento con minociclina / Progressive macular hypomelanosis: response to treatment with minocycline

La hipomelanosis macular progresiva (HMP) es una dermatosis caracterizada por máculas hipopigmentadas, que se observa con mayor frecuencia en las mujeres y en los fototipos III y IV. Se ha asociado a Cutibacterium acnes (C. acnes) de tipo III como factor etiológico. Se presenta el caso de una paciente de 30 años, con máculas hipopigmentadas redondeadas en el tronco y la raíz de los miembros inferiores, de 10 años de evolución. El estudio histológico informó disminución del número de melanocitos y de pigmento melánico en la capa basal e infiltrado inflamatorio mononuclear perivascular superficial. Se indicó minociclina 100 mg/día por vía oral durante 8 meses, tras lo cual se observó la resolución total de las lesiones.

Progressive macular hypomelanosis (PMH) is a dermatosis characterized by hypopigmented macules, most frequently found in females and in phototypes III and IV. Cutibacterium acnes (C. acnes) type III has been associated as an etiological factor. We present the case of a thirty-year-old female patient with a 10-year history of nummular hypopigmented macules located on the top of the lower limbs and on the trunk. The histological study reported a decrease in the number of melanocytes and melanotic pigment in the basal layer and the presence of superficial perivascular mononuclear inflammatory infiltrate. After an 8-month regimen of oral minocycline 100 mg/day, there was a complete resolution of the lesions.

Green-tea-synthesized silver nanoparticles as a sensing platform for determination of tetracycline in honey samples.

BACKGROUND: Silver nanoparticles (AgNPs) can be easily obtained in aqueous solution by chemical reduction using appropriate reducing agents and stabilizers. The development of environmentally friendly methods using non-toxic solvents and reagents has become an alternative for the synthesis of these particles and their future application as sensor probes for agricultural products. In this work, a straightforward method based on green tea extracts as reducing and capping agent is proposed for the synthesis of AgNPs, followed by their evaluation as a sensing platform for determination of tetracycline in honey samples. RESULTS: Highly stable nanoparticles were easily obtained by combining green tea aqueous extracts and ultrasound irradiation for 2 min. The as-synthesized AgNPs, spherical in shape and with average size of 8.5 nm, were evaluated for determination of tetracycline by following the changes on the localized surface plasmon resonance band at 450 nm induced by the presence of this antibiotic at pH 5.8. The method was successfully applied in the concentration range between 200 and 800 µg L-1 with R2 > 0.996 and limit of detection of 52.7 µg L-1 . Multiple honey samples were analyzed, and the recovery values obtained ranged between 82.8% and 116%, with relative standard deviation values lower than 6.69%. CONCLUSION: The results obtained demonstrate that the AgNPs synthesized using just green tea extracts represent a promising and sustainable alternative tool for the cost-effective determination of tetracycline antibiotics in honey. © 2021 Society of Chemical Industry.

Residues of tetracyclines and ß-lactams antibiotics induce carbonylation of chicken breast.

Background: Worldwide, chicken meat is widely consumed due to its low cost, high nutritional value and non-interference with religious or cultural beliefs. However, during animal husbandry chickens are exposed to many chemical substances, including tetracyclines and ß-lactams, which are used to prevent and cure several infections. Some residues of these compounds may bioaccumulate and be present in chicken meat after slaughtering, promoting oxidative reactions. Methods: In order to evaluate in vitro carbonylation induced by tetracyclines and ß-lactams residues, a proteomic approach was used. For this, chicken muscle was individually contaminated with tetracyclines (tetracycline, chlortetracycline, oxytetracycline, and doxycycline) and ß-lactams (ampicillin, benzathine penicillin, dicloxacillin and oxacillin) at 0.5, 1.0 and 1.5 times their maximum residue level (MRL). Then, sarcoplasmic, myofibrillar and insoluble proteins were extracted and their content were measured using the Bradford method. Protein carbonylation was measured using the 2,4-Dinitrophenylhydrazine alkaline method. Results: Residues of tetracyclines and ß-lactams induced in vitro carbonylation on sarcoplasmic, myofibrillar and insoluble proteins even at 0.5MRL concentrations ( p<0.05). When comparing the carbonylation induced by both antibiotics no differences were found ( p>0.05). Variables such as the partition coefficient (log P) and the concentration of these antibiotics showed a high correlation with the oxidative capacity of tetracyclines and ß-lactams on chicken breast proteins. Conclusions: This study shows that the presence of tetracyclines and ß-lactams residues at MRLs concentrations promotes in vitro carbonylation on chicken breast proteins. Our results provide important insights about the impact of antibiotics on the integrity of meat proteins intended for human consumption.

