Influence of pH on the adsorption-desorption of doxycycline, enrofloxacin, and sulfamethoxypyridazine in soils with variable surface charge

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this research, the adsorption/desorption of the antibiotics doxycycline (DC), enrofloxacin (ENR), and sulfamethoxypyradazine (SMP) was studied in 6 agricultural soils with predominance of variable charge, both before and after removing organic matter by calcination. DC adsorption was high at acidic pH, and decreased at pH values above 8. Removal of organic matter with calcination caused just a slight decrease in adsorption, and even in some soils adsorption was similar to that in non-calcined samples. The adsorption coefficients (Kd) were higher for the DC− species compared to DC+, DC0 and DC2−. Regarding DC desorption, the values were very low throughout the pH range covered in the study (2–12), both in the calcined samples and in those not subjected to calcination. ENR showed a similar behavior to DC regarding the effect of pH, since ENR adsorption also decreased at basic pH, but the effect of removing organic matter was different, as it caused a clear decrease in ENR adsorption. The species with the highest Kd was in this case ENR0, although ENR+ is also quantitatively important as regards Kd value in calcined samples. For this antibiotic, no differences in desorption were observed between calcined and non-calcined samples. Finally, SMP adsorption also decreased as pH increased, and, in addition, similarly to what happened with ENR, in general, there was a strong decrease in SMP adsorption when organic matter was removed. The species with the highest Kd in this case was SMP+ in non-calcined samples, but SMP0 and SMP− become more relevant in calcined samples. The percentages of SMP desorption were higher than those for the other two antibiotics, and an increase occurs at intermediate pH values, being higher for calcined samples. These results can be considered relevant in terms of increasing the knowledge as regards the possible evolution and fate of the three antibiotics studied. Specifically, for different pH conditions and with different organic matter contents, when they reach soils and other environmental compartments after being discharged as contaminants. This could have important repercussions on public health and the overall environmentMinisterio de Economía y Competitividad | Ref. CGL2015-67333-C2-1-RMinisterio de Economía y Competitividad | Ref. CGL2015-67333-C2-2-

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Degradation of Doxycycline, Enrofloxacin, and Sulfamethoxypyridazine under Simulated Sunlight at Different pH Values and Chemical Environments

In this work, the dissipation of the antibiotics doxycycline (DC) (from the group of tetracyclines), enrofloxacin (ENR) (a fluoroquinolone), and sulfamethoxypyridazine (SMP) (a sulfonamide) is investigated both under simulated sunlight and in the dark, at three different pH (4.0, 5.5, and 7.2), and in the presence of different salts and humic acids. The results indicate that all three antibiotics are very sensitive to photodegradation, and this sensitivity increased with rising pH values, from 4.0 to 7.2. The rise in pH also caused an increase in the degradation kinetic constants and a decrease in the half-lives of antibiotics. In general, the half-lives ranged from a few minutes to 6 h, depending on the pH conditions and the specific antibiotic, and followed the sequence DC > SMP > ENR, although at pH 5.5 the sequence changed to SMP > DC > ENR. After 24 h of simulated sunlight, mineralization was always lower than 10%, although the antibiotic was not quantifiable after the same time of exposure to light (24 h), which indicates that intermediate compounds were generated. The effect of the presence of salts on the dissipation of the three antibiotics was negligible for NaCl and NaNO3, while NaHCO3 did favor the dissipation of DC and ENR. The presence of humic acids showed no effect on the dissipation of SMP, and it only slightly increased the dissipation of DC and ENR. These results may be useful in the assessment of the persistence/degradation of the antibiotics studied when they reach different environmental compartments and may suffer exposure to light under different physicochemical conditions

Degradation, adsorption and desorption processes of three antibiotics in Galician crop soils

