Residues of veterinary antibiotics in manures from pig and chicken farms in a context of antimicrobial use reduction by implementation of health and welfare plans.

The use of antibiotics in food-producing animals can induce the presence of residual substances in manure, which are then released into the environment and may contribute to soil and groundwater contamination. During the on-farm implementation of strategies to improve animal health and welfare in chicken and pig farms, the consequences of antibiotic use were evaluated in terms of the occurrence and levels of antibiotic residues in manure. A set of 35 broiler farms from Cyprus, Greece, the Netherlands and 40 pig farms from France and Italy provided a total of 350 manure samples. The primary objective was to develop a specific LC/MS/MS method capable of quantifying antibiotic residues in both types of manure. The method was able to detect fifteen antibiotics belonging to nine classes, with validated limits of quantification of 10-20 µg/kg, and accuracies ranging from 81% to 138%. With the exception of amoxicillin, which was never detected in any manure, all antibiotics used were detected in manure from treated animals with typical concentrations ranging from 10 to 99198 µg/kg for both chickens and pigs. The occurrence of residual antibiotics was higher in chicken than in pig manure, especially for fluoroquinolones and doxycycline which were detected in 89% and 100% of the chicken manure, respectively, and in 28% of the pig manure. The impact of the health plans on the antibiotic load manure was assessed by measuring for each farm the ratio of the sum of all antibiotic concentrations measured after and before the implementation of the plan. The results showed that, in addition to the frequency of treatments, the class of antibiotic used is an important factor to consider as it strongly influences the stability/instability of the compounds, i.e. their ability to persist in the manure of food-producing animals.

The Selection of Antibiotic- and Bacteriophage-Resistant Pseudomonas aeruginosa Is Prevented by Their Combination.

Bacteria developing resistance compromise the efficacy of antibiotics or bacteriophages (phages). We tested the association of these two antibacterials to circumvent resistance. With the Hollow Fiber Infection Model (HFIM), we mimicked the concentration profile of ciprofloxacin in the lungs of patients treated orally for Pseudomonas aeruginosa infections and, independently, mimicked a single inhaled administration of phages (one or two phages). Each treatment selects for antibiotic- or phage-resistant clones in less than 30 h. In contrast, no bacteria were recovered from the HFIM at 72 h when ciprofloxacin was started 4 h post phage administration, even when increasing the initial bacterial concentration by 1,000-fold. The combination of phages with antibiotics used according to clinical regimens prevents the growth of resistant clones, providing opportunities to downscale the use of multiple antibiotics. IMPORTANCE In the treatment of bacterial infections, the use of antibiotics or bacteriophages (phages) is limited by the ability of bacteria to develop resistance. The resistance frequency depends on the exposure to antibacterials. Therefore, determination of concentration profiles of antibiotics is key to define optimal regimens during treatments. In the laboratory, the Hollow Fiber Infection Model (HFIM) mimics concentration profiles observed in patients. In this study, we used the HFIM to evaluate the killing efficacy of the combination of phages and ciprofloxacin. We demonstrated that dosing schedule of phages first and the antibiotic second prevent the selection of resistant bacteria. These results demonstrate that combination efficacy relies on a strong initial reduction of the bacterial population by phages followed by antibiotics before any resistant arise.

Microrradiografías, otra posibilidad para el diagnóstico / Microroentgenodontia, another possibility for diagnosis

La técnica de microroentgenodoncia ofrece una alternativa segura y eficaz para el diagnóstico. Con esta técnica, la definición de imagen es superada y es posible determinar con mayor facilidad el hallazgo de una patología o bien la evolución de un tratamiento. El presente trabajo expone las características, ventajas y resultados de la microroentgenodoncia y las compara con la técnica de bisectriz del ángulo