Tratamiento exitoso de lipodermatoesclerosis aguda con doxiciclina: reporte de diez casos / Successful treatment of acute lipodermatosclerosis with doxycycline: report of ten cases

Resumen La doxiciclina, una tetraciclina semisintética de segunda generación, ampliamente usada para el tratamiento de patologías dermatológicas por sus propiedades antimicrobianas, ha demostrado en varios estudios experimentales sus acciones como un potente fármaco antiinflamatorio, aprobado por estas características por la FDA como una terapia complementaria en la periodontitis del adulto, así como en el tratamiento de la forma papulopustulosa de la rosácea. Se describen además en la literatura otras indicaciones para procesos inflamatorios, tales como, calcinosis cutis, vasculitis livedoide, patologías ampollares, entre otras. Se presenta una serie de 10 pacientes con lipodermatoesclerosis que presentaron una respuesta eficaz a su patología al recibir tratamiento con doxiciclina durante 3 meses, destacando de esta forma su eficacia terapéutica, accesibilidad y baja asociación a efectos adversos.

Abstract Doxycycline, a second generation semi-synthetic tetracycline, widely used for the treatment of dermatological diseases for its antimicrobial effects, has shown in many clinical studies its actions as a powerful anti-inflammatory drug. Approved by the FDA as a complementary therapy in adult periodontitis, and of the papulopustular form of rosacea. In addition, other indications for inflammatory processes are described in the literature, such as calcinosis cutis, livedoid vasculitis, blistering pathologies, among others. We present a series of 10 patients with lipodermatosclerosis who presented an effective response to their pathology when receiving treatment with doxycycline for 3 months. Its therapeutic efficacy, accessibility and low association with adverse effects are highlighted.

Spironolactone in Dermatology: Uses in Acne, Hidradenitis Suppurativa, Female Pattern Baldness, and Hirsutism. / Uso de la espironolactona en dermatología: acné, hidradenitis supurativa, alopecia femenina e hirsutismo.

Spironolactone is an economical potassium-sparing diuretic with an anti-androgenic effect and a good safety profile. Our experience suggests that this diuretic is underexploited in dermatology even though there is evidence supporting its use in several skin conditions. When prescribed for acne in female patients (level 1-2 evidence; strength of recommendation, B), for example, it can reduce the need for antibiotics and possibly isotretinoin. Other diseases in which spironolactone is potentially useful are hidradenitis suppurativa and female androgenetic alopecia. We discuss the indications for spironolactone, dosing in dermatology, precautions to consider, and adverse effects. We also review new evidence that stresses the safety of long-term therapy and supports the use of this drug without the need for complementary testing in young women. We think that spironolactone merits a place among the medications commonly used in routine clinical practice.

Acondicionamiento radicular en el tratamiento periodontal no quirúrgico y quirúrgico / Root conditioning in non-surgical and surgical periodontal therapy

La instrumentación mecánica durante el tratamiento periodontal trae consigo la formación de escombros microcristalinos que inhiben la adhesión tisular a la superfi cie radicular y favorece la proliferación bacteriana, lo cual perjudica los resultados del tratamiento periodontal a corto y largo plazo. Hoy en día el acondicionamiento radicular con el uso de biomodifi cadores es una opción de tratamiento adicional en el tratamiento de la periodontitis y el tratamiento de cobertura radicular. El objetivo del presente estudio es realizar una revisión de la literatura acerca de las aplicaciones y del acondicionamiento radicular con ácido cítrico, tetraciclina, EDTA y láser en el tratamiento periodontal no quirúrgico y quirúrgico (AU)

Mechanical instrumentation during periodontal treatment brings the formation of microcrystalline debris that inhibits tissue adhesion to the root surface and favors bacterial proliferation, which harms the results of the short and long term periodontal treatment. Nowadays, root conditioning with the use of biomodifi cators is an additional treatment option in the treatment of periodontitis and root coverage therapy. The aim of the present study is to conduct a literature review about the applications and the root conditioning with citric acid, tetracycline, EDTA and laser in the non surgical and surgical periodontal treatment (AU)

Influence of therapeutic use of feedgrade tetracyclines in combination with tulathromycin metaphylaxis on animal health and performance of Holstein steer calves.

