AUTHOR=Pavez-Muñoz Erika , González Camilo , Fernández-Sanhueza Bastián , Sánchez Fernando , Escobar Beatriz , Ramos Romina , Fuenzalida Verónica , Galarce Nicolás , Arriagada Gabriel , Neira Víctor , Muñoz-Aguayo Jeannette , Flores-Figueroa Cristian , Johnson Timothy J. , Alegría-Morán Raúl 

TITLE=Antimicrobial Usage Factors and Resistance Profiles of Shiga Toxin-Producing Escherichia coli in Backyard Production Systems From Central Chile

JOURNAL=Frontiers in Veterinary Science

VOLUME=7

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2020.595149

DOI=10.3389/fvets.2020.595149

ISSN=2297-1769

ABSTRACT=<p>Shiga toxin-producing <italic>Escherichia coli</italic> (STEC) is a zoonotic pathogen and important cause of foodborne disease worldwide. Many animal species in backyard production systems (BPS) harbor STEC, systems characterized by low biosecurity and technification. No information is reported on STEC circulation, antimicrobial resistance (AMR) and potential drivers of antimicrobial usage in Chilean BPS, increasing the risk of maintenance and transmission of zoonotic pathogens and AMR generation. Thus, the aim of this study was to characterize phenotypic and genotypic AMR and to study the epidemiology of STEC isolated in BPS from Metropolitana region, Chile. A total of 85 BPS were sampled. Minimal inhibitory concentration and whole genome sequencing was assessed in 10 STEC strain isolated from BPS. All strains were cephalexin-resistant (100%, <italic>n</italic> = 10), and five strains were resistant to chloramphenicol (50%). The most frequent serotype was O113:H21 (40%), followed by O76:H19 (40%), O91:H14 (10%), and O130:H11 (10%). The <italic>stx</italic>1 type was detected in all isolated strains, while <italic>stx</italic>2 was only detected in two strains. The Stx subtype most frequently detected was <italic>stx</italic>1c (80%), followed by <italic>stx</italic>1a (20%), <italic>stx</italic>2b (10%), and <italic>stx</italic>2d (10%). All strains harbored chromosomal <italic>bla</italic><sub>AmpC</sub>. Principal component analysis shows that BPS size, number of cattle, pet and horse, and elevation act as driver of antimicrobial usage. Logistic multivariable regression shows that recognition of diseases in animals (<italic>p</italic> = 0.038; OR = 9.382; 95% CI: 1.138–77.345), neighboring poultry and/or swine BPS (<italic>p</italic> = 0.006; OR = 10.564; 95% CI: 1.996–55.894), visit of Veterinary Officials (<italic>p</italic> = 0.010; OR = 76.178; 95% CI: 2.860–2029.315) and close contact between animal species in the BPS (<italic>p</italic> = 0.021; OR = 9.030; 95% CI: 1.385–58.888) increase significantly the risk of antimicrobial use in BPS. This is the first evidence of STEC strains circulating in BPS in Chile, exhibiting phenotypic AMR, representing a threat for animal and public health. Additionally, we identified factors acting as drivers for antimicrobial usage in BPS, highlighting the importance of integration of these populations into surveillance and education programs to tackle the potential development of antimicrobial resistance and therefore the risk for ecosystemic health.</p>