Caracterización de enterobacterias productoras de β-lactamasas de espectro extendido aisladas en muestras alimentarias, ambientales y clínicas
Biología molecular de microorganismos
Materias Investigacion::Ciencias de la Salud::Microbiología y biología molecular
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OJER USOZ, Elena. “Caracterización de enterobacterias productoras de β-lactamasas de espectro extendido aisladas en muestras alimentarias, ambientales y clínicas”. Vitas, A. I. y González, D. (dirs.). Tesis doctoral. Universidad de Navarra, Pamplona, 2015.
Extended-spectrum β-lactamases (ESBLs) are currently considered one of the major public health concerns throughout over the world, being Escherichia coli the main ESBL-producing bacteria and the specie that causes the greatest number of infections. The emergence of these resistances in different environments suggests a successful selection and dissemination of this antibiotic resistant mechanism, representing a potential risk of failure in clinical treatments. According to the latest recommendations of the World Health Organization and the One Health initiative, there is a need for a collaborative, multidisciplinary and cross-sectorial approach to address potential or existing risks that originate at the animal-human-ecosystems interface. Therefore, the main aim of this study was to characterise the bla genes of ESBL-producing Enterobacteriaceae (ESBL-E) isolated from food, environmental and clinical samples in Navarra (Spain), in order to assess the spread of these bacteria. Samples from different origins were investigated for the presence of ESBL-E: food (n=794), waste water treatment plants (WWTP) (n=279), rivers (n=222), farms (n=91) and animal feeding (n=60). The clinical E. coli isolates (n=130) were provided by the Clínica Universidad de Navarra. The susceptibility to antimicrobial agents was determined by disc diffusion and microdilution methods. PCR and sequencing were used for the molecular characterization of β-lactamase genes (blaCTX-M, blaSHV, blaTEM and blaOXA). In order to characterize the clonal diversity of E. coli, the isolates were assigned to phylogenetic groups (A, B1, B2, D) and phylogenetic relationships were determine by MLST. The high prevalence of ESBL-E observed in meat products (59.4 %) and especially in poultry meat (85.2 %), suggests a possible transfer of resistances through the food chain. We observed high rates of multiresistant strains (> 80 %), especially associated with quinolones and aminoglucosides, but sensibility to carbapenems still continue high (97%). Molecular characterization determined CTX-M-1 the most extended BLEE, being blaCTX-M-1 predominant in environmental samples, blaCTX-M-14 in food, WWTP and animal feeding, blaSHV-12 in farms and blaCTX-M-15 in clinical samples. Regarding phylogenetic groups, A and B1 were prevalent among food and environmental isolates, but those corresponding to phylogroup B2 (more virulent ones) were detected not only in clinical, but also in food, farm and WWTP isolates. A high variability of STs (n=177) and clonal complexes (n=26) were identified, and most of ST addressed to aquatic environments have been detected in other niches. These results showed the wide dissemination of these ESBL producing E. coli among the different sources and the need to control the continuous spread of this resistance.

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