Feedgrade chlortetracycline (CTC) and oxytetracycline (OTC) are approved for use in beef cattle diets for the control of bovine respiratory disease (BRD). The objectives of this experiment were to compare CTC and OTC, administered according to label, for the treatment of BRD in Holstein calves and to characterize the influence of tulathromycin metaphylaxis in combination with tetracycline treatment. Summer-placed Holstein steer calves (n = 6,800) were randomly assigned to one of four treatments (11 blocks; initial BW = 140 ± 18 kg) as they passed through the squeeze chute at initial processing in a commercial feedlot. Treatments consisted of: (i) CTC and tulathromycin metaphylaxis (CTC+TUL), (ii) OTC and tulathromycin metaphylaxis (OTC+TUL), (iii) tulathromycin metaphylaxis only (TUL), or (iv) CTC only (CTC). Cattle were fed for an average of 118 d. Tetracycline feeding was instituted based on visual assessment of the attending veterinarian in accordance with the veterinary feed directive. When applicable, CTC was fed as a top-dress at a rate of 4 g CTC·steer-1·d-1 for 5 consecutive days, beginning on 6 d on feed (DOF). Three 5-d pulses were delivered to CTC+TUL and CTC cattle, with a 48-h time lapse between pulses. Cattle on OTC+TUL were administered 4 g OTC·steer-1·d-1 as part of a complete diet for 14 consecutive days beginning on 10 DOF. Within the first 30 d of the feeding period, BRD first pulls were reduced (P = 0.001) for CTC+TUL, OTC+TUL, and TUL relative to CTC alone. Percentage of BRD first pulls and total morbidity were lowest (P = 0.001) for CTC+TUL across the feeding period, with OTC+TUL and TUL being intermediate, and CTC alone exhibiting the highest percentage. Death loss and railers were not influenced (P ≥ 0.58) by treatment. Dry matter intake was greater (P = 0.001) for CTC+TUL than all other treatments. Final BW and ADG were greatest for CTC+TUL, lowest for TUL alone, and intermediate for the remaining treatments (P < 0.05) on a deads-and-railers-out basis. Deads-and-railers-in ADG was greatest (P < 0.05) for CTC+TUL compared to all other treatments. Feed conversion was not influenced (P ≥ 0.22) by treatment. In the current study, supplementation of OTC in combination with tulathromycin metaphylaxis did not benefit health over tulathromycin alone. Results suggest that CTC in combination with tulathromycin metaphylaxis reduces morbidity in Holstein steers calves, which may lead to improved performance.

Simultaneous quantification of antibiotics in wastewater from pig farms by capillary electrophoresis.

Pig farming is an important activity in the economic development of Mexico with millions of tons of meat produced annually. Antibiotics are used in therapeutic dose to prevent diseases, and sometimes as growth promoters. These compounds are not completely metabolized; they are carried into the environment in its active form at concentrations that could induce antibiotic resistance in bacteria, which could be transferred to human pathogens by horizontal gene transfer. The objective of this work was to develop methods of analysis for simultaneous quantification of the antibiotics Oxytetracycline (OXT), Chlortetracycline (CLT), Enrofloxacin (ENRO) and Ciprofloxacin (CIPRO) by field-amplified sampling injection in capillary zone electrophoresis (FASI-CZE). The method was validated by parameters of (1) linearity, obtaining a lineal range of 0.05 at 1 µg mL-1 for ENRO and CIPRO, and from 0.1 to 1 µg mL-1 for OXT and CLT; (2) precision, obtaining values <5% of standard deviation for CIPRO and ENRO and <10% of standard deviation for OXT and CLT; (3) accuracy, with recovery values from 93 to 115%; (4) selectivity, with values of resolution >2 for the all antibiotics tested. To prove the method, a sample of wastewater from a local pig farm was analyzed, detecting a concentration of 0.140 ±â€¯0.009 for OXT. This concentration was higher than the minimal selective concentration, indicating the point in which resistance to a determined antibiotic could develop. The methods were validated with precision and sensitivity comparable to chromatographic methods, which can be used to analyze wastewater from pig farms directly.

Detection of the antimicrobial resistance genes blaTEM-1, cfxA, tetQ, tetM, tetW and ermC in endodontic infections of a Mexican population.

