Resistance to colistin and production of extended-spectrum beta-lactamases and/or AmpC enzymes in Salmonella isolates collected from pigs in NW Spain between 2008 and 2009

SEVILLA, E.; MARTÍN-BURRIEL, I.; BOLEA, R.; VICO, J.P; DELGADO-BLAS, J.F.; MAINAR-JAIME, R.C.; URUÉN, C.; GONZALEZ-ZORN, B.

Berlin

Simposio; 13th SafePork 2019 ONE HEALTH ? Tear down interdisciplinary walls; 2019

Legal Organiser & PCO

In the pig industry, the nursery is a critical production period as piglets are susceptible to a variety of enteric infections after weaning, and antimicrobials are commonly used as prophylactics to control Gram-negative (GN) infections. Colistin has been traditionally used to prevent post-weaning diarrhoea. Until recently, prevalence of colistin resistance (CR) was considered low and associated with chromosomal mutations of pmrA and pmrB genes (Adams et al., 2009). The recent detection and spread of new plasmid-mediated CR-associated genes (Lima et al., 2019), prompted the WHO in 2017 to declare colistin as a ´reserve´ drug against multidrug resistant (MDR) infections in human. In 2015, its use as prophylactic had been banned in Europe. In Spain, the use of colistin remained high (31.4 mg/PCU) until 2015. In that year, a voluntary plan to reduce colistin use in pigs resulted in a significant drop in colistin use (9 mg/PCU) . β-lactam antibiotics have become some of the most used in pig production against GN bacteria (van Rennings et al., 2015). Resistance to these antibiotics is mediated by a wide range of genes coding for β-lactamase enzymes, which are associated with mobile genetic elements (Michael and Schwarz, 2016). The emergence of resistance to these antimicrobials in Salmonella enterica has been reported worldwide (Michael and Schwarz, 2016).We estimate and characterize the prevalence of CR on a collection of Salmonella strains isolated from slaughtered pigs in Spain between 2008-2009, that is, much before the official policies on colistin reduction in animals. We also tested a subset of these strains for the detection of extended-spectrum β-lactamases (ESBLs) or AmpC enzyme production.