Oral communication in International Meeting on Emerging Diseases and Surveillance IMED 2016

November 4^th, 2016

Esperon F., Delgado MM., Iglesias I., Carballo M., Ugarte-Ruiz M., Moreno MA., Tadeo JL. and de la Torre A.

Purpose: Antimicrobial resistances (AMRs) are an emerging threat for animal and public health. Among the different mechanisms of AMRs, plasmid-mediated antimicrobial resistance genes (PM-ARGs) are of major concern due to their capability of mobilization and transfer between bacteria. Since at least an 80% of bacteria are not cultivable, PM-ARGs should be studied directly in the microbiome, without previous culture.
AMRs are mainly studied in every step “from the farm to fork”, but less known is how can they be spread into the environment through animal waste. Animal manure is commonly used as agricultural fertilizer and may carry on PM-ARGs which could reincorporate to food chain by crops. An interesting alternative is composting the animal manure, which reduces the presence of pathogenic bacteria and improves its quality as fertilizer, offering an added value to the product. In this work, we tested plasmid-mediated tetracycline resistance genes (tet) during four different small-scale avian manure composting processes.
Methods & Materials: Four different avian manure composting processes (avian
manure+straw; avian manure+straw+fresh eggs; avian manure+straw+egg ashes; avian manure+straw+fresh eggs+egg ashes) at small scale were evaluated during eight weeks. Seven tet genes were quantified by real time PCR (tet(A), tet(B), tet(C), tet(K), tet(M), tet(Q) and tet(S)). Besides, the 16SARN gene was amplified for sample validation and to calculate the relative concentration of every gene (expressed as log of percentage of bacteria which carries a determinate gene). All genes, with the exception of tet(C), were detected.
Results: No apparent differences were observed among the types of composting. For every gene and every type of compost, there is an increase of gene quantity during the first week of composting. Also, there is a dramatic decrease of gene quantity during weeks 5-7, depending the gene. After this decrease, tet(M) and tet(S) genes were still under detection limit up to the final week; however, the rest of genes increase during the last weeks, to at least to initial levels.
Conclusion: Composting during 8 weeks doesn’t seem to reduce the quantity of tet genes.
Increase the number of weeks of composting as well as analyze other PM-ARGs will be
evaluated. This work is funded by RTA2014-00012- C03-02

	Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA).
	Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).