Los antibióticos veterinarios se emplean extensamente a nivel mundial como agentes terapéuticos y como promotores del crecimiento en la ganadería intensiva. Entre un 30 y un 80% de los mismos son excretados a través de orina y heces, acumulándose en estiércoles y purines que, al ser aplicados al suelo, pasan al medio natural. Para estimar el destino de los antibióticos y su comportamiento en el medio ambiente resulta necesario conocer su dinámica en el suelo. En este sentido, los fenómenos de retención, degradación y transporte son los que controlarán la persistencia y su movilidad en el medio, determinando así su paso a otros compartimentos y su posible entrada en la cadena alimentaria. Por otro lado, también resultaría de especial interés estudiar el impacto de estos compuestos sobre las comunidades microbianas del suelo, dado que existen evidencias de que la acumulación de antibióticos en el suelo puede inducir a la aparición de cepas bacterianas resistentes a estos compuestos. En muchas regiones este problema no fue suficientemente abordado, como es el caso de Galicia, donde la actividad agrícola y ganadera tiene mucho peso. Por lo tanto, el principal objetivo de este proyecto de Tesis es estudiar la presencia y dinámica de tres antibióticos (sulfametoxipiridazina, enrofloxacina y doxiciclina) en suelos agrícolas de Galicia, así como su impacto sobre los microorganismos del suelo. Una vez estudiados estos procesos, se evaluará la utilización de diferentes materiales bioadsorbentes con el objetivo de minimizar los efectos negativos de dichos compuestos.Os antibióticos veterinarios empréganse extensamente a nivel mundial como axentes terapéuticos e como promotores do crecemento na gandería intensiva. Entre un 30 e un 80 % dos mesmos son excretados a través de ouriña e feces, acumulándose en estercos e xurros que, ó ser aplicados ó solo, pasan ó medio natural. Para estimar o destino dos antibióticos e o seu comportamento no medio ambiente resulta necesario coñecer a súa dinámica no solo. Neste sentido, os fenómenos de retención, degradación e transporte son os que controlarán a persistencia e a súa mobilidade no medio, determinando así o seu paso a outros compartimentos e a súa posible entrada na cadea alimentaria. Por outro lado, tamén resultaría de especial interese estudar o impacto destes compostos sobre as comunidades microbianas do solo, dado que existen evidencias de que a acumulación de antibióticos no solo pode inducir á aparición de cepas bacterianas resistentes a estes compostos. En moitas rexións este problema non foi suficientemente abordado, como é o caso de Galicia, onde a actividade agrícola e gandeira ten moito peso. Polo tanto, o principal obxectivo deste proxecto de Tese é estudar a presenza e dinámica de tres antibióticos (sulfametoxipiridazina, enrofloxacina e doxiciclina) en solos agrícolas de Galicia, así como o seu impacto sobre os microorganismos do solo. Unha vez estudados estes procesos, avaliarase a utilización de diferentes materiais bioadsorbentes co obxectivo de minimizar os efectos negativos de ditos compostos.Veterinary antibiotics are widely used worldwide as therapeutic agents and promoters of intensive livestock growth. Between 30% and 80% of them are excreted through urine and feces, accumulating in manure and slurry that, when applied to the soil, pass into the environment. For estimating the fate of antibiotics and their behavior in the environment it is necessary to know their dynamics in the soil. In this sense, the retention phenomena, degradation and transport will control their persistence and mobility in the environment, thus determining their transference to other compartments and possible incorporation into the food chain. On the other hand, it would also be of particular interest to study the impact of these compounds on microbial soil communities, since there is evidence that the accumulation of antibiotics in the soil can lead to the appearance of bacterial strains resistant to these compounds. In many regions, this problem has not been successfully addressed, as in the case of Galicia, where agricultural and livestock activities are of crucial importance. Therefore, the main objective of this thesis project is to study the presence and dynamics of three antibiotics (sulfamethoxypyridazine, enrofloxacin and doxycycline) in agricultural soils from Galicia, as well as its impact onto soil microorganisms. Once these processes have been studied, the use of different bio-adsorbent materials will be evaluated in order to minimize the negative effects of these compounds into the soil

Degradation of doxycycline, enrofloxacin, and sulfamethoxypyridazine under simulated sunlight at different pH values and chemical environments

In this work, the dissipation of the antibiotics doxycycline (DC) (from the group of tetracyclines), enrofloxacin (ENR) (a fluoroquinolone), and sulfamethoxypyridazine (SMP) (a sulfonamide) is investigated both under simulated sunlight and in the dark, at three different pH (4.0, 5.5, and 7.2), and in the presence of different salts and humic acids. The results indicate that all three antibiotics are very sensitive to photodegradation, and this sensitivity increased with rising pH values, from 4.0 to 7.2. The rise in pH also caused an increase in the degradation kinetic constants and a decrease in the half-lives of antibiotics. In general, the half-lives ranged from a few minutes to 6 h, depending on the pH conditions and the specific antibiotic, and followed the sequence DC > SMP > ENR, although at pH 5.5 the sequence changed to SMP > DC > ENR. After 24 h of simulated sunlight, mineralization was always lower than 10%, although the antibiotic was not quantifiable after the same time of exposure to light (24 h), which indicates that intermediate compounds were generated. The effect of the presence of salts on the dissipation of the three antibiotics was negligible for NaCl and NaNO3, while NaHCO3 did favor the dissipation of DC and ENR. The presence of humic acids showed no effect on the dissipation of SMP, and it only slightly increased the dissipation of DC and ENR. These results may be useful in the assessment of the persistence/degradation of the antibiotics studied when they reach different environmental compartments and may suffer exposure to light under different physicochemical conditions.Ministerio de Economía y Competitividad | Ref. RTI2018–099574-B-C21Ministerio de Economía y Competitividad | Ref. RTI2018-099574-B-C22Ministerio de Economía, Industria y Competitividad | Ref. RYC-2016–2041