OBJECTIVES: The aim of this study was to identify the prevalence of genes encoding resistance to three groups of antimicrobial agents in root canal samples from primary infection or post-treatment disease in Mexico. METHODS: A total of 64 subjects requiring root canal treatment because of primary infection or post-treatment disease were enrolled in this cross-sectional analytical study. Root canal samples were obtained and DNA was isolated. Specific primers for six antimicrobial resistance genes (ARGs) and seven bacterial taxa (five genera and two species) were used. Student's t-test, χ2 test and Fisher's exact test were applied where appropriate to detect statistical differences. RESULTS: The blaTEM-1, ermC and tetM genes were found more frequently in the post-treatment disease group compared with the primary infection group. The occurrence of assessed bacteria was similar in both groups, except for Enterococcus spp. and Porphyromonas endodontalis, which were found at a significantly higher frequency in the post-treatment disease group. It was observed that the post-treatment disease group harboured more ARGs. The most frequent ARG was tetW, whereas tetQ and cfxA were not detected in any case. With respect to bacterial taxa, Fusobacterium spp. was present in 100% of samples, whereas Porphyromonas gingivalis was not observed in any of the samples. CONCLUSIONS: At least one ARG was detected in all cases; moreover, 32.8% of samples were positive for four ARGs, 54.7% for three ARGs, 9.4% for two ARGs and only 3.1% for one ARG. This indicates a high prevalence and diversity of ARGs in these root canal samples.

Graphene particles supported on silica as sorbent for residue analysis of tetracyclines in milk employing microextraction by packed sorbent.

This paper describes the use of graphene-based sorbents for determination of four tetracyclines in milk. The synthesized materials were combined with microextraction by packed sorbent (MEPS) to act as the sample preparation step. The extraction performance of these sorbents was compared to commercial phases, and graphene supported on silica provided the best results. The analytical method optimization was carried out by employing experimental design. Firstly, an evaluation of the experimental variables (elution solvent, use of EDTA, ionic force, and pH of the washing solution) was made by a 24-1 factorial experimental design. The variables sampling, washing and elution cycles of MEPS were further optimized under a full 23 experimental design. The validation parameters were determined under optimized conditions resulting in a linearity ranging from 15 to 110 µg/L with R2 values above 0.98, and LOQs ranging from 0.05 to 0.9 µg/L. The accuracy ranged from 87.9 to 118.4% and intra/inter-day precision reported by the RSDs were lower than 19%. The proposed and validated method was successfully applied to the analysis of 11 milk samples from different animals, revealing traces of tetracyclines in only two of them. This study focused on the evaluation of graphene-based sorbents combined with MEPS for tetracycline analysis provided equivalent or even better results than other proposed methods, suggesting being a sensitive, fast and reliable alternative method for the determination of tetracyclines in milk samples.

Interactions of tetracyclines with ovalbumin, the main allergen protein from egg white: Spectroscopic and electrophoretic studies.

The interactions of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) with ovalbumin (OVA), the main allergen protein of egg white, were investigated by molecular spectroscopy and electrophoresis at three pH conditions (1.5, 4.6 and 7.4). Molecular and synchronous fluorescence, UV-vis spectroscopy, electrophoresis and 1H NMR were used to study the interaction process. Tetracyclines interact with ovalbumin fluorescence by a static quenching mechanism with non-fluorescent complex formation changing the native protein structure. The binding constant (Kb) ranged from 2.11×104 to 58.4×104Lmol-1, and corresponding thermodynamic parameters were measured at different temperatures and pH values. The binding process was spontaneous (ΔG<0), and the magnitude of the interaction increased in the following order: TC

Direct extraction of tetracyclines from bovine milk using restricted access carbon nanotubes in a column switching liquid chromatography system.

This paper describes, for the first time, the use of restricted access carbon nanotubes (RACNTs) in the analysis of tetracyclines from milk samples, in a multidimensional liquid chromatographic system. Milk samples were initially acidified and centrifuged, and then the supernatant was directly analyzed in a column switching system in backflush configuration employing an extraction column of RACNTs. The sorbent was able to exclude all the remained proteins in less than 2.0min. The method was linear from 50 to 200µgL-1 and the coefficients of determination (r2) were 0.997, 0.992, 0.994 and 0.998 for oxytetracycline (OXI), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DOX), respectively. The analytical range included the maximum residue limits established by the regulatory agency.