Associations between Antimicrobial Resistance Genes in Fecal Generic Escherichia coli Isolates from Cow-Calf Herds in Western Canada

Abstract

The objective of this study was to examine associations among the genetic determinants of antimicrobial resistance (AMR) in 207 fecal generic Escherichia coli isolates obtained from 77 cow-calf herds in western Canada. Twenty-three resistance genes corresponding to six different antimicrobial families were assessed using DNA hybridization and PCR. The most common resistance genes in the study sample (207 isolates) were sul2 (48.3%), tet(B) (45.4%), and ant(3؆)-Ia (aadA1) (19.3%). Several statistically significant associations between the examined resistance genes were detected. The strongest associations observed were those between genes for resistance to chloramphenicol (catI) and trimethoprim (dhfrI) (odds ratio [

Resistencia a antimicrobianos en E. coli y Salmonella spp. de terneros del sur de Chile

“…In this context, it is interesting to observe that isolates from calves reported as "not treated" did not tend to be less resistant than those of calves reported as treated. These results are similar to findings in Canadian calves, where no association between previous treatment and AMR was found (26). This can be attributed either to poor records (in association to recall bias or failure to provide or register accurate information) or to the possibility that the untreated calves acquire highly resistant agents from the environment without having received treatment themselves.…”

“…These largely unknown processes could result in the finding of highly resistant bacteria in young calves, no increase in resistance with age (or even a decrease) and, no clearly defined trend at the yearly level. Furthermore, no statistical association was found between calf sex and AMR score, as previously reported (26).…”

“…Estos resultados concuerdan con un estudio que no observó ningún efecto de la edad sobre la resistencia a los that observed no effect of age on antimicrobial resistance in calves, while evaluating the effect on housing type and resistance (25). In contrast, other studies reported an effect of age in AMR (14,26). Nevertheless, it has been reported that ampicillin-resistant E. coli levels were typically low in the first 8 months of age (27), and our specimens were from calves <30 days of age.…”

“…En este contexto, es interesante observar que los aislamientos de terneros reportados como "no tratados" no tienden a ser menos resistentes que los de los terneros reportados como tratados. Estos resultados son similares a los hallazgos en terneros canadienses, donde no se encontró asociación entre el tratamiento previo y la RAM (26). Esto puede atribuirse a registros deficientes (en asociación con un sesgo de recuento o la imposibilidad de proporcionar o registrar información precisa) o a la posibilidad de que los terneros no tratados adquieran agentes altamente resistentes del medio ambiente sin haber recibido el tratamiento.…”

Characterization of sulphonamide-resistant Escherichia coli using comparison of sul2 gene sequences and multilocus sequence typing

“…Among them, the sul2 gene has previously been reported as the most prevalent one in Escherichia coli from pig and pork, poultry and poultry meat, cow and beef, mutton, human faeces and urinary tract infections (UTIs) (Blahna et al, 2006;Gow et al, 2008;Grape et al, 2003;Hammerum et al, 2006;Kerrn et al, 2002;Sunde & Norstrom, 2006;Trobos et al, 2008). Based on a few partial sequences, this gene seems highly conserved, whether it is carried on small nonconjugative or large conjugative resistance plasmids (Radstrom & Swedberg, 1988;Sorum & L'Abee-Lund, 2002).…”